Indoor Versus Outdoor: Does Occupational Sunlight Exposure Increase Melanoma Risk? A Systematic Review

Melanoma is the fifth most common cancer diagnosed in the United States, representing 5.6% of all new cancer cases. There are conflicting reports correlating a relationship between primarily outdoor occupations, associated with increased exposure to direct sunlight, and the incidence of cutaneous melanoma. Our objective was to outline and critically evaluate the relevant literature related to chronic occupational exposure to sunlight and risk of developing cutaneous melanoma.

The study protocol for this systematic review was submitted to the International Prospective Register of Systematic Reviews and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. For each relevant study included, the following information was extracted: author names, publication year, study name, study design, age, exposure assessment, outcome, comparison, number of cases, case ascertainment, and descriptive and adjusted statistics. Study quality and evidence certainty was assessed using the Grading of Recommendations, Assessment, Development and Evaluations model.

The initial database search yielded 1629 articles for review and following full-text screening, a total of 14 articles were included for final analysis. Of the studies included, seven articles were retrospective case control and seven were cohort studies. The studies did not report any differences in the likelihood of cutaneous melanoma development based upon membership in the outdoor versus indoor occupation groups included in each study.

Overall, the articles included in this systematic review did not report an increased risk of developing cutaneous melanoma among individuals with outdoor occupations. Further investigation is required to determine if other occupational or life-style-related risk factors exist, to help support the development of individualized skin screening recommendations and improve the early detection of melanoma in all populations.