An interview with Dr. Kimberly Allison from Stanford University School of Medicine and Dr. Antonio Wolff from Johns Hopkins University on "Estrogen and Progesterone Receptor Testing in Breast Cancer Guideline: ASCO/CAP Guideline Update." This guideline updates key recommendations of the American Society of Clinical Oncology/College of American Pathologists estrogen and progesterone receptor testing in breast cancer guideline, and focuses on low estrogen receptor expression cases. Read the full guideline at www.asco.org/breast-cancer-guidelines.