Cancer in Cats

Nobody likes to hear the "big C" word. Unfortunately, some cats do get cancer. Learning about cancer helps prepare a family to deal with the diagnosis and treatment of their cat.

Cancer is much more likely to develop in a cat that has reached her golden years, but even young cats can develop this condition. Cancer is not just one entity—it is any process of uncontrolled cell growth. Cancer can affect all cell types and, thus, any organ system in the body or even a number of systems at once. Cancers behave in very different ways depending on the nature of the tumor. The word "tumor" just describes a lump which is an overgrowth of cells but does not describe the behavior of those cells.

Types of Cancer in Cats

Cancerous tumors are lumps that are abnormal, and they are classified as benign or malignant depending on their behavior.

Some cancers grow very slowly and predictably. These are often well-encapsulated so that they can be easily removed with surgery or freezing, and they do not spread around the body. We refer to these as benign tumors.

Other tumors act like a wildfire, growing quickly, spreading throughout the body to distant locations, and they may lead to a quick demise of the unfortunate animal. These aggressive cancers we term malignant tumors. These tumors often have tendrils of microscopic cancer cells that extend along tissue planes quite a distance from the main lump and cannot easily be removed during a single surgery. Other cancers affect cells of the bone marrow and bloodstream, so they are present in the blood as it circulates. This is typical of the leukemias. Sometimes, a single tumor spreads by sending cells through the bloodstream into multiple locations. This is called seeding, and it frequently occurs in the lungs, resulting in lung cancer that is secondary to a tumor that started in another spot.

You can learn about the most common types of cancer seen in cats here: "Common Cancers in Cats."

Signs of Cancer in Cats

External cancers that can be felt or seen on the surface of the cat are much easier to notice than internal cancers. Home monitoring on a regular basis for unusual lumps and bumps can help a cat owner be a first line sentinel to identify new growths. Any new bumps should be brought to the attention of the veterinarian because cats have a high proportion of cancerous lumps.

Signs of internal cancers are tougher to check for at home. No signs may be present. Other times, vague signs of reduced appetite, weight loss and muscle wasting, reduced energy, vomiting, diarrhea, pale membranes, difficult breathing, or trouble moving around may occur. Signs tend to correlate with the system affected, so only a small subset of signs may be present.

You can learn more here: "Warning Signs of Cancer in Cats."

Diagnosis of Cancer in Cats

Diagnosis of cancer in cats typically involves carrying out blood tests, imaging studies, and a biopsy.

Advanced imaging is more widely available these days. CT scans, MRIs, and endoscopy give us a much better look into tissues than was possible even a few decades ago. Specific biomarker tests are still rare, but research into tumor markers in cats continues. Specific staining techniques of the biopsy tissue can help the pathologist make a very detailed analysis of the cellular nature of the tumor, and this has helped veterinarians improve treatment and provide more accurate assessments of prognosis in individual cases. Cancer is staged as with people, so that we can determine at what point along the spectrum of disease progression a particular patient sits. This helps the clinician counsel the owner regarding optimal treatment plans and prognosis.

What Causes Cancer in Cats?

Certain risk factors make some cats more likely to develop cancer. Cats with white on their ears and nose are more prone to developing squamous cell carcinoma, a cancer of the skin. Cats that have chronic viral diseases such as feline leukemia virus are more prone to lymphomas, fibrosarcoma , and other cancers. Members of some cat breeds are predisposed to mediastinal lymphosarcoma, such as the Oriental and Siamese breeds. The Abyssinian and Somali breeds can develop a rare thymoma-associated neuromuscular disorder. Cats that are spayed as adults rather than as kittens have an increased prevalence of mammary tumors.

Prognosis for Cancer in Cats

Early diagnosis of cancer is important for the outcome. Treatment options may include radiation, surgery, chemotherapy, immunotherapy, cryotherapy, or palliation and nursing care. Intervention with an early, well-designed therapy strategy allows many cats to enjoy an extended lifespan with an acceptable quality of life, and in some cases, cancer treatment in cats can be curative.

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