Effect of smoking on melanoma incidence: a systematic review with meta-analysis.

ABSTRACT

BACKGROUND: There is a strong correlation between cigarette smoking and the development of many cancer types. It is therefore paradoxical that multiple reports have suggested a reduced incidence of melanoma in smokers. This study aimed to analyze all existing studies of melanoma incidence in smokers relative to non-smokers. METHODS: Searches of MEDLINE and Embase were conducted for studies reporting data on melanoma in smokers and never-smokers. No study design limitations or language restrictions were applied. The outcome examined was the association between smoking status and melanoma. Analyses focussed on risk of melanoma in smokers and never-smokers generated from multivariable analyses and these were pooled using a fixed effects model. Risk of bias was assessed using the Newcastle-Ottawa tool. FINDINGS: Forty-nine studies that included 59,429 melanoma patients were identified. Pooled analyses showed that current-smokers had a significantly-reduced risk of melanoma both in males (risk ratio (RR) 0.60, 95%CI_0.56 to0.65, p < .001) and females (RR 0.79- 95%-CI-0.73-to-0.86, p < .001). Male former-smokers had a 16% reduction in melanoma risk compared to never-smokers (RR-0.84,-95%CI-0.77-to-0.93, p < .001), but no risk reduction was observed in female former-smokers (RR-1.0-95%CI-0.92-to-1.08). INTERPRETATION: Current-smokers have a significantly-reduced risk of developing melanoma compared to never-smokers, with a reduction in melanoma risk of 40% in men and 21% in women.