Fluke or Trend: Coffee vs Breast Cancer

Some days coffee is good for you, other days, it's not.  The pendulum has recently swung in favor of coffee consumption with a series of studies published demonstrating an association between more coffee and lower cancer risk.  Of course, the devil is in the details because coffee has a multitude of antioxidants, the amounts of which vary depending upon brewing method, and because cancer is not just one homogenous disease process.

With that in mind, a case-control study was released 2 weeks ago comparing 2,818 Swedish women with breast cancer to 3,111 without.  The authors concluded that drinking >5 cups of coffee daily was associated with 20% reduction in overall breast cancer risk and with 57% reduction in estrogen receptor negative breast cancer as compared to those who drank <1 cup/day.

In a study published last fall, the authors followed 64,603 Swedish men & women for 15 years and determined that those women who drank >4 cups of boiled coffee daily had a lower risk of developing breast cancer compared to those who drank <1 cup/day.  But again, it's important to analyze the details.  Specifically, the authors found that premenopausal filtered coffee drinkers had an increased risk of breast cancer while postmenopausal filtered drinkers had a decrease risk.  The study also looked closely at method of brewing and noted that overall, boiled coffee appeared to more protective than filtered coffee, the former having higher levels of antioxidants than the latter.

And in the spring of 2009, authors completed a meta-analysis of 9 cohort & 9 case-control studies that met strict inclusion criteria and concluded that drinking at least 2 cups of coffee daily might decrease breast cancer risk.

So what's the take home point, especially given the tendency of our daily newscasts to vacillate with the study du jour?  There appears to be a trend towards benefit from coffee consumption, especially more of the really strong stuff.  But remember that all these studies only demonstrate an association and therefore are good for developing hypotheses.  Given our limited knowledge, I'd recommend drinking coffee because you like it, not because you want to prevent breast cancer.  And don't forget Goldilock's approach.  Avoid drinking so much as to give yourself palpitations & tremors!