Sun damage and genetic risk in melanoma

Melanoma is the most deadly form of skin cancer, and affects over 13,000 Australians each year. In Queensland about 20% of melanomas are the patient's second or subsequent melanoma. Having fair, easily‐sunburned skin, many moles, or sun‐damaged skin increase the risk of melanoma, but genetics also plays a part. This study, from Queensland, Australia, aimed to find out if there were genetic differences between people with only one melanoma and people with multiple melanomas, and whether people with multiple melanomas were more likely to have their melanomas on a sun‐damaged body site. To do this, the authors took full‐body photographs of 1244 volunteers, with close‐up photos of their excision scar sites in 585 of the melanoma patients, and a DNA sample. They also checked medical records to confirm the number of melanomas and the age they first appeared, and assessed the scar site photos for signs of visible sun damage, like freckling, dark blotches and wrinkling. Patients with multiple melanomas were more likely to have mutations in MITF , ASIP and the red hair MC1R gene than people with a single melanoma. Patients who were unusually young (under 40 years old) when they first had a melanoma were more likely to have the melanoma on a sun‐protected part of the body, while older melanoma patients (over 40 years) more often had their melanoma on sun‐damaged skin. Younger melanoma patients were also more likely to have variant changes in CDKN2A , MC1R and MTAP genes, but these genetic differences were also more common in patients whose melanomas were all in sun‐damaged sites, compared to people with at least one melanoma in a sun‐protected site. Using a genetic risk score incorporating these findings, alongside visible risk factors like skin type, makes it easier to predict who is at high risk of having melanomas and who might benefit from regular skin checks with a doctor. Linked Article:   McMeniman et al. Br J Dermatol 2020; 183 :357–366.