Researchers from the National Cancer Institute who studied the health records of more than 476,000 men and women concluded that smoking increases the risk of head and neck cancers among both genders.

Head and neck cancers have long been associated with tobacco use, but the new study reveals that smoking plays a larger role in such cancers among women than men. Among men, 45 percent of head and neck cancers are related to smoking, researchers said, but smoking causes 75 percent of such cancers in women.

"Incidence rates of head and neck cancer were higher in men than in women in all categories examined, but smoking was associated with a larger relative increase in head and neck cancer risk in women than in men," wrote researcher Neal Freedman and colleagues.

The study is published in the Oct. 1, 2007 issue of the journal Cancer.