Low-tar cigarettes may reduce your chance of getting one kind of lung cancer, but they boost your risk of another lung cancer type, says a study reported in next month's issue of the journal Cancer. The work, done in Switzerland, supports the prevailing belief that low-tar cigarettes aren't much safer than their high-octane predecessors.
Fabio Levi of the Vaud Tumor Registry in Lausanne, Switzerland, and his colleagues analyzed 7423 lung cancer cases reported between 1974 and 1994 in two Swiss states, Vaud and Neuchâtel. The group found that the incidence of squamous-cell tumors in the larger lung tubes in men dropped 27% from 1974-79 to 1989-94. Meanwhile, the rates of adenocarcinoma, which affects the lung's mucus-secreting cells, rose 142% over the period. Overall, lung cancer rates in the region increased slightly, from 55.6 to 57.5 cases per 100,000 people.
The Swiss researchers blame the shifting lung cancer rates on the phase-in from the mid-1950s to the mid-'80s of cigarettes containing less tar, which is rich in carcinogens. As a result, they say, smokers would have fewer tar deposits in the larger lung tubes, accounting for the lower tumor rate there. But smoke from low-tar cigarettes is easier to inhale and tends to get sucked deeper into the lungs. Levi's group suggests that this deep breathing delivers more carcinogens to the smaller lung branches, where adenocarcinoma develops.
The authors acknowledge that other factors--from dietary changes to air pollution--may be at least partly responsible for the shift in lung cancer type. Nevertheless, the study confirms similar trends in U.S. cancer rates, says Neal Benowitz, a nicotine researcher at the University of California, San Francisco. Switching to low-tar cigarettes, he says, may lower the risk of some diseases, but it won't protect you from the real killers: "You're not going to change your risk of cancer or heart disease."