Lymphoma in Dogs
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 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
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).
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.