Diet and breast cancer prognosis: making sense of the Women's Healthy Eating and Living and Women's Intervention Nutrition Study trials

Abstract

Purpose of review: To clarify the role of dietary pattern on prognosis in breast cancer survivors.

Recent findings: Observational trials show mixed results that do not strongly support an independent role for dietary pattern in prognosis. Women's Intervention Nutrition Study and Women's Healthy Eating and Living (WHEL) are two large randomized controlled trials that address this question. The interventions from both studies achieved significant reductions in energy from fat, and the WHEL Study achieved large increases in vegetables, fruit and fiber. Women's Intervention Nutrition Study examined postmenopausal women only and reported a not-quite-significant improved prognosis for women in the intervention group, with the benefit focused on ipsilateral localized recurrences, but little improvement in the more important distal recurrences. This review considers only WHEL postmenopausal women to aid a direct comparison with Women's Intervention Nutrition Study. The WHEL Study reported a convincing lack of association between diet and prognosis. However, a secondary analysis suggests that the dietary intervention reduced distal recurrences among the subgroup without hot flashes at baseline.

Summary: There is no convincing evidence that changing dietary pattern following breast cancer diagnosis will improve prognosis for most women with early stage breast cancer. However, it would appear to be important for some subgroups. Further investigation of mechanisms for such selective action is needed.