Of 252 male lung cancer patients, 248 or 98% were cigarette smokers, significantly (P less than .001) more than in the control group (526 = 64% of 839). In relation to the relative risks (RR) of never-smokers, the adjusted (for age, total years smoked, and average number of cigarettes smoked per day) lung cancer RR for smokers who had exclusively smoked cigarettes belonging to group II (15-24 m...
