Types of Cancer in Cats

The types of cancer affecting cats vary depending on the type of cells causing the cancer and the tissues they affect. Cancer in cats can manifest either as malignant tumors (cells multiplying abnormally) or blood cancer. Cancer generally affects senior cats. In some cases, cancer is curable, provided it is diagnosed in time.

Types of Cancer in Cats

Cats, like humans and other animals, can get cancer. Cancer can be fatal, but advancements in veterinarian medicine have made it possible to cure the disease in some cases or, at least, prolong the life of the cat.

Cancer manifests either as tumors or as blood cancer. Tumors are the result of an abnormal cell growth and multiplication. The immune system does not fight cancerous tumors because they are formed of the body’s own cells and the antibodies do not perceive them as threats. Tumors can grow on almost any type of tissue in the body (except for muscular tissue). Leukemia is a type of cancer affecting the blood but it does not form tumors. It is caused by an abnormal production of white blood cells.

Depending on the tissue they affect, cancerous tumors can be:

  • Leukemia (affecting blood and bone marrow)
  • Lymphoma (affecting lymph nodes)
  • Osteosarcoma (bone tissue)
  • Fibrosarcoma (connective tissue)
  • Adenocarcinoma (skin and tissue covering internal organs)
  • Mast cells tumors (conjunctive tissue)
  • Basal cells tumors (epithelial cells)
  • Breast tumors (affecting mammary glands)

The treatment for cancer involves surgery, chemotherapy or radiation therapy. The prognosis varies depending on the location and the stage of development of the tumor. If the cancer has reached metastasis (malignant cells extended to other organs), it is fatal for the cat.

Leukemia in Cats

Leukemia affects the blood and the bone marrow. The most common type of leukemia affects the lymphocytes in the blood. In this case, surgery is not possible and the treatment consists of chemotherapy, blood transfusions, antibiotics and intravenous fluid therapy.

Cat Lymphoma

Lymphoma is the most common form of cancer affecting cats. It consists of the abnormal growth of lymphatic system cells and lymphocytes in the blood. Malignant cells are mainly found in the lymph nodes. This type of cancer easily extends to the liver, bone marrow and spleen.

Basal Cell Carcinoma

Basal cell carcinoma often affects the skin. White cats and cats that stay in the sun for extended periods of time are more likely to get skin cancer. Siamese cats are prone to developing basal cells carcinoma.

Generally, skin cancer can be treated through the surgical removal of the tumor.

Adenocarcinoma Cancer

Adenocarcinoma is a common skin, lung and intestinal cancer. It usually develops on the surface of an organ. Adenocarcinomas grow really fast and can cause organ blockage or extend to the lymphatic nodes.

The most common treatment consists of surgical removal generally followed by chemotherapy. Prognosis depends on the stage of the tumor when discovered.

Mast Cells Tumors

Mast cells are located in the tissue layer which connects different body organs (for instance, heart and lungs). Mast cells tumors have the form of nodules or lumps and can be surgically removed. If the mast cells tumors are located in the spleen, the veterinarian will remove the entire organ. Afterwards, the cat can survive for up to a year.

Breast Tumors

Breast tumors affect the mammary glands and are more common in female cats. The tumors look like nodules in the cat’s breasts. Early diagnosis is vital since malignant cells can easily expand to lymph nodes and lungs. Surgery involves the removal of all breast tissue to prevent recurrence of the tumors. Chemotherapy is also necessary.


Osteosarcoma is the most common type of bone tumor in cats. It is most commonly found in the legs but it can form on any bone in the body, spine included. If one of the legs is affected, the veterinarian might suggest amputation. Cats can easily adapt to living with only 3 legs. If amputation is not an option, chemotherapy and radiation therapy can help extend the pet’s life.


Fibrosarcoma affects connective tissue around the pelvis, ribs or skull. It can also affect the skin. Fibrosarcoma is very rare.