Women who eat more soy-based foods than average may have less risk for certain cancers in the ovaries and the lining of the uterus, according to the combined findings of a few studies.

The uterine lining cancers - also known as endometrial cancer - and the ovarian cancer are all known to be affected by hormones such as estrogen, which are mimicked by compounds in soy. While some soy compounds that act like estrogen are linked to a higher rate of breast cancer, studies have suggested the opposite for endometrial and ovarian cancer.

The new report, in BJOG, An International Journal of Obstetrics and Gynaecology, hints that odds of developing these cancers may be 40 percent lower among women who eat the highest amounts of soy-based foods.

One of the authors of the new analysis, Dr. Kwon Myung, at the National Cancer Center in Goyang, Korea, told Reuters Health that the data is too preliminary to draw any firm conclusions.

The National Cancer Institute estimates that more than 21,000 women will be diagnosed with ovarian cancer and more than 14,000 women will die of it in 2009. About 42,000 women will be diagnosed with endometrial cancer, according to the Institute, and about 8,000 will die of it.

The seven studies Myung’s team reviewed - they rejected others that were of poorer quality - included more than 169,000 women, of whom 3,516 had one of the two cancers. Most of the studies evaluated the intake of soy or soy components from foods such as legumes, soy curd, or soy protein.

Still, Myung said confirmation of the findings would require “a higher level of evidence,” and scientists have yet to determine the optimal amount of soy-based foods.

SOURCE: BJOG, An International Journal of Obstetrics and Gynaecology, December 2009