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Basal Cell Carcinoma

By Gregory L. Wells, MD, Staff Dermatologist, Ada West Dermatology, St. Luke’s Boise Medical Center, and St. Alphonsus Regional Medical Center

Basal cell carcinoma is a cancer that originates in the cells of the outer layer of the skin (epidermis).

  • Usually, a small, shiny bump appears on the skin and enlarges slowly.

  • The bumps may break open and form a scab, sometimes with bleeding, or become flat, resembling a scar.

  • Although this cancer can often be identified by sight, doctors usually do a biopsy.

  • The cancer is usually removed, but sometimes people may be given chemotherapy drugs applied to the skin or, occasionally, radiation therapy or drug therapy.

Basal cells are in the lowest layer of the epidermis (the outer layer of the skin). Although basal cell carcinoma may not develop from the basal cells, the disease is so named because the cancer cells look like basal cells under a microscope.

Basal cell carcinoma is the most common type of skin 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 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 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.


Basal cell carcinomas usually begin as small, shiny, firm, almost clear to pink in color, raised growths (nodules) with visible dilated blood vessels (telangiectases), but their appearance can vary greatly. Some tumors 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.


  • Biopsy

Doctors often can recognize a basal cell carcinoma simply by looking at it, but a biopsy is the standard procedure for confirming the diagnosis. During this procedure, doctors remove a piece of the tumor and examine it under a microscope.


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.


Because basal cell carcinoma is often caused by sun exposure, people can help prevent this cancer by doing the following:

  • Avoiding the sun: For example, seeking shade, minimizing outdoor activities between 10 am and 4 pm (when the sun’s rays are strongest), and avoiding sunbathing and the use of tanning beds

  • Wearing protective clothing: For example, long-sleeved shirts, pants, and broad-brimmed hats

  • Using sunscreen: At least sun protection factor (SPF) 30 with UVA and UVB protection used as directed and reapplied every 2 hours and after swimming or sweating but not used to prolong sun exposure

In addition, any skin change that lasts for more than a few weeks should be evaluated by a doctor.


  • Removal of the tumor (many different methods)

Doctors may remove the cancer in the office by scraping and burning it with an electric needle (a procedure called curettage and electrodesiccation) or by cutting it out. Doctors may destroy the cancer by using extreme cold (cryosurgery).

Certain chemotherapy drugs may be applied to the skin. Photodynamic therapy (see Using Lasers to Treat Skin Problems), in which chemicals and a laser are applied to the skin, also may be used. Occasionally, radiation treatment is used.

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.

People whose cancer has spread to nearby tissues or spread to other parts of the body (metastasized) and who are not candidates for surgery or radiation therapy may be given the drug vismodegib taken by mouth.

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