Journal: International Journal of Epidemiology. 2007 Jan 24; [E-publication ahead of print]
Authors and affiliation: Cade JE, Burley VJ, Greenwood DC. Centre for Epidemiology and Biostatistics, University of Leeds, Leeds, UK.
Background: Reports of relationships between dietary fibre intake and breast cancer have been inconsistent. Previous cohort studies have been limited by a narrow range of intakes.
Methods: Women who developed invasive breast cancer, 350 post-menopausally and 257 pre-menopausally, during 240,959 person-years of follow-up in the UK Women's Cohort Study (UKWCS) were studied. This cohort has 35,792 subjects with a wide range of exposure to dietary fiber with intakes of total fiber in the lowest quintile of <20 g/day up to >30 g/day in the top quintile.
Fiber and breast cancer relationships were explored using Cox regression modeling adjusted for measurement error. Effects of fiber, adjusting for confounders, were examined for pre- and post-menopausal women separately.
Results: In pre-menopausal, but not post-menopausal women a statistically significant inverse relationship was found between total fiber intake and risk of breast cancer (P for trend = 0.01).
The top quintile of fiber intake was associated with a hazard ratio of 0.48 [95% confidence interval (CI) 0.24-0.96] compared with the lowest quintile. Pre-menopausally, fiber from cereals was inversely associated with risk of breast cancer (P for trend = 0.05) and fiber from fruit had a borderline inverse relationship (P for trend = 0.09).
A further model including dietary folate strengthened the significance of the inverse relationship between total fiber and pre-menopausal breast cancer.
Conclusions: These findings suggest that in pre-menopausal women, total fiber is protective against breast cancer; in particular, fiber from cereals and possibly fruit.