Stephen M. Hahn is the Chair of the Department of Radiation Oncology at the MD Anderson Cancer Center.In 2014, Hahn became the Chair of Radiation Oncology at the University of Texas MD Anderson Cancer Center in Houston where he oversees the divisions of Clinical radiation oncology, Radiation physics, and Radiation biology. He is an active clinician, with specialism in treating lung and genitourinary cancers and in the use of photodynamic therapy.