Although exposure to ultraviolet radiation (UVR) is a well-known risk factor for skin cancer , the study found that individuals with certain variants of the MC1R gene – which affects skin pigmentation – are twice as likely to develop melanoma, regardless of their level of UVR exposure.
Writing in JAMA Dermatology, the authors say that the finding is of global relevance 'due to the frequency of these variants among the high-risk population'. They add that the research 'gives reason to re-evaluate the extent of sun exposure as a risk factor for melanoma, which might directly affect public health recommendations in the future'.
The study, conducted by Dr Judith Wendt and her team at the Medical University of Vienna in Austria, compared 991 patients with melanoma and 800 patients without skin cancer. As expected, they found that those who reported more than 12 sunburns in their lives and had signs of UV skin damage had a considerably higher risk of developing melanoma compared with those with lower lifetime levels of sun exposure.
More surprisingly, they found that patients with two or more MC1R gene variants had double the risk of melanoma compared with those who did not have any of the high-risk variants, even after controlling for sun exposure. Certain variants carried a particularly high risk – having just one of these very high-risk variants more than tripled the likelihood of developing the disease.
The research is in line with a recent study using a mouse model, which demonstrates that mice with MC1R variants that are analogous to red hair in humans exhibit DNA damage and aggressive melanoma, without UVR exposure.
There are around 13,000 new cases of malignant melanoma every year in the UK, and the disease accounts for three-quarters of all skin cancer deaths.
Despite the findings indicating a strong genetic component to melanoma, Dr Neil Box, assistant professor of dermatology at the University of Colorado, who was not involved in the study, said there should be no change to public health recommendations. Dr Box told WebMD: 'We cannot be sure that the findings are all that they are touted to be' because people don't tend to accurately remember their sunburns. 'The general public should still make every effort at sun safety, particularly those with red hair colour,' he concluded.