Squamous cell carcinoma sometimes develops from a precancerous skin growth called an actinic keratosis. The risk of developing this type of skin cancer is increased among fair-skinned and fair-haired people who have repeatedly been exposed to strong sunlight, individuals who had freckles as a child, and those with blue eyes. Other risk factors include taking immunosuppressants (drugs that weaken the immune system) and being exposed to industrial pollutants such as arsenic, tar, and industrial oils.
Having had genital warts in the past is a major risk factor for genital squamous cell carcinoma. Squamous cell carcinoma is the second most common type of skin cancer in the United States, after basal cell carcinoma, with about 700,000 diagnosed each year. It accounts for about 2,500 deaths.
Squamous cell carcinoma usually starts out as a small, red, painless lump or patch of skin that slowly grows and may ulcerate. It usually occurs on areas of skin that have been repeatedly exposed to strong sunlight, such as the head, ears, and hands.
Diagnosing squamous cell carcinoma
The main way to diagnose squamous cell carcinoma is with a biopsy. This involves having a small piece of tissue removed from the suspicious area and examined in a laboratory.
In the laboratory, a pathologist will examine the tissue under a microscope to determine if it is a skin cancer. He or she will also stage the cancer by the number of abnormal cells, their thickness, and the depth of penetration into the skin. The higher the stage of the tumor, the greater the chance it could spread (metastasize) to other parts of the body.
Squamous cell carcinoma on sun-exposed areas of skin (such as the face) usually does not spread. However, squamous cell carcinoma of the lip, vulva, and penis are more likely to spread. Contact your doctor about any sore in these areas that does not go away after several weeks.
Treating squamous cell carcinoma
Most (95% to 98%) of squamous cell carcinomas can be cured if they are treated early. Once squamous cell carcinoma has spread beyond the skin, though, less than half of people live five years, even with aggressive treatment. There are many ways to treat squamous cell carcinoma that has not spread. These include:
- cutting away the cancer and a small amount of healthy tissue around it. If a large area of skin is removed, a skin graft may be necessary.
- scraping away the cancer with a surgical tool. An electric probe is used to kill any cancerous cells left behind.
- freezing cancer cells with liquid nitrogen. This treatment is usually used only for very small tumors or for a patch of skin that looks abnormal but isn't yet cancerous.
- destroying the tumor with radiation.
- shaving away the cancer, one thin layer at a time. Each layer is examined under the microscope as it is removed. This technique helps the doctor preserve as much healthy skin as possible.
- applying drugs directly to the skin or injecting them into the tumor
- using a narrow laser beam to destroy the cancer.
The treatment that is best for you depends on the size and location of the cancer, whether it has returned after previous treatment, your age, and your general health. Once your treatment is finished, it's important to have regular follow-up skin exams. Your doctor may want to see you every three months for the first year, for example, and then less often after that. If squamous cell carcinoma has spread beyond the initial tumor site, radiation therapy can be effective if the cancer is growing in specific, identifiable sites. Widespread metastases do not respond well to chemotherapy.