Smoking and lung cancer: risk as a function of cigarette tar content.

The hypothesis of reduction in lung cancer risk associated with the adoption of low-tar cigarettes was examined in a subset of subjects from a population-based, case-control study of incident primary lung cancer among New Jersey white men. Risk was related to time-weighted average tar levels of cigarettes smoked in 1973-1980. Unadjusted estimates of risk were significantly low for the lowest tar (less than 14 mg/cig) smokers [odds ratio = 0.53 (0.29,0.97)] compared with the highest (21.1-28 mg/cig). However, adjustment by age and total pack-years rendered the risk reduction insignificant. Of note was the finding that cases who smoked low-tar cigarettes compensated for reducing tar by increasing the number of cigarettes they smoked by almost half a pack per day from the years 1963-1972 to 1973-1980, while in the same period controls and high-tar cigarette smoking cases did not increase the numbers smoked.