Cancer is something that every pet owner worries about when it comes to cat care. Plenty of owners believe that it’s incurable, with some thinking it’s a death sentence for cats. Some types of cancer in cats are challenging to treat, but others can be cured when detected early.

With that, we’ll talk about the common types of cancer in cats as well as the signs you can expect. 

What Is Cancer in Cats?

Cancer in cats occurs when cells in the body begin to grow and divide uncontrollably. These abnormal cells can invade other nearby tissues, sometimes spreading through the blood or lymphatic system. 

Tumors in cats can be benign or malignant. Benign tumors are less harmful, especially since they don’t spread and usually only cause discomfort because of the mass. Malignant tumors, on the other hand, spread quickly and can affect several parts of the body. This makes it dangerous. 

10 Common Types of Cancer in Cats

There are several types of cancer in cats, with each having different traits and characteristics.

1. Lymphoma

Lymphoma is by far the most common type of cancer in cats, affecting the lymphatic system and organs such as the spleen, liver, and gastrointestinal tract. However, it is commonly observed in the gastrointestinal tract. 

Since lymphocytes circulate all throughout the body, this type of cancer in cats can easily spread throughout the entire system. It is often associated with an infection of the feline leukemia virus, but can also occur in cats without the virus. 

• Vomiting and diarrhea

• Lethargy and lack of interest in activities

• Swollen lymph nodes

• Loss of appetite and weight loss

2. Squamous Cell Carcinoma

Squamous cell carcinoma primarily affects the face, usually with areas around the ears, eyelids, mouth, and lips. There are two main types: oral and skin cancer. 

Cats with lighter fur are at higher risk due to their susceptibility to UV damage. In the mouth, this cancer in cats can destroy the surrounding tissue, making simple functions difficult. These are the common signs.

• Sores or ulcers on the skin

• Bad breath and difficulty eating

• Visible growths or lumps

• Excessive drooling or blood in saliva

3. Mammary Gland Tumors

Mammary gland tumors are most commonly found in unspayed female cats and are often malignant. This cancer in cats often spreads quickly to the lungs and lymph nodes. It stems from abnormal cell growth due to estrogen, which is why it’s common in intact females. 

Lumps or masses near the mammary glands

• Swelling or redness around the affected area

• Discharge from the nipples

• Loss of appetite and lethargy

4. Fibrosarcoma

Fibrosarcoma develops in connective tissues and often presents as firm, painless masses under the skin. This cancer in cats is aggressive in the area it starts in, but can be slow to progress to other organs. Even after a successful removal surgery, the fibrosarcomas can come back.

• Lumps or bumps under the skin that grow over time

• Discomfort or pain 

• Lethargy and reduced mobility

• Weight and appetite loss

5. Osteosarcoma

Osteosarcoma is an aggressive cancer that targets the bones and limbs. This type of cancer in cats affects their mobility, which causes them a lot of pain and discomfort. It eats away at the affected area, which can cause inflammation and fractures over time. 

When things get worse, the cancer can spread to other parts of a cat’s body, such as the lymph nodes and chest.

• Swelling in the limbs or affected bones

• Lameness or reluctance to move

• Pain when touched or moved

• Weight loss and fatigue

6. Mast Cell Tumors

Mast cell tumors develop from mast cells, a type of immune cell that responds to allergic reactions. These develop when these cells rapidly replicate and divide. This type of cancer in cats can appear anywhere on the skin, typically on the head or neck.

Raised, itchy lumps on the skin

• Vomiting or abdominal discomfort

• Loss of appetite and weight loss

• Lethargy and weakness

7. Hemangiosarcoma

Hemangiosarcoma is a cancer in cats that starts from the endothelial cells of the blood vessels’ lining. While this type can be observed anywhere on the cat’s body, they are commonly seen in the heart, liver, and spleen. This cancer in cats is highly aggressive and can develop rapidly.

Hemangiosarcomas are highly vascular and can easily rupture. This can potentially lead to severe hemorrhage. 

• Rapid breathing

• Weakness and lethargy

• Difficulty breathing if internal tumors press on the lungs

• Pale gums and loss of appetite

8. Adenocarcinoma

Adenocarcinoma is a type of cancer in cats with several subtypes depending on where the affected area is. This aggressive cancer is commonly known to develop in areas such as the lungs, intestines, eyes, and pancreas. This means that the symptoms will depend on where the cancer manifests.

• Difficulty breathing 

• Vomiting or diarrhea 

• Weight loss and lethargy

• Decreased appetite

• Blood and mucus in the stool

9. Transitional Cell Carcinoma

Transitional cell carcinoma is another type of cancer in cats that primarily affects the lining of the urinary tract system. Because it’s highly aggressive, TCC can easily spread to the surrounding tissues and other nearby organs. 

As the cancer develops, it can lead to blockages and significant discomfort for your cat.

• Difficulty urinating or straining to urinate

• Blood in the urine

• Urinating in small amounts unexpectedly

• Pain or discomfort while urinating

10. Melanoma

Melanoma is a tumor that develops from the pigment-producing cells in the mouth, eyes, or anywhere on the skin. This means that symptoms will appear depending on where the cancer is present. While melanoma is rare compared to other types, it is very aggressive. 

• Swelling in the mouth or around the jaw

• Bad breath and drooling

• Difficulty eating or swallowing

• Visible tumors or growths in the mouth