1. Stephen Hahn was then recruited by his mentor, Eli J Glatstein to complete a separate residency in radiation oncology at the NIH between 1991 and 1994, where he eventually attained the rank of commander in the US Public Health Service Commissioned Corps between 1989 and 1995.
In 1996, Stephen Hahn joined the University of Pennsylvania School of Medicine as a radiation and medical oncologist as well as a researcher funded by the National Institutes of Health.
Stephen Hahn then held the Department of Radiation Oncology's fourth endowed Henry Pancoast Professorship as Department Chair until 2014.
Stephen Hahn remains Board Certified in Internal Medicine, Medical Oncology, and Radiation Oncology.
In 2015, Stephen Hahn became the chair of radiation oncology at the University of Texas MD Anderson Cancer Center in Houston, where he oversaw the Departments of Clinical Radiation Oncology, Radiation Physics, and Radiation Biology.
In 2018, Stephen Hahn was appointed as the Chief Medical Executive of MD Anderson Cancer Center.
On November 1,2019, US President Donald Trump announced his intent to nominate Stephen Hahn to be Commissioner of Food and Drugs Administration.
Stephen Hahn has factored prominently in the Trump administration's response to the novel coronavirus pandemic in the United States, although the FDA under his administration has been criticized for a lethargic response to the rapidly emerging outbreak in the United States.
Stephen Hahn is a member of the American Society of Clinical Oncology, American Society for Radiation Oncology, Radiation Research Society, American Society of Photobiology, American Association for Cancer Research, and the University of Pennsylvania's John Morgan Society.
Stephen Hahn has been married for more than 30 years and has four children.