STUDY:

JOURNAL: J Natl Cancer Inst 2003;95:132-141.

AUTHORS: Dr. Joanne F. Dorgan

ABSTRACT: Adolescent girls who follow a low-fat diet have reduced sex hormone levels that may decrease their risk of breast cancer in adulthood.

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COMMENTARY: However, whether these findings translate into a lower risk of breast cancer later in life is not clear, according to the report published in the January 15th issue of the Journal of the National Cancer Institute.

Reduced levels of estrogens and progesterones might slow down the rate of cell division, thereby decreasing the likelihood of carcinogenic mutations, lead author Dr. Joanne F. Dorgan, from the Fox Chase Cancer Center in Philadelphia, said in a statement.

Elevated body fat is another risk factor for premenopausal breast cancer, although it is not clear how excess fat may contribute to the risk.

To investigate the relationship between fat intake during puberty and blood levels of hormones associated with breast cancer, the research team studied 286 girls between 8 and 10 years of age. The girls were already enrolled in a study to evaluate the ability of a diet to lower levels of LDL cholesterol.

About half of the patients attended individual and group nutrition counseling sessions on how to follow a low fat diet, in which 28% of calories came from fat and 8% came from saturated fat. The other half received written material on nutrition from the American Heart Association, but did not take part in nutrition counseling.

After 5 years, the girls in the counseling group had lower levels of several estrogens that have been linked to breast cancer. For instance, estradiol levels were about 30% lower and estrone levels were about 20% lower, the study found. Levels of progesterone were also lower, the findings indicate.

Finally, girls in the counseling group reported eating fewer calories, less fat and saturated fat, and more fiber, compared with girls in the other group.

"These results suggest that the modest reductions in total fat, saturated fat, and perhaps energy intake during adolescence may alter the function of the hypothalamic-pituitary-ovarian axis, which regulates ovarian hormone production," the researchers note. Whether these differences ultimately influence breast cancer risk is currently unknown.