Basal cell carcinoma is a cancer that originates in cells of the outer layer of the skin (epidermis).
Basal cells are in the lowest layer of the epidermis (the outer layer of the skin). Although basal cell carcinoma may not originate in the basal cells, the disease is so named because the cancer cells resemble basal cells. Basal cell carcinoma is the most common type of cancer. More than 2.8 million people develop this type of cancer in the United States each year. It is more common among fair-skinned people with a history of sun exposure and is very rare among dark-skinned people. Basal cell carcinoma usually develops on skin surfaces that are exposed to sunlight, commonly on the head or neck.
The tumors usually begin as small, shiny, firm, almost clear to pink in color, raised growths (nodules) with visible dilated blood vessels (telangiectases). The tumors enlarge very slowly, sometimes so slowly that they go unnoticed as new growths. However, the growth rate varies greatly from tumor to tumor, with some growing as much as ½ inch (about 1 centimeter) in a year.
Basal cell carcinomas can vary greatly in their appearance. Some are raised bumps that may break open and form scabs in the center. Some are flat pale or red patches that look somewhat like scars. The border of the cancer is sometimes thickened and pearly white. The cancer may alternately bleed and form a scab and heal, leading a person to falsely think that it is a sore rather than a cancer.
Basal cell carcinomas rarely spread (metastasize) to other parts of the body. Instead, they invade and slowly destroy surrounding tissues. When basal cell carcinomas grow near the eyes, ears, mouth, bone, or brain, the consequences of spread can be serious and can lead to death. Yet, for most people, the tumors simply grow slowly into the skin.
Doctors often can recognize a basal cell carcinoma simply by looking at it, but a biopsy is the standard procedure for confirming the diagnosis (see see Diagnosis of Skin Disorders).
Because basal cell carcinoma is often caused by sun exposure, people can help prevent this cancer by staying out of the sun and using protective clothing and sunscreen. In addition, any skin change that persists for more than a few weeks should be evaluated by a doctor.
Doctors may remove the cancer in the office by scraping and burning it with an electric needle (curettage and electrodesiccation) or by cutting it out. Doctors may destroy the cancer by using extreme cold (cryosurgery). Also, certain chemotherapy drugs may be applied to the skin. A technique called Mohs microscopically controlled surgery may be required for some basal cell carcinomas that are large or regrow or occur in certain areas, such as around the nose and eyes. Occasionally, radiation treatment is used. Doctors may also use photodynamic therapy (see see Sidebar 1: Using Lasers to Treat Skin Problems).
People whose cancer has metastasized or has spread to nearby tissues and who are not candidates for surgery or radiation therapy may be given the drug vismodegib taken by mouth.
Treatment is nearly always successful, and basal cell carcinoma is rarely fatal. However, almost 25% of people with a history of basal cell carcinoma develop a new basal cell cancer within 5 years of the first one. Thus, anyone with one basal cell carcinoma should have a yearly skin examination.
Last full review/revision July 2013 by Gregory L. Wells, MD