Long-distance runners run higher risk of skin cancer

Graz, Austria - A recently published study says that marathoners may be subject to an increased risk of getting skin cancer.

According to the study, which was conducted by researchers at the Medical University of Graz and appears in the November issue of The Archives of Dermatology, excessive sun exposure and exercise-induced suppression of the body’s immune system may be involved in the higher risk factors. The study’s authors, however, did not reach a conclusion about the exact increase in risk marathoners face.

The researchers studied 210 marathon runners and a control group of 210 non-marathoners, matched for age and sex. All were white and had a risk factor for malignant melanoma. Each participant received a total skin examination, and the researchers recorded participants’ eye color, skin shade, history of severe sunburn and family history of skin cancer - all known risk factors for skin malignancies.

Though some of the nonrunners had more benign moles and freckles and significantly higher sun sensitivity as determined by eye color and skin shade, the marathon runners had more solar lentigines and more lesions suggestive of basal cell and squamous cell carcinomas, the study reported. Clinical examination by dermatologists showed that none of the participants had lesions that suggested malignant melanoma, but 24 of the marathon group and 14 of the control group were referred for surgical treatment of lesions that appeared to be basal or squamous cell carcinomas or actinic keratoses.

According to the study, about a third of the marathoners ran up to 25 miles a week, about half ran 25 to 45 miles, and 15 percent ran more than 45 miles a week. Almost all the runners dressed in clothing that exposed legs, arms, shoulders and upper back to the sun; only about half used sunscreen regularly. Those who trained the most had the highest rates of skin lesions.

While the obvious cause of the higher rates of skin lesions among the runners is long exposure to the sun, the authors write that high-intensity training and excessive exercise can lead to suppressed immune function, which in turn can lead to skin cancer. The study reminds readers that there is evidence that trauma sustained during extreme exercise can induce the release of cytokines, proteins that can stimulate the growth and activity of various immune cells and that may limit the ability of the immune system to fight potential cancers.

“The wake-up call this study brings to dermatologists is that it’s incumbent upon us to educate our patients who are runners about their increased risk and how they can reduce it,” says William Philip Werschler, M.D., assistant clinical professor of medicine/dermatology at the University of Washington School of Medicine. “We need to remind them about the necessity for sunscreen, their amount of exposure, dressing properly - all the proper sun-protection guidelines.”