MedWire News: Postmenopausal women who drink excessive amounts of alcohol are significantly more likely to develop a type of breast cancer that needs hormones to grow than their teetotal counterparts, research shows.

"This suggests that a woman should evaluate consumption of alcohol along with other known breast cancer risk factors, such as use of hormone replacement therapy," said lead researcher Dr Jasmine Lew, from the University of Chicago in Illinois, USA.

Dr Lew and team studied data on more than 184,000 postmenopausal women who were participating in a long-term diet and health study.

At the start of the study in 1995, all the women completed dietary questionnaires, which included information on the amount of alcohol they regularly consumed.

Over an average monitoring period of 7 years, 5461 of the women developed invasive breast cancer.

Analysis revealed that women who consumed up to one drink a day were 7% more likely to develop a type of breast cancer that requires the hormones oestrogen and progesterone to grow than women who never drank alcohol.

Furthermore, the risk of this type of cancer appeared to increase with higher levels of alcohol consumption. Indeed, compared with teetotal women, those who consumed up to two drinks a day faced a 32% increased risk of oestrogen- and progesterone-sensitive breast cancer, while those who consumed three or more drinks a day faced a 52% increased risk of the disease.

Dr Jasmine Lew concluded: "Our study at this point provides evidence for the notion that alcohol affects oestrogen metabolism, which increases risk of hormone sensitive breast cancer."

She added: "More study is needed to clarify the effect of alcohol on other tumour types."

The research was presented at the annual meeting of the American Association for Cancer Research in San Diego, California, USA.