Genetic variation raises melanoma risk in those who tan easily

Having dark hair and tanning easily does not necessarily make you less likely to develop skin cancer, according to data presented last week at the annual meeting for the American Association for Cancer Research in Denver. Researchers from the University of Pennsylvania, US, found that people who tan easily but have particular genetic variants in MC1R (melanocortin 1 receptor) could be at a higher risk of developing melanoma than previously thought.

The team, led by Professor Peter Kanetsky, analyzed 779 patients with melanoma from the Pigmented Lesion Clinic at the University of Pennsylvania and compared them with 325 healthy control patients. Amongst those with dark hair who tan easily, MCR1 variants were associated with a more than two-fold risk of melanoma but this was not true amongst those with blond or red hair. However, people with dark hair are not thought to be at increased risk for melanoma in general. In this study their risk for melanoma was increased only if they had dark hair and also inherited certain MC1R genetic variants.

'Traditionally, a clinician might look at a person with dark hair who did not sunburn easily and classify them as lower risk for melanoma, but that may not be true for all people in the population', said Professor Kanetsky. 'Just because you tolerate sun exposure fairly well doesn't mean that you're not at increased risk for melanoma'.

MC1R variants were also associated with increased risk among those with dark eye colour (3.2-fold increase), those who did not freckle (8-fold increase), who tanned after repeated sun exposure (2.4 fold increase) or who tanned immediately without burning (9.5-fold increase). People with these characteristics are usually thought to be at reduced risk for melanoma. It is clearly important that people who have the physical characteristics of reduced risk of melanoma are educated about preventing skin cancer just as those with red or blond hair and freckles would be.

Melanoma is the most serious form of skin cancer but is highly curable if caught early. The American Cancer Society estimate there were about 62,000 new cases of melanoma in the United States in 2008, and 8420 of these were fatal.