More Sun Equals More Skin Cancer, Researchers Say

WASHINGTON (Reuters) July 15, 2002 - The more sun you get, the higher your risk of skin cancer, U.S. researchers said in a report they claim is the first to show an individual's cumulative risk of melanoma. Many studies have linked sun exposure with skin cancer, but the team at the National Cancer Institute said their research was the first to show the intensity of sunlight a person receives over a lifetime is directly related to melanoma risk.

An ability to tan does not especially protect a person, according to a statement released by the institute's Thomas Fears, who led the study.

"The risk of melanoma is greatest for people who develop little or no tan," Fears said. "However, we've learned that where people live as both kids and adults, and how much UVB shines in those places are important factors -- regardless of tanning ability."

UVB rays are the sun's ultraviolet rays linked with tanning and burning. The sun's UVA rays are also linked with skin cancer and with the wrinkling that comes from sun exposure.

For their study, Fears' team questioned 718 melanoma patients in Philadelphia and San Francisco, and compared their answers to 945 people who did not have skin cancer.

The study was restricted to non-Hispanic whites, Fears noted.

Each was questioned about his or her ability to tan and tendency to burn, along with a careful history of their exposure to the sun where they lived, worked and vacationed.

UV meters, which measure the amount of solar radiation received in a particular location, were used to estimate how much UVB a person received. New Orleans, for example, receives 20 percent more UVB rays each year than Atlanta does, Fears said.

Researchers used the UVB exposure readings and the patients' ages to determine an average annual intensity of sun exposure for participants in the study.

Writing in the journal Cancer Research, Fears and his colleagues concluded a 10 percent increase in the average annual intensity of sun exposure led to a 19 percent increase in a man's risk for melanoma and a 16 percent increase for women.

The researchers also found that people spent more time outside in the summer before the age of 20 than after. This may account for the generally accepted idea that childhood exposure to sun is the most important factor in developing skin cancer. Doctors now warn everyone to reduce exposure to the sun's rays.

Melanoma is the deadliest form of skin cancer, but is easily treated if caught early. A typical sign is a black, irregularly shaped or bleeding mole.

The American Cancer Society estimates that 53,600 people will be diagnosed with melanoma in the United States in 2002, and 7,400 will die of it.