Lymphoma, sometimes known as lymphosarcoma, is a malignant cancer of the lymphatic system. According to the Animal Emergency Center in Wisconsin, it's one of the most common cancers of cats. An untreated cat typically lives only about four to six weeks. Fortunately, most forms of lymphoma respond well to chemotherapy, bringing a high rate of remission in affected cats. There are several factors to take into account when considering chemotherapy, including the form of lymphoma and the cat's quality of life.
What Is Chemotherapy?
Wendy C. Brooks, D.V.M., defines chemotherapy as the use of medications as therapy. In the case of lymphoma, several different drugs are commonly used, including cyclophosphamide, vincristine and doxorubicin, which are antitumor medications, and prednisolone, a steroid that has anti-inflammatory properties and well as some limited antitumor action. A chemotherapy protocol will take into account the type of lymphoma (there are several, and they vary in their response to chemo) and how advanced the disease is. The College of Veterinary Medicine at Washington State has found that multidrug protocols work better than those employing a single drug.
If the primary lymphoma tumours are localised or relatively accessible, surgery may be a treatment option. But because lymphoma tumours are often diffuse, or there are tumours in many locations, chemotherapy can be a better option. Most feline lymphomas respond well to chemotherapy. In a study done through Utrecht University in the Netherlands in 2001, 75 per cent of cats treated with chemo experienced a remission, 51 per cent were still disease-free after one year, and 38 per cent were still disease-free after two years. Chemotherapy can be used with surgery in some cases.
A Sample Protocol
According to the Feline Advisory Bureau, one typical protocol using two chemo drugs and prednisolone might look like this: One drug, vincristine would be given intravenously, once weekly for about four to six weeks. This is called the induction phase. It would then be given once every three to four weeks. A second chemo drug, cyclophosphamide, would be given, either IV or as a tablet, once every one to three weeks along with the vincristine. Prednisolone tablets would be given daily with the other drugs. Your veterinarian might choose among several other protocols, depending on the type of lymphoma being treated and other factors.
Obviously, treatment can be very involved, so there are several things to think about when you're considering chemotherapy. What kind of prognosis could you expect, given the type of lymphoma your cat has? How is your cat's overall heath, and is he FeLV/FIV negative? What are the possible side effects, the treatment schedule involved and the cost? How well will your cat respond to being hospitalised and treated weekly? Can you medicate him at home?
If chemotherapy is successful, your cat will go into remission. Defined by the Animal Emergency Center, that means a complete disappearance of all signs of disease. (Remission is not a cure.) The length of the remission depends on several factors, including the type and extent of lymphoma, the condition of your cat and the chemo protocol used. If your cat comes out of remission, different drugs can be tried, but second remissions are usually shorter than first ones. Chemotherapy usually continues during remission.
Most cats tolerate chemotherapy very well, and side effects are minimal. You can see decreased appetite, vomiting or diarrhoea, nausea, lethargy and secondary infections. Cats don't lose their hair, although sometimes their whiskers will fall out. Many potential side effects can be managed with medication, so that cats undergoing chemo can enjoy a good quality of life.