Skin Cancer: Basal Cell Carcinoma, Squamous Cell Carcinoma, and Malignant Melanoma

Skin cancer is the most common form of cancer in the United States.

Skin cancer is a tumor or growth of abnormal cells in the skin. Most experts agree that the primary cause of skin cancer is overexposure to sunlight. However, repeated exposure to X-ray radiation, certain chemical toxins and a family history of skin cancer can also increase your risk for skin cancer.

How can I reduce my risk? 
Prevention and early detection are the best ways to reduce your risk for skin cancer. 

Prevention is avoiding the sun (especially between 10 a.m. and 4 p.m.) and using sunscreens with a sun protection factor (SPF) of at least 30. It is very important to apply sunscreen to young children and infants after 6 months of age. Other prevention tips include:

Early detection involves regularly and thoroughly inspecting your body for any skin changes. Any new or changing moles, sores or discolorations should be evaluated by a physician as soon as you notice them.

In addition, total skin examinations should be done routinely by a physician to detect skin cancer. Special attention should be given to the back, legs, scalp, toes, soles, and the skin around the mouth, anus and vagina.

Determining your skin phototype
If you tan easily, your skin is phototype III or IV. If you don't tan easily, your skin is phototype I or II. If you have skin phototypes I or II, you have an increased risk for all skin cancers, especially if you have a history of sunburn or blistering as a result of overexposure to the sun. People with skin phototypes I and II should never sunbathe.

People with dysplastic moles, melanoma, or any diagnosed skin cancer, regardless of skin phototype, should never sunbathe and should wear protective clothing and sunscreen when outdoors.

Forms of skin cancer
The three forms of skin cancer are basal cell carcinoma, squamous cell carcinoma and malignant melanoma.

Basal cell carcinoma
Basal cell carcinoma is the most common type of skin cancer. It usually appears as a sore that bleeds, scabs, heals and then recurs. It can appear as a flat, scaly red patch; a small, smooth, shiny or waxy bump; a patch with large blood vessels; or a brown or black raised bump.

The head and neck are the most common areas affected, with 85 percent of all basal cell carcinomas occurring in these sun-exposed areas. Basal cell carcinoma can also affect sun-protected areas such as the genitals and breasts, but this is rare.

Although basal cell carcinoma rarely spreads to other areas (metastasizes), it can affect surrounding tissues if left untreated.

Who is at risk for basal cell carcinoma?
Men have a significantly higher incidence of basal cell carcinoma than women. It can occur at any age, but the incidence of this cancer increases greatly after age 40.

Fair-skinned people with skin phototypes I and II and a high degree of sun exposure are at increased risk. Basal cell carcinoma is rare in dark-skinned individuals. Frequent sun exposure in youth (before age 18) predisposes a person to basal cell carcinoma later in life.

X-ray radiation therapy and arsenic ingestion are also contributing risk factors.

Squamous Cell Carcinoma
Squamous cell carcinoma is the second most common type of skin cancer. It can appear as red or brown, hard scaly patches, or as soft red bumps or nodules.

Sun-exposed areas such as the face, tips of ears, scalp in bald men, backs of hands, forearms and trunk are the areas of the body that are typically affected.

Rarely, squamous cell carcinoma can develop in old scars, especially burn and radiation scars, or on the genitalia. Unlike basal cell carcinoma, squamous cell carcinoma can metastasize and has a higher mortality rate.

Who is at risk for squamous cell carcinoma?
Fair-skinned people with skin phototypes I and II have an increased risk. The incidence of squamous cell carcinoma increases in geographic areas that are predominately sunny, and in people with occupational sun exposure such as farmers, sailors and construction workers. Chemical carcinogens such as ingestion of arsenic and exposure to X-rays and gamma rays also have been linked, and are possible agents for squamous cell carcinoma development in dark-skinned individuals. The incidence of this cancer increases with age and men are twice as likely to be affected than women.

Malignant melanoma
Malignant melanoma is a cancer that arises in melanocytes, the pigment-producing cells of the skin. Melanoma is the most dangerous skin cancer. It grows rapidly and has the ability to metastasize to any organ. Melanoma represents 1 to 2 percent of all cancer deaths in the U.S.

Although malignant melanoma is more prevalent in Caucasians (the incidence is 20 times higher than in African Americans), melanoma can occur in people of all skin types.

By the year 2000, it is estimated that 1 in 75 individuals will develop melanoma. Early detection is especially important in melanoma because curability is directly related to the size and depth of the invading tumor.

About 30 percent of melanomas arise from preexisting moles, while 70 percent affect normal skin.

Initially, melanoma has a radial or horizontal growth phase, during which there is little, if any, invasive potential, since growth is primarily superficial. This phase can last from a few months up to 2 years. Subsequently, there is a vertical growth phase, during which the melanoma grows deep toward blood vessels, allowing the potential for metastasis. Detection of "thin" melanomas during the radial phase is essential for high cure rates following surgical removal of the tumor.

Who is at risk for malignant melanoma?
Individuals with skin phototypes I and II, especially with a history of prolonged or excessive sun exposure in youth, are at risk. Family history of melanoma or dysplastic "atypical" moles are added risk factors. People with more than 50 moles that are greater than 2.0 mm in diameter are also at increased risk. However, some people at risk may not have any moles; for example, people with red hair or who have freckles.

Malignant melanoma is the most common cancer in women ages 25 to 29 and the second most common cancer in women ages 30 to 34 and in men ages 30 to 49. Melanomas detected early, in the "thin" stage, have very high five-year survival rates of about 98 percent, while overall survival is 83 percent.

Know the ABCDE's for early melanoma detection
(Modified from The American Academy of Dermatology's ABCD's for early melanoma detection) 

Asymmetry in shape --one half unlike the other half
Border is irregular -- edges are scalloped, notched or blurred
Color is mottled and not uniform -- shades of brown, black, gray, red and white
Diameter -- the size of the mole is usually large: greater than the tip of a pencil eraser (6.0mm)
Elevation is almost always present, but may also be flat
Enlargement -- a history of increase in size is one the most important signs

Skin cancer treatment
Early detection and removal is the best defense against skin cancer. The cure rate for both basal cell and squamous cell carcinoma is 95 percent, when properly treated.

Any area of the skin that a physician determines is cancerous can be managed with various procedures. Basal and squamous cell carcinomas can be removed in the physician's office under local anesthetic. If the area is large, it can be removed surgically.

Cryotherapy (freezing), topical chemotherapy, radiation therapy and electrosurgery can also be done to treat basal and squamous cell carcinomas. Treatment of malignant melanoma depends on the thickness of the tumor. If discovered early, before any evidence of metastasis, treatment involves the surgical removal of the tumor and a small area of skin around it. If the tumor is large, a skin graft may be required to close the wound. Some of the lymph nodes around the area may need to be removed if there is any suspicion that the cancer has spread.

Careful follow-up with frequent doctor visits is essential for all types of skin cancers.

Should I be examined by my doctor?
If you have any of the following, you should be examined by your doctor:

ABCD's for early melanoma detection and photographs used in this brochure are reprinted with permission from The American Academy of Dermatology.  All rights reserved.

Copyright 1995-2005 The Cleveland Clinic Foundation. All rights reserved

 

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit www.clevelandclinic.org/health/ or www.clevelandclinicflorida.org. This document was last reviewed on: 9/22/2004

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