Caffeine appears to lower a woman's chances of developing ovarian cancer, U.S. researchers said on Tuesday, while smoking cigarettes and drinking alcohol do not.
The benefit for caffeine drinkers also seemed strongest for women who had never used oral contraceptives or postmenopausal hormones, the researchers wrote in the journal Cancer.
"With regard to caffeine and caffeine-containing beverages, we generally observed a lower risk of ovarian cancer with increasing intake," Shelley Tworoger of Harvard Medical School and colleagues wrote.
Worldwide there are more than an estimated 190,000 new cases of ovarian cancer each year, a disease more common after age 50. Women often have mild or no symptoms until the disease has progressed.
Previous studies have linked caffeine consumption with lowered cancer risk, but the researchers said further work was needed to determine the biological reasons driving the protective benefits they found in ovarian cancer.
The team examined data taken from health questionnaires of more than 121,000 women aged 30-35 as part of a Utah study.
The researchers found no significant link between current or past smoking or drinking and overall ovarian cancer risk, though cigarettes seemed to raise the likelihood of one rare form of the disease.
Risk also appeared to decline the more total caffeine and coffee a woman consumed, the study found. Decaffeinated coffee had no apparent benefit.
"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 researchers wrote.