Strengths and limitations of methodologic approaches to the study of diet and cancer: summary and future perspectives with emphasis on dietary fat and breast cancer.
For many years, scientists have been studying the relationship between diet and certain cancers in animal and human population studies. With the exception of leukemia, nine of the leading cancers in humans may be associated positively or negatively with diet. Extensive literature reviewed by an expert group convened by the National Academy of Sciences concluded that the strongest evidence of an association between the incidence of certain cancers and dietary components is that for dietary fat, particularly for breast cancer (Committee on Diet, Nutrition and Cancer, National Research Council, National Academy of Sciences; Diet, Nutrition and Cancer; Washington, DC: National Academy Press, 1982). The conclusions reached by this group and the consensus of other advisory experts provided the rationale for the National Cancer Institute (NCI) to sponsor a multi-institutional breast cancer prevention trial. This trial was designed to test whether a diet containing 20% of calories from fat compared with the usual diet containing twice that amount would reduce breast cancer incidence in 45- to 69-year-old women. Ensuing controversies about the nature of the research evidence and methodologic issues related to the conduct of this trial led NCI, on advice of its counselors, to discontinue the full-scale implementation. It is clear from these debates that experts have looked at the same data and differed both in their interpretation and in their conception of what constitutes convincing evidence.
Greenwald
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Division of Cancer Prevention and Control, National Cancer Institute, Bethesda, Maryland 20892-3100.
D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology*; D002986:Clinical Trials as Topic; D004041:Dietary Fats / Q000009:adverse effects*; D005260:Female; D006801:Humans; D012107:Research Design
D004041:Dietary Fats