This is a good article on the differences between canine and feline lymphoma and the types of treatment available, from AVMA member Dr. Jennifer Coates.

“Lymphoma (or lymphosarcoma, as it is also called) results from the unregulated growth of malignant lymphocytes (a type of white blood cell). In dogs, the disease typically affects lymph nodes (most obviously observed in the chest region, armpits, behind the knees, groin, and/or under the jaw), bone marrow, liver, and spleen, but can also be seen in the eyes, skin, and gastrointestinal tract. In cats, the chest, kidneys, nose, skin, spine, and gastrointestinal tract are the most commonly involved parts of the body”.

http://www.pawnation.com/2012/08/07/canine-and-feline-lymphoma-similar-but-not-identical-diseases/#page=1