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What Kinds of Cancers Are Most Common in Cats?

Common Types of Feline Cancer and What to Do About Them

A cat can develop a variety of different types of cancers, just like humans and other animals. Just like a family member being diagnosed with this disease, having a cat diagnosed with cancer can cause you to feel overwhelmed, afraid, and worried about your beloved pet.

As unfortunate as a cancer diagnosis is, with modern medicine and advancements, there are multiple treatment options. Today's surgical, chemotherapy and radiation treatments are producing more positive results than ever. Still, understanding what your cat could be up against will help you deal with her journey if she ever is diagnosed with cancer.

Here are the five most-common types of cancer in cats and the medicines that are used to treat them.


Lymphoma is the most-common type of cancer to affect felines. This type of cancer develops in a certain type of blood cell in the body called lymphocytes, which are found in the lymphoid tissues. Lymphoid tissue can be found throughout the body so this type of cancer can develop in a variety of different areas, such as in the lymph nodes, liver, kidneys, spleen, gastrointestinal tract, and elsewhere.

Lymphoma may develop in any age, sex, and breed of cat, but it is most commonly seen in middle-age to senior cats. Cats who already have the feline leukemia virus (FeLV) are much more at risk of developing lymphoma. Drugs to treat Lymphoma may include cyclophosphamide, doxorubicin, vincristine, chlorambucil, L-asparaginase, and lomustine.

Feline Leukemia Virus (FeLV)

Feline leukemia virus attacks a cat's immune system, and while it is not necessarily a type of “cancer,” it is an illness that causes different types of cancers in FeLV-infected cats. The two most-common cancers associated with FeLV are lymphoma and fibrosarcoma.

This infectious disease is most often found in male cats aged between one to six years, but any sex, age, or breed may contract it. Because this disease is transmitted via blood and saliva, outdoor cats are especially prone to getting it.

Mammary Cancer

About 85% of mammary tumors in cats are malignant, and these types of tumors metastasize very quickly, making early detection important. Mammary cancer is most commonly found in female cats, but while rare, males can develop it too. Older cats are the most at-risk for mammary cancer, but the risk can be reduced in cats who are spayed prior to their first heat cycle.

Surgical removal of tumors is the usual treatment for mammary cancer, followed by a chemotherapy program consisting of doxorubicin and cyclophosphamide.

Squamous Cell Carcinoma (Skin Cancer)

Most skin tumors found on cats are squamous cell carcinoma, or skin cancer. Such tumors tend to be light-colored or unpigmented and they are most commonly found on the ears, the nose, and the eyelids because these areas are the most exposed to the sun's rays (overexposure is a leading cause). This type of cancer also can occur within the oral and nasal cavities.

Any sex, age, or breed of cat can get to skin cancer, but it is most commonly found in hairless breeds or light-haired cats. Chemotherapy drugs that are used by veterinarians to treat squamous cell carcinoma include cyclophosphamide and mitoxantrone.


Fibrosarcoma is an aggressive soft-tissue cancer that is not uncommon in cats. As aggressive as the cancer is, it usually is slow to metastasize. Fibrosarcoma typically starts in the cells found in the body's connective tissues as well as in subcutaneous connective tissues. Chemotherapy treatment may be needed after the tumors are surgically removed in most cases because fibrosarcoma grows back.

The chemotherapy drugs that are used to treat cats with fibrosarcoma include carboplatin, cyclophosphamide, doxorubicin, and vincristine.

About the Author

Dr. Evan Ware

Dr. Evan Ware is a veterinary practitioner in Phoenix, Arizona. He received both his undergraduate degree in microbiology and his Doctorate of Veterinary Medicine from The Ohio State University.

Dr. Ware is currently the Medical Director of University Animal Hospital (VCA) and is also the owner of two other hospitals, including Laveen Veterinary Center and Phoenix Veterinary Center. His areas of expertise include orthopedic medicine and surgery, veterinary oncology and chemotherapy, and general and advanced soft-tissue surgery.