Reuters Health Aug 14 - Regular consumption of estrogens found in plant foods may reduce the risk of endometrial cancer for some women, according to a report in the August 6th Journal of the National Cancer Institute.

Estrogen exposure without cyclic exposure to progesterone contributes to the development of endometrial cancer, the authors explain, and phytoestrogens have been shown to lower endogenous estrogen levels.

Dr. Pamela L. Horn-Ross from Northern California Cancer Center in Union City, California, and colleagues conducted the first analytic epidemiologic study that has quantified the intake of specific phytoestrogenic compounds and related them to endometrial cancer risk.

The top quartiles of consumption of total isoflavones and of total lignans were associated with a 41% and 32% reduced risk, respectively, of endometrial cancer, compared with the lowest quartiles of consumption, the authors report.

Specifically, the reduced risk of endometrial cancer was associated with higher levels of consumption of the two major isoflavones -- genistein and daidzein -- and of the lignan secoisolariciresinol, the report indicates.

The reduced endometrial cancer risk was particularly evident among postmenopausal women who consumed high levels of isoflavones and lignans, the researchers note.

Though the number of obese women in the study was small, the results suggest that obese postmenopausal women consuming the lowest levels of isoflavones or lignans had the highest risk of endometrial cancer.

"Based on these findings and other literature on phytoestrogens, I believe that recommending a balanced diet that includes reasonable amounts of phytoestrogen-rich foods is an appropriate public health message at this time," Dr. Horn-Ross told Reuters Health. "In my opinion, however, we don't have enough information on phytoestrogen supplements in pill form to make any recommendations in either direction regarding these supplements."

Dr. Horn-Ross cautioned, "There is a lot of variability between people, and benefit (or harm) from a given exposure is unlikely to apply across the board. We are working on furthering our understanding of the relationships between phytoestrogens and cancer risk."

"In the meantime," she concluded, "it appears that soy-based and lignan-rich foods may have beneficial effects in some women, with some evidence that it will be greater in postmenopausal women and overweight/obese women. However, we still have much to learn."

J Natl Cancer Inst 2003;95:1158-1164.

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