There are substantial data on breast
tumorigenesis in animals that suggest that diet may be an important factor in human
breast cancer etiology. The promotional effects of
dietary fat, and, in particular,
unsaturated fats, on mammary
tumors in rodents is well established. The geographic distribution of
breast cancer in humans correlates with international differences in average fat intake. Differences in dietary habits among populations in the United States and their
breast cancer risk also have been observed. In the United States, the trend has been toward increased total fat consumption and increased use of polyunsaturated
fats. However,
breast cancer incidence among white women in the United States has changed very little. Case-control studies of dietary intake and
breast cancer risk have shown inconsistent results, and prospective studies of
breast cancer mortality and serum
cholesterol and serum
lipids show no differences in risk between women with high levels of
cholesterol and serum
lipids compared with women with low levels. Laboratory studies also suggest the possibility that natural inhibitors of
breast cancer may occur in the diet as well.
Antioxidants, inducers of microsomal
enzyme activity, and
retinoids, all have been implicated in the metabolic epidemiology of
breast cancer. Research results at Roswell Park memorial Institute have associated lower levels of intake of dietary
vitamin A with a slightly elevated risk of
breast cancer. To date, the epidemiologic data do not indicate with confidence that any specific dietary risk factor may be associated with
breast cancer risk in the United States population. Additional epidemiologic studies on inhibition or promotion of
breast cancer following the leads of previous laboratory research may clarify the nature and practical significance of the relationship between diet and
breast cancer.