University of Pennsylvania Cancer Center
Last Modified: May 17, 1999
Researchers have found that a soy phytoestrogen preparation was ineffective for diminishing hot flashes in breast cancer survivors. This is despite soy phytoestrogen being touted by some to be helpful for diminishing hot flashes.
Charles Loprinzi, MD, and colleagues developed a double-blind, placebo-controlled clinical trial in which breast cancer surivovrs with bothersome hot flashes were randomized to receive a soy phytoestrogen tablet three times daily for four weeks, followed by four weeks of a placebo tablet; or thyerapy in the reverse order. Hot flashes were measured using a daily diary.
There were no significant toxicities experienced by the 132 women in the tiral. After four weeks of treatment, mean hot flash numbers decreased by 22 percent for women on soy and 33 percent for women on placebo. Hot flash "scores" (determined by multiplying hot flash numbers by mean hot flash severities) decreased 26 percent for women on soy and 36 percent for women on placebo. At the conclusion of the study, 33 percent of the women indicated a preference for the soy preparation, 37 percent preferred the placebo and 37 percent indicated no preference.