By Kimberly Beauchamp, ND

Healthnotes Newswire (January 18, 2007)—Marathon runners are at increased risk for developing skin cancer. Excessive sun exposure or depressed immune system might be to blame, says a new study in the Archives of Dermatology.

It is well known that moderate physical exercise generally benefits health, but long distance runners may suffer from compromised immune systems during and after periods of intense training. Certain cells of the immune system don’t function as well after rigorous endurance exercise, leaving athletes more susceptible to infections. For example, marathon runners are more prone to respiratory tract infections in the weeks following a race.

Training for a marathon also requires that runners spend more time outdoors, increasing their exposure to ultraviolet light. Prolonged and repeated sun exposure and having a fair skin type and a history of sunburns increase skin cancer risk. Having multiple moles—especially “atypical” moles (irregular-appearing noncancerous moles)—is also a risk factor for skin cancer.

After noticing an alarming number of malignant melanoma cases in their practice, a team of Austrian dermatologists set out to determine if marathon runners were more likely to develop melanoma than were other people. “We were concerned by this observation because all of us are enthusiastic runners and two of us regularly participate in marathons,” the researchers said.

Over 400 people took part in the study; half of them were marathon runners. None of the people had malignant melanoma, but they all had several risk factors for the development of skin cancer. The marathon runners had more atypical moles and other sun-related skin damage, and they were referred to dermatologists more often than the nonrunners for the removal of “suspicious” growths.

Most of the marathon runners didn’t wear adequate sun-blocking clothing, and only 56% of them reported using sunscreen regularly.

The research team explained, “Overtraining, high-intensity training, and excessive exercise, such as cumulative training for a marathon, and the marathon itself may lead to suppressed immune function.” In combination with excessive sun exposure, these factors might make runners more prone to getting skin cancer.

The researchers concluded, “Runners should be alerted to the crucial role of UV radiation in the development of malignant melanoma and nonmelanoma skin cancer. In particular, they should be advised to reduce UV exposure during exercising by choosing training and competition schedules with low sun exposure, wearing adequate clothing, and regularly using water-resistant sunscreens.”

(Arch Dermatol 2006;142:1471–4)

Kimberly Beauchamp, ND, earned her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She cofounded South County Naturopaths in Wakefield, RI. Dr. Beauchamp practices as a birth doula and lectures on topics including whole-foods nutrition, detoxification, and women’s health.

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