Types of dietary fat and breast cancer: A pooled analysis of cohort studies

Recently, there has been interest in whether intakes of specific types of f at are associated with breast cancer risk independently of other types of f at, but results have been inconsistent. We identified 8 prospective studies that met predefined criteria and analyzed their primary data using a stand ardized approach. Holding total energy intake constant, we calculated relat ive risks for increments of 5% of energy for each type of fat compared with an equivalent amount of energy from carbohydrates or from other types of f at. We combined study-specific relative risks using a random effects model, In the pooled database, 7,329 incident invasive breast cancer cases occurr ed among 351,821 women. The pooled relative risks (95% confidence intervals [Cl]) for an increment of 5% of energy were 1.09 (1.00-1.19) for saturated , 0.93 (0.84-1.03) for monounsaturated and 1.05 (0.96-1.16) for polyunsatur ated fat compared with equivalent energy intake from carbohydrates, For a 5 % of energy increment, the relative risks were 1.18 (95% Cl 0.99-1.42) for substituting saturated for monounsaturated fat, 0.98 (95% CI 0.85-1.12) for substituting saturated for polyunsaturated fat and 0.87 (95% Cl 0.73- 1.02 ) for substituting monounsaturated for polyunsaturated fat, No associations were observed for animal or vegetable fat intakes. These associations were not modified by menopausal status. These data are suggestive of only a wea k positive association with substitution of saturated fat for carbohydrate consumption; none of the other types of fat examined was significantly asso ciated with breast cancer risk relative to an equivalent reduction in carbo hydrate consumption, (C) 2001 Wiley-Liss, Inc.