The article in the Journal of the National Cancer Institute details a study of 76,000 women over more than a decade, which found the usual link between smoking and cancer. Lung cancer was 13 times more common in current smokers, and four times more common in former smokers, than in non-smokers.
The study found no statistically significant relationship between lung cancer and exposure to passive smoke, however. Only among women who had lived with a smoker for 30 years or more was there a relationship that the researchers described as “borderline statistical significance.” Over at the Velvet Glove, Iron Fist blog, however, journalist Christopher Snowden notes “there’s no such thing as borderline statistical significance. It’s either significant or it’s not,” and the reported hazard ratio was not.
The study doesn’t cover the many other ill effects of breathing somebody else’s cigarette smoke, of course, which include asthma and possibly cardio-pulmonary disease. I called Gerard Silvestri of the Medical University of South Carolina and member of the National Cancer Institute’s Screening and Prevention Board, and he said the study merely confirms what many researchers already believed.
“What this study basically showed is what people kind of knew already: At low passive exposures the risk is not that great,” he said. “While that’s good news, it shouldn’t stop anyone from saying, “I don’t want to be a in a bar or any place else with someone who is smoking.”
One researcher in the article said the most important effect of indoor-smoking bans may be on smokers.
“The strongest reason to avoid passive cigarette smoke is to change societal behavior: to not live in a society where smoking is a norm,” said Dr. Jyoti Patel of Northwestern University School of Medicine.
Previous cancer studies have had mixed results, the researchers said, although the Centers for Disease Control and Prevention still calculate secondhand smoke is responsible for 46,000 heart disease deaths and 3,400 deaths from cancer a year. The problem is many studies showing the strongest association between secondhand smoke and cancer were case-control studies that can suffer from “recall bias,” or the tendency of people with a disease that can be blamed on a past exposure t0 be more likely to recall it.
Among the 76,000 study participants, however, only 4,000 reported no exposure to passive smoke, making it difficult to “tease out a difference” showing a connection, as one researcher said.
Still, the study goes a long way toward eliminating the premise of a groundbreaking lawsuit on behalf of 60,000 flight attendants who sought damages for lung cancer from passive smoke that was common back in the days when you could light up in an airliner. Tobacco companies settled that by paying $300 million to establish the Flight Attendant Medical Research Institute, to support research into tobacco-related diseases. Lawyers for flight attendants have been battling to have FAMRI shut down and the proceeds paid directly to flight attendants, saying the elimination of smoking on airliners has ended its usefulness to the class.