Future possibilities in the prevention of breast cancer: Fat and fiber and breast cancer research

The hypothesis that a reduction in dietary fat in Western populations will lead to reductions in breast cancer risk has been promulgated for some decades. Its evaluation has been the goal of considerable research, and subject to considerable controversy (for example [1*,2*]). In effect, the testing of this hypothesis has become a prominent test case in a debate over the study designs and research strategies that are needed to obtain reliable information in the broader research area of diet and chronic disease. On the one hand, some evidently believe that reliable information on the fat and breast cancer relationship can be based on self-reported diet in the context of observational studies. This perspective led investigators involved in a recent pooled analysis of cohort studies of fat consumption and breast cancer risk [3*] to conclude that 'In the context of the Western lifestyle, lowering the total intake of fat in midlife is unlikely to reduce the risk of breast cancer substantially.' On the other hand, the US National Institutes of Health-sponsored Women's Health Initiative clinical trial [4*] is about half way to completion. This Initiative includes a randomized controlled clinical trial, one component of which is to assess the impact of a 'low-fat-eating pattern' on the incidence of breast cancer and colorectal cancer (and coronary heart disease secondarily) among 48 837 postmenopausal women in the USA. The existence of this large, complex intervention trial reflects the view of others that the hypothesis that a low-fat-eating pattern helps to prevent breast cancer is worth testing, and that observational studies alone may not be able to provide sufficiently reliable information on the fat and breast cancer association, regardless of their size or duration.The hypothesis that the increased consumption of dietary fiber may reduce breast cancer risk has also existed for some decades. The relationship between estimated fiber consumption and breast cancer risk ha