• Highlights
• Introduction
• Other Skin Cancers
• Causes
• Risk Factors
• Prognosis
• Prevention
• Diagnosis
• Treatment for Melanoma
• Treatment for Other Skin Cancers
• Resources
• References

Melanoma and other skin cancers

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of melanoma.

Alternative Names

Skin cancer; Squamous cell cancer; Basal cell cancer; Actinic keratosis

Other Skin Cancers

There are two other types of skin cancers: Basal Cell and Squamous Cell. Basal cell is the most common form of skin cancer.

Basal Cell Carcinomas

Basal cell carcinoma (BCC) is named for the round basal cells located in the lower part of the epidermis (the outermost layer of the skin), from which it arises. Like melanoma, the cancer has been increasing at a dramatic rate.

Prevalence and Risk Factors. Basal cell carcinoma occurs in 800,000 people every year, and 30% of people, almost exclusively Caucasians, can expect to have basal cell carcinoma, on average, by age 55. Some experts posit that genetic mutations caused by factors other than sunlight may also contribute to basal cell cancer.

Interestingly, a 2001 study reported that people with more wrinkles were less likely to develop basal cell carcinomas, even among high-risk groups. Some experts suggest that people prone to wrinkles may respond to sun exposure with biologic mechanisms that protect against basal cell carcinoma. More research is needed confirm this.

Characteristics. The lesions usually develop later in life in areas that have received the most sun exposure, such as the head, neck and back, and especially the nose. About a third of basal cell carcinomas appear in areas not exposed to the sun.

Basal cell carcinomas (BCCs) have many different appearances:

• They usually appear as a round area of thickened skin that does not change color or cause pain or itching.
• Very slowly, the lesion spreads out and develops a slightly raised edge, which may be translucent and smooth. Infrequently, basal cell carcinomas resemble malignant melanomas in color.
• Eventually, the center becomes hollowed and covered with a thin skin, which can become sore and open.
• A form known as aggressive-growth basal cell carcinoma resembles a scar with a hard base. This is type is more likely to spread and must be treated very aggressively.

Basal cell cancers are sometimes hard to tell from benign skin conditions. For instance, occasionally they arise in unexposed skin, where they may mimic an ordinary mole, cyst, or pimple. They may be particularly difficult to distinguish from benign cysts when they occur near the eyes.

Outlook. Usually, basal cells are slow growing. They are rarely fatal. Most basal cell carcinomas need not be treated as an emergency, although late treatment can cause disfigurement, so they should be removed as early as possible.

The basal cell carcinomas that are most likely to spread are larger ones (more than 1 centimeter), scar-like BCCs, particularly those located on the cheek, and any BCC on the nose, neck, earlobe, eyelid, or temple.

Some studies are indicating that people with basal cell carcinoma may be at higher risk for second cancers, including melanoma, cancer of the lip, salivary glands, larynx, lung, breast, and kidney and non-Hodgkin's lymphoma. Those at higher risk for such cancers appear to be men and anyone diagnosed before 60 with BCC.

Squamous Cell Carcinoma and Bowen's Disease

Characteristics. Squamous cell carcinoma (SCC) develops from keratinocytes, flat, scale-like skin cells that lie under the top layer of the epidermis. The majority of squamous cell carcinomas occur on sun-exposed areas, especially the forehead, temple, ears, neck, and back of the hands. People who have spent considerable time sunbathing may develop them on their lower legs. Their appearance changes with its stage:

• Squamous cell carcinoma in situ (often referred to as Bowen's disease ). This is the earliest stage when the cancer is local and has not spread. Lesions are typically large reddish patches (often over one inch) that are scaly and crusted.
• Invasive squamous cell carcinoma. These are lesions that are highly likely to spread (metastasize). They enlarge either rapidly (over months) or slowly (over years). Eventually they become ulcerated.

Prevalence and Risk Factors. About 160,000 people develop squamous cell carcinomas every year. The incidence of this cancer is increasing.

Sun exposure and sun damage are the greatest risk factors, and the addition of other factors compound the risk:

• Older age.
• Being fair skinned, particularly having red hair.
• Living in sunny climates.
• Treatments for psoriasis -- including PUVA (psoralen and UVA radiation) and immunosuppressant agents, such as cyclosporine -- also pose a risk for squamous cell carcinoma (SCC). [A 2005 study found that the rheumatoid arthritis drug etanercept (Enbrel) does not increase squamous cell cancer risk.]
• Genital warts (human papillomavirus) may also increase the risk in the genital and anal areas and around fingernails.

Outlook and Severity. Prompt treatment is desirable because squamous cell carcinomas are more likely to spread to local lymph nodes than are basal cell carcinomas, the other common skin cancer. Mortality rates for this cancer are very low, although squamous cell cancer still kills between 2,000 and 2,500 Americans each year. The risk for metastases (the spread of cancer to other organs) ranges from 0.5% to 16%, depending on risk factors. Squamous cell carcinomas most likely to spread include the following:

• Deep lesions, those larger than 2 cm in diameter, or patches with poorly defined margins.
• Recurrent lesions.
• SCC on neck, earlobe, eyelid, lips, or temple.
• SCC that develop in ulcers.
• SCC that develops on skin areas that have been previously treated with radiation or exposed to carcinogenic chemicals.

People with squamous cell carcinomas seem to be at higher risk for other cancers, including melanoma itself, lung cancer, non-Hodgkin lymphoma, bladder cancer, leukemia, testicular and prostate cancer in men, and breast cancer in women.

Precancerous Skin Disorders

Actinic (Solar) Keratoses. Actinic (also called solar) keratoses are the most common of all precancerous skin lesions. In fact, evidence now strongly supports the belief that actinic keratoses are actually squamous cell carcinomas in situ (the early stage of SCC). It should be noted, however, that not all actinic keratoses progress to carcinomas. One long-term study in 1999 indicated that the rate of malignant transformation might be about 10% over a 10-year period, while other studies show higher rates of progression to SCC.

Actinic keratoses occur after years of sun exposure and afflict over half of Caucasians aged 40 or older who live in hot, sunny climates. They occur predominantly on sun-exposed skin such as the face, neck, back of the hands and forearms, upper chest, and upper back. Men may develop keratoses along the rim of the ear.

Actinic keratoses have the following characteristics:

• Lesions typically occur on the surface of the skin and have a sandpaper-like feel. In fact, they are sometimes more easily felt than seen.
• Most lesions are pink and even flesh-colored. Some are red or brown, scaly, and tender. At times, they can resemble melanomas; even dermatologists may have trouble telling the two apart.
• They can range in size from microscopic to several inches in diameter.

Keratoacanthomas. Keratoacanthomas closely resemble squamous cell carcinomas, but they are not malignant. The majority occur in sun-exposed skin, usually on the hands or face. They are typically skin colored or slightly reddish when they first develop, but their appearance typically changes:

• In the early stages, keratoacanthomas are smooth, red, and dome shaped.
• Within a few weeks, they can grow rapidly, usually to 1 or 2 centimeters. Some reach the size of a quarter in less than a month and can be rather disfiguring.
• They eventually stop growing and become crater-like with an outer rim of tissue surrounding and a sometimes crusty interior.

Most will spontaneously regress within a year, but they almost always scar after healing. Also about 25% develop into squamous cell carcinomas, most frequently in older people and in sun-exposed areas. Removal by surgery (sometimes by radiation) is recommended. They may also be treated with 5-fluorouracil, either as a cream (Efudex) or with injections.

• Review Date: 6/7/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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