Effect of dietary fiber intake on breast cancer risk according to estrogen and progesterone receptor status

Background/Objectives: There is few data on the association between dietary fiber intake and estrogen receptor (ER)/progesterone receptor (PR)-defined breast cancer risk. The present study aimed to investigate the associations between total dietary fiber and dietary fiber fractions intake and breast cancer risk by ER and PR status in a hospital-based case-control study among Chinese women. Subjects/Methods: Four hundred and thirty-eight cases with primary breast cancer were consecutively recruited from June 2007 to August 2008 and frequency matched to 438 controls by age (5-year interval) and residence (rural/urban). A validated food frequency questionnaire was used to assess the dietary intake through a face-to-face interview. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence interval (CI) after adjusting for various potential confounders. Results: A statistically significant inverse association was found between total dietary fiber and fiber fractions intake and breast cancer risk. The adjusted ORs (95% CIs) for the highest versus the lowest quartile of intake were 0.31 (0.20-0.47) for total dietary fiber, 0.73 (0.48-1.11) for soy fiber, 0.48 (0.22-0.97) for vegetable fiber and 0.54 (0.31-0.92) for fruit fiber. No association was observed for cereal fiber intake and risk. An inverse association between dietary fiber intake and breast cancer risk was observed in ER+, ER-, PR+, ER+ PR+ and ER-PR+ tumors. Conclusions: Our results suggest that consumption of total dietary fiber and fiber from vegetable and fruit was inversely associated with breast cancer risk. These inverse associations were more prominent in some subtypes of ER and PR breast cancers. European Journal of Clinical Nutrition (2011) 65, 929-936; doi:10.1038/ejcn.2011.57; published online 4 May 2011