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

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 nonsmokers.

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 focused on risk of melanoma in smokers and never-smokers generated from multivariable analyses, and these analyses were pooled using a fixed-effects model. Risk of bias was assessed using the Newcastle-Ottawa tool.

Results: Forty-nine studies that included 59 429 patients with melanoma were identified. Pooled analyses showed statistically significant reduced risks of melanoma in male smokers (risk ratio [RR] = 0.60, 95% confidence interval [CI] = 0.56 to 0.65, P < .001) and female smokers (RR = 0.79, 95% CI = 0.73 to 0.86, P < .001). Male former smokers had a 16% reduction in melanoma risk compared with male 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).

Conclusions: Current smokers have a statistically significant reduced risk of developing melanoma compared with never-smokers, with a reduction in melanoma risk of 40% in men and 21% in women.