Coffee lowers risk of breast cancer: study

Drinking coffee may help curb the risk of developing a certain type of breast cancer, Swedish researchers have found.

When they compared coffee consumption in postmenopausal women with breast cancer and women of the same age without cancer, they found those who drank five or more cups of java a day showed a 0.43 times lower risk of estrogen-receptor negative cancers. 

Estrogen-receptor (ER) negative breast cancer is less likely to respond to hormone treatments than estrogen-receptor positive breast cancers.

Dr. Per Hal, a professor in the medical epidemiology and biostatistics department at the Karolinska Institute in Stockholm, and his co-authors noted there is often conflicting information about the beneficial health effects of coffee.

"When we compared our results to that of a German study we discovered that their data showed the same trend, but the relationship was much weaker," the study's authors wrote in Wednesday's online issue of the journal Breast Cancer Research.

"We suggest that this may have something to do with the way the coffee was prepared, or the type of bean preferred. It is unlikely that the protective effect is due to phytoestrogens present in coffee since there was no reduction in the incidence of ER-positive cancer in this study."

 The researchers noted the mechanisms by which coffee may protect against this cancer, and the compounds involved, are not yet clear.

The only firm message to draw from the findings of this study and previous research looking at coffee consumption and risk of breast cancer risk is that, "Drinking coffee doesn't seem to increase the overall risk of breast cancer," Shumin Zhang of Harvard Medical School told WebMD.

For the study, Hal and his colleagues analyzed data on 2,818 people with breast cancer and 3,111 study participants who did not have breast cancer. Participants were all between the ages of 50 to 74.

The researchers asked participants about their coffee consumption as well as other lifestyle factors such as education, family history of breast cancer, age at menopause, weight, and exercise habits.