Skin cancer is the most common of all cancer types. More than 1 million skin cancers are diagnosed each year in the United States. That’s more than cancers of the prostate, breast, lung, colon, uterus, ovaries, and pancreas combined. The number of skin cancer cases has been on the rise for the past few decades.
The good news is that there is a lot you can do to protect yourself and your family from skin cancer, or to catch it early enough so that it can be treated effectively. Most skin cancers are caused by too much exposure to ultraviolet (UV) rays. Much of this exposure comes from the sun, but some may come from manmade sources, such as tanning beds.
This document discusses how skin cancer develops and some simple steps you can take to help protect yourself from getting it. It also describes how to look for signs of skin cancer on your body. Finding possible skin cancers doesn’t require any x-rays or blood tests – just your eyes and a mirror. If skin cancer does develop, finding it early is the best way to ensure it can be treated effectively.
What is skin cancer?
Skin cancers are divided into 2 main types: keratinocyte cancers (basal and squamous cell skin cancers) and melanomas.
Basal and squamous cell skin cancers are the most common cancers of the skin. They develop from cells called keratinocytes, the most common cells in the skin.
Melanomas are cancers that develop from melanocytes, the cells that make the brown pigment that gives skin its color. Melanocytes can also form benign growths called moles.
There are several other types of skin cancers as well, but these are much less common.
It is important for doctors to tell these types of skin cancer apart, because they are treated differently. It is also important for you to know what melanomas and basal and squamous cell skin cancers look like. That way, you can find them at the earliest possible stage, when they are cured most easily.
Basal and squamous cell cancers (keratinocyte cancers)
Basal cell cancers and squamous cell cancers are the most common cancers of the skin. They develop from skin cells called keratinocytes. Both basal cell and squamous cell cancers are found mainly on parts of the body exposed to the sun, such as the head and neck, and their occurrence is related to the amount of sun exposure over a person’s lifetime.
These cancers (especially basal cell cancers) rarely spread elsewhere in the body and are less likely than melanomas to be fatal. Still, they are important to recognize. If left untreated, they can grow quite large and invade into nearby tissues, causing scarring, disfigurement, or even loss of function in some parts of the body.
Keratinocyte cancers are discussed in more detail in a separate American Cancer Society document, Skin Cancer: Basal and Squamous Cell.
Melanomas can occur anywhere on the body, but are more likely to develop in certain locations. The trunk is the most common site in men. In women, the legs are the most common site. Some experts think that melanomas develop more often in these spots because these areas are exposed to sun off and on and are more likely to get sunburned. Rarely, melanomas can also develop in other parts of the body, such as the eyes.
Melanoma occurs much less often than basal cell and squamous cell skin cancers, but it can be far more serious. Like basal cell and squamous cell cancers, melanoma is almost always curable in its early stages. But if left alone, melanoma is much more likely than basal or squamous cell cancer to spread to other parts of the body, where it can be very hard to treat.
Melanomas are discussed in more detail in a separate American Cancer Society document, Melanoma Skin Cancer.
What is ultraviolet (uv) radiation?
Ultraviolet (UV) rays are a form of invisible energy given off by the sun. Ultraviolet radiation is divided into 3 wavelength ranges:
- UVA rays cause skin cells to age and can cause some damage to cells’ DNA (the substance in each cell that controls its growth, division, and function). UVA rays are mainly linked to long-term skin damage such as wrinkles, but are also thought to play a role in some skin cancers.
- UVB rays are mainly responsible for direct damage to the DNA, and are the rays that cause sunburns. They are also thought to cause most skin cancers.
- UVC rays don’t penetrate our atmosphere and therefore are not present in sunlight. They are not normally a risk factor for skin cancer.
Although UVA and UVB rays make up only a very small portion of the sun’s wavelengths, they are mainly responsible for the harmful effects of the sun on the skin. UVB radiation can damage the DNA of skin cells. If this damage affects the DNA of genes that control skin cell growth, skin cancer may be the result. Recent research has found that UVA also contributes to skin cancer formation. Scientists now believe that both UVA and UVB rays damage skin and cause skin cancer. There are no safe UV rays.
Skin cancers are one result of getting too much sun, but there are others as well. The short-term results of unprotected exposure to UV rays are sunburn and tanning, which are forms of skin damage. Long-term exposure causes prematurely aged skin, wrinkles, loss of skin elasticity, dark patches (lentigos, sometimes called “age spots” or “liver spots”), and pre-cancerous skin changes (such as dry, scaly, rough patches called actinic keratoses).
The sun’s UV rays also increase a person’s risk of cataracts and certain other eye problems and can suppress their immune system. Although dark-skinned people are generally less likely to get skin cancer than light-skinned people, they can still get cataracts and immune system suppression.
The UV Index
The amount of UV light reaching the ground in any given place depends on a number of factors, including the time of day, time of year, elevation, and cloud cover. To help people better understand the intensity of UV light in their area on a given day, the Environmental Protection Agency (EPA) and the National Weather Service have developed the UV Index. The UV Index number, on a scale from 1 to 11+, is a measure of the amount of UV radiation reaching the earth’s surface during an hour around noon. The higher the number, the greater the exposure to UV radiation.
The UV Index is given daily for regions throughout the country. Many newspaper and television weather forecasts now include the projected UV Index for the following day. As with any forecast, local changes in cloud cover and other factors may change the actual UV levels experienced, but the UV Index reminds the public to take precautions against too much exposure.
Are some people more prone to sun damage?
Everyone’s skin and eyes can be affected by the sun and other forms of UV rays. Although people with light skin are much more likely to have sun damage, darker-skinned people, including African Americans and Hispanic Americans, also can be affected.
People with darker skin tan more easily than others. But tanning is still a form of skin damage. Tanning occurs when UV radiation is absorbed by the skin, causing an increase in the activity and number of melanocytes, the cells that make the pigment melanin. Melanin helps to block out damaging rays up to a point, which is why darker-skinned people burn less easily.
People with lighter skin are more likely to burn. Sunburns are thought to increase your risk of skin cancer, especially melanoma. But UV exposure can raise skin cancer risk even without causing sunburn.
Aside from skin tone, other factors can also affect your risk of damage from UV light. You need to be especially careful in the sun if you:
- have lots of moles, irregular moles, or large moles
- have freckles and burn before tanning
- have fair skin or blond, red, or light brown hair
- were previously treated for skin cancer
- have a family history of skin cancer, especially melanoma
- live or vacation at high altitudes (UV radiation increases 4% to 5% for every 1,000 feet above sea level)
- live or vacation in tropical or subtropical climates
- work indoors all week and then get intense sun exposure on weekends
- spend a lot of time outdoors
- have certain autoimmune diseases, such as systemic lupus erythematosus (SLE, or “lupus”)
- have had an organ transplant
- take medicines that lower your immunity
- take oral contraceptives (birth control pills)
- take tetracycline, sulfa drugs, or certain other antibiotics
- take naproxen sodium or certain other non-steroidal anti-inflammatory drugs (NSAIDs)
- take phenothiazines (major tranquilizers and anti-nausea drugs)
- take tricyclic antidepressants
- take thiazide diuretics (medicines used for high blood pressure and some heart conditions)
- take sulfonylureas (a form of oral anti-diabetic medication)
Ask your doctor, nurse, or pharmacist about the risk of any medicines you may be taking that could increase your sensitivity to sunlight.
How do I protect myself from UV rays?
It isn’t possible or practical to completely avoid sunlight, and it would be unwise to reduce your level of activity to avoid the outdoors. Time in sunlight also helps your body make vitamin D, which can be important for good health. But too much sunlight can be harmful. There are some steps you can take to limit your amount of exposure to UV rays.
Some people think about sun protection only when they spend a day at the lake, beach, or pool. But sun exposure adds up day after day, and it happens every time you are in the sun. “Slip! Slop! Slap! … and Wrap” is a catch phrase that reminds people of the 4 key methods they can use to protect themselves from UV radiation. Slip on a shirt, slop on sunscreen, slap on a hat, and wrap on sunglasses to protect the eyes and sensitive skin around them from ultraviolet light.
Following these practical steps can help protect you from the effects of the sun. These steps complement each other — they provide the best protection when used together.
When you are out in the sun, wear clothing to protect as much skin as possible. Clothes provide different levels of protection, depending on many factors. Long-sleeved shirts, long pants, or long skirts cover the most skin and are the most protective. Dark colors generally provide more protection than light colors. A tightly woven fabric protects better than loosely woven clothing. Dry fabric is generally more protective than wet fabric.
If you can see light through a fabric, UV rays can get through too. Be aware that covering up doesn’t block out all UV rays. A typical light T-shirt worn in the summer usually protects you less than sunscreen with a sun protection factor (SPF) of 15 or higher.
The ideal sun-protective fabrics are lightweight, comfortable, and protect against exposure even when wet. A few companies in the United States now make sun-protective clothing. They tend to be more tightly woven, and some have special coatings to help absorb UV rays. Some sun-protective clothes have a label listing the ultraviolet protection factor (UPF) value — the level of protection the garment provides from the sun’s UV rays (on a scale from 15 to 50+). The higher the UPF, the higher the protection from UV rays.
Children’s swimsuits made from sun-protective fabric and designed to cover the child from the neck to the knees are popular in Australia. They are now available in some areas of the United States.
Newer products are now available to increase the UPF value of clothes you already own. Used like laundry detergents, they add a layer of UV protection to your clothes without changing the color or texture.
Use a sunscreen with a sun protection factor (SPF) of 15 or higher
A sunscreen is a product that you apply to your skin for some protection against the sun’s UV rays, although it does not provide total protection. Sunscreens are available in many forms — lotions, creams, ointments, gels, wipes, and lip balms, to name a few.
Some cosmetics, such as lipsticks and foundations, also are considered sunscreen products if they contain sunscreen. Some makeup contains sunscreen, but only the label can tell you. Makeup, including lipstick, without sunscreen does not provide sun protection. Check the labels to find out.
Read the labels: When selecting a sunscreen product, be sure to read the label before you buy. Experts recommend products with a sun protection factor (SPF) of at least 15. The SPF number represents the level of protection against UVB rays provided by the sunscreen — a higher number means more protection.
It is important to remember that sunscreen does not give you total protection. When using an SPF 15 and applying it correctly, you get the equivalent of 1 minute of UVB rays for each 15 minutes you spend in the sun. So, 1 hour in the sun wearing SPF 15 sunscreen is the same as spending 4 minutes totally unprotected.
The SPF number indicates protection against UVB rays only. Sunscreen products labeled “broad-spectrum” protect against UVA and UVB radiation, but at this time there is no standard system for measuring protection from UVA rays. Products with an SPF of 15 or higher that also contain avobenzone (Parsol 1789), ecamsule, zinc oxide, or titanium dioxide are likely to be effective against UVB and most UVA rays.
The Food and Drug Administration (FDA), which regulates sunscreens in the United States, has proposed a new set of rules for sunscreen labels. Part of this includes a rating system for UVA protection. Under the new system, sunscreens would be rated from 1 to 4 stars, with 1 star being a low level of UVA protection and 4 stars being the highest. It is not yet clear when this new rule might go into effect.
Check for an expiration date on the sunscreen container to be sure it is still effective. Most sunscreen products are no longer as effective after 2 to 3 years.
Some sunscreen products can irritate skin. Many products claim to be “hypoallergenic” or “dermatologist tested,” but the only way to know for sure whether a product will irritate your skin is to apply a small amount for 3 days. If your skin does not turn red or become tender and itchy, the product should be okay for you.
Be sure to apply the sunscreen properly. Always follow the label directions. Most recommend applying sunscreen generously to dry skin 20 to 30 minutes before going outside so your skin has time to absorb the chemicals. When applying it, pay close attention to your face, ears, hands, and arms, and generously coat the skin that is not covered by clothing. If you’re going to wear insect repellent or makeup, apply the sunscreen first. For high-glare situations, a higher SPF sunscreen or zinc oxide may be used on your nose and lips.
Be generous. About 1 ounce of sunscreen (a “palmful”) should be used to cover the arms, legs, neck, and face of the average adult. For best results, most sunscreens must be reapplied at least every 2 hours and even more often if you are swimming or sweating. Products labeled “waterproof” may provide protection for at least 80 minutes even when you are swimming or sweating. Products that are “water resistant” may provide protection for only 40 minutes. Remember that sunscreen usually rubs off when you towel yourself dry, so you will need to reapply.
Sunless tanning products, such as bronzers and extenders (described below), give skin a golden color. But unlike sunscreens, these products provide very little protection from UV damage.
Wear a hat
A hat with at least a 2- to 3-inch brim all around is ideal because it protects areas often exposed to the sun, such as the neck, ears, eyes, forehead, nose, and scalp. A shade cap (which looks like a baseball cap with about 7 inches of fabric draping down the sides and back) also is good. These are often sold in sports and outdoor supply stores.
A baseball cap can protect the front and top of the head but not the back of the neck or the ears, where skin cancers commonly develop. Straw hats are not recommended unless they are tightly woven.
Wear sunglasses that block UV rays
Research has shown that long hours in the sun without protecting your eyes increase your chances of developing eye disease. UV-blocking sunglasses can help protect your eyes from sun damage.
The ideal sunglasses do not have to be expensive, but they should block 99% to 100% of UVA and UVB radiation. Check the label to be sure they do. Some labels may say, “UV absorption up to 400 nm.” This is the same as 100% UV absorption. Also, labels that say “Meets ANSI UV Requirements” mean the glasses block at least 99% of UV rays. Those labeled “cosmetic” block about 70% of the UV rays. If there is no label, don’t assume the sunglasses provide any protection.
Darker glasses are not necessarily better because UV protection comes from an invisible chemical applied to the lenses, not from the color or darkness of the lenses. Look for an ANSI label.
Large-framed and wraparound sunglasses are more likely to protect your eyes from light coming in from different angles. Children need smaller versions of real, protective adult sunglasses — not toy sunglasses.
Ideally, all types of eyewear, including prescription glasses and contact lenses, should absorb the entire UV spectrum. Some contact lenses are now made to block most UV rays. But because they don’t cover the whole eye and surrounding areas, they are not recommended for eye protection use alone.
Limit direct sun exposure during midday
Another way to limit exposure to UV light is to avoid being outdoors in sunlight too long. UV rays are most intense during the middle of the day, usually between the hours of 10 am and 4 pm. If you are unsure about the sun’s intensity, take the shadow test: If your shadow is shorter than you, the sun’s rays are the strongest. Plan activities out of the sun during these times. If you must be outdoors, protect your skin.
UV rays reach the ground throughout the year, even on cloudy days. UV rays can also pass through water, so don’t think you’re safe if you’re in the water and feeling cool. Be especially careful on the beach and in the snow because sand and snow reflect sunlight, increasing the amount of UV radiation you receive.
Some UV rays can also pass through windows. Typical car, home, and office windows block most of the UVB rays but a smaller portion of UVA rays, so even if you don’t feel you’re getting burned your skin may still get some long-term damage. Tinted windows help block more UVA rays, although this depends on the type of tinting. UV radiation that comes through windows probably doesn’t pose a great risk to most people unless they spend extended periods of time close to a window that receives direct sunlight.
If you plan to be outdoors, you may want to check the UV Index for your area. The UV Index usually can be found in the local newspaper or on TV and radio news broadcasts. It is also available on the EPA’s web site at www.epa.gov/sunwise/uvindex.html.
Avoid tanning beds and sunlamps
Many people believe the UV rays of tanning beds are harmless. This is not true. Tanning lamps give out UVA and frequently UVB rays as well. Both UVA and UVB rays can cause serious long-term skin damage, and both contribute to skin cancer. Because of these dangers, many health experts advise people to avoid sunlamps and tanning beds.
Protect children from the sun
Children require special attention, since they tend to spend more time outdoors and can burn more easily. Parents and other caregivers should protect children from excess sun exposure by using the measures described above. Older children need to be cautioned about sun exposure as they become more independent. It is important, particularly in parts of the world where it is sunnier, to cover your children as fully as is reasonable. You should develop the habit of using sunscreen on exposed skin for yourself and your children whenever you go outdoors and may be exposed to large amounts of sunlight. If you or your child burns easily, be extra careful to cover up, limit exposure, and apply sunscreen.
Babies younger than 6 months should be kept out of direct sunlight and protected from the sun using hats and protective clothing.
What about tanning pills and other tanning products?
Several products claim to give a tan without UV radiation.
Tanning pills and accelerators
Tanning pills contain color additives similar to beta-carotene, the substance that gives carrots their orange color. The additives are distributed throughout the body, especially the skin, turning it an orange-like color. Although the Food and Drug Administration (FDA) has approved some of these additives for coloring food, they are not approved for use in tanning agents. They may be harmful at the high levels that are consumed in tanning pills. The main ingredient in sunless tanning pills, canthaxanthin, can show up in your eyes as yellow crystals, which may cause injury and impaired vision. There have also been reports of liver and skin problems, as well as one reported case of a woman who died from aplastic anemia, which her doctor attributed to her use of tanning pills.
Tanning accelerators, such as lotions or pills that contain the amino acid tyrosine or its derivatives, are not effective and may be dangerous. Marketers promote these products as substances that stimulate the body’s own tanning process, although most evidence suggests they don’t work. The FDA considers them unapproved new drugs that have not been shown to be safe and effective.
No tanning pills have been approved by the FDA.
Bronzers and extenders
Two other sunless tanning products, bronzers and extenders, are considered cosmetics for external use and are not thought to be harmful when used properly.
Bronzers, made from color additives approved by the FDA for cosmetic use, stain the skin for a short time when applied and can be washed off with soap and water.
Extenders (also known as sunless tanners or self-tanners) are applied to the skin as lotions or creams, where they interact with protein on the surface of the skin to produce color. Like a tan, the color tends to wear off after a few days. The only FDA-approved color additive for extenders is dihydroxyacetone (DHA). Because application of these products can sometimes lead to uneven coloring, some tanning salons have begun to offer whole body sprays in tanning booths. A concern here is that DHA is approved for external use only and should not be sprayed in or on the mouth, eyes, or nose. People who choose to get a DHA spray should make sure to protect these areas.
Although they can give skin a darker color, these products do not protect you from the damaging effects of UV radiation.
Examining your skin
Get your skin checked by your doctor
As part of a routine cancer-related checkup, your doctor should check your skin carefully. He or she should be willing to discuss any concerns you might have about this exam.
How to check your own skin
It’s important to check your own skin, preferably once a month. A self-exam is best done in a well-lit room in front of a full-length mirror. You can use a hand-held mirror for areas that are hard to see. A spouse or close friend or family member may be able to help you with these exams, especially for those hard-to-see areas like the lower back or the back of your thighs.
The first time you inspect your skin, spend a fair amount of time carefully going over the entire surface of your skin. Learn the pattern of moles, blemishes, freckles, and other marks on your skin so that you’ll notice any changes next time. Any trouble spots should be seen by a doctor. Follow these step-by-step instructions to examine your skin:
Check your face, ears, neck, chest, and belly. Women will need to lift breasts to check the skin underneath. Check the underarm areas, both sides of your arms, the tops and bottoms of your hands, in between your fingers, and fingernail beds.
Check the front of your thighs, shins, tops of your feet, in between your toes, and toenail beds. Use the hand mirror to look at the bottoms of your feet, your calves, and the backs of your thighs, first checking one leg and then the other.
Use the hand mirror to check the buttocks, genital area, lower back, upper back, and the back of the neck. Or it may be easier to look at your back in the wall mirror using a hand mirror. Use a comb or hair dryer to part your hair so that you can check your scalp.
What should I look for?
Basal and squamous cell cancers
Basal cell cancers and squamous cell cancers are most often found in areas that get exposed to a lot of sun, such as the head, neck, and arms, but they can occur elsewhere. Look for new growths, spots, bumps, patches, or sores that don’t heal after 2 to 3 months.
Basal cell carcinomas often look like flat, firm, pale areas or small, raised, pink or red, translucent, shiny, waxy areas that may bleed after a minor injury. They may have one or more abnormal blood vessels, a lower area in their center, and/or blue, brown, or black areas. Large basal cell carcinomas may have oozing or crusted areas.
Squamous cell carcinomas may look like growing lumps, often with a rough, scaly, or crusted surface. They may also look like flat reddish patches in the skin that grow slowly.
Both of these types of skin cancer may develop as a flat area showing only slight changes from normal skin.
Actinic keratosis, also known as solar keratosis, is a skin condition that is sometimes pre-cancerous and is caused by too much sun exposure. Actinic keratoses are usually small (less than ¼ inch), rough spots that may be pink-red or flesh-colored. Usually they develop on the face, ears, back of the hands, and arms of middle-aged or older people with fair skin, although they can arise in younger people or on other sun-exposed areas of the skin. People with one actinic keratosis usually develop many more. Some can grow into squamous cell cancers, but others may stay the same or even go away on their own. Because they can turn cancerous, such areas should be looked at regularly by a doctor. Your doctor can then decide whether these areas should be removed.
The “ABCD rule” is an easy guide to the usual signs of melanoma. Be on the lookout and tell your doctor about any spots that match the following description:
- A is for ASYMMETRY: One half of a mole or birthmark does not match the other.
- B is for BORDER: The edges are irregular, ragged, notched, or blurred.
- C is for COLOR: The color is not the same all over and may include shades of brown or black, or sometimes with patches of pink, red, white, or blue.
- D is for DIAMETER: The spot is larger than 6 millimeters across (about ¼ inch — the size of a pencil eraser), although melanomas can sometimes be smaller than this.
Another very important sign of possible melanoma is a change in the size, shape, or color of a mole or the appearance of a new spot. Some melanomas do not fit the ABCD rule described above, so it is very important to tell your doctor about any changes in skin markings or new spots on your skin.
Other warning signs are:
- a sore that does not heal
- spread of pigment from the border of a spot to surrounding skin
- redness or a new swelling beyond the border
- change in sensation — itchiness, tenderness, or pain
- change in the surface of a mole — scaliness, oozing, bleeding, or the appearance of a bump or nodule
- a mole that looks very different from your other moles
What if I find something suspicious?
It’s important to know the difference between melanoma and a harmless mole. A normal mole is most often an evenly colored brown, tan, or black spot on the skin. It can be either flat or raised. It can be round or oval. Moles are usually less than 1/4 inch across, or about the width of a pencil eraser. Moles can be present at birth or they can appear later. Several moles can appear at the same time.
Once a mole has developed, it will usually stay the same size, shape, and color for many years. Moles may fade away in older people.
Most people have moles, and almost all moles are harmless. But it is important to recognize changes in a mole — such as its size, shape, or color — that suggest a melanoma may be developing.
Be sure to show your doctor any area that concerns you. A qualified doctor should be able to identify any suspicious areas you may have. If your doctor suspects you might have skin cancer, he or she will use one or more of the following methods to find out.
History and physical exam
Usually the first step is to take your medical history (ask questions about symptoms and risk factors). The doctor probably will ask your age, when the mark on the skin first appeared, and if it has changed in size or appearance. You may also be asked about past exposures to known causes of skin cancer and if you or anyone in your family has had skin cancer.
During your physical exam, your doctor will note the size, shape, color, and texture of the area in question, and if there is bleeding or scaling. The rest of your body may be checked for spots and moles that may be related to skin cancer.
The doctor may also feel the lymph nodes (bean-sized collections of immune system cells) under the skin near the suspicious area. Some skin cancers may spread to lymph nodes. Affected lymph nodes may become larger and firmer than usual.
If you are being seen by your primary doctor and skin cancer is suspected, you may be referred to a dermatologist (a doctor who specializes in skin diseases), who will look at the area more closely.
Along with a standard physical exam, many dermatologists use dermoscopy (also known as epiluminescence microscopy (ELM), surface microscopy, or dermatoscopy) to help determine if a spot might be a melanoma or other type of skin cancer. This involves the use of a dermatoscope, which is a special magnifying lens and light source held near the skin. Sometimes the doctor will use a thin layer of oil with this instrument. A digital or photographic image of the spot may be taken. The use of these tests by experienced dermatologists can improve accuracy in finding skin cancers early. It can also often reassure you that a lesion is benign (non-cancerous) without the need for a biopsy.
If the doctor thinks that an area of skin might be cancerous, he or she will take a sample of skin from that area to look at under a microscope. This is called a skin biopsy. Different methods can be used for a skin biopsy. The choice of method depends on the possible type of skin cancer, where it is on the body, and the size of the affected area. For more detailed information on biopsies, see our documents, Melanoma Skin Cancer and Skin Cancer: Basal and Squamous Cell.
If a spot is found to be cancerous or pre-cancerous, your doctor may recommend further tests or treatment. If the spot is small and localized, a more extensive biopsy or some type of surgery may be needed. For cancers that might be more extensive (especially melanomas), imaging tests might be done, and treatment might include chemotherapy or radiation. Again, for more detailed information, see our skin cancer documents.