Ultraviolet Radiation and Skin Cancer

What is ultraviolet radiation?

Ultraviolet (UV) radiation is a form of energy that the sun produces. You can’t see UV radiation because its wavelengths are shorter than visible light.

The UV energy that the sun produces reaches the Earth and provides vitamin D for your body to help you survive. You can also find UV radiation in human-made sources like tanning beds. Exposure to too much ultraviolet radiation greatly increases your risk of developing skin cancer.

What are the three types of ultraviolet radiation?

There are three different types of ultraviolet radiation based on the size of the wavelength:

• UVA causes your skin to wrinkle, tan and/or burn. Too much exposure leads to skin cancer.
• UVB can damage the outermost layers of your skin. It can cause sun spots, tanning, sunburns and blistering, which can lead to skin cancer.
• UVC is absorbed by the Earth’s atmosphere and the UV light you experience on Earth is either UVA or UVB, not UVC.

How does my skin change after exposure to the sun?

Exposure to the sun causes changes to your skin. While many people think that a glowing complexion means good health, changes to your skin tone from being in the sun can speed up the effects of aging and increase your risk of developing:

• Skin cancer.
• Wrinkles.
• Freckles.
• Liver spots.

Over time, the sun’s ultraviolet light damages the fibers in your skin called elastin. When these fibers break down, your skin begins to sag, stretch and lose its ability to go back into place after stretching. Your skin also bruises and tears more easily, in addition to taking longer to heal. So, while sun damage to your skin may not be apparent when you’re young, it’ll show later in life.

Changes in your skin related to sun exposure include:

• Precancerous (actinic keratosis) and cancerous skin lesions caused by loss of your skin’s immune function.
• Tumors.
• Skin discoloration, mottled pigmentation or a yellow tone.
• Dilated small blood vessels (telangiectasias).
• Damaged elastic tissues that cause wrinkles (elastosis).
• Damage to your eyes, like cataracts or macular degeneration.
• Premature aging.

How does ultraviolet radiation lead to cancer?

Too much ultraviolet radiation causes skin cancer. Your body needs some UV light for vitamin D, which is a vitamin you need to survive. When your skin has too much exposure to UV radiation, it damages your cells. Within your cells, you have DNA. DNA tells your cells how to form and function within your body. Too much UV radiation targets the DNA in your cells, which causes them to misunderstand their function. As a result, your cells divide and replicate too frequently. Your cells then clump together to form tumors, which can be cancerous.

Ultraviolet radiation from the sun is the primary cause of skin cancer, but UV light from tanning beds is just as harmful. Exposure to sunlight during the winter months puts you at the same risk of exposure during the summertime.

Cumulative sun exposure causes basal cell and squamous cell skin cancer, while episodes of severe blistering sunburns, usually before age 18, can cause melanoma later in life.

What is skin cancer?

Skin cancer is the uncontrolled growth of skin cells. While healthy cells grow and divide in an orderly way, cancer cells grow and divide in a rapid, haphazard manner. This abnormal growth causes tumors that are either benign (noncancerous) or malignant (cancerous). There are three main types of skin cancer:

• Basal cell carcinoma.
• Squamous cell carcinoma.
• Melanoma.

Basal cell and squamous cell cancers are less serious types and make up 95% of all skin cancers. These cancers are nonmelanoma skin cancers. This means that they’re highly curable when treated early.

Melanoma, made up of abnormal skin pigment cells called melanocytes, is the most serious form of skin cancer and causes 75% of all skin cancer deaths. If left untreated, melanoma can spread to other organs and is difficult to control.

Who is at risk for skin cancer caused by ultraviolet radiation?

Anyone can get skin cancer from ultraviolet radiation. The risk is greatest in people who have:

• Fair skin.
• Freckled skin.
• Skin that burns easily.
• Light eyes.
• Blond or red hair.

People who have a darker skin tone can get skin cancer, but their risk is lower than people who have a lighter skin tone.

In addition to your complexion, other risk factors include:

• Having a biological family history or personal history of skin cancer.
• Having an outdoor job or spending a lot of time in the sunshine.
• Living in a sunny climate.
• Having a history of severe sunburns.
• Having large and irregularly shaped moles.

What are the symptoms of skin cancer?

The most common warning sign of skin cancer is a change on your skin. Changes are typically a new mole, a new skin lesion or sore, or a change to an existing mole.

• Basal cell carcinoma may appear as a small, smooth, pearly or waxy bump on your face or neck, or as a flat, pink/red- or brown-colored lesion.
• Squamous cell carcinoma can appear as a firm, red nodule or as a rough, scaly, flat lesion that may itch, bleed and become crusty.
• Melanoma usually appears as a pigmented patch or bump. It may resemble a normal mole, but usually has a more irregular appearance.

Where will I have symptoms of skin cancer?

Symptoms of skin cancer caused by ultraviolet radiation usually affect the skin on your body that has sun exposure, but cancer can form anywhere on your skin. This could include on your:

• Arms.
• Legs.
• Chest and back.
• Face.
• Neck.

What are the signs of melanoma?

When looking for signs of melanoma, think about the alphabet. ABCDE tells you what signs to look out for on moles or lesions on your skin:

• Asymmetry: The shape of one half doesn’t match the other.
• Border: Edges are ragged or blurred.
• Color: Uneven shades of brown, black, tan, red, white or blue.
• Diameter: A significant change in size (greater than 6 millimeters).
• Evolution: Changes in the way a mole or lesion looks or feels (itchy, bleeding, etc.).

Do skin cancers spread?

It’s rare for nonmelanoma cancers like basal cell or squamous cell carcinomas to spread. Melanoma spreads quickly throughout your body. If you have changes to your skin or skin cancer, you should seek treatment immediately to prevent it from spreading and affecting other parts of your body.

How can I prevent ultraviolet radiation exposure and skin cancer?

While it isn’t possible to completely prevent skin cancer or undo previous effects of ultraviolet radiation and sun damage, you can take steps to reduce your risk by:

• Applying sunscreen with a sun protection factor (SPF) of 30 or greater 30 minutes before sun exposure and then every two to three hours after. Reapply sooner if you get wet or sweat significantly.
• Wearing sunglasses with total UV protection.
• Selecting cosmetic products that offer UV protection.
• Avoiding direct sun exposure as much as possible during peak UV radiation hours, between 10 a.m. and 4 p.m.
• Performing skin self-exams regularly to become familiar with existing skin growths and to notice any changes or new growths.

Does my skin have a natural barrier to protect against cancer-causing ultraviolet radiation?

The stratum corneum exists in the outermost layer of your skin (epidermis) and is your body’s natural barrier to protect you from cancer-causing ultraviolet radiation. Too much sun exposure can break down your body’s natural defense, which can lead to skin cancer. Even though you have this barrier, you still need to take steps to protect your skin from UV radiation.

If you have a darker skin tone, melanin, which is the substance in your body that produces hair, eye and skin pigmentation, helps protect your skin from ultraviolet radiation. While you do have an additional barrier to protect your skin, you can still get skin cancer.

Understanding the UV index

You might see ratings from the UV index on weather reports. The numbers represent the risk of unprotected sun exposure to the average person. You may think that the lower index numbers mean you don’t have to take action, but the risk of sun exposure to unprotected skin always exists. You might also think that cloudy days mean you can spend unlimited time in the sun, but this isn’t true.

• Low, 0-2: At the low stage, experts advise you to wear sunglasses if the sun is bright. Use sunscreen and protective clothing if you burn easily.
• Moderate, 3-5: At the moderate stage, you should cover up and use sunscreen. Avoid direct sunlight at midday, when the sun is most powerful. Stay in the shade.
• High, 6-7: At the high stage, you should use all protection against sun damage (protective clothing, wearing a hat and sunglasses, using sunscreen). Limit time in the sun from 10 a.m. to 4 p.m.
• Very high, 8-10: At the very high stage, you should be extra careful, using clothing, hats, sunscreen and sunglasses. Avoid the sun between 10 a.m. and 4 p.m. Your skin can burn quickly at this stage.
• Extreme, 11+: At the extreme stage, you should use all methods of prevention. It will only take minutes of exposure to result in a burn. Don’t go out in the sun from 10 a.m. to 4 p.m. Wear protective clothing, a hat, sunglasses and sunscreen. At this stage and all others, remember that snow, sand and water all increase UV exposure by reflecting the sun’s rays.

What can I expect if I have ultraviolet radiation damage?

Long-term effects of ultraviolet radiation exposure or overexposure to the sun can lead to premature aging and skin cancer. The sun’s UV rays reach the DNA within the cells in your skin and cause them to malfunction. You can reduce your risk of skin cancer by wearing protective clothing when you go outdoors and reapplying sunscreen throughout the day. You can also wear protective accessories like sunglasses to shade your skin and eyes from ultraviolet radiation. Treatment is available for all types of skin cancer, but your outlook is best when you receive an early diagnosis and treatment.

Is there a cure for skin cancer?

The cure for most skin cancers is early detection and treatment to remove cancer from your body. An early diagnosis, especially for melanoma, targets cancer before it spreads to other parts of your body. Nearly 90% of people diagnosed with basal cell carcinoma make a full recovery after treatment to remove cancer.

When should I see my healthcare provider?

If you notice any changes to your skin that worry you, contact a healthcare provider immediately. It’s also essential to perform regular skin checks to verify that your skin appears normal and you don’t have any new spots or changes to your skin.

What questions should I ask my doctor?

• What are the long-term effects of sun exposure?
• What type of skin cancer do I have?
• What caused my skin cancer?
• How do I protect myself from the sun’s UV rays?

A note from Cleveland Clinic

Ultraviolet (UV) radiation is necessary because it provides vitamin D to help you survive, but it’s also harmful with overexposure. You can take care of your skin and prevent skin cancer from ultraviolet radiation by wearing sunscreen outdoors and staying out of the sun when it’s at its brightest in the middle of the day. Nearly 80% of a person’s lifetime sun exposure occurs before age 18. You can become a good role model and foster skin cancer prevention habits for your family by taking preventive measures when you go outside.