Women married to men who smoke at home double their risk of adenocarcinoma, a common type of small-cell lung cancer that accounts for 70 percent of female lung-cancer cases, according to Japanese researchers.

The Yomiuri Shimbun reported Dec. 13 that researchers from Japan's Health, Labor and Welfare Ministry studied 28,000 nonsmoking women ages 40 to 69 and found that those with husbands who smoked at home were twice as likely to get lung cancer as those with nonsmoking spouses.

The risk was 1.7 times higher for women married to men who smoked less than 20 cigarettes per day, and 2.2 times higher for those married to smokers who consumed more than 20 cigarettes daily.

The researchers estimated that 40 percent of the women studied would not have developed cancer if they had not been exposed to tobacco smoke at home.