Fiber Intake and Postmenopausal Breast Cancer Risk

Byron's Comments:

Fiber intake is importat at all ages, here shown to be of extreme and life-saving value in post menopausal women.

Study Title:

Dietary fiber intake and risk of breast cancer in postmenopausal women: the National Institutes of Health–AARP Diet and Health Study

Study Abstract:

Background: Although dietary fiber has been hypothesized to lower risk of breast cancer by modulating estrogen metabolism, the association between dietary fiber intake and risk of breast cancer by hormone receptor status is unclear.

Objective: The objective was to examine the relation of dietary fiber intake to breast cancer by hormone receptor status and histologic type among postmenopausal women in the National Institutes of Health–AARP Diet and Health Study (n = 185,598; mean age: 62 y).

Design: Dietary intakes were assessed with a food-frequency questionnaire. Incident breast cancer cases were identified through linkage with state cancer registries. Cox proportional hazard models were used to estimate relative risks (RRs) and 2-sided 95% CIs.

Results: During an average of 7 y of follow-up, 5461 breast cancer cases were identified, of which 3341 cases had estrogen receptor (ER) and progesterone receptor (PR) status. Dietary fiber intake was inversely associated with breast cancer risk [RR for the highest quintile (Q5) compared with the lowest quintile (Q1): 0.87; 95% CI: 0.77, 0.98; P for trend: 0.02]. The inverse association appeared to be stronger for ER–/PR– tumors (RRQ5vsQ1: 0.56; 95% CI: 0.35, 0.90; P for trend: 0.008; 366 cases) than for ER+/PR+ tumors (RRQ5vsQ1: 0.95; 95% CI: 0.76, 1.20; P for trend: 0.47; 1641 cases). The RRQ5vsQ1 of lobular tumors was 0.66 (95% CI: 0.44, 0.97; P for trend: 0.04), and the RRQ5vsQ1 of ductal tumors was 0.90 (95% CI: 0.77, 1.04; P for trend: 0.10). Fiber from grains, fruit, vegetables, and beans was not related to breast cancer.

Conclusion: Our findings suggest that dietary fiber can play a role in preventing breast cancer through nonestrogen pathways among postmenopausal women.

Study Information:

Yikyung Park, Louise A Brinton, Amy F Subar, Albert Hollenbeck and Arthur Schatzkin Dietary fiber intake and risk of breast cancer in postmenopausal women: the National Institutes of Health–AARP Diet and Health Study Am J Clin Nutr 2009 September 90: 664-671.
From the Divisions of Cancer Epidemiology and Genetics and Cancer Control and Population Sciences, National Cancer Institute, Bethesda, MD, and the AARP, Washington, DC.