4 Most Common Cancers in Cats: Vet Approved Facts & Treatments

Vet approved

Reviewed & Fact-Checked By

Dr. Maja Platisa

In-House Veterinarian, DVM MRCVS

The information is current and up-to-date in accordance with the latest veterinarian research.

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Cancer is, unfortunately, a fairly common occurrence in cats, especially as they age. While some cat breeds, such as Siamese, have a genetic predisposition that makes them more at risk of developing certain cancers even at a younger age, any cat can end up with some form of cancer.¹ Current research into cat cancer risk factors shows limited results and a need for further studies when it comes to genetics, as cat breeds are genetically far closer and more similar to each other in comparison to dogs.²

One in five cats will develop cancer in their lifetime. So, while it’s understandably difficult for cat owners to think about the possibility of cancer, being well-informed can help you detect early signs and provide the best treatment for your cat.

This article is here to provide information on the common cancers found in cats and the types of veterinary care and attention available for cats with cancer.

The 4 Most Common Cancers in Cats:

1.  Lymphoma

Lymphoma is one of the most common forms of cancer in cats and makes up about 30% of cat cancer diagnoses.³ It used to be even more prevalent due to its link to the feline leukemia virus (FeLV), and to a lesser extent, the feline immunodeficiency virus (FIV). The development of the FeLV vaccine has somewhat reduced occurrences of lymphoma.

Lymphoma affects a type of white blood cells called lymphocytes.  Because cancerous lymphocytes travel throughout the body, lymphoma is considered a systemic disease. The three most common types of lymphoma in cats are intestinal lymphoma, mediastinal lymphoma, and renal lymphoma.

2. Fibrosarcoma

Fibrosarcoma is a type of soft tissue sarcoma that affects fibrous and connective tissues in the body. One of the most common types of fibrosarcoma in cats is oral fibrosarcoma, but it can also affect other parts of the body. They can also present as lumps on or under the skin. In rare cases, tumors may grow in the nasal passage and internal organs (spleen). Fibrosarcoma makes up around 12%-41% of feline skin tumors and affects middle-aged and older cats at an average age of 9.6 years ⁴.

Different factors can trigger fibrosarcoma, including viruses (rare), trauma near the eyes, and vaccines. Injection site or vaccine associated sarcomas are rare but have been reported to occur at a rate of 1 case per 10000 – 30000 vaccinated cats ⁵.

As worrying as all this may sound, the benefits of your cat being vaccinated are far greater. The risk of your cat contracting a serious infectious disease from not being vaccinated is much higher than the very low chance of developing an injection site sarcoma.

3. Mammary Cancer

Mammary cancer is most prevalent in intact female cats. In some cases, spayed female cats can get mammary cancer. While it’s extremely rare, male cats can also develop mammary cancer. Spaying your cat before they turn one year old can significantly reduce the likelihood of developing mammary cancer ⁶. However, the procedure isn’t effective if your cat already has mammary cancer.

The majority of cases of mammary tumors are malignant (80-96%), and the tumor size is correlated to survival rates, which means the smaller the tumor, the better the chance for a longer survival time after surgery. So, early detection often plays an important role in a cat’s prognosis. Cats typically show signs of mammary cancer when they’re middle-aged or older, between 10–12 years old. Domestic Shorthairs and Siamese cats have a higher prevalence of mammary cancer than other breeds.

4. Skin Cancer

A cat develops skin cancer when there is abnormal cell growth in the skin. These cancerous cells eventually grow and form masses or tumors. Skin cancer can appear just about anywhere, but it’s most commonly detected on the head, around the eyes, and on the nose and tips of the ears. The tumors that result from sun exposure occur most commonly in lightly pigmented or white cats in areas that are hairless or sparsely haired and prone to sunburn.

Cat breeds that are more susceptible to varying types of skin cancer are Persians, Himalayans, and Siamese. Some risk factors for skin cancers include genetics and hereditary factors, environmental factors such as chronic skin irritation, compulsive licking, sun exposure and physical trauma. Generally, a complex mix of factors leads to skin cancer in cats.

Other More Common Tumors in Cats

Oral cavity or mouth tumors account for only about three percent of feline cancers, but approximately three-quarters of these are squamous cell tumors. This is a cancer developing in the mouth or throat, often involving the tongue, that can sometimes spread to the local bone and lymph nodes. Cats might struggle to eat, have bad breath (halitosis), and drool excessively. Sometimes, there is bleeding from the mouth. Treatment can be challenging depending on size and location, and might involve a combination of surgery and radiotherapy, or palliative care with pain killers if surgery is not possible.

Bone tumors in cats are fortunately rare, averaging about 5 cases per 10000 cats. From these, osteosarcoma is responsible for 70-80% of the cases. This is a malignant tumor that mostly affects the long bones in a cat’s legs, primarily the femur and tibia bones in the hindlimb. It’s very painful and causes limping, reluctance to walk and play, swelling of the affected leg, lethargy, and reduced appetite. Bones sometimes get so weakened that they can easily break. Although osteosarcoma in cats usually occurs in middle-aged and older cats (8 to 10 years of age), it has been diagnosed in cats with a wide range of ages, from 1 to 20 years of age.

Treatment Options for Cancer in Cats

The prognosis of cancer in cats depends on the type of cancer, its location and size, the presence of local spread to other tissues, and the stage it’s detected. Veterinarians can run a wide variety of diagnostic tests and may even recommend an MRI or CT scan. Blood tests can also help to look for certain cancers that may cause abnormalities in the blood work (such as high calcium), but are more often used as indicators of general health status. Tumor-specific markers used in human medicine are not available for veterinary patients, and despite the general misconception, cats with tumors can often have completely normal blood results. The majority of cases require a biopsy or aspiration of the tumor to confirm the type, and these methods are considered the gold standard for establishing diagnosis.

Cancers are often removed surgically. They can also be treated with chemotherapy or radiation therapy. Once your veterinarian completes diagnostic testing, they will be able to provide all possible treatment options. Speak to your vet or a feline oncologist (specialist for cancer) to make sure you understand what your cat is going through, what the available treatment options are, their success rates, and what you can expect in the future. We know this is a very difficult diagnosis, and it’s important that you and your vet develop a trusting relationship that will provide your cat with the best possible care. If you’re ever feeling unsure about your cat’s treatment, speak to your vet, as they will be able to answer all of your questions and can even contact an oncologist for first-hand specialist advice.

Does Pet Insurance Cover Cancer Treatment?

Fortunately, in most cases pet insurance can help pay for medical bills related to cancer. An accident and illness plan might cover diagnostic tests, surgeries, and therapies related to the cancer diagnosis. However, this depends on your specific policy terms and conditions, and you should contact your insurance provider before assuming you will have full cover. Some policies will have a limitation based on annual cost of treatment or number of years a certain condition will be covered for.

Because pet insurance companies don’t cover pre-existing conditions, it’s important to enroll your cat in a plan before it receives a cancer diagnosis. This is best done from kitten age or as soon as you get your cat. Pet insurance plans won’t help pay for any medical bills related to any diagnoses your cat receives before it gets on a plan.

While all pet owners will benefit from a pet insurance plan, you can potentially experience significant savings if you have a cat breed that’s known to be predisposed to certain cancers.

Final Thoughts

You can also look into pet insurance plans to help you budget veterinary care costs and familiarize yourself with available options. Taking the time to learn about certain chronic illnesses can help you feel more prepared and have a plan for any health issues your cat may experience as it ages.

Featured Image Credit: brodtcast, Shutterstock