Dr. Efstathiou is Professor of Radiation Oncology at Harvard Medical School (HMS) and Director of the Genitourinary (GU) Division in the Department of Radiation Oncology and Clinical Co-Director of The Claire and John Bertucci Center for GU Cancers at the Massachusetts General Hospital. He is a recognized leader in the field of GU malignancies and Radiation Oncology. His research has informed clinical guidelines and made novel contributions to organ preservation therapy for bladder cancer, technology assessment of proton beam therapy for prostate cancer, as well as global oncology outreach efforts. Dr. Efstathiou holds multiple leadership positions within professional societies (ASTRO, ASCO, ABR, ACRO, ROI) serving on multiple Boards, within the NCI where he serves as Co-Chair of the Bladder Cancer Task Force, and within NRG Oncology where he is the Vice-Chair of the GU Steering Committee and Bladder Lead. This year he also is serving as the Chair of the Genitourinary Cancers Symposium (GU ASCO) Program Committee for 2021-2022. In addition, he has a strong proven track record in teaching and mentorship and was recently awarded the A. Clifford Barger Excellence in Mentoring Award from HMS. Dr. Efstathiou holds a B.S. from Yale University, M.D. from HMS, D.Phil. from the University of Oxford, and completed his residency training in the Harvard Radiation Oncology Program.