Smoking and risk of skin cancer: a prospective analysis and a meta-analysis

Background The association between smoking and the risk of skin cancer has not been well established. Methods In two large cohorts in the USA, we prospectively examined the risks of melanoma, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) among participants grouped according to smoking variables. Results Among men, compared with never smokers, ever smokers had a significantly lower risk of melanoma [relative risk (RR) = 0.72; 95% confidence interval (CI): 0.58-0.86]; those who smoked for epsilon 30 years had an RR of 0.65 (95% CI: 0.48-0.89) (P-trend = 0.003); those who smoked epsilon 15 cigarettes per day had an RR of 0.32 (95% CI: 0.13-0.78) (P-trend = 0.006) and those who smoked for > 45 pack years had an RR of 0.66 (95% CI: 0.45-0.97) (P-trend = 0.03). Ever smokers also had a slightly lower risk of BCC (RR = 0.94; 95% CI: 0.90-0.98). There was no significant association for SCC (RR = 0.99; 95% CI: 0.89-1.12). In women, no significant association was found for melanoma (RR = 0.96; 95% CI: 0.83-1.10). Compared with never smokers, ever smokers had a slightly higher risk of BCC (RR = 1.06; 95% CI: 1.03-1.08) and a higher risk of SCC (RR = 1.19; 95% CI: 1.08-1.31). A significant inverse association between smoking and melanoma was limited to the head and neck (RR = 0.65; 95% CI: 0.42-0.89). Conclusions Smoking was inversely associated with melanoma risk, especially on the head and neck. Further studies are warranted to investigate the underlying mechanism(s).