Lymphoma is the most common type of cancer in cats. The disease, which is also sometimes called lymphosarcoma, develops when cells (lymphocytes) that are a normal part of the immune system become cancerous and replicate in an out of control manner.
Lymphoma can invade almost any part of the body including the gastrointestinal tract, lymph nodes, lungs, kidneys, skin, eyes, brain, spinal cord, and more. A cat’s symptoms will depend on the location of the cancer. For example, lymphoma of the brain can cause seizures and other neurological problems while gastrointestinal lymphoma typically results in vomiting and/or diarrhea. Oftentimes, a cat’s symptoms will initially be somewhat vague but worsen over time.
Testing is necessary to definitively diagnose lymphoma because all of its symptoms can be caused by other diseases as well. The first step is often a general health examination that involves some combination of lab work and imaging (x-rays or ultrasound). Once a particular part of the body has been identified as the probable location of the problem, tissue samples must be taken and sent to a pathologist for examination. He or she can usually definitively diagnose lymphoma as well as make a determination as to what type of cells are involved (T- or B- lymphocytes) and how aggressive they are (in other words, “grading” the cancer), all of which is important for coming up with a treatment plan and determining what a cat’s prognosis might be.
Chemotherapy is the primary way in which veterinarians treat lymphoma. In some cases, surgery or radiation therapy might also be appropriate. The outcome of treatment depends upon the part(s) of the body that are affected, the type of lymphoma cells that are involved, the cancer’s grade, and also a degree of luck. In some cases, a cure or long-term remission is possible. At other times, a few months of symptom relief is all that can be expected. The pet’s veterinarian or a veterinary oncologist familiar with the case is in the best position to recommend a form of treatment that is in the best interests of both the pet and owner, but sometimes the only way to know if treatment is going to work is to try it and see what happens.
When an owner does not elect to pursue chemotherapy, surgery, or radiation treatment, palliative therapy can improve a cat’s quality of life and sometimes extend life as well. Corticosteroids like prednisolone or Depo-Medrol, nutritional therapy, and pain relievers can all be used to help keep cats with lymphoma comfortable until euthanasia becomes necessary.