No Link Between Caffeine Consumption, Breast Cancer Risk
Researchers at Brigham and Women's Hospital (BWH) have dispelled a past belief that caffeine consumption may increase breast cancer risk. Their findings, published in Archives of Internal Medicine, show that caffeine consumption does not appear to be linked with overall breast cancer risk.
Caffeine, one of the most commonly consumed drugs worldwide, was previously thought to increase the risk of breast cancer after a study showed that women with non-cancerous breast disease experienced relief from their symptoms after removing caffeine from their diet. In this study, Ken Ishitani, MD, Ph.D, of BWH, and colleagues studied 38,432 women 45 years or older who provided dietary information in 1992-1995. Over an average of 10 years of follow-up, 1,188 of the women developed invasive breast cancer.
Although caffeine was not statistically significantly associated with overall risk of breast cancer, researchers note that there is a possibility of increased risk for women with benign breast disease or for tumors that are hormone-receptor negative or larger than 2 centimeters. This potential risk was observed in women with the highest consumption; four or more cups of coffee daily. Researchers also note that consuming caffeine was associated with a 68 percent increased risk of estrogen receptor–negative and progesterone receptor–negative breast cancer, or tumors to which the hormones estrogen and progesterone do not bind, and a 79 percent increased risk for breast tumors larger than 2 centimeters.
"The mechanisms by which caffeine may affect the development of breast cancer are complex and remain unclear. Our findings indicate that caffeine consumption may affect breast cancer progression, and such an effect may be independent of the estrogen pathway," said Shumin Zhang, MD,ScD,MSC. "Further study is required to better understand caffeine's role."