So-called "light" cigarettes with holes in the filter could be the reason why a specific kind of lung cancer has been on the rise in recent decades, researchers said Monday.
Adenocarcinoma is the most common form of lung cancer and occurs deep in the lungs.
While other kinds of lung cancer have declined along with diminishing numbers of smokers in the past 50 years, cases of lung adenocarcinoma have climbed.
Researchers believe that the higher rates of lung adenocarcinoma are due to filter ventilation holes, "which allow smokers to inhale more smoke that also has higher levels of carcinogens, mutagens and other toxins," said the report in the Journal of the National Cancer Institute.
"The filter ventilation holes change how the tobacco is burned, producing more carcinogens, which then also allows the smoke to reach the deeper parts of the lung where adenocarcinomas more frequently occur," said lead author Peter Shields, deputy director of The Ohio State University Comprehensive Cancer Center.
"Our data suggests a clear relationship between the addition of ventilation holes to cigarettes and increasing rates of lung adenocarcinoma seen over the past 20 years," he said.
"What is especially concerning is that these holes are still added to virtually all cigarettes that are smoked today," he added, calling on US regulators to ban the practice.
Manufacturers began issuing cigarette filters with holes in them some 50 years ago, marketing them as "light" and claiming these were "low-tar."
"This was done to fool smokers and the public health community into thinking that they actually were safer," said Shields.
Instead, the current study confirms previous research showing that light cigarettes are actually not better for the health than stronger varieties, said the report.
"These cigarettes have actually caused more harm," it said.
The study was based on an analysis of existing literature, including chemistry and toxicology studies, human clinical trials and epidemiological studies.
Researchers looked at peer-reviewed scientific literature and internal tobacco company documents.
More than 36 million Americans smoke, and about 40 percent of cancers are linked to tobacco use, according to the US Centers for Disease Control and Prevention.