The two most common kinds of skin cancer are basal cell carcinoma and squamous cell carcinoma, which are sometimes called nonmelanoma skin cancer. These cancers are carcinomas that begin in the cells that cover or line an organ.
Basal cell carcinoma accounts for more than 90 percent of all skin cancers in the United States and is the most common of all cancers. Typically, it is a slow-growing cancer that seldom spreads to other parts of the body.
Squamous cell carcinoma also rarely spreads, but does so more often than basal cell carcinoma. It is important that skin cancers are found and treated early because they can invade and destroy nearby tissue. Organ transplant recipients have a 65-fold higher risk of developing squamous cell carcinoma than others. UCSF Medical Center offers a High Risk Skin Cancer Clinic for those at high risk for non-melanoma skin cancers, such as transplant recipients.
The most common warning sign of skin cancer is a change on the skin, especially a new growth or a sore that doesn't heal. The cancer may start as a small, smooth, shiny, pale or waxy lump. It also may appear as a firm red lump. Sometimes, the lump bleeds or develops a crust.
Both basal and squamous cell cancers are found mainly on areas of the skin that are exposed to the sun — the head, face, neck, hands and arms. But skin cancer can occur anywhere.
An early warning sign of skin cancer is the development of an actinic keratosis, a precancerous skin lesion caused by chronic sun exposure. These lesions are typically pink or red in color and rough or scaly to the touch. They occur on sun-exposed areas of the skin such as the face, scalp, ears, backs of hands or forearms.
Actinic keratoses may start as small, red, flat spots but grow larger and become scaly or thick, if untreated. Sometimes they're easier to feel than to see. There may be multiple lesions next to each other.
Basal cell carcinoma and squamous cell carcinoma are generally diagnosed and treated in the same way. When an area of skin doesn't look normal, your doctor may remove all or part of the growth. This process is called a biopsy and it's the only sure way to detect cancer.
Doctors generally divide skin cancer into two stages — local, affecting only the skin, or metastatic, spreading beyond the skin.
Because skin cancer rarely spreads, a biopsy often is the only test needed to determine the stage. In cases where the growth is very large or has been present for a long time, your doctor will carefully check the lymph nodes in the area.
If your doctor is concerned your cancer may have spread to other parts of your body, you may need additional tests, such as special X-rays. Identifying the stage of skin cancer will help your doctor plan your treatment.
Numerous treatment options are available for basal cell and squamous cell carcinoma. Your therapy will depend upon the type of skin cancer you have and its stage.
Reviewed by health care specialists at UCSF Medical Center.