Health and Science Story

22 November 2008 18:15 BST

Caffeine may not increase breast cancer risk

Caffeine consumption may not increase the overall risk of contracting breast cancer, health experts have claimed.

In a report published in Archives of Internal Medicine today researchers did find, however, that there is a possibility of increased risk for women with benign breast disease or for tumours that are hormone-receptor negative.

It was previously thought that caffeine may increase the risk of breast cancer after a study found that women suffering from non-cancerous breast disease experienced relief from their symptoms once they removed caffeine from their diet.

Researchers studied 38,432 women aged 45 or older who provided dietary information between 1992 and 1995. Over an average of ten years of follow-up tests, 1,188 of the women developed invasive breast cancer.

"Consumption of caffeine and caffeinated beverages and foods was not statistically significantly associated with overall risk of breast cancer," the authors of today's report write.

It was found, though, that consuming caffeine was associated with a 68 per cent increased risk of oestrogen receptor–negative and progesterone receptor–negative breast cancer, or tumors to which the hormones oestrogen and progesterone do not bind, and a 79 per cent increased risk for breast tumors larger than two centimetres.

"The mechanisms by which caffeine may affect breast carcinogenesis [cancer development] are complex and remain unclear," the authors write.

"In the present investigation, caffeine consumption was associated with increased risk of breast cancers negative for both oestrogen receptors and progesterone receptors or larger than two centimeters, which have less favorable prognoses," the report adds.

"These findings indicate that caffeine consumption may affect breast cancer progression, and such an effect may be independent of the oestrogen pathway."