The benefits of coffee consumption appeared to be related to the caffeine content of the beverages, with no benefits observed from decaffeinated coffee, stated the researchers in the journal Cancer. Shelley Tworoger and co-workers from Harvard Medical School and the Harvard School of Public Health also state that the benefits were more pronounced for postmenopausal women and their younger counterparts who had never used oral contraceptives. "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 biologic mechanisms," wrote Tworoger. Of all the cancers of the female reproductive system, ovarian cancer has the highest mortality. In the UK, ovarian cancer causes more than 4,000 deaths per year, according to Cancer Research UK. While in 2003 in the US, a total of 14,657 women died from ovarian cancer, said the Ovarian Cancer National Alliance (OCNA). According to OCNA figures, one in 69 women will develop ovarian cancer in their lifetime and another one in 95 women will die from the disease. Tworoger and co-workers used data from the 121,701 US female registered nurses participating in the Nurses' Health Study. The women completed questionnaires at the start of the study (1976) when they were aged between 30 and 35, and completed follow-up questionnaires at bi-annual intervals thereafter. A 'modest' 20 per cent risk reduction in ovarian cancer was reported among all the women for caffeine intake greater than 500 milligrams per day, compared to women with a daily intake of less than 136 milligrams. When the analysis was limited to women who had never used either oral contraceptives, the highest daily intake of caffeine was associated with a 35 per cent risk reduction, compared to women with the lowest daily intakes. Moreover, the highest daily intake of caffeine was linked to a 43 per cent reduction in the risk of the cancer among postmenopausal women, stated Tworoger. No associations were reported for current or past smoking habits, or alcohol consumption and ovarian cancer risk, added the researchers. "With regard to caffeine and caffeine-containing beverages, we generally observed a lower risk of ovarian cancer with increasing intake. However, these results should be interpreted with caution," stated Tworoger and co-workers. They go on to note that no benefits were observed with respect to tea consumption were observed when they used early data, while some benefits were observed at a later stage. "This latter difference may be in part because tea could have different effects early versus late in the carcinogenic process," they added. Furthermore, Tworoger and co-workers note that previous studies have reported an increase in oestrogen concentrations and shorter menstrual cycles in pre-menopausal women with increased tea consumption. "Conversely, in postmenopausal women, caffeine intake may be associated with higher sex hormone-binding globulin (SHBG) and lower free oestrogen concentrations; this mechanism may act through an effect on the hepatic production of SHBG.
"This potential interaction should be examined further in studies with larger numbers of pre-menopausal women," they added. Source: Cancer Published online ahead of print, 22 January 2008, doi: 10.1002/cncr.23275
"Caffeine, Alcohol, Smoking, and the Risk of Incident Epithelial Ovarian Cancer" Authors: S.S. Tworoger, D.M. Gertig, M.A. Gates, J.L. Hecht, S.E. Hankinson