-
- There are three main types of skin cancer; basal cell carcinoma, squamous cell carcinoma (the nonmelanoma skin cancers), and melanoma.
- Skin cancer is the most common form of cancer in humans.
- Ultraviolet light, which is in sunlight, is the main cause of skin cancer.
- The most common warning sign of skin cancer is a change in the appearance of the skin, such as a new growth or a sore that will not heal. Unexplained changes in the appearance of the skin lasting longer than two weeks should be evaluated by a doctor.
- Nonmelanoma skin cancer is generally curable. The cure rate for nonmelanoma skin cancer could be 100% if the lesions are brought to the attention of a doctor before they have a chance to spread.
- Treatment of nonmelanoma skin cancer depends on the type and location of the skin cancer, the risk of scarring, as well as the age and health of the patient. Methods used include curettage and desiccation, surgical excision, cryosurgery, and Mohs micrographic surgery.
- Avoiding sun exposure in susceptible individuals is the best way to lower the risk for all types of skin cancer. Regular examination in susceptible individuals, both by self-examination and by annual skin checks done by a physician are recommended for those at high risk. Anyone who has already had any form of skin cancer should have regular medical checkups by a physician.
The two most common forms of skin cancer are basal cell carcinoma and squamous cell carcinoma. Together, these two are also referred to as nonmelanoma skin cancer. Melanoma is generally the most serious form of skin cancer because it tends to spread (metastasize) throughout the body quickly.
Basal Cell Carcinoma
Basal cell carcinoma is the most common form of skin cancer and accounts for more than 90 percent of all skin cancer in the U.S. These cancers almost never spread (metastasize) to other parts of the body. They can, however, cause damage by growing and invading surrounding tissue.
What are risk factors for developing basal cell carcinoma?
Light-colored skin and sun exposure are both important factors in the development of basal cell carcinomas. The face remains the most common location for basal cell lesions. However, about 20 percent of these skin cancers occur in areas that are not sun-exposed, such as the chest, back, arms, legs, and scalp. Weakening of the immune system, whether by disease or medication, can also promote the risk of developing basal cell carcinoma.
According to the U.S. National Institutes of Health, ultraviolet (UV) radiation from the sun is the main cause of skin cancer. Artificial sources of UV radiation, such as sunlamps and tanning booths, can also cause skin cancer. The risk of developing skin cancer is also affected by where a person lives. People who live in areas that receive high levels of UV radiation from the sun are more likely to develop skin cancer. In the United States, for example, skin cancer is more common in Texas than it is in Minnesota, where the sun is not as strong. Worldwide, the highest rates of skin cancer are found in South Africa and Australia, which are areas that receive high amounts of UV radiation. Skin cancer is related to lifetime exposure to UV radiation. Most skin cancers appear after age 50, but the sun''s damaging effects begin at an early age. Therefore, protection should start in childhood in order to prevent skin cancer later in life.
What are risk factors for developing squamous cell carcinoma?
The single most important factor in producing squamous cell carcinomas is sun exposure. Many such growths can develop from precancerous spots, called actinic or solar keratoses. These lesions appear after years of sun damage on parts of the body such as the forehead and cheeks, as well as the backs of the hands. Sun damage takes many years to develop into skin cancer. It is therefore common for people who stopped being "sun worshipers" in their twenties - to develop precancerous or cancerous spots decades later.
Several uncommon factors that may predispose a patient to squamous cell carcinomas include exposure to arsenic, hydrocarbons, heat and/or x-rays. Some squamous cell carcinomas arise in scar tissue; also, suppression of the immune system by infection or drugs may also promote such growths.
Can squamous cell carcinoma of the skin spread (metastasize)?
Yes. Unlike basal cell carcinomas, squamous cell carcinomas can metastasize, or spread to other parts of the body. These tumors usually begin as firm, skin-colored or red nodules. Squamous cell cancers that start out within solar keratoses or on sun damaged skin are easier to cure and metastasize less often than those that develop in traumatic or radiation scars. One location particularly prone to metastatic spread is the lower lip. A proper diagnosis in this location is, therefore, especially important.
How are squamous cell carcinomas diagnosed?
As with basal cell carcinoma, a proper diagnosis occurs when a doctor performs a biopsy. This involves taking a sample by injecting the area surrounding the lesion with local anesthesia and punching out a small piece of skin using a circular punch blade. The skin that is removed is then examined under a microscope to check for cancer cells.
How are squamous cell carcinomas treated?
Techniques for treating squamous cell carcinoma are similar to those for basal cell carcinoma (for detailed descriptions see above under treatment of basal cell carcinoma). The possibility of metastasis makes it especially important to diagnose and treat squamous cell carcinomas early.
How are squamous cell carcinomas prevented?
Even more so than is the case with basal cell carcinoma, the key principles of prevention are minimizing sun exposure and getting regular checkups. Common sense preventive techniques are the same as for basal cell carcinoma (see above under prevention of basal cell carcinomas).
Nonmelanoma Skin Cancer - In Review
Also see Melanoma
