TORONTO (CP) - Women with early-stage lung cancer survive on average longer than their male counterparts, suggesting that female biology may have an inherent advantage when it comes to the deadly disease, a study says.
The study, presented Tuesday at the annual meeting of the American College of Chest Physicians in Montreal, showed that female lung cancer patients lived longer than men with the disease no matter which treatment was employed.
Lead investigator Dr. Juan Wisnivesky, an assistant professor of medicine at New York's Mount Sinai School of Medicine, said researchers looked at U.S. health records for almost 19,000 patients with early-stage lung cancer between 1991 and 1999.
The patients were divided into three groups: those who had surgery; those who had radiation or chemotherapy, but no surgery; and those with no treatment at all.
"Within each of these groups, women did better than men, even among those who were untreated, suggesting that what's really different is the biology of cancer - and it's not related to the responses to treatment," Wisnivesky said in an interview from Montreal.
Among patients who had surgery only, women lived on average a year longer than men. Among those in the untreated group, women's average survival was extended five to six months beyond that of men.
Overall, adjusting for such variables as age, race and income level, woman had a 25 per cent lower death rate from lung cancer than men battling the disease.
Dr. Michael Alberts, president of the American College of Chest Physicians, said the question researchers now need to ask is how does the information help doctors in providing support and information to patients.
"For any one individual patient, it probably doesn't help," said Alberts, a pulmonologist and chief medical officer for the Moffitt Cancer Center in Tampa, Fla. "In other words, you could say: 'You may live longer or you may not live longer.'
"But it does suggest that maybe there's some hormonal influence that affects a cancer or some other gender-specific influences that impact the natural history of lung cancer and translates into longer survival for women.
"So I think it's exciting information, but perhaps more to suggest further inquiry into the cellular aspects of lung cancer, the hormonal influences, that type of thing."
Many factors may play a role in this gender difference, Wisnivesky said, including smoking patterns (women tend to smoke less and inhale less deeply than men), the body's metabolism of carcinogens and the effects of female hormones like estrogen.
Still, that shouldn't suggest to women that they can get away with smoking while men can't, Wisnivesky stressed.
"In general, lung cancer is a deadly disease whether you're a man or a woman. So I think this shouldn't be a message encouraging women to smoke."
This year, 12,000 men and 10,200 women in Canada will be diagnosed with lung cancer; an estimated 10,700 men and 8,300 women will die of the disease, making it the most common and lethal of all cancers.
In other presentations Tuesday, a study of U.S. smokers found women who light up are more concerned about their habit and their ability to quit than men are, yet both sexes appear to be poorly informed about smoking and its link to cancer.
"Men who smoke spend little time thinking about their habit and the harmful effects of smoking, especially if they have few physical side-effects," said lead author Virginia Reichert, director of the Center for Tobacco Control at the North Shore-Long Island Jewish Health System in Great Neck, N.Y.
"Women who smoke seem to have a great deal of anxiety about smoking," Reichert said in a release. "They are worried about their health, feel guilty about not quitting and believe that cigarettes are controlling their lives."
The study of more than 1,100 smokers involved in a tobacco cessation program also found that most smokers mistakenly believed nicotine causes cancer, leading many to smoke "light" cigarettes because of the notion these products are less harmful.
A survey found 72 per cent of women and 60 per cent of men believed nicotine causes cancer, while 75 per cent of women and 65 per cent of men admitted to worrying that smoking may give them cancer. More women than men (about three-quarters versus almost two-thirds) reported smoking "light cigarettes."
"People smoke to get the addictive drug, nicotine, but the drug alone does not cause cancer," said Reichert. "The delivery system, a cigarette full of hundreds of toxic chemicals that are inhaled along with nicotine, does.
"This misinformation leads many smokers to smoke light cigarettes, thinking they will inhale less nicotine. In reality, smokers tend to smoke more light cigarettes and inhale more deeply to get nicotine from light cigarettes, resulting in a significant amount of harmful chemicals being inhaled."
While men on average smoked more "pack years" than women (33 years compared to 27.5), the sexes showed no difference in nicotine dependency scores.
The study also found there was no difference in attempts to quit - two each for both men and women - or in quit rates.
© The Canadian Press, 2005