FRIDAY, June 13 (HealthDay News) -- Women who smoke are just as likely to get lung cancer as men who smoke, a large U.S. study found.

But, women who never smoked appear to be at greater risk of lung cancer than men who never smoked, according to the report from the National Cancer Institute (NCI).

"It has been known for a long time that smoking is strongly associated as a cause of lung cancer," said lead researcher Neal Freedman, a cancer prevention fellow at NCI. "But there has been quite a bit of debate about whether the association is similar in men and women."

In the study, the largest of its type, the incidence of lung cancer in men and women who smoked comparable amounts of cigarettes was quite similar, Freedman said. "Before this, there was some evidence that women were more susceptible to carcinogens in cigarette smoking than men," he said.

Freedman's team collected data on 279,214 men and 184,623 women between 50 and 71 years of age from eight states. The data included questions about diet, exercise, alcohol consumption, and whether they were current smokers, ex-smokers or had never smoked.

The researchers found that 1.47 percent of the men and 1.21 percent of the women developed lung cancer. But among women who had never smoked, they were 1.3 times more likely to develop lung cancer than men who never smoked.

For both men and women, those who smoked more than two packs a day were about 50 times more likely to develop lung cancer than people who never smoked.

In terms of the type of lung cancer, people who never smoked were more likely to develop adenocarcinomas, which were more common in women than men. However, the rate of small cell, squamous cell, and undifferentiated tumors was the same for both men and women.

The findings were published online June 14 in the July edition of The Lancet Oncology.

"The most effective way to prevent lung cancer is for men and women not to smoke, or if they are smoking to quit," Freedman said.

Thomas Glynn, the American Cancer Society's senior director of international tobacco control, said the study was very useful, given the debate over the last decade whether women were more susceptible to tobacco-related lung cancers than men.

"The conclusion reached that women are more or less susceptible to lung cancer goes back to the adage, 'Women who smoke like men die like men,' " Glynn said. "This study shows that women who smoked like men get lung cancer like men."

More information

For more on lung cancer, visit the American Lung Association.