Fibers and breast cancer risk.

Data from a multicenter case-control study on breast cancer conducted in Italy were used to analyze the relationship between various types of fibers and breast cancer risk. Cases were 2,569 women with histologically confirmed, incident breast cancer; controls were 2,588 women admitted to the same network of hospitals for acute, nonneoplastic, non-hormone-related diseases. Cases and controls were interviewed between 1991 and 1994 using a validated food frequency questionnaire. The data were modeled through multiple logistic regression, controlling for demographic and reproductive breast cancer risk factors. The continuous odds ratios for the difference between the upper cut point of the fourth and the first quintile of intake were 0.90 [95% confidence interval = 0.82-0.98, p (for trend) < 0.05] for cellulose and 0.94 (95% confidence interval = 0.86-1.02) for soluble fibers. The protection tended to be stronger in premenopausal women. No material association was found for noncellulose polysaccharides and lignin. This study, based on a large data set from various Italian regions, suggests that fiber intake may confer some protection against breast cancer, particularly for cellulose and also for soluble fibers, i.e., those of vegetable origin. This possible protection has been related to an influence of fibers on levels and availability of estrogens and other steroid hormones in breast carcinogenesis.