Post-estradiol challenge (IMAGE) Washington University School of Medicine Caption Bright spots indicate that cancer cells have responded to a one-day challenge with estrogen in this positron emission tomography (PET) scan of a woman with breast cancer. In a small study, researchers at Washington University School of Medicine in St. Louis found that only women whose tumors responded to estrogen challenge benefited from hormone therapy. The findings could help doctors choose the treatments most likely to help their patients. Credit Farrokh Dehdashti Usage Restrictions This image is to be used in accordance with the mission, policies and guidelines of Washington University in St. Louis. Visit https://wustl.edu/about/compliance-policies/media-policies/multimedia-use/ for more information. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.