Squamous cell carcinoma

Skin cancer is more common in white-coated cats and is caused by prolonged exposure to the sun.

Overview

Cats, particularly white-coated ones are prone to sunburn and skin cancer around the head and neck, and particularly the ears, nose, and eyelids. Cats don't have to have access to the outdoors to suffer from this condition as UV radiation can pass through windows.

Chronic sunburn can result in further skin diseases such as skin cancer if not managed early and appropriately. And the burns can leave the skin more susceptible to skin infections such as ringworm or bacterial infections.

Skin squamous cell carcinoma

Skin cancer, otherwise known as squamous cell carcinomas, tends to affect middle-aged to older cats and those with a white or light-colored coat. Studies have also shown an increased prevalence in cats that wear flea collars and those that live in smoking households.

Skin cancers are one of the most common forms of tumors that affect cats. The majority of skin cancers in cats are considered malignant (aggressive and spread to other parts of the body).

Oral squamous cell carcinoma

Squamous cell carcinomas are the most common cause of oral cancers in cats. They tend to be locally aggressive appearing under the tongue on the palate or within the jaw.

Predispositions to oral squamous cell carcinoma:

• Middle-aged to senior cats
• Flea collars
• High quantities of tinned food
• Exposure to household smoke

Signs

Sunburn

Common signs of ear sunburn:

• Hair loss
• Crusting
• Weepy discharge
• Slow-healing sores

The skin cancer lesions are crusty, ulcerated, raised, or cauliflower-like and don't heal. Depending on the location, signs of cancer can also include face rubbing, bad breath, decreased grooming, bloody saliva, sneezing, or coughing.

Skin squamous cell carcinoma

Common areas where skin cancer forms:

• Ear
• Nose
• Eyelids
• Temple
• Lips
• Inside the mouth

Oral squamous cell carcinoma

Common signs of oral squamous cell carcinoma:

• Mouth mass or swelling
• Loose teeth
• Pain on eating
• Excessive drooling
• Blood-tinged saliva
• Lack of grooming
• Decreased appetite
• Weight loss

Diagnosis

Diagnosis of skin cancer is made based on a fine needle aspirate or biopsy of the affected area. Bloodwork, urine analysis, lymph node assessment, and x-rays may also be performed to determine the severity of cancer. CT scans may assist in determining the severity of oral cancer.

Cancer stages:

T1 or TI	Primary tumor <2cm
T2 or TII	Primary tumor 2-4cm
T3 or TIII	Primary tumor >4cm

Management

Skin squamous cell carcinoma

Management of squamous cell carcinoma:

• Biopsy
• Surgical removal where possible
• CT or MRI to determine the extent of a tumor
• Cryotherapy (freezing)
• Topical chemotherapy
• Radiation therapy

If you notice a mass on your cat, particularly ones that appear to grow rapidly or change suddenly, seek veterinary attention. Your vet will be able to take a cell or tissue sample to determine what type of tumor it is.

Oral squamous cell carcinoma

Depending on the size of a tumor, surgery may be an option for removing the oral tumor. However, more commonly cats present with masses >2cm which is often too large to attempt surgery. In these cases, radiation therapy and chemotherapy may be recommended with anti-inflammatories to offer pain relief. 

Prognosis

Skin squamous cell carcinoma

The earlier, smaller lesions that undergo full surgical removal offers the best outcome for cats with skin cancer. For skin cancer on the nose, tumor stage is linked to the prognosis for tumor control e.g. Smaller tumors or T1 tumors showed less than 50% having recurring tumors with control for at least 53 months, whereas larger tumors or T3 tumors were controlled for around 9 months with treatment.

Cryotherapy treatment for facial lesions is more effective on tumors less than 1 cm with studies showing a disease-free interval between 6-14 months.

Oral squamous cell carcinoma

Unfortunately, the prognosis for this form of oral cancer is about 3-6 months. Those that undergo radical surgical removal have an increased life expectancy of about a year with a 43% survival rate at 2 years.

Prevention

Tips to help prevent ear sunburn and skin cancer:

• Limit sun exposure during the peak UV hours
• Apply pet-approved sunscreen on the ears, nose and hairless areas
• UV protected windows
• Keep your pet indoors

Most human sunscreens contain zinc oxide, which is toxic to pets. Pets that ingest creams containing zinc oxide can develop anemia, diarrhea, stomach pain, vomiting, and fever. To help keep your pet safe, use pet-approved sunscreen or sunscreen that does not contain zinc oxide.