Further studies are needed, but researchers hope one day this finding may lead to a genetic test that could help doctors determine which women are most likely to benefit from tamoxifen. This type of test is not currently offered clinically.
Rae and Daniel F. Hayes, M.D., director of breast oncology at the U-M Comprehensive Cancer Center, are part of the Pharmacogenetics Research Network, a multidisciplinary research group conducting a prospective clinical trial to confirm whether genetic testing can be used to identify patients likely to respond to endocrine therapy, including tamoxifen. This group is led by David A Flockhart, M.D., Ph.D. at Indiana University School of Medicine.
More than 210,000 women in the United States will develop breast cancer. Approximately 70 percent of these cancers are fueled by estrogen, many of which are treated with tamoxifen, a drug designed to block the effects of estrogen in breast tissue. The findings from this trial were derived from a large North Central Cancer Treatment Group study in which women were treated with tamoxifen, a pill that is taken daily, for a total of five years.
Additional authors included the following researchers from the Mayo Clinic Cancer Center: Vera Suman, Ph.D.; Stephanie Safgren; Matthew Ames, Ph.D.; Daniel Visscher, M.D.; Carol Reynolds, M.D.; Fergus Couch, Ph.D.; Wilma Lingle, Ph.D.; and James Ingle, M.D., in Rochester, Minn.; and Edith Perez, M.D., in Jacksonville, Fla.; David Flockhart, M.D., Ph.D., and Zeruesenay Desta, Ph.D., both from Indiana University are also co-authors.