Relation of Caffeine and Breast Cancer

Caffeine is probably the most commonly consumed drug worldwide, present in coffee, tea, chocolate and some medications, according to background information in the article. It was hypothesised that caffeine may 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.

Ken Ishitani and colleagues studied 38,432 women 45 years or older who provided dietary information in 1992 to 1995. Over an average of ten years of follow-up, 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 write. Among women with benign breast disease, a non-significant positive association with breast cancer risk was observed for those in the highest quintile (one-fifth) of caffeine consumption and a significant association was observed for those in the highest category of coffee consumption (four cups or more daily).

Consuming caffeine was also associated with a 68 percent increased risk of estrogen receptor–negative and progesterone receptor–negative breast cancer, or tumours to which the hormones estrogen and progesterone do not bind, and a 79 percent increased risk for breast tumours larger than two centimeters.

“The mechanisms by which caffeine may affect breast carcinogenesis [cancer development] are complex and remain unclear,” the authors write. “Our findings indicate that caffeine consumption may affect breast cancer progression, and such an effect may be independent of the estrogen pathway.” Further study is required to better understand caffeine’s role, they note.; Source: American Medical Association (AMA)