Drinking coffee may raise risk of certain breast cancers
Reported October 15, 2008Wednesday October 15, 2008 (foodconsumer.org) — Drinking coffee or eating caffeine-laden foods does not seem to increase the overall risk of breast cancer in the general population, according to researchers at Brigham and Women’s Hospital and Harvard Medical School in Boston.
But Dr. Shumin M. Zhang, coauthor of the study, warned that drinking high amounts of caffeine or four cups or more coffee daily may increase risk for breast cancer in women with benign breast disease or for breast tumors that have less favorable prognoses.
The study was funded by the National Institutes of Health and published in the Oct 13, 2008 issue of the Archives of Internal Medicine.
For the study, Zhang and colleagues from Tokyo Women’s Medical University in Japan surveyed the diets of 39,000 women ages 45 or older for a period of four years between 1992 and 1995.
Study subjects were medical care professionals with three quarters registered nurses. During the follow-up of a decade, 1,190 women developed invasive breast cancer.
The researchers found there was no significant association between drinking coffee or caffeine containing foods and risk of breast cancer.
Drinking four cups of coffee or more was linked to an 8 percent increased risk of breast cancer whereas drinking two cups of tea daily was associated with a 3 percent increased risk. The comparison is made against those who did not drink any.
But among those who had a history of benign breast disease, consumption of highest amounts of caffeine appeared to increase risk for them to develop breast cancer by 32 percent while drinking 4 cups of coffee daily raised the risk by 35 percent.
Also among those who consumed caffeine, the risk for developing tumors larger than two centimeters was increased by 79 percent.
Caffeine consumption increased the risk for developing estrogen and/or progesterone receptor-negative breast cancer by 68 percent.
The researchers conclude “These data show no overall association between caffeine consumption and breast cancer risk. The possibility of increased risk in women with benign breast disease or for tumors that are estrogen and progesterone receptor negative or larger than 2 cm warrants further study.”