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Ultraviolet radiation from the sun causes most skin cancers

CLAIM: There are steps you can take to lower your risk of skin cancer.

TRUE. Limiting exposure to ultraviolet radiation can help prevent skin cancer.

Exposure to ultraviolet radiation is the main factor for someone developing skin cancer.

Skin cancer is the most common type of cancer. The main factor in someone developing skin cancer is exposure to ultraviolet (UV) radiation, which most often comes from the sun. UV radiation damages the DNA in skin cells. Over time, the effects of that damage build up and make the cells more likely to develop into cancer. Genetic factors, such as having a close family member with skin cancer or having fair skin that burns but does not tan easily, can also increase risk.

You cannot change your genetics, but you can control your sun exposure. To reduce your own skin cancer risk, you can take extra precautions if you know that you are prone to burning or have a family history of skin cancer.

The effects of UV damage accumulate over one’s entire lifetime. Cancer may not appear until years or even decades after the damage first occurred.


Ways to reduce the risk of skin cancer.

Medical experts recommend reducing UV exposure when possible to decrease skin cancer risk. One way of limiting UV exposure is to avoid tanning beds. Experts recommend staying inside or in the shade during mid-day, when the UV is most intense. UV intensity can vary with the season, cloud cover, location, and time of day. The intensity is highest in the middle of the day. One rule of thumb is that if your shadow is shorter than you are, it is a high-UV time of the day.


Sunscreen can help prevent skin cancer.

If you are in the sun, wearing protective clothing, a hat, and sunglasses can help. Reducing exposure also includes using a broad-spectrum sunscreen with SPF 30 or higher, especially during peak UV times. Sun protection is especially important for children because UV exposure early in life has been linked to a higher risk of skin cancer later on.

Sunscreen protects the skin by reducing the amount of UVB and UVA radiation that reaches the cells. For best results, use enough sunscreen to cover the skin thoroughly and apply it as often as recommended on the package, or at least every 2 hours. It will need to be reapplied more often after being in water, sweating, or toweling off.

Sunscreen is not intended to extend how much time you can spend outside. Staying out in the sun longer, even with sunscreen on, may put you at a higher risk of skin damage. Sunscreens are most effective if used correctly and regularly.

There is strong evidence that using sunscreen regularly can reduce skin cancer risk. A large study done in Australia starting in the 1990s compared rates of skin cancer in 1,600 fair-skinned adults who used sunscreen either daily or at their own chosen frequency. This randomized controlled trial compared people who were at similar skin cancer risk except for their sunscreen use. After 4 years, significantly fewer of the daily sunscreen users had developed squamous cell carcinoma.

The researchers have continued to follow these study participants. Over time, they have found that there was a 40% lower risk of squamous cell cancer as well as fewer cases of melanoma or basal cell carcinoma among people who used daily sunscreen during the study.

The health of a person's immune system may also be an important factor in cancer risk. People whose immune systems are suppressed (due to an illness, drug treatment, or other reasons) are more likely to get skin cancer, especially squamous cell cancer. When they do, the cancers are more aggressive and more often fatal. People with weaker immune systems should be especially careful to maximize sun protection.


Types of skin cancer.

There are three main kinds of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. Each type affects different cells in the skin.

  • Basal cell is the most common and the least likely to spread to other parts of the body. This skin cancer can usually be treated with surgery or other localized treatment.
  • Squamous cell carcinoma is less common but are also treatable. It is unlikely to spread except in elderly people and those with compromised immune systems.
  • Melanoma is the least common but most serious type of skin cancer. It is the most likely to spread to other parts of the body and the most likely to lead to death. It may require more intensive treatment.

All three types of skin cancer have been linked to UV exposure, although some cancers develop in areas not exposed to the sun. Good UV protection, especially early in life, will reduce your risk of all types of skin cancer.