Lung Cancer and the Sexes

By Christine Gorman

For years researchers have debated whether smoking affects the lungs of men and women differently. So far, there's been as much evidence against a sex bias as for one. But that may be starting to change. In the most compelling study on the topic to date, researchers determined that women are twice as vulnerable to lung cancer as men but, in a surprising twist, they die at half the rate of men.

The study, which was published last week in the Journal of the American Medical Association (J.A.M.A.), included 9,427 men and 7,498 women from throughout North America who were healthy, at least 40 years old and either current or former smokers. Over the course of more than eight years, a group of investigators led by Dr. Claudia Henschke of the Weill Medical College in New York City identified lung tumors in 113 of the men and 156 of the women. Then the researchers kept track of who lived and for how long, as well as the treatment participants were given. The study showed that both sexes tended to be in their late 60s when they received a lung-cancer diagnosis but that the women usually had smoked considerably less than the men. Still, at each stage of lung cancer, the women lived longer than the men.

Henschke argues that the J.A.M.A. findings are more scientifically rigorous than previous research because the doctors started following participants before anyone knew who would become sick. (Other studies were so-called retrospective reports, which can lead investigators to jump to conclusions since they already know the outcome.) She and her colleagues are also trying to determine whether the experimental CT scans they used to find the tumors could help detect lung cancers in current and former smokers at a much earlier stage, thereby increasing the likelihood of successful treatment.

If the results reported in J.A.M.A. are confirmed, there are a few hints from other research that might explain the sex difference. Women's bodies appear to have greater difficulty repairing the damage to their genes caused by smoking, but there is also some evidence that estrogen, which is found in women's lungs as well as their ovaries, may interfere with some tumors' ability to grow.

There's one thing about which all investigators already agree: lung cancer is particularly deadly (85% of patients die within five years of their diagnosis) and almost entirely preventable (85% of people with lung cancer are current or former smokers). So the take-home message is clear: don't smoke--and if you do smoke, quit. You would think no one would still have to say that in 2006. But the sad fact of the matter is that more women are smoking--and dying-- than ever before in the U.S., and smoking is also increasing among men and women around the world. No matter what your sex, you're taking your chances if you light up.