Nonsmoking Japanese women married to smokers are 34 percent more likely to develop lung cancer than those married to men who have never smoked, Reuters reported Feb. 25.

Researchers at Tokyo's National Cancer Center studied the cancer history of 28,414 nonsmoking women and correlated that data with information on spousal smoking. "Although smoking is a major cause of lung cancer, the proportion of lung cancer cases among Japanese women who never smoked is high," reported researcher Norie Kurahashi and colleagues. "As the prevalence of smoking in Japan is relatively high in men, but low in women, the development of lung cancer in nonsmoking Japanese women may be significantly impacted by passive smoking."

"Particularly in Japan, where room sizes tend to be small and living conditions congested, sidestream smoke may be directly transmitted to nonsmoking women before dilution by room air," the researchers added.

About half of the women in the study were exposed to secondhand smoke from husbands who were smokers, and 109 developed lung cancer during the 13.3-year study period.

The researchers also found that exposure to secondhand smoke in the workplace raised the risk of lung cancer by 32 percent among nonsmoking Japanese women.

The study was published in the Feb. 1, 2008 issue of the International Journal of Cancer.