Postmenopausal women who consume even moderate amounts of alcohol may face an increased risk of breast cancer, say US researchers, particularly if their cancer is fuelled by the hormones estrogen or progesterone.
Lead researcher Chen and colleagues tracked over 120,000 women, focusing on breast cancer rates in women who reported drinking small amounts of alcohol - less than a glass of beer or wine a day.
Chen, based at Boston's Dana-Farber Cancer Institute, said that although the women's overall risk of breast cancer was low, they developed the disease at a higher rate than women who were non-drinkers.
"The elevated risk was most pronounced in those whose tumour growth was stimulated by the hormones estrogen or progesterone," underline the scientists.
According to the study, the results were consistent regardless of the women's body mass index, type of alcoholic beverage consumed, or use of hormone replacement therapy.
"Women need to consider the possible effects of alcohol on breast cancer risk when weighing the risks and benefits of alcohol consumption," comments Chen.
The scientists, that included researchers at Harvard School of Public Health, used data from the 'Nurses' health study' in the US - a project led by Boston's Brigham and Women's Hospital that has tracked the health of 122,000 registered nurses since 1976.