The Rest of the Story
Last week, a new study out of the FDA's Center for Tobacco Products reported that the risk of lung cancer death is significantly and substantially lower among menthol cigarette smokers than among non-menthol smokers.
See: Rostron B. Lung cancer mortality risk for U.S. menthol cigarette smokers. Nicotine & Tobacco Research 2012. Published online ahead of print on March 1, 2012. doi: 10.1093/ntr/nts014.
The study was a survival analysis of smokers from the 1987 National Health Interview Survey Cancer Control Supplement. Approximately 4800 smokers were followed up to determine mortality rates by linking to the National Death Index. Mortality rates, controlling for a wide set of demographic factors and smoking behavior variables, were compared for menthol and non-menthol smokers.
The results were as follows: "The overall HR [hazard ratio] for lung cancer mortality for menthol smokers was 0.69 (95% CI = 0.45–1.06). The HR for lung cancer mortality for menthol smokers at ages 50 and over was 0.59 (95% CI = 0.37–0.95)."
The study concludes as follows: "We found evidence of lower lung cancer mortality risk among menthol smokers compared with nonmenthol smokers at ages 50 and over in the U.S. population. It is not known, however, if these differences are due to the impact of menthol on cigarette smoking or long-term differences in cigarette design between menthol and nonmenthol cigarettes."
The results of this study comport with those of an earlier study which reported finding a statistically significant adjusted hazard ratio for lung cancer mortality of 0.69 associated with smoking menthol cigarettes vs. non-menthol cigarettes.
It is important to note that these results do not prove that the menthol itself confers a degree of decreased lung cancer risk. It is highly possible, and actually likely, that the real reason for the observed lung cancer mortality difference is that menthol smokers and non-menthol smokers have differing patterns of cigarette use and smoke inhalation. For example, Rostron postulates, quite plausibly, that because of the full flavor and absence of filter tip ventilation of menthol cigarette brands, smokers may not need to inhale as deeply, resulting in reduced tar exposure.
Rostron writes: "Cigarette ventilation is one possible cause of differences in risk for menthol cigarettes, given that the delivery of carcinogenic constituents can be altered by ventilation (Hoffmann & Hoffmann, 1997). Smokers of ventilated cigarettes often inhale more deeply in order to ensure consistent nicotine delivery (Hoffmann & Hoffmann, 1997). Popular menthol brands in the U.S. market often have little or no filter tip ventilation, particularly for their “full-flavor” subbrands (Kozlowski, Mehta, & Sweeney, 1997). As a result, differences in lung cancer mortality for menthol and nonmenthol smokers may be due in part to differences in inhalation caused by product design and not necessarily to menthol itself."
Regardless of the explanation for the reduced lung cancer mortality observed among menthol cigarette smokers, I believe that this finding is going to put the final nail in the coffin for the prospect of any ban on menthol cigarettes.