Dietary fiber, carbohydrates, glycemic index, and glycemic load in relation to breast cancer prognosis in the HEAL cohort.

BACKGROUND Dietary intake of fiber, carbohydrate, glycemic index (GI), and glycemic load (GL) may influence breast cancer survival, but consistent and convincing evidence is lacking. METHODS We investigated associations of dietary fiber, carbohydrates, GI, and GL with breast cancer prognosis among n = 688 stage 0 to IIIA breast cancer survivors in the Health, Eating, Activity, and Lifestyle (HEAL) study. Premenopausal and postmenopausal women from Western Washington State, Los Angeles County, and New Mexico participated. Usual diet was assessed with a food frequency questionnaire. Total mortality, breast cancer mortality, nonfatal recurrence, and second occurrence data were obtained from SEER (Surveillance, Epidemiology, and End Results) registries and medical records. Cox proportional hazards regression estimated multivariate-adjusted hazard ratios and 95% confidence intervals (CI). RESULTS During a median of 6.7 years follow-up after diagnosis, n = 106 total deaths, n = 83 breast cancer-specific deaths, and n = 82 nonfatal recurrences were confirmed. We observed an inverse association between fiber intake and mortality. Multivariate-adjusted hazard rate ratios (HRR) comparing high to low intake were 0.53 (95% CI 0.23-1.23) and 0.75 (95% CI 0.43-1.31). A threshold effect was observed whereby no additional benefit was observed for intakes of 9 g/d or more. Fiber intake was suggestively inversely associated with breast cancer-specific mortality (HRR = 0.68, 95% CI 0.27-1.70) and risk of nonfatal recurrence or second occurrence (HRR = 0.68, 95% CI 0.27-1.70), but results were not statistically significant. CONCLUSION Dietary fiber was associated with a nonsignificant inverse association with breast cancer events and total mortality. Further studies to assess and confirm this relationship are needed in order to offer effective dietary strategies for breast cancer patients. IMPACT Increasing dietary fiber may an effective lifestyle modification strategy for breast cancer survivors.