International correlation, case-control and cohort studies have associated the incidence of breast cancer with high fat consumption9-14. A significantly increased risk of breast cancer has been shown with increased consumption of milk and dairy products, gravy, beef and pork15. Many recent studies however, have questioned the role of fats is causing breast cancer17-19. There appears to be no consensus on the role of fats in mammary carcinogenesis19-23. Our study fails to correlate fat intake with the occurrence of breast cancer. In our study, decreased intake of fish by cases is an interesting finding. Japanese and Eskimos have some of the lowest rates of getting breast cancer1,7. Both consume diets traditionally based on fish and other marine animals. Recent changes in the traditional diet of Japanese and Eskimos have been associated with the rising incidence of breast cancer. These changes may well involve decreased consumption of fish. Some previous case- control studies have shown a negative effect of fish consumption on the incidence of breast cancer15,24. Animal studies also indicate that unlike other fats, fish oils inhibit mammary tumorigenesis25,26-29. This inhibitory effect on mammary carcinogenesis may be related to the inhibitory effect of fish oils on prostaglandin synthesis30. Eicosanoid activity has been associated with the development, aggressiveness, extent and mortality from breast cancer31,32. Our study also reveals increased consumption of green leafy vegetables and carotene rich fruits by controls as compared to cases. Many other case-control studies have assessed the relationship between breast cancer and consumption of fruits and vegetables33-39. Although vegetables including green leafy vegetables and carotenoids were reported to be protective in some studies33-35,38,39, no association was reported by others40,41. Iscovich et al also reported a significant protective effect of citrus fruit consumption33. In a re-analysis of combined data from nine different studies, Howe et al reported a significant protective effect of fruits and vegetables against breast cancer43. It may be that the fruits and vegetables contain desirable chemo-preventive agents43,44. They may also be an important source of essential micronutrients, vitamins and minerals. Case-control studies are fraught with many pitfalls45. Dietary habits of cases may change after the diagnosis of breast cancer is made. These changes may be induced by the disease, its treatment, or newly acquired knowledge regarding the role of dietary factors in mammary carcinogenesis. In our study, information recorded was not of the present dietary habits but the recent past. This was done specifically to exclude these recent changes. This, however, may create the problem of validity of data based upon recall. It has previously been demonstrated that recall of past diet maybe affected by the present dietary habits. However, reproducibility of recall past diet is acceptable in most of the studies with less than 20 percent variation. We have not yet analyzed the reproducibility of our data, although such a study is in progress at our institution. Breast cancer is the commonest cancer in females. In the United States, more than 150,000 new cases of breast cancer are diagnosed annually and this disease results in approximately 45,000 cancer deaths per year46,47. The incidence of this disease has increased by almost one percent per year. Presently there are no known methods to decrease this rising incidence. If nutritional factors are indeed casually related to the incidence of breast cancer, dietary changes based upon the findings of this and other similar studies may be a simple and inexpensive way to decrease the incidence of breast cancer.
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