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• 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

Prevention

Australia and Scotland have reported improved survival rates from melanoma after aggressive detection and prevention programs were started. In addition to encouraging regular self-examination, such programs include eliminating the sales tax on sunscreens, discouraging suntans and midday sports, and planting trees and placing canopies over children's playgrounds.

Self-Examinations for General Population

Anyone with risk factors for this cancer should be vigilant and check the entire body every month or so. Some experts have defined three specific areas for locating melanomas:

• Areas visible to anyone, such as the arms or face. (About 60% of melanomas are found here.)
• Areas usually covered with clothing and visible only to the patients or their partners. (About 34% of melanomas are detected in these areas.)
• Hidden areas usually found by health professionals (scalp, buttock folds, oral cavity.) About 6% are found here, but they also most likely to be more advanced and dangerous. Partners are useful in checking these areas. (A hair dryer to separate hair is useful for examining the scalp.)

Experts suggest drawing a map of the body indicating locations of moles, areas of discoloration, lumps, or other blemishes. Whenever a person conducts a self-examination, the map is checked for new lesions, lumps, or moles and for changes in shape, color, and size.

Professional Examination for High-Risk Individuals

Some experts recommend regular full-body screening by a trained health professional in high-risk individuals. High-risk people include those with personal or family history of melanoma and individuals with atypical nevi (irregular moles that are also larger than normal).

Such people should protect themselves from overexposure to sunlight and have a medical examination of the entire skin surface every 3 to 12 months, with the frequency depending on risk factors. Doctors may take photographs of any moles at each visit and compare them with previous photos for any changes. A self-examination should be performed every two months.

Routine screening for everyone does not appear to save many additional lives. In any case, individuals who are worried about any suspicious areas should see a dermatologist or be sure their primary care doctor is able to recognize skin cancers.

Examinations for Patients Previously Treated for Melanoma. People who have had melanoma and been treated successfully are at risk for recurrence or a second primary melanoma. Based on recurrence rates by cancer stage, a team of researchers suggested the following guidelines for being reexamined by the doctor after treatment:

• Stage I patients: Annual examinations.
• Stage II patients: Every 6 months for years 1 and 2 and annually thereafter.
• Stage III patients: Every 3 months for the first year, every 4 months for year 2, and every 6 months for years 3 to 5.

All patients should be checked annually from the sixth year onward. These are guidelines only and may be modified, depending on individual patient characteristics. Some studies also indicate that regular screening of family members of people with melanoma could prevent a number of serious cases.

General Guidelines for Avoiding the Sun and UV Radiation

The best way to prevent skin damage in any case is to avoid episodes of excessive sun exposure. The following are some specific guidelines:

• Use sunscreens that block out both UVA and UVB radiation. However, do not rely on them only for sun protection. Also wear protective clothing and sunglasses.
• Avoid exposure particularly during the hours of 10 AM to 4 PM, when sunlight pours down 80% of its daily UV dose.
• Avoid reflective surfaces, such as water, sand, concrete, and white-painted areas. (Clouds and haze are not protective and in some cases may intensify UVB rays.)
• Ultraviolet intensity depends on the angle of the sun, not heat or brightness. So the dangers are greater the closer to the summer-start date. For example, in the Northern Hemisphere, UV intensity in April (two months before summer starts) is equal to that in August (two months after summer begins).
• The higher the altitude the quicker one sunburns. (One study suggested, for example, that an average complexion burns at 6 minutes at 11,000 feet at noon compared to 25 minutes at sea level in a temperate climate.)
• Avoid sun lamp, and tanning beds or salons. They provide mostly high-output UVA rays. Some experts believe that 15 to 30 minutes at a tanning salon are as dangerous as a day spent in the sun. People should not be misled by advertising claims of "safe" tanning or promotions offering unlimited tanning.

Sunscreens. The use of sunscreens is complex, and everyone should understand how and when to use them. The bottom line is not that people should avoid sunscreens or sunblocks, but that they should always use them in combination with other sun-protective measures.

Protective Clothing. Wearing sun-protective clothing is extremely important and protects even better than sunscreens. Special clothing is now available for blocking UV rays and is rated using SPF ratings or a system called the UPF (ultraviolet protection factor) index, with 50 UPF being the highest. (According to one study, this is a very reliable indicator of protection.) The clothing is expensive, however. The following are some tips for anyone:

• Everyone, including children, should wear hats with wide brims. (Even wearing a hat, however, may not be fully protective against skin cancers on the head and neck.)
• People should look for loosely fitted, unbleached, tightly woven fabrics. The tighter the weave the more protective the garment.
• Washing clothes over and over improves UPF by drawing fabrics together during shrinkage. An easy way to assess protection is simply to hold the garment up to a window or lamp and see how much light comes through. The less the better.
• Everyone over age 1 should wear sunglasses that block all UVA and UVB rays when in the sun.

Chemical Tanners

Some research suggests that melanin and dihydroxyacetone (DHA), the active ingredients in many self-tanning lotions, may help filter out UVA and UVB radiation and so be protective. More research is underway.

Role of Fats

One study indicated that people who reduced their intake of fat to 20% of their daily diet were significantly less likely than those on a high-fat diet to develop actinic keratosis, a common aging skin disorder that can also be a precursor to nonmelanoma skin cancer. Low-fat diets, however, appear to have no effect on basal cell carcinoma. In fact, some studies have suggested that certain fatty acids, such as those found in monounsaturated fats (e.g., olive and canola oils) or fish oils, may help protect the skin against sun-related diseases.

Oral Retinoids

The oral retinoids acitretin, etretinate, and isotretinoin have been shown to prevent nonmelanoma skin cancer in patients with basal cell nevus syndrome, xeroderma pigmentosum, and transplanted organs. They may also prevent the development of squamous cell carcinoma in patients for whom retinoids are used to treat psoriasis.

Antioxidants and other Natural Substances

Antioxidants are substances that act as scavengers of free radicals, mopping up unstable particles that, in excess, can damage the basic structure of cells, including their genetic material (DNA). Nevertheless, it is not yet known whether antioxidants can effectively protect against cancer, heart disease, premature aging, and other maladies. Among the most well-known antioxidants for the skin are vitamins C and E, and coenzyme Q10 (CoQ10).

Topical Antioxidants. Although there are wide claims about the benefits of antioxidants for wrinkles when used in skin creams, to date, only vitamins E and C and selenium applied topically have been proven to have any benefits for reducing sun damage in the skin. Even with these antioxidants, however, most available brands contain very low concentrations of them. In addition, they are also not well absorbed and have a short-term effect. New delivery techniques, however, may prove to offset some of these problems.

• Vitamin E. Studies suggest that topical vitamin E, particularly alpha tocopherol (a form of vitamin E) cream decreased skin roughness, length of facial lines, and wrinkle depth. Studies on mice have also reported reductions in UV-induced skin cancer with its use.
• Vitamin C, or ascorbic acid. This is a very potent antioxidant, and most studies on the effects of antioxidants on the skin have used this vitamin. In laboratory studies, large amounts reduced skin swelling and protected immune factors from sunlight. It may even promote collagen production. Vitamin C by itself is unstable, but products that solve the delivery problem are now available (for example, Cellex-C, Avon's Anew Formula C Treatment Capsules, and others).
• Selenium in the form of L-selenomethionine has protected against sun damage and even delayed skin cancer in animal studies. It is not known if such benefits apply to people.

Oral Antioxidants. One small study found that taking a combination of vitamins oral C and E supplements may help reduce sunburn reactions, although the protection is much less than from sunscreens. (Taking the vitamins singly does not appear to have the same effect.)

Other Natural Substances. The following natural substances have antioxidant properties and are being tried for sun-protection:

• Both green and black tea and ginger appear to have properties that may provide some protection against skin cancers and photoaging. A 2001 study using extracts of topical green tea suggested that it might protect against ultraviolet damage. More research is warranted. Green tea skin care products are now available, but their quality is unregulated.
• The substance silymarin, found in the milk thistle family (which includes artichokes), may inhibit UVB-promoted cancers in animals.
• In one interesting study, eating garlic protected animals very effectively against UVB damage by interfering with urocanic acid in the skin. Whether these results may be applied to humans, and what quantities of garlic might be beneficial, is still unknown.

Warning Note: A wide range of herbal products -- both oral and topical -- may contribute to dermatological problems. Some Chinese herbal creams have been found to contain corticosteroids; mercury or arsenic contaminants have been found in some Ayurvedic therapies. In addition, several oral herbal remedies used for medical or emotional conditions may produce irritation in reaction to sunlight (photosensitivity). They include, but are not limited to, St. John's Wort, kava, and yohimbe.

Chemopreventive agents

Chemopreventive agents include a wide range of substances used for other diseases that may inhibit the development of melanoma. Agents under investigation and showing promise include statins and fibrates (cholesterol-lowering drugs), retinoids (anti-aging skin drugs), nonsteroidal anti-inflammatory drugs (for arthritis and other pain relief), difluoromethylornithine (DFMO), catechins (phytochemicals found in certain foods), and imiquimod (a treatment for warts).

Exercise

Studies have shown that mice with round-the-clock access to an exercise wheel developed skin cancer more slowly when exposed to UVB. Their tumors were also fewer in number and smaller. Analysis of the data suggested that exercise might trigger the death of the developing cancer cells faster than they can grow. Exercise also made the mice lose weight, and the number of tumors decreased as fat disappeared.

Experimental Agents

Ointments that Prevent Skin Cancers on a Molecular Level. Of interest are studies suggesting the compounds that target genetic mechanisms in the skin may prove to be beneficial ingredients in topical products (e.g., creams, lotions) that prevent skin cancers on a molecular level. They include the cytokine interleukin-12 and an enzyme called T4 endonuclease 5 (T4N5).

Sunscreen Guidelines When choosing a sunscreen, look at the ingredients. Preparations that help block UV radiation are sometimes classified as sunscreens or sunblocks, according to the substances they contain. In general, sunscreens contain organic formulas and sunblocks inorganic formulas. However, the term sunblock is used less and less as sunscreens increasingly contain both kinds of ingredients: Organic formulas contain UV-filtering chemicals such as octocrylene, octyl salicylate, homosalate, and octyl methoxycinnamate (block UVB), avobenzone-Parsol 1789 (blocks UVA), cinoxate, ethylhexyl p-methoxycinnamate (blocks UVB and small amounts of UVA), oxybenzone, and benzophenone-3 (blocks UVA/UVB). People should look for a wide-spectrum sunscreen that contains combinations of these ingredients and filter both UVA and UVB. Of note: para-amino benzoic acid (PABA), once a popular ingredient, is now used infrequently. It is not known if they have the same effects. PABA may actually break down in the presence of UV exposure and release harmful oxidants. And many people have an allergic reaction to it. Some products contain PABA derivatives, such as padimate O or octyl dimethyl PABA. Inorganic formulas contain the UV-blocking pigments zinc oxide or titanium dioxide. Zinc and titanium oxides lie on top of the skin and are not absorbed. They prevent nearly all UVA and UVB rays from reaching the skin. Older sunblocks are white, pasty, and unattractive, but current products use so-called microfine oxides, either zinc (Z-Cote) or titanium. They are transparent and nearly as protective as the older types. Microfine zinc oxide may be more protective and less pasty-colored than microfine titanium oxide. Inexpensive products work as well as expensive ones with the same ingredients. Unfortunately, there are still no standards for sunscreens, and even those claiming UVA protection may offer very little. In one study, the average UVA protection from a wide range of brands was only 23%. In fact, the average protection on brands not making the claim was 37%! Organic formulas and inorganic microfine oxides do not protect against visible light, which is a problem for people who have light-sensitive skin conditions, including actinic prurigo, porphyria, and chronic actinic dermatitis. Inorganic sunscreens that protect against visible light and are still cosmetically acceptable are now available in Europe, but not yet in the US. In July 2006, the FDA approved a new sunscreen for protection against UVB and UVA, with a sun protection factor of 15. Anthelios SX, made by L'Oreal, contains the UVA-blocking ingredient ecamsule, previously unavailable in the U.S. but marketed in Europe and Canada since 1993 as Mexoryl SX. Calculating the SPF The sun protection factor (SPF) on all sunscreen labels is a ratio based on the amount of UVB (not UVA) radiation required to turn sunscreen- or sunblock-treated skin red compared to non-treated skin. For instance, people who sunburn in 5 minutes and who want to stay in the sun for 150 minutes might use an SPF 30. The formula would be: 30 (the SPF number) times 5 (minutes to burn) = 150 minutes in the sun. Protection offered by sunscreens may be classified as follows: Minimal: SPF 2 to 11 Moderate: SPF 12 through 29. High: 30+. (Although some sunscreens claim SPFs higher than 30, the added protection at such higher levels is insignificant.) SPF Levels by Age Group Certain groups should have higher or lower SPFs depending on age and other factors: Although sunscreens are safe in most toddlers and children, they should not be the first and only lines of defense. In fact, experts are worrying that by relying too much on sunscreen and not providing other protective measures, parents may actually be increasing their children's risk for melanoma. All young children should be well covered with clothing, sunglasses, and hats as the first line of defense against sunburn. Children should be kept out of the sun during peak sunlight periods. Do not use sunscreens on babies younger than six months without consulting a doctor. Older children and adults (even those with darker skin) benefit from using SPFs of 15 and over. Some experts recommend that most people should use SPF 30 on the face and 15 on the body. Adults who burn easily instead of tanning and anyone with risk factors for skin cancer should use at least SPF 30. Timing and Amount of Application Apply sunscreen or sunblock liberally as follows: Adults should include sunscreen with a daily skin regimen, even if going outdoors for only a short time. Apply a large amount to all exposed areas, including ears and feet. To achieve protection as indicated by the sunscreen's SPF, experts recommend half a teaspoon each for the head, neck, and each arm and a teaspoon each for the chest area, the back, and each leg. Apply initially 30 minutes before venturing outdoors for best results. (This allows time for the sunscreen to be absorbed. Then reapply every 15 to 30 minutes while being in the sunlight. Also reapply each time after exercise or swimming. (Choose a waterproof or water-resistant formula even if activities don't include swimming. Waterproof formulas last for about 40 minutes in the water, whereas water-resistant formulas last half as long.) Insect repellents reduce sunscreen SPFs by up to one-third. Use higher SPFs and very liberal application when applying both. Possible Hazards of Sunscreens, Sun Avoidance, or Both When used generously and appropriately, sunscreen products and sun avoidance help reduce the severity of many aging skin disorders, including squamous cell cancers. There are certain concerns, however. Sunscreen Use May Not Protect Against Basal Cell and Melanoma Cancers-and May Even Increase the Risk. Although sunscreens help prevent squamous cell carcinomas and other skin disorders, sunscreens do not appear to provide protection against melanoma and some basal cell cancers. In fact, some studies have reported a higher association with sunscreen use and these skin malignancies, though not all studies report such negative results. The reasons for this possible increased risk are unclear, though some theories include the following: Until recently, many sunscreens blocked only or predominantly blocked UVB rays and not UVA, the more deeply penetrating rays now known to be especially dangerous. Studies then may not have reflected the effects of the broad-spectrum sunscreens now available, which block both UVA and UVB. People who apply sunscreens may feel safe and stay out longer during high sun-exposure hours than is safe. Even if a person doesn't sunburn, UVA rays can still penetrate the skin and do harm. People may not put on enough sunscreen. In fact, according to a 2002 study, people generally apply only 20 - 60% of the recommended amount, which can provide significantly less protection than the given SPF. (A 2003 study reported that when applied at the recommended amount, a broad-screen sunscreen prevents DNA damage from UV exposure. However, omitting it even once resulted in significant cell injury.) Sunscreens Use May Increase the Risk for Health Problems Related to Sunlight Deficiencies. There is some major concern that underexposure to sunlight, due to the use of sunscreens or sun-avoidance measures, may produce other health problems, such as the following: Vitamin D Deficiency. Vitamin D is found in foods, but it is primarily manufactured through a chemical reaction to ultraviolet B sunlight. Vigorous sun-protection measures, then, may increase a person's risk for developing vitamin D deficiency. Vitamin D is important for prevention of rickets and osteoporosis and some cancers, including melanoma. People who need to avoid sunlight and whose diet is low in foods that contain vitamin D should check with their doctor about taking supplements. People with darker skin are at higher risk for deficiencies from sun protection than those with whiter skin. (Note: Vitamin D is toxic in high doses.) Other Cancers. Although sunlight is implicated in skin cancers, it is also associated with lower risks for breast, prostate, ovarian, and colon cancers. Some protection against these cancers may be related to vitamin D production by sunlight. Depression. Many people suffer from SAD (seasonal affective disorder), a form of depression that generally occurs in winter and is associated with exposure to less sunlight. The bottom line is that some sunlight is important and even necessary for a healthful and high-quality life. Some experts recommend that adults may benefit from daily moderate tanning (20 to 30 maximum minutes of exposure during lower-risk hours) over a number of days to slowly build up pigment in the skin.

• 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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