Dr. Tadahiko Shien MD, Ph.D. (Ph.D.-surgical medicine) is a director of the Breast and Endocrine Surgery Department at Okayama University Hospital and the JCOG Breast Cancer Study Group chair. He is a surgical oncologist researching the treatment strategy for de-novo stage IV breast cancer (PI of JCOG1017 study) and Oligometastasis. His clinical and research interests primarily focus on breast surgical oncology, tumor biology, clinical trials, and translational research. He is a member of the American Society of Clinical Oncology (ASCO), Japan Surgical Society (JSS), Japan Society of Clinical Oncology (JSCO), Japan Breast Cancer Society (JBCS), Japan Society of Medical Oncology (JSMO), International Society of Surgery (ISS), Japan Oncoplastic Breast Surgery Society (JOBSS), Japan Association of Endocrine Surgery (JAES), and Breast Surgery International (BSI). His board-certified specialties are JSS, JSCO, and JAES, and the Board of JBCS and JAES. He is an associate editor of BMC Women’s Health, Frontier in Oncology, and Oncology letters.