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Answers from vets about your cat:

The 3 Most Common Cancers in Cats

Reviewed by Dr. Celeste Clements, DVM, DACVIM on Tuesday, June 30, 2015
Posted July 08, 2015 in Cat Diseases & Conditions A-Z

Persian cat lying on the ground looking into camera

Did you know that according to the Animal Cancer Foundation (ACF), 1 in every 5 cats develop cancer in their lifetime? Cats can develop many of the same cancers seen in humans:

The three most common cat cancers are lymphoma, soft-tissue sarcoma and squamous cell carcinoma.

Lymphoma in cats
Lymphoma is the most common cancer seen in cats. Lymphoma is a type of blood cancer that occurs when lymphocytes proliferate uncontrollably. Lymphocytes are white blood cells that protect the body from infection. In cats, lymphoma typically affects the:

Feline leukemia virus (FeLV) was one of the leading causes of lymphoma in cats until the development of the FeLV vaccine. Therefore, the FeLV vaccine not only protects cats against FeLV, but indirectly also protects them against certain forms of lymphoma.

Besides being occasionally preventable, lymphoma is also one of the most treatable cancers. Chemotherapy is the standard treatment for most forms of lymphoma and cats treated for lymphoma typically have a very good quality of life. Lymphoma is typically very responsive to chemotherapy and studies show up to 75% of cats treated with chemotherapy will go into remission, according to Colorado State’s Animal Cancer Center. Approximately one third may do well for more than 2 years with aggressive treatment. Ultimately, response rate and remission duration are site and type dependent.

Squamous cell carcinoma in cats
Squamous cell carcinoma (SCC) is another common type of feline cancer. SCC is a type of skin cancer that typically develops on exposed skin, such as on the ears, nose and eyelids, especially in white cats in sunny climates. The prognosis for solar-induced SCC is good if identified and treated early. Likewise it can be prevented if cats are kept indoors and out of the sun’s ultraviolet rays. SCC can also develop in the mouth, and oral SCC alone accounts for 10% of cancer in cats1. In general SCC is an aggressive cancer, and oral tumors in particular have a poor prognosis despite treatment. Fortunately, researchers are investigating new treatments that may improve the quality of life for cats with SCC.

Click here to learn more about squamous cell carcinoma.

Fibrosarcoma in cats
Fibrosarcoma is another cancer seen in cats. Fibrosarcoma is an aggressive tumor that develops from fibrous connective tissue. Fibrosarcoma has developed at the site of injection of various necessary medications and preventives, where it is called feline injection-site sarcoma (FISS).

Fibrosarcoma has been associated with injections of2:

  • Vaccines
  • Corticosteroids
  • Antibiotics
  • Insulin
  • Subcutaneous fluids

The occurrence of this complication is quite rare, estimated at 1 case per 10,000 to 30,000 vaccinations by the American Veterinary Medical Association. Still, veterinarians will limit the frequency of vaccinations and specify where vaccines should be injected. Likewise, they may suggest specific vaccines (especially those that do not contain aluminum), to help reduce the irritation at the injection site that appears to increase the risk of FISS. These steps have been taken to reduce the risk of fibrosarcoma at injection sites, but current thinking suggests multiple risk factors are likely involved including dosing and genetic factors.

When it can’t be prevented, treatment for fibrosarcoma is aggressive surgery with or without radiation or chemotherapy.

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Ruth has more than 15 years of experience in the veterinary industry as a companion animal veterinarian in private practice. Along with being a writer and media personality, she is also a founding member of IDEXX’s Pet Health Network team.