In a rare example of good news for the big three in legal drugs — coffee, cigarettes and alcohol — a new study finds that cigarette smoking and alcohol consumption have no effect on a woman's chances of getting ovarian cancer. Incredibly, caffeine intake may actually lower the risk. But before you head out to celebrate, you may want to read further.

The new study was designed to try to reconcile the conflicting results of previous studies that looked for a link between ovarian cancer and smoking, caffeine and alcohol. Dr. Shelley S. Tworoger of Harvard Medical School and the Harvard School of Public Health and her colleagues examined questionnaire data from the Brigham and Women's Hospital−based Nurses' Health Study, which includes 121,701 female registered nurses in the U.S.. The Nurses' Health Study was established in 1976, when women aged 30−35 completed and returned initial health questionnaires. New questionnaires are sent to the women every other year for follow−up.

..."reducing alcohol intake and cessation of smoking is not likely to have a substantial impact on risk of ovarian cancer." They add that "the possibility that caffeine may reduce ovarian cancer risk...

The researchers examined associations between smoking and ovarian cancer risk among 110,454 women and between alcohol or caffeine and ovarian cancer risk among 80,253 women, all followed between June 1, 1976 and June 1, 2004.

They found that there was no association between current or past smoking and ovarian cancer risk in general. (Smoking was strongly associated, however, with increased risk of mucinous tumors, a very rare type of ovarian cancer). They also found no association between drinking alcohol and ovarian cancer risk.

The shocker in the study was the discovery that a woman's risk of developing ovarian cancer declined if she drank caffeinated coffee. Decaffeinated coffee did not affect risk either way. The reduction in risk with higher caffeine intake appeared to be strongest for women who had never taken hormones, either in the form of oral contraceptives or postmenopausal hormones.

The authors concluded that, "reducing alcohol intake and cessation of smoking is not likely to have a substantial impact on risk of ovarian cancer." They add that "the possibility that caffeine may reduce ovarian cancer risk, particularly for women who have not previously used exogenous hormones, is intriguing and warrants further study, including an evaluation of possible biological mechanisms."

The study is published in the March 1, 2008 issue of Cancer, a peer−reviewed journal of the American Cancer Society.