Advanced Search Abstract Background: Results of several studies have suggested that diet during adolescence may influence the risk of breast cancer in adulthood. We evaluated whether an intervention to lower fat intake among adolescent girls altered their serum concentrations of sex hormones that, in adults, are related to breast cancer development. Methods: We conducted an ancillary hormone study among of the girls who participated between and in the Dietary Intervention Study in Children, in which healthy, prepubertal, 8- to year-olds with elevated low-density lipoprotein cholesterol were randomly assigned to usual care or to a behavioral intervention that promoted a low-fat diet.
Median time on the intervention was 7 years. All P values are two-sided. Results: At the year 5 visit, girls in the intervention group had At the last visit, the luteal phase progesterone level was Conclusion: Modest reductions in fat intake during puberty are associated with changes in sex hormone concentrations that are consistent with alterations in the function of the hypothalamicโpituitaryโovarian axis.
Whether these changes influence breast cancer risk is currently unknown. The relationship between dietary fat and breast cancer risk has been studied extensively since the s, when Tannenbaum 1 observed that rats fed a high-fat diet had a higher incidence of mammary tumors than rats fed a low-fat diet. Comparisons of the breast cancer mortality rates among different countries according to the per capita fat consumption support the hypothesis that a high-fat diet may increase the incidence and mortality from breast cancer 2.
However, results of caseโcontrol studies that have examined the relationship between adult diet and breast cancer risk are inconclusive, and cohort studies generally do not support such an association 3. Early age at menarche is an established risk factor for breast cancer 7 , and diet is associated with the timing of menses onset 8 โ Furthermore, adult height is influenced by childhood diet and is positively associated with breast cancer risk 7.
Although results of caseโcontrol studies generally do not support an association between childhood diet and breast cancer risk 11 โ 13 , those studies relied on recall of diet in the distant past, which may have caused some individuals to be misclassified, thus biasing the results. Breast cancer is a hormone-dependent cancer, and postmenopausal women with elevated serum estrogen and androgen concentrations are more likely to develop breast cancer than postmenopausal women with low levels of these hormones 14 โ A pooled analysis of prospective studies 19 found that postmenopausal women whose serum estradiol, estrone, estrone sulfate, testosterone, androstenedione, dehydroepiandrosterone DHEA , and DHEA sulfate DHEAS levels were in the highest quintile were approximately twice as likely to develop breast cancer as postmenopausal women whose serum levels of those hormones were in the lowest quintile.
