Soy can block the action of the enzyme tyrosine kinase; an overactivity of this enzyme is linked to cancer.

      Soybeans contain a class of compounds called phytoestrogens. These weak estrogens-like compounds may attach to receptors on breast cells and prevent naturally produced estrogen from making a connection.
[It's normal for men to have significant levels of both testosteroe and estrogen.]

      Animal studies show that subjects on a high soybean diet, with low breast cancer rates, also had high concentrations of phytoestrogens attached to breast cells.
      Stephen Barnes, associate professor of pharmacology and biochemistry at the U. of Alabama at Birmingham produced research in 1990 indicating soybean consumption lowered tumor growth in rats.

      In rats given identical diets except for soybeans, the soybean-consumers had 50 to 70% fewer breast cancers when they were exposed o a breast-specific carcinogen.
      [Supporting evidence of this phenomena was provided by cheetahs at the Cinncinatti Zoo who were infertile because their estrus cycles had stopped. Dr. Ken Setchell of Children's Hosp. Medical Center, Cinncinatti, discovered the problem was caused by anti-estrogen soybean compounds. When the animals were taken off the soybean diet, their estrus cycles resumed.]

      Women in Asian countries w/high soybean content in their diet have breast cancer rates 5% lower than rates in the U.S..

      Swedish researchers report that feeding animals soy causes cancer cells to "commit suicide" (apoptosis).

      Genestein is a compound found in high concentrations in soybeans (and, to a lesser degree in cruciferae). In test tubes, it blocks anngiogenesis (growth of new blood vessels - essential for some tumors to grow and spread) and deters proliferation of cancer cells.

      Dr. Lothat Schweigerer (Children's Hosp./Heidelburg, Germany), in the April '93 issue of the Proceedings of the National Academy of Sciences, reported that in those on a traditional Japanese diet, urine levels of genistein are at least 30% higher than those of Westerners. This may explain the sharp rise in invasive prostate cancer in Japanese who leave their country and spend several years in the US or Europe.
      Tiny cancers kept in check by daily soy intake would be free to grow under a Western diet.

      Dr. Judah Folkman, Harvard Medical School:
  "This is a fascinating report...nobody has ever suggested before that you could find in the urine certain dietary factors that inhibit the proliferation of blood vessels..."

      Natalie Angier, NYT Science Times (4.13.93, pg. 85):
  "Beyond its supression of blood vessel growth, genistein deters the proliferation of cancer cells in test tube experiments."

      Australian studies indicate soybeans and derivative may also help relieve negative symptoms of menopause, such as hot flashes and vaginal dryness.

      Raw soybeans, unprocessed soy flour, tofu, soy milk and textured vegetable protein (TVP) contain phytoestrogens, but soy sauce does not.

      Lianne Latkany, nutrition research manager at Sloan-Kettering Cancer Center , estimates that
"there may be an association with one serving of soy per day and a reduced risk of cancer. That works out to about one cup of soy milk or one-half cup of tofu."

[Michael W. Pariza, director of the Food Research Institute at the U. of Wisconsin-Madison, isolated a soy sauce compound, HEMF (produced during fermentation) that reduces the risk of esophageal cancer n mice.]