Up to one half of current lung cancer occurrence could be attributable to cigarette design, according to David Burns and Christy Anderson of the University of California at San Diego School of Medicine.
Consequently, the study concludes, lung cancer rates could be reduced by up to 50 percent through more regulatory control of cigarette composition.
The study examined lung cancer rates as well as changes in the design and smoke composition of both American and Australian cigarettes over the last four decades. Both countries saw a rise in the use of low tar cigarettes, as well as the introduction of ventilated filters.
The major known difference in cigarettes between the two countries is the level of tobacco-specific nitrosamines, a lung-specific carcinogen that causes adenocarcinoma--one of the four major cell types of lung cancer. Nitrosamines are found in far higher levels in American cigarettes than in Australian cigarettes, the study reports.
The study also shows that the increase in the overall incidence of lung cancer in the U.S. has largely been driven by an increase in risk in adenocarcinoma. By contrast, adenocarcinoma makes up a smaller percentage of lung cancer cases in Australia, where age-specific lung cancer death rates are lower than in the U.S.
& Cigarette Design
Download the UCSD School of Medicine Report
David Sutton, a spokesperson for tobacco company PhilipMorrisUSA, said his company has been aware of concerns over nitrosamines for some time and has taken steps to reduce the levels of the carcinogen in tobacco.
For instance, the company requires its tobacco growers to use indirect heating systems during the curing process to prevent the tobacco from being exposed to the combustion gases that increase the presence of nitrosamines. For growers that do not use a heat-based curing system, PhilipMorrisUSA requires the use of a tobacco seed that has been shown to produce less nitrosamines.
Sutton said today's presentation of the study did not give enough data to explain why the level of nitrosamines may be higher in American-grown tobacco versus Australian-grown tobacco.
"It's impossible to get a significant conclusion," he said. "When the full study is published, we'll evaluate it."
He added that PhilipMorrisUSA has for eight years supported tough but reasonable regulation of tobacco and supports the medical consensus that cigarettes are harmful to one's health.
"There is no safe cigarette," he said.
By Stephanie Condon