12 Jan 2018 --- Two estrogen-mimicking compounds found in many foods appear to potently reverse the effects of palbociclib/letrozole, a popular drug combination for treating breast cancer, according to research by scientists from The Scripps Research Institute (TSRI). Their study, published in the journal Cell Chemical Biology, suggests that exposure to chemical compounds called xenoestrogens may significantly reduce the effectiveness of anti-estrogen treatments for cancer.