Indoor tanning tied to increased risk of multiple primary melanomas, study says

The study was published in the form of a research letter in the Journal of the American Academy of Dermatology on November 15, 2022

A history of above ten indoor tanning exposures is linked with increased melanoma risk. Further, it is reported that indoor tanning is the most common cause of multiple primary melanomas (MPMs). Andrew Roth from Feinberg School of Medicine at Northwestern University, Chicago, Illinois, and colleagues performed a case-control study to explore this relationship. Cases were defined as patients with two or more (2+) primary melanomas, and controls were patients with a single primary melanoma (SPM). The ages of the participants varied from 20 to 70 years at the time of data extraction. They were diagnosed with at least one primary melanoma at the Northwestern Memorial Hospital between 2015 to 2018.

A total of four hundred fifty-three patients were included; 335 had single primary melanoma, and 118 had multiple primary melanomas. The mean age was (SPM, 53 years; MPM, 51 years) similar and was slightly skewed towards women (SPM, 53%; MPM, 58%). Patients were then classified by a history of > 10 lifetime indoor tanning exposures and zero exposures.

The researchers also performed a systematic review of the literature and meta-analysis per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to compare the MPMs risk associated with the most common mutations in familial melanomas. The odds ratio was calculated for multiple primary melanomas related to a family history of melanoma, indoor tanning, and a germline mutation predisposing to melanoma. These included low-/intermediate-penetrance (MITF, MC1R) and high-penetrance (CDKN2A) genes.

The study's findings were as follows:

• The proportion of patients with more than ten exposures increased from 19% for patients with an SPM to 53% for those with 4+ MPMs.
• In both multivariable and univariate analyses, the associated risk for multiple primary melanomas was remarkable for 2+, 3+, and 4+ melanomas.
• At 2+ melanomas, the risk linked with indoor tanning (OR, 1.97) surpassed that of family history (OR, 1.46) and resembled the risk associated with germline mutations in MITF (OR, 2.45) and MC1R (OR, 1.38). At these lower MPMs numbers, a germline mutation in CDKN2A carried a more significant risk (OR, 5.81).
• There was little data for higher numbers of MPMs, but it indicated that the risk related to indoor tanning might exceed that of low-/intermediate-penetrance germline mutations.

"The prevalence of indoor tanning is a critical consideration with latest estimates of indoor tanning bed use at about 10% versus <0.1% for germline mutations in CDKN2A," the researchers wrote. "Therefore, it is more likely that clinicians will encounter patients with an indoor tanning history, stressing the significance of continued education of the general populations on the risks of these devices."

To conclude, the authors found a significant risk for multiple primary melanomas linked with indoor tanning, indicating the need for closer monitoring of these patients. Also, they encouraged involvement in public health campaigns concerning the risk of tanning devices.

Reference:

The study "Indoor tanning is associated with an increased risk of multiple primary melanomas: A case-control study" was published in the Journal of the American Academy of Dermatology.

DOI: https://doi.org/10.1016/j.jaad.2022.09.038