Lung cancer doesn't just affect smokers, though. People who have never smoked still have a lifetime risk of about 0.5%-1.0%. And the study was studying self-r

Lung cancer doesn't just affect smokers, though. People who have never smoked still have a lifetime risk of about 0.5%-1.0%. And the study was studying self-reported non-smokers in addition to smokers. "We found that B6 and B12 had sex- and source-specific associations with lung cancer risk. In addition, the association in men was more pronounced in cigarette smokers." http://ascopubs.org/doi/full/10.1200/JCO.2017.72.7735 http://ascopubs.org/doi/full/10.1200/JCO.2017.72.7735