Lymphoma in Cats
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 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
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.
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