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Douglas Stewart, M.D.

Senior Investigator

NCI Shady Grove | Room 6E450


Dr. Stewart received his M.D. from the University of Pennsylvania School of Medicine in 1998. He completed a residency in internal medicine at the Hospital of the University of Pennsylvania in 2001 and training in medical genetics at the Children’s Hospital of Philadelphia in 2004. He is board-certified in both internal medicine and clinical genetics. He had postdoctoral training in genetics in the laboratory of Richard Spielman at Penn from 2002-2004. In 2004 he joined the National Human Genome Research Institute as part of the Physician Scientist Development Program to investigate the tumor predisposition syndrome neurofibromatosis type 1 (NF1). In recognition of his work in NF1, he was named one of NIH’s first Earl Stadtman Investigators when he joined the National Cancer Institute’s Clinical Genetics Branch in the summer of 2010. At CGB, he investigated the natural history study of DICER1-related tumor predisposition. From that work, his group contributed fundamental knowledge on the phenotype, prevalence, and penetrance of germline DICER1 variants and continued to contribute to understanding of NF1. He was awarded NIH scientific tenure and promoted to senior investigator in 2019. In 2023, he was elected a member of the American Society for Clinical Investigation, one of the nation’s oldest medical honor societies.

Now Enrolling 

Pleuropulmonary Blastoma Cancer Study

Enrolling children and family members with PPB or related tumors and conditions.

NCI RASopathies Study

Enrolling individuals and family members with a rasopathy.

Research Interests

Dr. Stewart is an internist and a clinical geneticist with a long-standing interest in improving the health and care of people with an increased genetic risk of cancer. In his research, Dr. Stewart quantifies the risk of cancer in children and adults from rare germline variation and develops evidence-based strategies to reduce that risk.

Genome-first Genetics

The genome-first approach in clinical genetics uses genomic (rather than phenotypic) ascertainment to quantify prevalence, penetrance, and phenotype using population-scale cohorts of electronic health record-linked exome- and genome-sequencing. Dr. Stewart is the PI of a multi-year, funded collaboration with Geisinger to investigate the genome-first approach in cancer genetics using their cohort of >170,000 individuals with electronic health record-linked exome sequencing.  

Clinical Investigation

Dr. Stewart is the principal or associate investigator on multiple natural history studies at NIH/NCI of monogenic disorders associated with an increased risk of cancer. These include IRB-approved protocols currently recruiting participants with RASopathies, DICER1-Related Tumor Predisposition, Maffucci syndrome/Ollier disease, and neurofibromatosis type 1. 

Evidence-based Strategies to Reduce Cancer Risk

For individuals who harbor germline cancer risk variants, evidence-based guidance on surveillance and risk reduction is critical for their clinical care. Working with national and international colleagues, Dr Stewart incorporates knowledge gained from his active studies to develop evidence-based clinical guidance to manage cancer risk.

Current and Former Fellows

Current Fellows 

Former Fellows

  • Cindy Choi, B.S., post-baccalaureate fellow
  • Toniya Brown, B.A., post-baccalaureate fellow
  • Brenna Douhitt, summer intern
  • Nicholas Khan, B.S., M.S.P.H., post-baccalaureate fellow
  • Sun Young Kim, MD, Ph.D., visiting fellow
  • Sirisha Karra, summer intern
  • Jung Kim, Ph.D., post-doctoral fellow 
  • Jessica Merberg, B.S., summer intern
  • Anand Pathak, M.D., Ph.D., M.P.H., postdoctoral fellow
  • Radhika Srivastava, B.S., post-baccalaureate fellow 
  • Esteban Astiazaran Symonds, M.D., postdoctoral fellow
  • Lauren M. Vasta, M.D., F.A.A.P., fellow at Walter Reed National Military Medical Center
  • Talia Wegman-Ostrosky, M.D., Ph.D., visiting fellow

Press Contacts

To request an interview with NCI researchers, contact the NCI Office of Media Relations. | 240-760-6600