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Oncology is the study and treatment of cancer; veterinary oncology is the study and treatment of cancer in dogs, cats, ferrets, birds, and other exotic and domestic animals.

The Oncology service sponsors the North Carolina Animal Cancer Program (NCACP), a comprehensive treatment, medical education, and research center. The NCACP, part of the Veterinary Hospital, is one of the few oncology services on the East coast with access to all types of cancer treatment–chemotherapy, radiation therapy, surgery, and canine bone marrow transplants.

Beautiful dog rhodesian ridgeback hound outdoors on a forest background

Treatment of Cancer in Pets

The North Carolina Animal Cancer Program promotes an organized, comprehensive approach to management of cancer in animals. Cancer therapy is a rigorous undertaking, requiring multidisciplinary diagnostic and treatment capabilities. Excellent personnel and physical resources in the College of Veterinary Medicine support NCACP activities. Various treatment options are available, including surgery, chemotherapy, radiation therapy and hyperthermia. The multi-institutional nature of the program provides access to the latest cancer-related information and treatment strategies. Pets with cancer are typically elderly and have become integrated into the family. Often, difficult decisions regarding these patients have to be made. The program aims to provide the advice and expertise to help make and implement the best decision concerning the welfare of the pet.

When a patient is referred for evaluation, the pet is examined by students and veterinarians and options are presented to the owner describing what tests are necessary to reach the final diagnosis or, if the diagnosis is already known, what treatments are recommended. All of the resources of the Veterinary Hospital at North Carolina State University are available for use if needed. At North Carolina State University, we are fortunate to have a highly educated and enthusiastic faculty of veterinarians to support the healthcare process. Additionally, very high quality diagnostic and therapeutic options are available. In the Oncology Service, we are very concerned that pet owners make the best possible decision regarding the care of their pet.

Commonly Encountered Tumors

Apocrine Gland Carcinoma

What is Apocrine Gland Carcinoma of the Anal Sac?

Apocrine gland carcinoma of the anal sac is detected as an incidental finding during annual examination in approximately 50% of dogs diagnosed with this tumor, and rectal palpation should therefore be part of any complete physical examination. Tumors are locally invasive and have a moderate rate of spread to other places in the body (called metastasis). Apocrine gland carcinoma of the anal sac can also produce a pseudohormone leading to marked elevations in blood calcium levels (paraneoplastic hypercalcemia).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved and to determine whether paraneoplastic hypercalcemia is present. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • +/- ionized calcium
  • Thoracic radiographs
  • Abdominal sonogram
  • +/- Contrast urethrocystogram

Treatment

Treatment for apocrine gland carcinoma of the anal sac is aimed both at controlling the tumor in the site where it originates and delaying or preventing metastasis. Controlling the tumor in the site where it originates is best accomplished with either wide surgical excision (which may be difficult for large tumors in this area) or the combination of surgery to remove obvious gross disease and radiation therapy to destroy residual microscopic disease. In conjunction with local treatment, we recommend systemic carboplatin chemotherapy to delay or prevent the onset of metastasis. Carboplatin is given at 3-week intervals for a total of four treatments. Doxorubicin is also believed to have activity against this cancer. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will inform the owner what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

If definitive treatment is not an option, palliative radiation therapy can be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. We recommend that the treatment be repeated in one month if no disease or symptom progression is noted in hopes of extending the duration of response.

The reported median survival time for dogs with apocrine gland adenocarcinoma of the anal sac treated with surgery alone is approximately 12 months. This may be improved upon with the addition of radiation therapy and chemotherapy, and a more recent study based at North Carolina State University reported an overall median survival time of 18 months for dogs treated with a variety of treatment combinations. Four negative prognostic factors have been identified: tumor size, pulmonary metastasis, sublumbar lymph node metastasis, and hypercalcemia; each of the latter two have been associated with a significantly shorter survival time of approximately 6 months.

Selected References

  • Williams LE, JM Gliatto, RK Dodge, et al. Canine carcinoma of the apocrine glands of the anal sac: 113 cases (1985-1995). J Am Vet Med Assoc 2003;223(6):825-831.
  • Ross JT, Scavelli TD, Matthiesen DT, et al. Adenocarcinoma of the apocrine glands of the anal sac in dogs: a review of 32 cases. J Am Anim Hosp Assoc 1991;27:349-355.

Hemangiosarcoma

What is Hemangiosarcoma?

Hemangiosarcoma is the most common primary tumor of the spleen in dogs. Less commonly it originates in the heart or subcutaneous tissues. Hemangiosarcoma leads to the formation of abnormal blood vessels which can rupture and bleed. It also commonly spreads to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Thoracic radiographs
  • Abdominal sonogram
  • Cardiac evaluation (echocardiogram)

Treatment

Treatment of hemangiosarcoma is aimed at both removing the primary tumor with surgery and using systemic medication (chemotherapy) in an effort to delay or prevent metastasis. Doxorubicin is the drug of choice. It is given at 3-week intervals for a total of 4-6 treatments. There are also reports of a combination protocol consisting of vincristine + doxorubicin + cyclophosphamide (VAC). There is a biologic rationale for combination therapy over single-agent therapy, although the benefit of VAC over doxorubicin alone remains unclear for hemangiosarcoma (reported studies have included different populations of dogs, for example). Regardless, we recommend that the initial treatment be given with doxorubicin alone and if this is well tolerated, then consideration be given to adding the other two drugs. Also, due to the potential for cardiotoxicity with doxorubicin, we recommend follow-up cardiac evaluation, consisting of an echocardiogram and ECG, prior to the 4th treatment.

Chemotherapy drugs work by targeting fast-growing cells and cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what you should watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

While the quality of life for dogs following surgery is generally very good, it is unfortunately not of long duration. Survival times following surgery alone for splenic hemangiosarcoma are approximately 2-3 months. With the addition of chemotherapy, survival times extend to approximately 5-7 months.

Following completion of chemotherapy, or if chemotherapy is not pursued, metronomic therapy may be considered. Metronomic chemotherapy involves the administration of chronic oral low-dose chemotherapy (cyclophosphamide) in conjunction with other medications (carprofen or deracoxib and doxycycline). It is believed that this treatment approach may inhibit angiogenesis (new blood vessel growth) and thereby inhibit tumor growth.

Selected References

  • Hammer AS, Couto CG, Filppi J, et.al. Efficacy and toxicity of VAC chemotherapy (vincristine, doxorubicin, and cyclophosphamide) in dogs with hemangiosarcoma. J Vet Intern Med ;1991;5:160-166.
  • Sorenmo KU, Jeglum KA, Helfand SC. Chemotherapy of canine hemangiosarcoma with doxorubicin and cyclophosphamide. J Vet Intern Med 1993;7:370-376.
  • Ogilvie GK, Powers BE, Mallinckrodt CH, et.al. Surgery and doxorubicin in dogs with hemangiosarcoma. J Vet Intern Med 1996;10:379-384.

Lymphoma

What is Lymphoma?

Lymphoma is a systemic disease that most often develops within the body’s lymph nodes. It may also affect the liver, spleen, and bone marrow as well as other organs.

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Lymph node aspiration for cytology, PCR and/or flow cytometry
  • Thoracic radiographs
  • Abdominal sonogram
  • +/- Bone marrow aspiration

Treatment

Because it is a systemic disease, lymphoma is treated with systemic chemotherapy. The most effective chemotherapy treatment protocol developed at North Carolina State University consists of five different chemotherapy drugs (L-asparaginase, vincristine, doxorubicin, cyclophosphamide, prednisone) given over 11 weeks, followed by radiation to the front half, and 3 weeks later to the back half, of the body. Each of the chemotherapy drugs used is effective for treating lymphoma. By using the drugs in combination, we achieve better tumor control, less drug resistance, and longer remissions. Chemotherapy drugs work by targeting fast-growing cells and cancer cells divide faster than normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what you should watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

In general, dogs receiving chemotherapy for lymphoma enjoy a very good quality of life and can participate in all of their normal activities. With our chemotherapy/ radiation therapy protocol, 75-90% of dogs achieve complete remission and we hope to control the pet’s cancer for approximately 16 months. If/when the cancer relapses, we can discuss additional “rescue” treatment protocols. If finances are a concern, we can discuss alternative protocols that are less intensive, although somewhat less efficaceous. These protocol options include doxorubicin alone or in combination with cytoxan (median remission 6 months), COP (median remission 4-6 months), oral cyclophosphamide + prednisone, and prednisone alone (median remission 2-3 months).

Selected References

Williams LE, Johnson JL, Hauck ML, et al. Chemotherapy followed by half- body radiation therapy for canine lymphoma. J Vet Intern Med 2004;18(5):703- 709.

Mammary Gland Carcinoma

What is Mammary Gland Carcinoma?

In dogs, approximately half of all mammary tumors are malignant. Mammary carcinoma is locally invasive, extending into underlying normal tissues, and has the potential to spread to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs
  • Abdominal sonogram

Treatment

Treatment of mammary tumors is aimed both at local control (removing the primary tumor and minimizing the likelihood of local recurrence) and systemic control (delaying or preventing metastatic disease). The surgery of choice (lumpectomy/reasonably wide excision vs. radical mastectomy) is debatable. In general, the recommendation is to remove sufficient tissue to ensure adequately wide and histologically clean margins. In addition to surgery and depending on identification of various prognostic factors identified below, adjuvant systemic chemotherapy can be considered in an effort to delay or prevent metastasis. Based on somewhat limited reports in the literature and responses in other types of carcinomas, two drugs could be considered: doxorubicin or a platinum drug (carboplatin or cisplatin) given at 3-week intervals for a total of four-six treatments. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what you should watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

Another medication to consider is piroxicam. This oral Non-Steroidal Anti-Inflammatory Drug (NSAID) has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

Various prognostic factors for canine mammary tumors have been identified including:

  • Tumor size: In one study, dogs with tumors >5cm in diameter had a median survival time of 40 weeks compared to 112 weeks for animals with smaller tumors following surgery.
  • Histologic grade: In one study where histologic grade was adopted from a human pathologic staging system, carcinomas were divided into 4 categories. In that study, only 19% of the dogs with grade 0 (in situ or non-invasive) carcinomas had recurrence or metastasis in 2 years, compared with 60% of dogs with grade I (stromal invasion) carcinomas and 97% of dogs with grade II (angiolymphatic invasion) carcinomas. A grading scheme based on nuclear differentiation has also been reported in which dogs with poorly differentiated tumors had an increased risk of developing recurrent or metastatic carcinoma within 2 years of surgery, with an overall rate of 90% compared to 68% and 24% for dogs with moderately- or well-differentiated carcinomas, respectively. (We recommend contacting the pathologist for this information on Oreo).
  • Lymph node metastasis
  • Lymphoid cellular activity: Lymphocyte infiltration may indicate an antitumor response and is associated with a more favorable prognosis.

Selected References

  • Bostock DE . Canine and feline mammary neoplasms. Br Vet J 1986;142:506-515.
  • Gilbertson SR, Kurzman ID, Zachrau RE, et al. Canine mammary epithelial neoplasms: Biological implications of morphologic characteristics assessed in 232 dogs. Vet Pathol 1983;20:127-142.

Mast Cell Tumors

What are Mast Cell Tumors?

Mast cell tumors are one of the most common skin tumors in dogs. They are highly variable in appearance. We recommend that all masses be evaluated with fine needle aspiration cytology which can readily diagnose most mast cell tumors as well as a variety of other tumors. Once a mast cell tumor is identified, we recommend that a biopsy be performed to confirm the diagnosis and determine the tumor “grade.” The specific behavior, treatment recommendations and prognosis correlate with the grade of the tumor.

Tumor Grades/Diagnostic Testing

Grade I mast cell tumors are minimally invasive and spread to other places in the body (called metastasis) is not expected. Wide surgical excision should be curative.

Grade II mast cell tumors are invasive into adjacent tissues, although again, metastasis is uncommon. Diagnostic tests are recommended to ensure there is no obvious evidence of spread to other places in the body. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Lymph node aspiration cytology
  • Abdominal sonogram

Wide and complete surgical excision is the treatment of choice. If this is not possible, the combination of surgery (to remove obvious gross disease) followed by radiation therapy (to destroy residual microscopic disease) is very effective. This combination is associated with a 95% chance of 1-year tumor control and an approximately 85-95% chance of 2-5 year control.

Grade III mast cell tumors are locally invasive and differ from grade II tumors in having a moderate-high rate of metastasis. Diagnostic tests are recommended to ensure there is no obvious evidence of spread to other places in the body. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Lymph node aspiration cytology
  • Abdominal sonogram
  • Liver aspiration cytology
  • Spleen aspiration cytology
  • Buffy coat prep
  • Bone marrow aspiration cytology

Treatment

Treatment ideally consists of local therapy as described for grade II mast cell tumors combined with systemic chemotherapy aimed at delaying or preventing the onset of metastatic disease. Our current protocol involves a combination of prednisone, vinblastine, and CCNU, the three drugs with demonstrated effectiveness against mast cell tumors. Chemotherapy can also be used alone if surgery and radiation therapy are not performed. Mast cells contain and can release numerous granules (e.g. histamine) and when present in high concentrations, these substances can become irritating to the stomach and other organs. To protect the body from these granules, we recommend that dogs with grade III mast cell tumors be treated continuously with both H1 (diphenhydramine) and H2 (cimetidine, famotidine, or ranitidine) receptor antagonists.

Selected References

  • Al-Sarraf R, Mauldin GN, Patnaik AK , et al. A prospective study of radiation therapy for the treatment of grade 2 mast cell tumors in 32 dogs. J Vet Int Med 1996;10:376-378.
  • Frimberger AE, Moore AS , LaRue SM, et al. Radiotherapy of incompletely resected, moderately differentiated mast cell tumors in the dog: 37 cases (1989-1993). J Am Anim Hosp Assoc 1997;33:320-324.
  • LaDue T, Price GS, Dodge R, et al. Radiation therapy for incompletely resected canine mast cell tumors. Vet Radiol Ultrasound 1998;39:57-62.
  • McCaw DL, Miller MA, Ogilvie GK, et al. Response of canine mast cell tumors to treatment with oral prednisone. J Vet Int Med 1994;8:406-408.
  • Rassnick KM, Moore AS , Williams LE, et al. Treatment of canine mast cell tumors with CCNU (lomustine). J Vet Int Med 1999;13:601-605.
  • Thamm DH, Mauldin EA, Vail DM. Prednisone and vinblastine chemotherapy for canine mast cell tumor – 41 cases (1992-1997). J Vet Int Med 1999;13:491-497.

Oral Malignant Melanoma

What is Oral Malignant Melanoma?

Melanoma is the most common malignant oral tumor in dogs. It is locally invasive (meaning it readily invades adjacent normal tissues) and has a moderate rate of spread to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Chemistry panel
  • Urinalysis (U/A)
  • Lymph node aspiration cytology
  • Thoracic radiographs

Treatment

Treatment is aimed both at controlling the tumor in the site where it originates (local treatment) and delaying the onset of metastasis (systemic treatment). The treatment of choice for a locally invasive tumor is complete surgical resection. In the oral cavity, this often requires aggressive procedures with removal of a portion of underlying bone. If surgical excision with adequately wide margins is not possible, then surgical debulking in conjunction with radiation therapy or radiation therapy alone is recommended. Radiation therapy consists of 19 treatments given on a Mon-Fri schedule. Radiation is associated with a median disease free interval of approximately 7-10 months. In a study of 140 dogs treated with radiation therapy at NCSU, median time to first event for all dogs was 5 months, however three prognostic factors were identified which influenced the time to first event. The risk factors identified were: microscopic > macroscopic disease, lack of bony invasion > bony invasion, and location rostral to PM4 > caudal location. For dogs with none of the identified risk factors, median time to first event was 21 months as compared to 11, 5, and 3 months for dogs with 1, 2, and 3 identified risk factors, respectively. Potential side effects of radiation include oral mucositis and moist desquamation that generally develops midway through treatment and lasts 2-4 weeks before resolving. During this time, patients are managed with anti-inflammatory analgesic medications as needed. There is also the potential, though unlikely, for late irreversible changes to underlying bone, muscle, nerve.

Due to the potential for metastasis, adjuvant carboplatin chemotherapy can be considered. This drug is given at 3-week intervals for a total of four-six treatments. Chemotherapy drugs work by targeting fast-growing cells and cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what you should watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

Another medication to consider is piroxicam. This oral Non-Steroidal Anti-Inflammatory Drug (NSAID) has anti-inflammatory and analgesic properties as well as possibl e anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

If metastasis beyond the lymph node is confirmed or definitive therapy not an option, chemotherapy and/or palliative radiation therapy can still be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. This treatment course is repeated in one month if no disease or symptom progression is noted.

Selected References

Proulx DR, Ruslander DM, Dodge RK, et al. A retrospective analysis of 140 dogs with oral melanoma treated with external beam radiation. Vet Radiol Ultrasound 2003;44(3):352-359.

Oral Squamous Cell Carcinoma

What is Oral Squamous Cell Carcinoma?

Oral squamous cell carcinoma of the gingiva is locally invasive, but does not readily metastasize.

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs

Treatment

Treatment ideally consists of complete surgical resection of the tumor. In the oral cavity, this often requires removal of a portion of underlying bone. Following surgery, outcome, function, and cosmesis are generally very good after an initial adjustment and healing period. If the tumor is too extensive for complete surgical excision, radiation therapy can be considered as an alternative treatment option – either to destroy residual microscopic disease or for macroscopic disease, bearing in mind that the efficacy is diminished when there is significant bulky disease. Radiation therapy consists of 19 treatments administered on a Mon-Fri schedule. Potential side effects of radiation include oral mucositis and moist desquamation that generally develops midway through treatment and lasts 2-4 weeks before resolving. During this time, patients are managed with anti-inflammatory analgesic medications as needed. There is also the potential, though unlikely, for late irreversible changes to underlying bone, muscle, nerve. Complete surgical excision with adequately wide margins suggests a very good long term prognosis. Reports on the use of radiation alone also describe the tumor to be radiation-responsive, with median disease control times of approximately 12-18 months. Several prognostic factors have been identified for canine oral squamous cell carcinoma including location (maxilla > mandibule; rostral > caudal) and tumor/radiation field size.

We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

If definitive treatment is not an option, palliative radiation therapy can be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. We recommend that the treatment be repeated in one month if no disease or symptom progression is noted in hopes of extending the duration of response.

Osteosarcoma

What is Osteosarcoma?

Osteosarcoma is the most common bone cancer in dogs. It most often develops in the limbs of large-giant breed dogs. This tumor is locally aggressive (meaning it both destroys existing normal bone and makes abnormal new bone) and it also readily spreads to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs

Treatment

Treatment of osteosarcoma is aimed at both removing the painful tumor and using systemic medication to delay the onset of metastasis. Removal of the tumor requires amputation for the vast majority of affected dogs. While this is a big surgery, most dogs do very well following an initial adjustment period. Approximately two weeks following surgery, we recommend systemic chemotherapy in an effort to delay or prevent metastasis. Platinum (cisplatin or carboplatin) and doxorubicin have efficacy against this form of cancer. Treatments are given at 2-3 week intervals for a total of 4-6 treatments. Chemotherapy drugs work by targeting fast-growing cells and cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy.

There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what you should watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

With surgery alone, most dogs experience a good quality of life for approximately 4-6 months. With the addition of chemotherapy, survival times extend to approximately 10-12 months.

Following completion of chemotherapy, or if chemotherapy is not pursued, metronomic therapy may be considered. Metronomic chemotherapy involves the administration of chronic oral low-dose chemotherapy (cyclophosphamide) in conjunction with other medications (carprofen or deramaxx and doxycycline). It is believed that this treatment approach may inhibit angiogenesis (new blood vessel growth) and thereby inhibit tumor growth.

If amputation is not an option, palliative radiation therapy can be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. Approximately 70% of patients with osteosarcoma benefit from palliative radiation therapy with relief lasting 2-4 months. We recommend that the treatment be repeated in one month if no disease or symptom progression is noted in hopes of extending the duration of response.

Selected References

  • Spodnick GJ, Berg J, Rand WM, et al. Prognosis for dogs with appendicular osteosarcoma treated by amputation alone: 162 cases (1978-1988). J Am Vet Med Assoc 1992;200:995-9.
  • Shapiro W, Fossum TW, Kitchell BE, et al. Use of cisplatin for treatment of appendicular osteosarcoma in dogs. J Am Vet Med Assoc 1988;192:507-511.
  • Thompson JP, Fugent MJ. Evaluation of survival times after limb amputation, with and without subsequent administration of cisplatin, for treatment of appendicular osteosarcoma in dogs: 30 cases (1979-1990). J Am Vet Med Assoc 1992;200:531-533.
  • Bergman PJ, MacEwen EG, Kurzman ID, et al. Amputation and carboplatin for treatment of dogs with osteosarcoma: 48 cases (1991-1993). J Vet Intern Med 1996;10:76-81.
  • Berg J, Weinstein MJ, Springfield DS, et al. Results of surgery and doxorubicin chemotherapy in dogs with osteosarcoma. J Am Vet Med Assoc 1995;206:1555-1560.
  • Bailey D, Erb H, Williams L, et al. Carboplatin and doxorubicin combination chemotherapy for the treatment of appendicular osteosarcoma in the dog. J Vet Intern Med 2003;17:199-205.
  • Mauldin GN, Matus RE, Withrow SJ, et al. Canine osteosarcoma: treatment by amputation versus amputation and adjuvant chemotherapy using doxorubicin and cisplatin. J Vet Intern Med 1988;2:177-180.
  • Kent MS, Strom A, London CA, et al. Alternating carboplatin and doxorubicin as adjunctive chemotherapy to amputation or limb-sparing surgery in the treatment of appendicular osteosarcoma in dogs. J Vet Intern Med 2004;18:540-544.

Soft Tissue Sarcomas

What are Soft Tissue Sarcomas?

Soft tissue sarcomas are tumors originating from structural and connective tissues. They are most often evident as masses in the skin or subcutaneous tissues. Although seemingly diverse in their tissues of origin, these tumors share similar biologic behavior and are therefore considered together. Examples of soft tissue sarcomas include fibrosarcoma, hemangiopericytoma, liposarcoma, nerve sheath tumor and leiomyosarcoma.

Soft tissue sarcomas are locally invasive tumors and readily invade adjacent normal issues with finger-like projections. The rate of metastasis can be predicted by determining the histologic grade of an individual tumor. Low-grade tumors have a low rate of metastasis (10%), while high-grade tumors have a moderate rate of metastasis (40%).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs
  • +/- Abdominal sonogram (indicated for tumors on the caudal portion of the trunk or proximal hindlimbs)

Treatment

There are several treatment options for soft tissue sarcomas. Ultimately the decision to pursue a particular treatment is based on the tumor location, histologic grade, stage, clients’ wishes and consultation with a veterinarian or veterinary oncologist. The following is a list of commonly discussed treatment options:

Option 1 – Surgery
Complete excision with adequately wide margins generally involves resection of approximately 3cm margins laterally and removal of one intact fascial plane deep to the tumor. When these margins can be achieved, surgery is generally considered the treatment of choice.

Option 2 – Surgery + radiation therapy
This involves a combination of surgery to remove the obvious bulk of the tumor (macroscopic disease) + radiation therapy to destroy residual microscopic disease. This combination treatment generally provides a 60-80% chance of controlling the tumor long term. At North Carolina State University , radiation therapy consists of 16 (pre-operative) or 19 (post-operative) treatments given on a Mon-Friday schedule. Potential side effects of radiation include an early, reversible reaction to rapidly dividing tissues (skin, hair) that develops midway through treatment and lasts 2-4 weeks before healing. During this time, patients are treated with anti-inflammatory, analgesic medications and topical medications as needed. There is also the potential, although unlikely, for late irreversible side effects to slowly dividing tissues (bone, muscle, nerves). A CT scan or radiographs are performed prior to radiation therapy to aid the radiation oncologist in planning treatment for the individual animal in a way that optimizes the effect against the tumor and minimizes the impact on adjacent normal tissues.

Option 3 – Chemotherapy
Systemic medication is recommended for dogs with high-grade tumors, given the increased likelihood of metastasis. It may also be considered for patients with incompletely-excised tumors and for whom radiation therapy is not an option or for patients with non-resectable tumors. The drug of choice for treating soft tissue sarcomas is doxorubicin. It is given at 3-week intervals for a total of 4-6 treatments. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems. A unique side effect of doxorubicin is its ability to weaken the heart muscle with multiple doses. A heart ultrasound (called an echocardiogram) is recommended prior to the fourth doxorubicin treatment to monitor for this.

Option 4 – Palliative radiation therapy
If a tumor cannot be removed surgically, cannot be treated with the combination of surgery + radiation therapy, or if distant metastasis is identified, palliative radiation therapy can be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. We recommend that the treatment be repeated in one month if no disease or symptom progression is noted in hopes of extending the duration of response.

We currently have a partially-funded clinical trial investigating physiologic changes associated with hyperthermia. Patient enrolled in this study must have measurable gross disease . The client is responsible for charges associated with initial evaluation and work up. Patients are treated with 25 fractions of radiation therapy and five hyperthermia treatments. The hyperthermia treatments are paid for and clients are given $3000 towards the cost of radiation therapy. Following completion of the radiation therapy and hyperthermia study, surgery or any other treatments can be pursued at the owners’ expense.

Selected References

  • Bostock DE , Dye MT. Prognosis after surgical excision of canine fibrous connective tissue sarcomas. Vet Pathol 1980;17:581-588.
  • Kuntz CA , Dernell WS, Powers BE, et al. Prognostic factors for surgical treatment of soft-tissue sarcomas in dogs: 75 cases (1986-1996). J Am Vet Med Assoc 1997;211:1147-1151.

Thyroid Carcinoma

What are Thyroid Tumors?

Thyroid tumors originate in the thyroid gland located along the trachea. The thyroid gland is responsible for producing thyroid hormone which plays a role in regulating metabolic rate and other functions. Despite its important role in producing hormones, the majority of thyroid tumors are “non-functional,” meaning they do not produce thyroid hormones. Occasionally functional tumors are identified and evaluation of thyroid hormone levels should be performed in any dog with a thyroid tumor. Thyroid tumors are locally invasive and have a moderate-high rate of spread to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs
  • +/- Abdominal sonogram (indicated for tumors on the caudal portion of the trunk or proximal hindlimbs)

Treatment

Treatment for thyroid carcinomas is aimed both at controlling the tumor in the site where it originates and delaying or preventing metastasis. Controlling the tumor in the site where it originates is best accomplished with either wide surgical excision or the combination of surgery to remove obvious gross disease and radiation therapy to destroy residual microscopic disease. In one study, dogs with moveable thyroid tumors and no evidence of metastasis were treated with surgery alone with a median survival of >36 months. However, many thyroid tumors are “fixed” (deeply attached) and invasive into adjacent soft tissues. These tumors that are not freely moveable are unlikely to be removed with clean margins and the best option is a combination of radiation therapy and surgery. The recommendation of the North Carolina State University Animal Cancer Treatment Program involves pre-operative radiation therapy consisting of 19 treatments administered on a Mon-Fri schedule with a follow-up CT scan done 3 months after completion of radiation therapy to determine resectability. This is based on reports of the gradual reduction in tumor size with thyroid tumors and an attempt to optimize timing of surgery. These are difficult surgeries given the many nerves in the area and the thyroid’s rich blood supply with the associated risk of significant hemorrhage. A board-certified surgeon is often recommended for these reasons.

In conjunction with surgery and radiation therapy, we recommend systemic chemotherapy (carboplatin, cisplatin and doxorubicin have reported activity) to delay or prevent metastasis. In our hospital, chemotherapy is given as an intravenous injection at 3-week intervals for a total of four-six treatments. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

If definitive treatment is not an option, palliative radiation therapy can be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. We recommend that the treatment be repeated in one month if no disease or symptom progression is noted in hopes of extending the duration of response.

Selected References

  • Klein MK, Powers BE, Withrow SJ, et.al. Treatment of thyroid carcinoma in dogs by surgical resection alone: 20 cases (1982-1989). J Am Vet Med Assoc; 1995;206:1007-1009.
  • Theon AP, Marks SL, Feldman ES, et al. Prognostic factors and patterns of treatment failure in dogs with unresectable differentiated thyroid carcinomas treated with megavoltage irradiation. J Am Vet Med Assoc 2000;216:1775-1779.
  • Brearley MJ, Hayes AM, Murphy S. Hypofractionated radiation therapy for invasive thyroid carcinoma in dogs: a retrospective analysis of survival. J Sm Anim Pract 1999;40:206-210.
  • Fineman LS, Hamilton TA, de Gortari A, et al. Cisplatin chemotherapy for treatment of thyroid carcinoma in dogs: 13 cases. J Am Anim Hosp Assoc 1998;34:109-1112.

Transitional Cell Carcinoma

What is Transitional Cell Carcinoma?

Transitional cell carcinoma is the most common tumor of the canine lower urinary tract. Scottish Terriers are predisposed to developing this cancer. Transitional cell carcinomas is locally invasive, extending into underlying normal tissues, and has a moderate-high rate of spread to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Thoracic radiographs
  • Abdominal sonogram
  • +/- Contrast urethrocystogram

Treatment

Tumors are often located in the trigone area where complete surgical removal is not possible (our surgeons are trying newer more aggressive surgeries that may be an option for some dogs). We have occasionally used definitive radiation therapy to treat transitional cell carcinoma, and if a tumor is small and localized this may be something to consider, although the efficacy of radiation therapy is diminished when used to treat bulky disease. Radiation therapy consists of 19 treatments given on a Mon-Fri schedule. Because of the inability to perform complete surgical removal and the limitations of radiation therapy, treatment often consists solely of chemotherapy. Cisplatin, carboplatin, doxorubicin and mitoxantrone all have reported activity with response rates of approximately 30-35%. In our hospital, chemotherapy is administered with a single drug given at 3-week intervals and the tumor reassessed at 6-week intervals. If/when tumor progression is noted, treatment can be changed to an alternate agent. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as anti-tumor activity against transitional cell carcinoma. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

Selected References

  • Moore AS , Cardona A, Shapiro W, et al. Cisplatin (cisdiamminedichloroplatinum) for treatment of transitional cell carcinoma of the urinary bladder or urethra. J Vet Intern Med 1990;4:148-152.
  • Chun R, Knapp DW, Widmer WR, et al. Cisplatin treatment of transitional cell carcinoma of the urinary bladder in dogs: 18 cases (1983-1993). J Am Vet Med Assoc 1996;209:1588-1591.
  • Chun R, Knapp DW, Widmer WR, et al. Phase II clinical trial of carboplatin in canine transitional cell carcinoma of the urinary bladder. J Vet Intern Med 1997;11:279-283.
  • Rocha TA, Mauldin GN, Patnaik AK, et al. Prognostic factors in dogs with urinary bladder carcinoma. J Vet Intern Med 2000;14:486-490.
  • Henry CJ, McCaw DL, Turnquist SD, et al. Clinical evaluation of mitoxantrone and piroxicam in a canine model of human invasive urinary bladder carcinoma. Clin Cancer Res 2003;9:906-11.
  • Knapp DW, Richardson RC, Chan TC, et al. Piroxicam therapy in 34 dogs with transitional cell carcinoma of the urinary bladder. J Vet Intern Med 1994;8:273-278.

Lymphoma

What is Lymphoma?

Lymphoma is a systemic disease that has the potential to affect any organ. In cats, high-grade lymphoblastic lymphoma is most often categorized according to the site(s) affected. The most common form is multicentric lymphoma, in which the liver, spleen, and lymph nodes may be involved as well as other sites within the abdominal cavity. Other forms include: gastric, intestinal, renal, thymic (mediastinal), and spinal lymphoma.

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Lymph node aspiration for cytology, PCR and/or flow cytometry
  • Thoracic radiographs
  • Abdominal sonogram
  • +/- Bone marrow aspiration

Treatment

While surgery may be indicated for some patients (e.g. those with a discrete intestinal mass), because it is a systemic disease, systemic chemotherapy remains the mainstay of treatment for lymphoma. One potential exception to this rule occurs with nasal lymphoma, where disease often remains confined to the nose and radiation therapy is the treatment of choice.

Our most effective chemotherapy treatment protocol consists of six different chemotherapy drugs (L-asparaginase, vincristine, doxorubicin, cyclophosphamide, prednisone, methotrexate). Each of these is an effective drug for treating lymphoma. By using the drugs in combination, we achieve better tumor control, less drug resistance, and longer remissions. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster than normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals in quality of life, so the dosages are lower than used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatment to prevent recurrent problems. In general, 50-75% of cats achieves complete remission with chemotherapy and enjoy a good quality of life for approximately 6-10 months (this varies somewhat according to the sites affected, with some cats surviving for years).

If/when the cancer relapses, “rescue” treatment can be considered. There are also several other alternative protocols that are less intensive, although somewhat less efficacious, and less costly. These protocol options include doxorubicin alone, COP, oral cyclophosphamide + prednisone, and prednisone alone.

Selected References

  1. Spodnick GJ, Berg J, Moore FM, et al. Spinal lymphoma in cats: 21 cases (1976-1989). J Am Vet Med Assoc 1992;200:373-376.
  2. Mooney SC , Hayes AA, MacEwen EG, et al. Treatment and prognostic factors in lymphoma in cats: 103 cases (1977-1981). J Am Vet Med Assoc 1989;194:696-699.
  3. Ogilvie GK, Moore AS , Obradovich JE, et al. Toxicoses and efficacy associated with administration of mitoxantrone to cats with malignant tumors. J Am Vet Med Assoc 199;202:1839-1844.
  4. Kristal O, Lana SE, Ogilvie GK, et al. Single-agent chemotherapy with doxorubicin for feline lymphoma: a retrospective study of 19 cases 91994-1997). J Vet Intern Med 2001;15:125-130.
  5. Cotter SM. Treatment of lymphoma and leukemia with cyclophosphamide, vincristine, and prednisone. II. Treatment of cats. J Am Anim Hosp Assoc 1983;19:166-172.
  6. Fondacaro JV, Richter KP, Carpenter JL, et al. Feline gastrointestinal lymphoma: 67 cases (1988-1996). Eur J Comp Gastroenterol 1999;4:5-11.
  7. Elmslie RE, Ogilvie GK, Gillette EL, et al. Radiotherapy with and without chemotherapy for localized lymphoma in 10 cats. Vet Radiol 1991;32:277-280.

Mammary Gland Carcinoma

What is Mammary Gland Carcinoma?

In cats, approximately 80-90% of all mammary tumors are malignant. Mammary carcinoma is locally invasive, extending into underlying normal tissues, and has the potential to spread to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs
  • Abdominal sonogram

Tumor size has been shown to be an important prognostic factor. Cats with tumors >3cm have a reported median survival of 6 months, cats with tumors 2-3cm in diameter have a median survival of 2 years, and cats with tumors <2cm have a median survival of approximately 3 years following surgery. Tumor histologic grade has also been shown to be an important prognostic factor.

Treatment

Treatment of mammary tumors is aimed at both local control (removing the primary tumor and minimizing the likelihood of local recurrence) and systemic control (delaying or preventing metastatic disease). The surgery of choice is a radical mastectomy, since this type of surgery significantly reduces the chance of local recurrence. In addition to surgery, we recommend systemic chemotherapy to delay or prevent metastatic disease. Two drugs could be considered: adriamycin (either alone or in combination with cytoxan) or carboplatin, given at 3-week intervals for a total of 4-6 treatments. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.

Another medication to consider is piroxicam. This oral Non-Steroidal Anti-Inflammatory Drug (NSAID) has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

Selected References

  1. MacEwen EG, Hayes AA, Harvey HJ, et al. Prognostic factors for feline mammary tumors. J Am Vet Med Assoc 1984;185:201-204.
  2. Castagnaro M, Casalone C, Bozzetta E, et al. Tumour grading and the one-year post-surgical prognosis in feline mammary carcinomas. J Comp Path 1998;119:263-275.

Oral Squamous Cell Carcinoma

What is Oral Squamous Cell Carcinoma?

Oral squamous cell carcinoma is locally invasive, but it does not readily spread to other places in the body (called metastasis).

Diagnostic Testing

Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Regional lymph node evaluation
  • Thoracic radiographs

Treatment

The treatment of choice for a locally invasive oral tumor would ideally be complete surgical resection. Unfortunately, this is a difficult decision because of the often extensive nature of these tumors coupled with the relatively small jaw size of cats and their poorer tolerance to maxillectomy/mandibulectomy as compared to dogs. The use of radiation therapy could therefore be considered – ideally in conjunction with surgery or if that is not possible, then as single modality therapy. Again, results have been discouraging. In reports of cats treated with aggressive surgery or the combination of surgery and radiation therapy, median survival times are only approximately 2-4 months, although many of these cats may have had larger tumors in more difficult locations (such as sublingual). Even the addition of chemotherapy has failed to lead to significant improvements. In one group of cats treated with definitive radiation therapy and mitoxantrone chemotherapy, median survival time was 6 months with only 30% of cats surviving to one year.

Because of the lack of long-term tumor control in spite of aggressive therapy, another reasonable option to consider is palliative radiation therapy. Palliative radiation therapy consists of two consecutive days of twice-daily radiation treatments and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. This treatment course is repeated in one month if no disease or symptom progression is noted.

We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.

Selected References

  1. Reeves NCP, Turrel JM, Withrow SJ. Oral squamous cell carcinoma in the cat. J Am Anim Hosp Assoc 1993;29:438-441.
  2. Hutson CA , Willauer CC, Walder EJ, et al. Treatment of mandibular squamous cell carcinoma in cats by use of mandibulectomy and radiotherapy: seven cases (1987-1989). J Am Vet Med Assoc 1992;201:777-781.

Vaccine-Associated Sarcomas

What are Soft Tissue Sarcomas?

Soft tissue sarcomas are tumors originating from structural and connective tissues. They are most often evident as masses in the skin or subcutaneous tissues. Although seemingly diverse in their tissues of origin, these tumors share similar biologic behavior and are therefore considered together. Examples of soft tissue sarcomas include fibrosarcoma, malignant fibrous histiocytoma, and myxosarcoma.

Soft tissue sarcomas are locally invasive tumors and readily invade adjacent normal issues with finger-like projections. While they are locally invasive, spread to other places in the body (called metastasis) is less common; the overall metastatic rate is between 11-23%.

Diagnostic Testing

Diagnostic tests are recommended for all cats diagnosed with soft tissue sarcomas to determine which sites in the body are involved. These tests include:

  • Complete blood count (CBC)
  • Serum biochemistry panel
  • Urinalysis (U/A)
  • Lymph node aspiration
  • Thoracic radiographs
  • +/- Abdominal sonogram (indicated for tumors on the caudal portion of the trunk or proximal hindlimbs)

Treatment

There are several treatment options for soft tissue sarcomas. Ultimately the decision to pursue a particular treatment is based on the tumor location, stage, clients’ wishes and consultation with a veterinarian or veterinary oncologist. The following is a list of commonly discussed treatment options:

Option 1 – Surgery Complete excision with adequately wide margins generally involves resection of approximately 3cm margins laterally and removal of one intact fascial plane deep to the tumor. When these margins can be achieved, surgery is generally considered the treatment of choice. Although in cats, this can be very difficult unless the tumor is very small or located on a distal extremity. Because of this difficulty, one study of vaccine-associated sarcomas reported a median time to recurrence of 3 months.

Option 2 – Surgery + radiation therapy This involves the combination of surgery to remove the obvious bulk of the tumor (macroscopic disease) + radiation therapy to destroy microscopic disease. If multimodality therapy is a possibility, we recommend that cats be evaluated before any surgery (i.e., with gross disease present) by both a radiation oncologist and a surgeon so that an ideal treatment plan can be formulated. Because of the need for very wide excision (relative to body size) to effectively treat these tumors, many cats are optimally treated with radiation therapy prior to surgical removal. In our hospital, radiation therapy consists of 16-19 treatments given on a Mon-Friday schedule. Potential side effects of radiation include an early, reversible reaction to rapidly dividing tissues (skin, hair) that develops midway through treatment and is generally very mild in cats. There is also the potential, although unlikely, for late irreversible side effects to slowly dividing tissues (bone, muscle, nerves, underlying organs). A CT scan is performed prior to radiation therapy to aid the radiation oncologist in planning treatment for the individual animal in a way that optimizes the effect against the tumor and minimizes the impact on adjacent normal tissues. With this combination, the risk of recurrence is decreased and delayed with median control times of approximately 19-20 months. In a study reported by NCSU, the impact of surgical margins when surgery was performed after radiation therapy was demonstrated. In cats where clean margins were achieved following radiation therapy, the median disease control was approximately 3 years, compared to approximately 10 months for cats with dirty margins.

Option 3 – Chemotherapy While generally used for tumors with a higher likelihood of metastasis, chemotherapy can be considered for cats with vaccine-associated sarcomas as another tool for targeting cancer cells. The drug of choice for treating soft tissue sarcomas is doxorubicin. It is given at 3-week intervals for a total of 4-6 treatments. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems. A unique side effect of doxorubicin is its ability to weaken the kidneys with multiple doses. Periodic blood tests will be done to monitor this.

Option 4 – Palliative radiation therapy If a tumor cannot be removed surgically, cannot be treated with the combination of surgery + radiation therapy, or if distant metastasis is identified, palliative radiation therapy can be considered. Palliative radiation therapy consists of two consecutive twice-daily doses of radiation therapy and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. We recommend that the treatment be repeated in one month if no disease or symptom progression is noted in hopes of extending the duration of response.

Selected References

  1. Kass PH, Barnes WG JR, Spangler WL, et al. Epidemiologic evidence for a causal relation between vaccination and fibrosarcoma tumorigenesis in cats. J Am Vet Med Assoc 1993;203:396-405.
  2. Hendrick MJ, Shofer FS, Goldschmidt MH, et al. Comparison of fibrosarcomas that developed at vaccination sites and at nonvaccination sites in cats: 239 cases (1991-1992). J Am Vet Med Assoc 1994;205:1425-1429.
  3. Davidson EB, Gregory CR, Kass PH. Surgical excision of soft tissue fibrosarcomas in cats. Vet Surg 2001;26:265-269.
  4. Hershey AE, Sorenmo KU, Hendrick MJ, et al. Prognosis for presumed feline vaccine-associated sarcoma after excision: 61 cases (1986-1996). J Am Vet Med Assoc 2000;216:58-61.
  5. Cronin K, Page RL, Spodnick G, et al. Radiation therapy and surgery for fibrosarcoma in 33 cats. Vet Radiol Ultrasound 1998;39:51-56.
  6. Kobayashi T, Hauck ML, Dodge R, et al. Preoperative radiotherapy for vaccine associated sarcoma in 92 cats. Vet Radiol Ultrasound 2002;43:473-479.
  7. Cohen M, Wright JC, Brawner WR, et al. Use of surgery and electron beam irradiation, with or without chemotherapy, for treatment of vaccine-associated sarcomas in cats: 78 cases (1996-2000). J Am Vet Med Assoc 2002;219:1582-1589.
  8. Bregazzi VS, LaRue SM, McNiel E, et al. Treatment with a combination of doxorubicin, surgery, and radiation versus surgery and radiation alone for cats with vaccine-associated sarcomas. J Am Vet Med Assoc 2001;218:547-550.
  9. Barber LG, Sorenmo KU, Cronin KL, et al. Combined doxorubicin and cyclophosphamide chemotherapy for nonresectable feline fibrosarcoma. J Am Anim Hosp Assoc 2000;36:416-421.
  10. Poirier VJ, Thamm DH, Kurzman ID, et al. Liposome-encapsulated doxorubicin (Doxil) and doxorubicin in the treatment of vaccine-associated sarcoma in cats. J Vet Intern Med 2002;16:726-731.

Appointment Policy and Resources

Appointment Guidelines
The Oncology service is a referral-only service. Once the primary veterinarian calls and sets up the referral, the owner may call and arrange an appointment. If the patient has been seen by our service recently, owners may call Oncology directly to set up an appointment.

Hours: Monday-Friday, 8AM-5PM
Regular appointments:
9:30AM-1:00PM
Drop-offs: 7:30AM-8:30AM
Discharges: 4PM-6PM

What will happen at an appointment?
An appointment includes taking a history, performing a physical examination, and a discussion of prognosis and treatment options. The patient will typically remain in the hospital for 1-2 days for purposes of evaluation of the extent of the tumor-called staging.

Options are presented to the pet owner describing what tests are necessary to reach the final diagnosis or, if the diagnosis is already known, what treatments are recommended. All of the resources of the Veterinary Hospital at North Carolina State University are available for use, if needed. At North Carolina State University, we are fortunate to have a highly educated and enthusiastic faculty of veterinarians to support the health care process. Additionally, very high quality diagnostic and therapeutic options are available. In the Oncology Service, we are very concerned that pet owners make the best possible decision regarding the care of their pet.

What will it cost?

The fee for the consultation with the oncology service is approximately $192. There are additional costs for emergencies. For a full list of cost estimates, click here. A typical visit including the clinical evaluation of extent of disease (which may include radiographs, ultrasound, aspiration of lymph nodes) costs $800-1,000. If advanced imaging techniques are needed, such as a CT scan, the cost may be higher. Treatment costs vary widely, depending on the treatment plan agreed upon.

There are research treatment protocols which may pay for treatment or defray some of the costs associated with treatment. A pet must be evaluated by the service before we can determine if they are eligible for one of the funded protocols.

Will my pet be sick on chemotherapy?

Dogs and cats seem to tolerate chemotherapy much better than people, so it is unlikely that your pet will be extremely nauseated or be vomiting. Occasionally, an animal will be more sensitive, and in those cases appropriate steps are taken to minimize side effects.

Will my pet be bald?

Cats and most dogs will not become bald from chemotherapy as their hair is not continuously growing. Fur that is shaved may not regrow while on chemotherapy, and fur in the radiation treatment field may or may not grow back, or may grow back white. Certain breeds, such as poodles and Old English sheepdogs, may lose the majority of their hair during chemotherapy. When hair is lost during chemotherapy, it will typically grow back when chemotherapy is finished. Cats and dogs will lose their whiskers during chemotherapy.

Is my pet just going to be sick and miserable for the rest of his life if I treat him?

Our intention is to cure your pet of cancer, or, failing that, to give them as much good quality time with you as possible.

If I come in for a consultation, do I have to treat my pet’s cancer?

No. Our job as oncologists is to give you the most accurate information available on what you can expect with various treatment options, and to give you recommendations for treatment of your pet’s cancer. The final decision on which, if any, treatment option is chosen belongs to the pet’s family.

Is treating cancer expensive?

Some treatments are more expensive than others. When the oncologist discusses treatment options, they will also provide expected costs associated with those treatments. Find estimated costs here.

The North Carolina Animal Cancer Program (NCACP) began in 1984, and is part of the Veterinary Hospital in the College of Veterinary Medicine, North Carolina State University. In addition to being multidisciplinary, the NCACP is multi-institutional, involving collaborative activities with Colorado State University, Duke University Medical Center, and the University of North Carolina at Chapel Hill.

The primary functions of the NCACP are:

  • To provide a comprehensive treatment center for privately-owned pet animals with cancer
  • To provide instruction in clinical and investigative oncology to professional students in the College of Veterinary Medicine
  • To provide residency programs in medical and radiation oncology for graduate veterinarians
  • To provide graduate study in fields relating to cancer biology and/or treatment
  • To conduct high quality research in cancer-related fields

Research efforts

The NCACP has a long and productive history of studying tumor biology and new methods of cancer treatment. Through this effort, we hope that information will be provided that will be useful to veterinarians treating animal cancer and to physicians treating cancer in people. Ongoing research in the NCACP involves:

  • Targeted drug delivery via gene therapy and liposources
  • Cytogenetic abnormalities and abnormalities in protein expression of tumors
  • Development of targeted radiotherapy

Occasionally, ongoing clinical trials provide funds to partially offset the cost of cancer treatment in pets.

Liaison with Duke University Medical Center

There has been fruitful collaboration with investigators at Duke University Medical Center since the inception of the North Carolina Animal Cancer Program in 1984. Drs. Mark Dewhirst and Jeannie Poulson, both veterinarians, and faculty members in the Department of Radiation Oncology at Duke University Medical Center, are intimately involved with investigations of new cancer therapy and studies of cancer biology in pets with cancer. Drs. Dewhirst and Poulson also hold Adjunct Faculty appointments in the College of Veterinary Medicine at North Carolina State University. Also, some faculty from North Carolina State University hold adjunct faculty appointments at Duke University Medical Center and are also members of the Duke University Comprehensive Cancer Center.

Collaboration with Duke University Medical Center allows the latest in scientific discovery to be brought to the North Carolina Animal Cancer Program.

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