Sarah Stewart was born in Mexico to an American father and Mexican mother. She moved with her family back to the United States at age 5. She graduated from New Mexico State University in 1927.

Stewart earned her MS in Microbiology from University of Massachusetts-Amherst in 1930 and her Ph.D. in Microbiology from the University of Chicago in 1939. She later became the first woman to receive an M.D. from Georgetown University in 1949 (at the age of 43). 

She worked at the NIH while also completing her Ph.D., but her request to study the link between viruses and cancer was denied. The National Cancer Institute at the NIH cited a lack of education and experience with human research as the reason for their refusal to fund her. She left the NIH in 1944 to teach at Georgetown University in the medical school. While teaching, she was able to take medical courses until she was able to officially enroll in medical school when Georgetown began accepting women in 1947.

The NIH continued to deny Stewart’s funding to study cancer, so she took a temporary position at a hospital in Staten Island to gain more experience. Finally, after an appointment to medical director in the United States Public Health Service (PHS) Commissioned Corps and a position at the NCI in Baltimore, the NIH accepted her request to study cancer. She returned to the NIH in 1951 to work at their National Cancer Institute (NCI). Dr. Stewart was the Head of the Human Virus Studies Section in the Laboratory of Viral Oncology at the NCI.

In 1956 she isolated the SE (Stewart-Eddy) polyoma virus with Dr. Bernice Eddy of the Division of Biologics Standards (DBS) Laboratory of Virology & Rickettsiology. The SE polyoma virus induces parotid gland tumors and a variety of other primary neoplasms in mice and other animals, which had implications for future viral oncology research.

Twice Drs. Stewart and Eddy were nominated for the Nobel Prize for their work on the S-E polyoma virus, but unfortunately, they never won.

Dr. Stewart won several awards during her career, including the Federal Woman’s Award presented by President Lyndon B. Johnson in 1965.

She retired from the NIH in 1970 and unfortunately died of cancer in 1976.