Objective: Previous studies suggest that smoking may be inversely associated with risk of melanoma. We attempted to replicate this finding using data from the Cancer Prevention Study II (CPS-II) and CPS-II Nutrition cohort, two large prospective cohort studies of cancer mortality and incidence, respectively, with long-term follow-up.
Methods: Cox proportional hazards regression analysis was used to examine the association between smoking status and risk of melanoma mortality and incidence among Caucasians in these cohorts. Analyses were adjusted by age, occupation, latitude and educational status.
Results: The incidence rate of melanoma was lower in current than never smokers in both men [hazard ratio (HR): 0.70, 95% confidence interval (CI): (0.48-1.02)] and women [0.50 (0.30-0.83)]; incidence was not lower in former than in never smokers for either sex. The death rate from melanoma was lower in male current than never smokers [0.77 (0.62-0.94)], and in male and female former smokers [0.86 (0.73-1.01)] and [0.83 (0.65-1.06)], respectively. No trends in incidence or mortality were observed in male or female current smokers with years of smoking or cigarettes per day.
Conclusions: This study provides limited support for the hypothesis that smoking reduces melanoma risk. The inconsistent results by smoking status and lack of clear dose-response relationships weaken the evidence for causality.