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Skin Cancer & UV


In this section you can learn about skin cancer and its primary cause, UV radiation. Find answers to common questions by clicking on the links below:

About Skin Cancer

About UV Rays


About Skin Cancer

How common is skin cancer?
This year more than one million Americans will be diagnosed with skin cancer. That's more than all other types of cancer combined. Over 10,000 Americans (more than one per hour) will die from the disease.

The incidence of malignant melanoma in the U. S. has been increasing faster than any other type of cancer and has doubled since 1973. The annual incidence rate of melanoma in Colorado is higher than the national average. This year in Colorado, it is estimated that there will be 1,180 new cases of melanoma and 128 deaths from the disease.1

1National Cancer Institue, American Cancer Society

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How common is melanoma in Colorado?

Colorado Melanomas of the Skin

Source: NCI SEER Stats (; Cancer in Colorado: 1992-2002

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Are there different types of skin cancer?
Yes, the three most common types of skin cancer are:

Each of these cancers is named for the type of skin cell from which it arises. Melanoma is a malignancy of the skin’s pigment-producing cells or melanocytes. Squamous cell carcinoma is a malignancy of the cells of the middle or upper epidermis, while basal cell carcinoma occurs when the cells at the base of the epidermis turn malignant.

Melanoma is less common than the other two types of skin cancer, but is far more deadly. It is almost always curable in its early stages, but because of its potential to metastasize (spread to other regions of the body), early detection and treatment is crucial.

Squamous cell carcinoma is not as aggressive as melanoma. Cure rates are in excess of 95% when the tumor is detected and treated early. Chronic overexposure to the sun, as might occur with outdoor employment is a major cause. Actinic keratosis (AK) is a very common skin lesion which is now recognized as the earliest stage in the development of skin cancer. Left untreated, these lesions can progress to squamous cell carcinoma.

Basal cell carcinoma is the most common and least aggressive type of skin cancer. However, it can be quite destructive and has the potential to spread if left untreated.

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What does skin cancer look like?
Melanoma most commonly has the appearance of an unusual mole. It frequently exhibits the “ABCDE’s” of: Asymmetry, Border irregularity, Coloration which is dark or in multiple shades, Diameter the size of a pencil eraser or larger, and Evolving, or changing over time - look out for any mole that is new, enlarges, changes shape, darkens or begins to look odd compared to typical moles. Melanoma can appear on previously normal skin, or can develop in a pre-existing mole.

Squamous cell carcinoma usually appears as a reddish-colored firm lump or plaque with a scaly surface. Actinic keratosis (a precursor of squamous cell carcinoma) is a small pinkish scaly patch. Each of these irregularities is most commonly found on areas of the body that have been chronically exposed to the sun, such as the face, ears, hands, and the scalp of bald men or women.

Basal cell carcinoma, in its classic form, is a small bump with a translucent quality. It is somewhat red due to enlarged “bloodshot” vessels on its surface. As it grows larger, the surface often ulcerates or forms a scab.

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Who is at risk?
Did you know the three major factors that increase your risk of developing skin cancer? The first, intense UV exposure that leads to sunburn; and accumulated UV exposure that results in tanned skin. Second, family history and whether skin cancer runs in your family. Third, skin type or how easily you burn.

Where you live
Areas closer to the equator, higher in elevation and with many dry, sunny days increase the UV exposure people receive each day. Most regions of Colorado are not only at higher elevations, but also have 300+ sunny days each year. This means that if you live, work or play here, you have to be concerned about sun safety. Also, remember that if you are in the mountains, you have even less protection from UV. At an altitude of 10,000 feet, UV is 50 percent more intense than at sea level.

Who you are
Fair-skinned and fair-haired people with light eyes and many moles are at the highest risk, but no matter the color of one's skin it is still possible to develop skin cancer.

What you do
Your work and extracurricular activities have an effect on your skin cancer risk. Think about the choices you make. Do you sunbathe to get a tan? Do you visit tanning salons before going on vacation? Do you use various forms of sun protection while spending time outdoors?

Skin's susceptibility to burning can be determined on a six-point scale as shown in the following table1:

Though everyone is susceptible to damage as a result of excessive sun exposure, people with skin types I and II are at highest risk.

Skin Type Tanning and Sunburning History
I Always burns, never tans, sensitive to sun exposure
II Burns easily, tans minimally
III Burns moderately, tans gradually to light brown
IV Burns minimally, always tans well to moderately brown
V Rarely burns, tans profusely to dark
VI Never burns, deeply pigmented, least sensitive

1 Fitzpatrick TB. Arch Dermatol. Jun 1988:124(6):869-71.

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What does skin cancer cost to treat?
While most skin cancer is curable with minor surgery, the sheer number of cases makes this a very costly disease. The 2004 tab for treating skin cancer and actinic keratosis in the U.S. was $2.9 billion according to the Society of Investigative Dermatology and the American Academy of Dermatology. This does not include the indirect costs of lost productivity or decreased quality of life. Sun protection would not only help to prevent human suffering, but would significantly reduce health care costs as well.

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Can skin cancer be prevented?
Yes! Skin cancer is largely preventable by avoiding overexposure to UV radiation. Most people attain up to 25% of their lifetime sun exposure before their 18th birthday1 and just two or more blistering sunburns during adolescence nearly doubles the risk of melanoma.2

Remember these prevention strategies:

1Godar, DE: UV doses of young adults. Photochem and Photobiol. 2003;77(4):453-457
2Weinstock MA, Colditz GA, Willett WC, et al. Pediatrics. Aug1989;84(2):199-204

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About UV Rays

What are ultraviolet (UV) rays? UV rays are invisible waves of radiation generated by the sun. While some of the sun’s radiation is in the form of visible light and heat, UV rays are shorter in length. This shorter wavelength gives UV its capacity to penetrate into the skin. The one beneficial result is the conversion of Vitamin D into its active form. However, UV rays are also just the right length to damage cells and to act as a human carcinogen.

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Are there different kinds of UV rays?
Yes. Ultraviolet radiation is actually a continuous spectrum of wavelengths which scientists have divided into three categories: UVA, UVB, and UVC. Rays with the longest wavelength are designated as UVA. UVB rays are shorter, and UVC rays are the shortest of all. Because ozone in the atmosphere absorbs all UVC and most UVB, 95% of the radiation reaching the surface of the earth is UVA while just 5% is UVB. UVB penetrates only into the epidermis (upper layer) of the skin but is the major cause of sunburns. UVA penetrates more deeply, down into the dermis of the skin. Tanning beds emit mostly UVA, however both UVA and UVB are highly damaging and can cause skin cancer.

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How do UV rays damage the skin?
When ultraviolet radiation strikes the skin, the rays penetrate beneath the surface and can damage an epidermal cell’s genetic material, or DNA. While the body can usually repair the damage, sometimes this mechanism fails, resulting in a mutation. The skin cancer that can result is named for the type of cell where the mutation occurred. For example, melanoma is a tumor of malignant melanocytes.

UV rays can also damage the dermis and suppress the skin’s immune system, both of which contribute to cancer formation in the epidermis above. Solar damage to the dermal collagen and elastic fibers is a major contributor to skin aging, manifested as wrinkling and sagging.

A helpful rule of thumb is: “A (UVA) is for aging, B (UVB) is for burning.” Check out the diagram below for better understanding of UVA and UVB.

An illustration of how UV rays damage the skin

When UVB rays penetrate into the skin, they are just the right wavelength to be absorbed by the cell’s genetic material, or DNA. Such bombardment of the DNA can cause it to break apart. While the body can repair most of these molecular injuries, sometimes this mechanism fails, especially in the case of a large dose of radiation, such as a sunburn. This results in mutations which can lead to cancer.

UVA rays penetrate more deeply. They contribute to the formation of skin cancer by inhibiting the tumor suppressive action of the body’s immune cells in the dermis.

In addition to causing skin cancer, damage done by UV exposure includes:

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How does the sun cause eye damage?
Overexposure to the sun also can damage your eyes and cause cataracts, macular degeneration and melanoma of the eye. With cataracts, the lens of the eye becomes thick and cloudy, resulting in reduced vision or blindness. According to the World Health Organization, 16 million people worldwide are currently blind as a result of cataracts and as many as 20% of these may be due to UV exposure.

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Are tanning beds safe?
No. UVA is the predominant wavelength provided by most tanning beds. Don’t be fooled just because UVA is less likely to cause sunburn than UVB. The ultraviolet radiation emitted by tanning lights is declared to be a known human carcinogen by the U.S. Government. There is no safe dose of a carcinogen. The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC), as well as the American Academy of Dermatology (AAD), encourage people to avoid using tanning beds or sun lamps.

Recently, the Federal Trade Commission investigated deceptive advertising practices associated with the indoor tanning industry. It found the industry did not properly disclose potentially harmful health concerns such as skin cancer risk, when using tanning beds. Click here to read the report.

For more information check out these resources:

AAD: Tanning Fact Sheet
WHO: Sunbeds, Tanning and UV Exposure
FDA: Indoor Tanning: The Risks of Ultraviolet Rays

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What determines UV intensity?

Time of Year
Time of Year: The sun's angle varies with the seasons, causing the intensity of UV rays to change. UV intensity tends to be highest during the summer months.

Time of Day
Time of Day: The amount of UV varies throughout the day. The period of highest danger is between 10 a.m. and 4 p.m.

Scattered & Reflected Rays
Scattered and Reflected UV Rays: UV rays reflect off snow, water, sand, and concrete. Thin cloud cover scatters UV rays in all directions and allows UV rays to reach your skin even when you are wearing a hat or are under an umbrella.

Altitude: UV rays are more intense at higher altitudes because the thinner atmosphere filters out fewer UV rays. UV rays increase approximately 4% with every 1,000 feet above sea level.

Latitude: UV rays are strongest close to the equator because the sun is more directly overhead. UV rays must travel through less ozone before hitting the earth in these areas. The ozone layer is also naturally thinner in the tropics. At higher latitudes, the UV rays enter the ozone layer at an angle, which decreases UV intensity.

Climate/Weather: Clouds block some UV rays from hitting the earth and decrease the UV intensity. However, clouds do not block all UV rays and it is possible to sunburn on cloudy days.

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What is the UV Index?
The UV Index was developed by the National Weather Service and the Environmental Protection Agency. It provides a forecast of the expected risk of overexposure to UV rays and indicates the degree of caution you should take when outdoors. It predicts exposure levels on a 0 to 11+ scale, where values of 2 or less indicate a low danger, while 11+ signifies an extreme risk of harm from unprotected sun exposure. Get in the habit of checking the UV index. It is available online and printed on the weather page of many newspapers.

UV Index Expected Risk and Precautions
2 or less:

A UV Index reading of 2 or less means low danger from the sun's UV rays for the average person:

  • Wear sunglasses on bright days. In winter, reflection off snow nearly doubles UV strength.
  • If you burn easily, cover up and use sunscreen.

A UV Index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.

  • Take precautions, such as covering up, if you will be outside.
  • Stay in shade near midday when the sun is strongest.

A UV Index reading of 6 to 7 means high risk of harm from unprotected sun exposure. Apply a sunscreen with an SPF of at least 15. Wear a wide-brim hat and sunglasses to protect your eyes.

  • Protection against sunburn is needed.
  • Reduce time in the sun between 10 a.m. and 4 p.m.
  • Cover up, wear a hat and sunglasses, and use sunscreen.
Very High

A UV Index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Minimize sun exposure during midday hours, from 10 a.m. to 4 p.m. Protect yourself by liberally applying a sunscreen with an SPF of at least 15. Wear protective clothing and sunglasses to protect the eyes.

  • Take extra precautions. Unprotected skin will be damaged and can burn quickly.
  • Minimize sun exposure between 10 a.m. and 4 p.m. Otherwise, seek shade, cover up, wear a hat and sunglasses, and use sunscreen.

A UV Index reading of 11 or higher means extreme risk of harm from unprotected sun exposure. Try to avoid sun exposure during midday hours, from 10 a.m. to 4 p.m. Liberally apply sunscreen with an SPF of at least 15 every 2 hours.

  • Take all precautions. Unprotected skin can burn in minutes. Beach-goers should know that white sand and other bright surfaces reflect UV and will increase UV exposure.
  • Try to avoid sun exposure between 10 a.m. and 4 p.m.
  • Seek shade, cover up, wear a hat and sunglasses, and use sunscreen.

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What’s the UV Index for my city?
Find the UV Index in your neighborhood by entering your zip code below.

Zip Code:

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How can overexposure to UV rays be avoided?
We cannot stay completely out of the sun. There will be many occasions when we need or desire to be outdoors for exercise, work, or recreation. However, by taking relatively simple steps, most sun damage can be avoided.

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What does SPF mean?
SPF stands for Sun Protection Factor. Something that many people are unaware of is that SPF is a greater predictor of the length of protection rather than the strength of protection. To find out more visit the Sunscreen section.

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Do I need to reapply water-resistant sunscreen after my child goes swimming?
Yes. It is very important to reapply sunscreen, even water-resistance sunscreens, after your child gets wet. Whether your child gets wet in a pool, running through the sprinkler or sweating a lot at soccer practice reapply sunscreen often.

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Why does my child get sunburned even when it's cloudy?
Clouds only block 20-40% of damaging UV rays. That means that as much as 80% of UV rays may reach your children’s skin even on cloudy days. Check the UV Index for a reading of the day’s UV forecast to help you plan for a sun safe day. The UV Index can be found in your local newspaper or you can check your UV index online.

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Is getting a “base tan” before going on vacation a good idea?
There is no such thing as a healthy tan. A suntan is skin damage. The body produces melanin, the pigment in your skin, to protect itself from the damaging UV rays. Skin damage is happening while your skin tans and this damage can lead to skin cancer.

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Should I go out in the sun to get vitamin D?
Experts recommend getting adequate vitamin D through vitamin supplementation or 5-15 minutes of incidental sun exposure (which can be accumulated before and after peak sun hours). If you are concerned with the amount of Vitamin D you are getting, try introducing some fortified foods into your diet like orange juice and milk. For more information, check out this article from the World Health Organization: Are There Beneficial Effects of UV Radiation?

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Why do people get melanoma in areas of their body that are not exposed to the sun?
The skin is the largest organ in our bodies. Skin cancer can attack the melanocyte cells (moles) throughout this organ and manifest themselves anywhere.

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How common are sunscreen allergies?
Fortunately, allergic reaction to sunscreen is very uncommon and, if one does occur, it is generally a minor reversible skin rash. Less than 1% of people have some reaction to some ingredients in certain sunscreens. Hypoallergenic and fragrance-free products are good choices especially for people already known to have skin allergies. PABA which was responsible for many people’s allergic reaction has been removed from most sunscreens.

Before parents put sunscreen on their child, they should perform a test by dabbing a small amount on the back of the child's hand. If a rash or itching develops, a doctor or pharmacist can help recommend products that might be better for the child's skin.

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Why should we be concerned about ultraviolet (UV) radiation?
UV radiation is recognized by Congress, the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA) and other agencies as a know human carcinogen. UV radiation is on the same list that cigarettes and asbestos are on and can cause some very serious health concerns. The sun’s UV radiation can cause skin damage, eye damage and in some cases skin cancer. Educating your family about sun safety and being a role model for your kids may help reduce possible diseases in the future.

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How long will sunscreen last after I purchase it?
Unless the expiration date says otherwise, susncreen will last for about two years. So, when you buy your sunscreen write the date on the bottle with a permenant marker and dispose of it after two years.

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At what age can I start using sunscreen on my child?
Do not use sunscreen on your child unless they are at least six months old. Before six months of age, keep your child out of the sun as much as possible and use shade, cover-up clothing, hats and sunglasses any other time. Remember that for kids of all ages, sunscreen should be used in conjuction with the use of shade, cover-up clothing, hats and sunglasses.

If you have further questions you would like answered, send an email to the experts.

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