He grew up in Cleveland, Ohio and earned his medical degree at Case Western Reserve. Dr. Horwitz completed an internship and residency in internal medicine at the University of Rochester/ Strong Memorial Hospital in Rochester, New York and then completed a fellowship in medical oncology at Stanford University Medical Center. Dr. Horwitz has a clinical research focus in non- Hodgkin lymphomas, in particular many of the more rare lymphomas such as T-cell lymphomas and lymphomas of the skin.