Squamous cell cancer (also known as squamous cell carcinoma) is a type of skin cancer that affects cells just under the outer layer of the epidermis. Squamous cell cancer, so named because of the cells' flat shape, is usually found on skin that is exposed to the sun, particularly parts of the head, neck, and hands. This type of skin cancer is usually slow growing. However, if left untreated, it can affect nearby bone and tissue.
Skin cancer in general (including melanoma, basal cell, and squamous cell cancer) is the most common type of cancer. According to American Cancer Society estimates, about 2.2 million basal and squamous cell skin cancers are diagnosed each year in the United States. About 20 percent of those will be squamous cell cancers. Squamous cell carcinomas are more aggressive than their basal cell cousins, sometimes spreading into fatty tissue and lymph nodes, but very few squamous cell cancers result in death.
Sun exposure (or ultraviolet light radiation) is the biggest risk factor for developing squamous cell cancer. Caucasians have a higher risk than people of other races because their skin contains less protective melanin, or skin pigment. Age is another risk factor, although the rate of basal cell and squamous cell cancers is increasing in younger people, most likely because of sun exposure. Men are about three times as likely as women to have squamous cell cancers of the skin. Smokers are more likely to develop squamous cell cancer, especially on the lips. Exposure to industrial metals and chemicals also raises risk.
Many skin cancers can be avoided. Limiting ultraviolet (UV) exposure by avoiding prolonged exposure to the sun, steering clear of tanning beds, wearing protective clothing, wearing a wide-brimmed hat, using sunscreen and wearing sunglasses that block UVA and UVB light decreases risk. It is very important to protect children as frequent sunburns in childhood may increase the risk for future squamous cell cancer.
Squamous cell cancers can be found early through a routine skin-checkup by a health-care professional or through a self-exam. Any new bumps or growths, or any changes in the size, shape or color of existing moles, freckles, and marks on the skin could be cause for concern. Squamous cell carcinomas might look like rough, crusty lumps or like flat red patches that form on the face, ear, neck, lips, hands, and – less frequently – the genitals.
If squamous cell cancer is diagnosed, it can usually be removed by minor surgery or topical treatments. Some tumors can be excised using a local anesthetic; others are scraped and treated with an electric needle (in a process called curettage) to kill any remaining cells. Tumors in delicate areas like the face might require Mohs Surgery, a technique performed by highly trained doctors, in which the tumor is removed layer by layer, and microscopically examined during the procedure to ensure removal of the cancer but also preservation of the skin area. If lymph nodes are involved, they may be biopsied or removed.
Small tumors and pre-cancerous lesions are often treated by freezing cells with liquid nitrogen (cryosurgery), by using a topical chemotherapy cream, or by light, laser or other, more experimental, treatments. Radiation may be used for large or oddly-situated tumors or on patients who cannot tolerate surgery. It can also be used after surgery as adjuvant (additional) therapy to kill any remaining cancer cells or to treat cancer that has spread to lymph nodes or other organs. Chemotherapy may be used to treat skin cancer that has metastasized.