The role of diet on breast cancer incidence and survival is an active area of research with more questions than answers, though some trends are emerging.

“It is very important to understand the role of diet in breast cancer incidence and mortality,” Ömer Küçük, MD, professor of hematology/oncology and urology at Emory University in Atlanta, Georgia, told Cancer Therapy Advisor.

Though dietary factors have been studied extensively, only alcohol is consistently associated with an increased risk of developing breast cancer. Studies in other disease states found some diets to be protective: the Mediterranean diet, for example, is associated with a reduced risk of cardiovascular disease and mortality.1

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There is no surefire diet to prevent or cure breast cancer, though observational and cohort studies identified diets or dietary components that may reduce the risk of breast cancer or breast cancer–specific mortality.

Overall Diet Pattern

A prospective cohort study of 62,573 women aged 55 to 69 was initiated in 1986 with cancer incidence follow-up for 20.3 years. The researchers’ aim was to evaluate the role of the Mediterranean diet and risk of postmenopausal breast cancer.1

“When it comes to diet and breast cancer risk, dietary patterns may be of greater importance than individual foods or nutrients,” wrote the authors.

The study calculated adherence to the Mediterranean diet by using the alternate Mediterranean diet score (aMED) and aMED excluding alcohol (aMEDr). High adherence was associated with physical activity, higher education, and oral contraception use, but inversely associated with older age, nulliparity, smoking, and a family history of breast cancer.

High adherence to a Mediterranean diet was associated with a reduced risk of estrogen receptor (ER)-negative breast cancer compared with low adherence (hazard ratio [HR], 0.60; 95% CI, 0.39-0.92; P = .032).

There was a similar, though nonsignificant, trend with ER-positive breast cancer (HR, 0.87; 95% CI, 0.69-1.10; P = .101) and total breast cancer risk (HR, 0.87; 95% CI, 0.72-1.06; P = .066).

The authors also conducted a meta-analysis of similar studies, which supported the inverse relationship between Mediterranean diet adherence and risk of breast cancer.

“Assuming causality, we estimated that 32.4% of ER-negative breast cancer, and 2.3% of total and ER-positive breast cancer could be avoided if the population would shift intake towards the highest Mediterranean diet category,” the authors concluded.