A new study reported in Breast Cancer Research online concluded that women who drank at least five cups of coffee daily had a significantly reduced risk of postmenopausal breast cancer However, this association was most strongly observed with ER-negative (estrogen receptor) tumors.
Previous studies have had contradictory results on the association of coffee drinking and breast cancer. Thus, this study included both a large Swedish Study population and a large validation German Study population. The case-controlled studies included 2,818 postmenopausal women with breast cancer and 3,111 age-matched controls. All women were between age 50 and 74, born in Sweden, and living there between 1993 and 1995. The validation German study included 3,464 patients with cancer and 6,657 age-matched controls. Information on breast cancer risk factors, lifestyle factors, and socioeconomic variables were provided by all participants. The strongest association of all risk factors for breast cancer was for heavy coffee drinking and ER-negative breast cancer. The combination of heavy coffee drinking and ER-negative tumors resulted in a 57% reduction in the risk for breast cancer. Analysis of the validation German data confirmed that heavy coffee drinking had a protective effect for ER-negative tumors.
