A diagnosis of cancer is always frightening. One of the most common forms of this disease in cats is lymphoma. This is a cancer of the lymph nodes and can arise almost anywhere in the body. However modern treatment protocols can be highly effective in providing some control of the disease and it is possible for affected cats to have several years of normal life following treatment.
What is Lymphoma?
Lymphoma is a cancer of the white blood cells. In cats the disease can take many forms and these are typically distinguished by the area of the body that is affected. Lymphoma affecting some sites such as nasal lymphoma and lymphoma of the cranial mediastinum (tumor in the chest, in front of the heart and between the lungs) is associated with a better outcome. Historically, infection with FeLV has often been associated with an increased risk of lymphoma and leukemia but this association seems to be declining.
How would I know if my cat has lymphoma?
Currently, the most common form of feline lymphoma is the intestinal form. Cats with this type of lymphoma often present with a history of reduced appetite, intermittent vomiting and sometimes a mass can be felt in the abdomen.
Another frequent presentation is cranial mediastinal lymphoma. For an unknown reason cranial mediastinal lymphoma is seen more frequently in young cats, often as young as one year old. The first sign of illness in cats with this form of disease is often severe breathing difficulty.
Kidney lymphoma appears to be a disease of the older cat. The first signs are usually reduced appetite and weight loss. Often an owner identifies a large mass in the abdomen that is actually the enlarged left kidney. These cases invariably have a degree of renal failure and may show excessive drinking and urination.
Cats with nasal lymphoma usually present with sneezing or a discharge from the nose.
How will my veterinarian know if my cat has lymphoma?
Your veterinarian will first want to examine your cat. They may be able to feel a mass in your cat's abdomen or a thickening of the intestines.
Chest X-rays or ultrasound may be needed to identify the presence of a tumor in the chest or abdomen.
Diagnosis is made by taking a sample of the tumor tissue for examination. This can be done using a fine needle aspirate, core biopsy or surgical biopsy. A sample of the fluid in the chest or some cells from an enlarged kidney can be examined under a microscope.
Can lymphoma be treated?
Multiple treatment options have been described. Currently there appears to be some uncertainty about which is the best type of treatment protocol to use. Two basic protocols are used by most vets, the three drug COP protocols which use the drugs vincristine, cyclophosphamide and prednisolone, and the four drug CHOP protocols which also use the drug doxorubicin. When doxorubicin is used as part of the treatment plan there appears to be a significantly increased risk of gastrointestinal side effects, mostly anorexia. It is unclear whether the addition of doxorubicin adds a real benefit in terms of overall survival.
Your veterinarian will advise you on the best treatment for your cat.
Will my cat get better?
Sadly, there is no cure for lymphoma. Chemotherapy in cats is aimed at providing prolonged high quality life.
There appear to be 3 groups of feline lymphoma patients. Some cases fail to show a good response to any chemotherapy offered. For these patients, their lymphoma is unfortunately fairly rapidly progressive over a few weeks.
Patients in the middle group tend to show a degree of response to the treatment but never achieve complete normality and for these patients there is an average life expectancy of approximately 4 months.
A third group of cats achieve complete remission from their lymphoma and their life expectancy can be measured in years. Cats with fluid in their chest due to a mediastinal lymphoma may appear to be very sick but can be extraordinarily responsive to chemotherapy provided that the initial respiratory complaint can be stabilized.
Whilst cats with kidney lymphoma can respond well to chemotherapy, the significant kidney damage that has inevitably arisen prior to diagnosis persists. This has consequences both in the short and the long term. In the short term, it may be harder for these cats to handle the chemotherapy. In the long term, renal damage is likely to be progressive and therefore, even if the lymphoma enters complete remission, life expectancy can be reduced.