Effect of cigarette tar yield and mentholation on the occurrence of lung cancer

Lung cancer is the major cause of cancer mortality among both men and women in the United States. Despite declines in smoking prevalence over the past forty years, approximately 50 million people—25% of adults—in the U.S. still smoke cigarettes. There are potentially important differences between cigarettes that may somewhat ameliorate or further increase the risk of lung cancer. The studies described herein address the impact of tar yield and mentholation on the occurrence of lung cancer among long-term smokers.; The first study used a case-control design to compare the effect of cigarettes with lower tar ratings to cigarettes with higher tar ratings on the overall and histologic-specific incidence of lung cancer among current smokers or recent quitters who had smoked for at least twenty years. Smokers in the lowest quintile of average tar rating had an odds ratio (OR) for the occurrence of lung cancer of 0.71 (95% confidence interval (CI) .49–1.04) compared to those in the highest quintile. These results were consistent with partial compensation for reduced yield among smokers of lower-yield cigarettes resulting in exposure greater than predicted by standard tar ratings. Compared to those in the highest quintile, smokers in the lowest tar quintile had a similar reduction in risk for both squamous cell carcinoma (OR: 0.76, 95% CI: .44–1.33) and adenocarcinoma (OR: 0.76,95% CI: .47–1.23).; The second study compared the location of tumors according to tar level among a group of lung cancer cases from the first study. Location was assigned as central or peripheral based on review of radiological imaging studies or reports. Smokers of lower-tar cigrarettes were more likely to have tumors in a peripheral location (OR: 1.66, 95% CI: .85–3.24). These results are consistent with the theory that smokers of lower tar cigarettes inhale more deeply and expose the peripheral region of the lung to relatively more carcinogens.; The third study compared the occurrence of lung cancer in menthol and nonmenthol smokers using a case-control design. Long-term users of menthol cigarettes did not have an increased risk of lung cancer compared to smokers of other cigarettes (OR = 0.97; 95% CI: 0.70–1.34).