A prospective study of cigarette smoking and basal cell carcinoma

To investigate the relationship between smoking and primary basal cell carcinoma (BCC), we analyzed data from a 16 year prospective study among randomly selected adults in Nambour, Queensland, Australia. Participants underwent a skin examination in 1992 and took part in an intervention study and follow-up. Information about complexion type and smoking habits including duration and number of cigarettes smoked per day and sun exposure behavior were collected at baseline in 1992, with updates to end of follow-up in 2007. Newly-diagnosed BCCs were ascertained from regional pathology laboratories. Relative risks (RR) of BCC among former and current smokers were estimated using generalized linear models specifying a Poisson distribution with robust error variance and (log) person-years at-risk as offset, adjusting for BCC risk factors. From 1992 to 2007, 281 BCCs were diagnosed in 1,277 participants with available smoking history and no past BCC. Relative to non-smokers, a non-significant inverse association between current smoking and BCC was seen (RR 0.69; 95 % CI 0.45-1.05) but not for former smokers (RR 1.05; 95 % CI 0.84-1.31). Amongst current smokers, inverse associations with BCC were found in those who smoked for up to 18 years (RR 0.44) but not more and those who smoked up to 15 cigarettes per day but not more. The associations with both current and former smoking varied by degree of sunburn propensity. The modest inverse association between current smoking and BCC is considered unlikely to be causal given lack of clear relation with duration or intensity of smoking.