Background: Marathon running has surged in popularity; it is generally believed to be healthy, but may be associated with medical risks. Over the past decade, we observed 8 ultramarathon runners with malignant melanoma. UV exposure, immunosuppression due to long-term intensive exercise, or both have been discussed as potential triggers in these patients. To further evaluate risk factors for malignant melanoma in marathon runners, we examined anamnestic, phenotypic, sun-related, and clinical variables in 210 athletes and compared them with those of an age- and sex-matched control group.
Observations: Although control subjects exhibited higher sun sensitivity and more common melanocytic nevi, marathon runners presented with more atypical melanocytic nevi, solar lentigines, and lesions suggestive of nonmelanoma skin cancer. These findings correlated with increasing training intensity. During exercising, most runners wore shorts (96.7%) and shirts (98.6%) that would not or would only partially cover their back and extremities. Regular use of sunscreen was reported in only 56.2% of runners.
Conclusions: Compared with a representative control group, marathon runners presented with an increased risk for malignant melanoma and nonmelanoma skin cancer. They should reduce UV exposure during exercising by choosing training and competition schedules with low sun exposure, wearing adequate clothing, and regularly using water-resistant sunscreens.