Use of sunscreen and risk of melanoma and non-melanoma skin cancer: a systematic review and meta-analysis.

The use of sunscreen is a key component of public health campaigns for skin cancer prevention, but epidemiological studies have raised doubts on its effectiveness in the general population. This systematic review and meta-analysis aimed to assess the association between risk of skin cancer and sunscreen use. We searched PubMed, BIREME and Google Scholar from inception to May 17, 2017, to identify observational studies and controlled trials. We used a random-effects model for conventional and cumulative meta-analyses. We included 29 studies (25 case-control, two cohort, one cross-sectional, and one controlled trial) involving 313,717 participants (10,670 cases). The overall meta-analysis did not show a significant association between skin cancer and sunscreen use (odds ratio (OR) = 1.08; 95% CI: 0.91-1.28, I2  = 89.4%). Neither melanoma (25 studies; 9,813 cases) nor non-melanoma skin cancer (five studies; 857 cases) were associated with sunscreen use, with a pooled OR (95% CI) of 1.10 (0.92-1.33) and 0.99 (0.62-1.57), respectively. The cumulative evidence before the 1980s showed a relatively strong positive association between melanoma and sunscreen use (cumulative OR: 2.35; 95% CI: 1.66-3.33). The strength of the association between risk of skin cancer and sunscreen use has constantly decreased since the early 1980s, and the association was no longer statistically significant from the early 1990s. While the current evidence suggests no increased risk of skin cancer related to sunscreen use, this systematic review does not confirm the expected protective benefits of sunscreen against skin cancer in the general population.