The incidence of cancer and tumors in cats is on the rise. There are a variety of cancerous masses that can affect cats, and the discovery of a mass should always raise concern.
As they age, dogs have a high likelihood of developing lipomas, tumors beneath the skin made of fat deposits. Many dogs will develop an array of lipomas as they age, but most of these tumors are benign and often do not require removal, so long as they are not causing pain or discomfort. Unfortunately, lipomas are not as common in cats as they are in dogs. If you feel a lump or notice any odd swelling on your cat, prompt veterinary attention should be sought. The chance of successfully treating and curing a cancerous mass in your cat is much greater if the problem is caught sooner rather than later.
Common Types of Cancerous Tumors in Cats
One of the most common types of cancer in cats is squamous cell carcinoma (SCC). This tumor affects the skin, most commonly seen in light-colored or unpigmented areas. The nose, eyelids, and tips of the ears are frequent locations for SCC. Older cats, particularly those with white coats or white tips on their ears and face, are most affected. Prolonged exposure to direct sunlight, especially in outdoor cats, is often attributed to the cause of SCC.
Signs of SCC in a cat may include small ulcer-like lesions that bleed frequently and continue to grow in size. On the nose, advanced SCC can erode parts of the nose, becoming raw and uncomfortable. A biopsy of the affected tissue is required to confirm the presence of squamous cell carcinoma. Depending on the biopsy results, your veterinarian may recommend surgery or a consultation with a veterinary oncologist.
Despite the high rate of occurrence in some cats, squamous cell carcinoma rarely metastasizes to other parts of the body, and treatment to remove the cancerous lesion is usually curative. Surgical excision is commonly performed, or in some cases, cryosurgery or laser surgery may be more effective.
Another commonly seen skin tumor in cats is the Mast Cell Tumor (MCT). Frequently seen on the head and neck, MCTs can also be found on the body, legs, and even in the mouth. While cats may show no signs of severe illness, the tumor can cause itchiness and may ulcerate. Mast cell tumors are often small, about the size of a pencil eraser or smaller, and appear as firm, raised, hairless masses that are pink or white in color.
Because it can be difficult to visually differentiate between mast cell tumors and other benign skin growths, such as cysts, any suspicious growth on your cat should be biopsied via fine-needle aspiration. This procedure takes a sample of the cells within the mass, which will then be microscopically examined to determine the type of mass.
If the tumor is found to be a mast cell tumor, surgical excision is the treatment of choice. Since mast cell tumors may be larger under the skin than they appear on the surface, wide margins must be taken to ensure complete removal. Unlike in dogs, mast cell tumors in cats have a smaller likelihood of recurrence or spread, and surgery is generally curative. However, depending on your cat’s specific situation, your veterinarian may recommend X-rays to check for tumor spread and may suggest a consultation with a veterinary oncologist.
Mammary tumors are another form of cancerous growth in cats, occurring in the breast tissues. Similar to human breast cancer, mammary tumors are a serious concern and can be fatal. These tumors are the most common cancer in female cats (though they can occur in male cats, albeit rarely) and are especially common in older, intact female cats.
The cause of mammary tumors is not fully understood, though studies have shown that hormones like estrogen play a role in their development. Cats spayed before their first heat cycle have reduced exposure to these hormones and have less than a 1% risk of developing a mammary tumor in their lifetime. However, cats spayed later in life, after several heat cycles or pregnancies, have a significantly higher risk.
Mammary tumors can feel either soft or hard under the skin and may cause bruising of the skin around the mammary gland. More advanced tumors may cause open wounds or bleeding. While about half of mammary tumors are benign, malignant tumors are very aggressive and can quickly spread to the lymph nodes, lungs, and other organs. For this reason, every mammary tumor should be treated as malignant until proven otherwise.
If you suspect a mammary tumor in your cat, prompt medical treatment is necessary. Your veterinarian may perform a fine-needle aspiration to determine the type and severity of the tumor. Bloodwork will be done to assess your cat’s general health, and chest X-rays may be taken to check for the spread of the disease to the lungs. Additional tests may be recommended to get a clearer picture of your cat’s health and to determine the best course of treatment.
Surgical treatment often involves a mastectomy, which removes the tumor and the associated mammary gland. Surrounding lymph nodes may also be removed if they are affected. If your cat is intact, a spay procedure may be performed at the same time as the tumor removal. A consultation with a veterinary oncologist is also suggested, as chemotherapy or radiation therapy may be recommended, particularly if the cancer has spread beyond the mammary gland.
The prognosis for cats with mammary tumors varies and largely depends on how quickly the cancer is detected and treated. In all cases, the best outcomes are associated with prompt recognition and treatment. If you suspect a tumor in your cat, seeking veterinary care immediately can significantly improve the outcome of treatment.
