Coffee Lowers Risk for Estrogen-Receptor-Negative Breast Cancer

Jim Kling

May 11, 2011

May 11, 2011 — Among postmenopausal women, heavy coffee consumption is associated with a lower incidence of estrogen receptor (ER)-negative breast cancer, according to a study published online May 11 in Breast Cancer Research.

Coffee contains a wide array of chemicals that may have carcinogenic, chemopreventive, antioxidative, and weakly estrogenic properties. For example, it contains the phytoestrogen trigonelline, which may activate ER through an estrogen-independent mechanism, explain the authors led by Jingmei Li, PhD, from the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.

That complexity has led to uncertainty regarding whether coffee has a net positive or negative effect on breast cancer risk, although a significant body of evidence suggests a modest decrease in risk.

Breast cancer can be broadly separated into hormone-responsive (ER-positive) and non-hormone-responsive (ER-negative) subtypes. Previous research has suggested that coffee intake may have heterogeneous effects on the risk of developing the 2 subtypes.

The researchers looked at the association between coffee consumption and postmenopausal breast cancer risk in a large, population-based study (2818 cases and 3111 control patients). They determined the odds ratios (OR) for cancer overall and for each ER tumor subtype, using multivariate logistic regression models in a stratified case-control analysis.

There was a small decrease in overall breast cancer risk associated with coffee consumption (OR for more than 5 cups/day compared with 1 or fewer cups/day, 0.80; 95% confidence interval, 0.64 - 0.99; P = .028). Among heavy coffee drinkers (>5 cups a day), there was a strong reduction in risk for ER-negative breast cancer (OR for more than 5 cups/day compared with 1 or fewer cups/day, 0.43; 95% CI, 0.25 - 0.72; P = .0003) in a multivariate-adjusted model.

The effect of coffee consumption on breast cancer risk reduction was higher for ER-negative tumors than for ER-positive tumors (P heterogeneity [age-adjusted] = .004).

Two study limitations include the use of self-reported food recall surveys and the fact that receptor data were only available for 65.4% of the population studied.

"We found no evidence that coffee consumption increases the overall risk of postmenopausal breast cancer," the authors conclude. "However, a high daily intake of coffee was found to be associated with a significant decrease in ER-negative breast cancer among postmenopausal women. Future studies are needed to confirm the effects of coffee consumption in the light of breast cancer subtypes."

The study was supported by the National Institutes of Health and by the Märit and Hans Rausing's Initiative against Breast Cancer. The authors have disclosed no relevant financial relationships.

Breast Cancer Res. Published online May 11, 2011. Full text


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