Skin cancer is the most common of all human cancers. Some form of skin cancer is diagnosed in more than 1 million people in the United States each year.
Cancer occurs when normal cells undergo a transformation during which they grow and multiply without normal controls.
• As the cells multiply, they form a mass called a tumor. Tumors of the skin are often referred to as lesions.
• Tumors are cancerous only if they are malignant. This means that they encroach on and invade neighboring tissues because of their uncontrolled growth.
• Tumors may also travel to remote organs via the bloodstream or lymphatic system.
• This process of invading and spreading to other organs is called metastasis.
• Tumors overwhelm surrounding tissues by invading their space and taking the oxygen and nutrients they need to survive and function.
Skin cancers are of three major types: basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma.
• The vast majority of skin cancers are BCCs or SCCs. While malignant, these are unlikely to spread to other parts of the body. They may be locally disfiguring if not treated early.
• A small but significant number of skin cancers are malignant melanomas. Malignant melanoma is a highly aggressive cancer that tends to spread to other parts of the body. These cancers may be fatal if not treated early.
Like many cancers, skin cancers start as precancerous lesions. These precancerous lesions are changes in skin that are not cancer but could become cancer over time. Medical professionals often refer to these changes as dysplasia. Some specific
dysplastic changes that occur in skin are as follows:
• Actinic keratosis is a patch of red or brown, scaly, rough skin, which can develop into squamous cell carcinoma.
• A nevus is a mole, and dysplastic nevi are abnormal moles. These can develop into melanoma over time.
Moles (nevi) are simply growths on the skin. They are very common. Very few moles become cancer.
• Most people have 10-40 moles on their body.
• Moles can be flat or raised; some begin as flat and become raised over time.
• The surface is usually smooth.
• Moles are round or oval and no larger than ¼-inch across.
• Moles are usually pink, tan, brown, or the same color as the skin. Other colors are sometimes noted.
• An individual's moles usually look pretty much alike. A mole that looks different from the others should be examined by your health-care provider.
Dysplastic nevi are not cancer, but they can become cancer.
• People with dysplastic nevi often have a lot of them, perhaps as many as 100 or more.
• People with many dysplastic nevi are more likely to develop melanoma, either within an existing nevus or on an area of normal skin.
• Dysplastic nevi are usually irregular in shape, with notched or fading borders.
• Dysplastic nevi may be flat or raised, and the surface may be smooth or rough ("pebbly").
• Dysplastic nevi are often large, ¼-inch across or even larger.
• Dysplastic nevi are typically of mixed color, including pink, red, tan, and brown.
Recent studies demonstrate that the number of skin cancer cases in the United States is growing at an alarming rate. Fortunately, increased awareness on the part of Americans and their health-care providers has resulted in earlier diagnosis and improved outcomes.
CAUSES OF SKIN CANCER
Ultraviolet (UV) light exposure, most commonly from sunlight, is overwhelmingly the most frequent cause of skin cancer.
Other important causes of skin cancer include the following:
• Use of tanning booths
• Immunosuppression-impairment of the immune system, which protects the body from foreign entities, such as germs or substances that cause an allergic reaction. This may occur as a consequence of some diseases or can be due to medications prescribed to combat autoimmune diseases or prevent organ transplant rejection.
• Exposure to unusually high levels of x-rays
• Contact with certain chemicals-arsenic (miners, sheep shearers, and farmers), hydrocarbons in tar, oils, and soot (may cause squamous cell carcinoma)
The following people are at the greatest risk:
• People with fair skin, especially types that freckle, sunburn easily, or become painful in the sun
• People with light (blond or red) hair and blue or green eyes
• Those with certain genetic disorders that deplete skin pigment such as albinism, xeroderma pigmentosum
• People who have already been treated for skin cancer
• People with numerous moles, unusual moles, or large moles that were present at birth
• People with close family members who have developed skin cancer
• People who had at least one severe sunburn early in life
Basal cell carcinomas and squamous cell carcinomas are more common in older people. Melanomas are more common in younger people. For example, melanoma is the most common cancer in people 25-29 years of age.
SYMPTOMS
A basal cell carcinoma (BCC) usually looks like a raised, smooth, pearly bump on the sun-exposed skin of the head, neck, or shoulders.
• Small blood vessels may be visible within the tumor.
• A central depression with crusting and bleeding (ulceration) frequently develops.
• A BCC is often mistaken for a sore that does not heal.
A squamous cell carcinoma (SCC) is commonly a well-defined, red, scaling, thickened patch on sun-exposed skin.
• Like BCCs, SCCs may ulcerate and bleed.
• Left untreated, SCC may develop into a large mass.
The majority of malignant melanomas are brown to black pigmented lesions.
• Warning signs include change in size, shape, color, or elevation of a mole.
• The appearance of a new mole during adulthood, or new pain, itching, ulceration, or bleeding of an existing mole should all be checked by a health-care provider.
The following easy-to-remember guideline, "ABCD," is useful for identifying malignant melanoma:
• Asymmetry-One side of the lesion does not look like the other.
• Border irregularity-Margins may be notched or irregular.
• Color-Melanomas are often a mixture of black, tan, brown, blue, red, or white.
• Diameter-Cancerous lesions are usually larger than 6 mm across (about the size of a pencil eraser), but any change in size may be significant.
TREATMENT
Treatment for basal cell carcinoma and squamous cell carcinoma is straightforward. Usually, surgical removal of the lesion is adequate. Malignant melanoma, however, may require several treatment methods, including surgery, radiation therapy, and chemotherapy. Because of the complexity of treatment decisions, people with malignant melanoma may benefit from the combined expertise of the dermatologist, a cancer surgeon, and an oncologist.
PREVENTION
You can reduce your risk of getting skin cancer.
• Limit sun exposure. Attempt to avoid the sun's intense rays between 10 a.m. and 2 p.m.
• Apply sunscreen frequently. Use a sunscreen with sun protection factor (SPF) of at least 15 both before and during sun exposure. Select products that block both UVA and UVB light. The label will tell you.
• If you are likely to sunburn, wear long sleeves and a wide-brimmed hat.
• Avoid artificial tanning booths.
• Conduct periodic skin self-examinations.
Skin self-examination
Monthly self-examination improves your chances of finding a skin cancer early, when it has done a minimum of damage to your skin and can be treated easily. Regular self-exam helps you recognize any new or changing features.
• The best time to do a self-exam is right after a shower or bath.
• Do the self-exam in a well-lighted room; use a full-length mirror and a handheld mirror.
• Learn where your moles, birthmarks, and blemishes are, and what they look like.
• Each time you do a self-exam, check these areas for changes in size, texture, and color, and for ulceration. If you notice any changes, call your primary-care provider or dermatologist.
Check all areas of your body, including "hard-to-reach" areas. Ask a loved one to help you if there are areas you can't see.
• Look in the full-length mirror at your front and your back (use the handheld mirror to do this). Raise your arms and look at your left and right sides.
• Bend your elbows and look carefully at your palms, your forearms (front and back), and upper arms.
• Examine the backs and fronts of your legs. Look at your buttocks (including the area between the buttocks) and your genitals (use the handheld mirror to make sure you see all skin areas).
• Sit down and examine your feet carefully, including the soles and between the toes.
• Look at your scalp, face, and neck. You may use a comb or blow dryer to move your hair while examining your scalp.
