TUESDAY, Nov. 21 (HealthDay News) --Marathoners face heightened odds for skin cancer, including melanoma, new European research shows.

The study "confirms things we already know," said Dr. Robin Ashinoff, chief of dermatologic, Mohs, and laser surgery at Hackensack University Medical Center in Hackensack, N.J. "We should be counseling these people to try and do their outside activities not when the sun is strongest, to wear a hat, T-shirt, long sleeves, and to put on sunblock. They're at high risk."

According to background information in the study, there is evidence to suggest that endurance exercise, including marathon running, may raise the risk of skin cancer. Not only are outdoor exercisers exposed to high levels of ultraviolet radiation, but endurance exercise may suppress the immune system.

"Anybody who spends a lot of time outdoors -- runners, bicyclists, golfers, tennis players -- all have a lot of sun damage," confirmed Ashinoff, who was not involved in the current study.

"People who spend more time in the sun have an increased melanoma risk," added Dr. Vijay Trisal, assistant professor of surgical oncology at City of Hope Cancer Center in Duarte, Calif.

Melanoma is one of the deadliest and most aggressive of all cancers. Other forms of skin cancer, such as basal cell carcinoma and squamous cell carcinoma, tend to be less deadly but can be disfiguring.

The study's Austrian authors, themselves avid runners, treated eight ultramarathon runners with malignant melanoma over the past decade. All of the melanomas were located on parts of the body that were not covered or were only partially covered by clothing during exercising.

For this study, the team from the Medical University of Graz recruited 210 marathon runners (166 of them men), aged 19 to 71, at a local marathon and compared them to a group of 210 controls recruited at a skin cancer screening campaign.

All participants were examined for skin cancer and completed a questionnaire about any personal and family history of skin cancer, sun sensitivity and sun exposure. Marathoners also answered questions about their training.