Vineis et al report a prospective case-control study examining 123 479 “healthy” never smokers or former smokers. Over 7 years of follow up, cases were defined as “respiratory cancers” or deaths from COPD. Controls were well matched. Information about tobacco smoke exposure and a thorough list of confounders was obtained by questionnaire at recruitment. This strengthens the study by cutting out recall bias. Follow up data were from multiple sources. A subset of subjects and controls were tested for the presence of genetic polymorphisms implicated in carcinogenesis.

Exposure to tobacco smoke was associated with increased …