Mildred Vera Peters, OC (28 April 1911 – 1 October 1993) was a Canadian oncologist and clinical investigator. Peters received her medical degree from the University of Toronto in 1934. In 1950 she published a landmark paper demonstrating for the first time that many patients with early Hodgkin's disease, then considered incurable, could be completely cured if given high-dose radiation. She later went on to study the use of radiation therapy in the treatment of breast cancer. Her research, carried out at the Princess Margaret Hospital, demonstrated that breast-conserving surgery (lumpectomy) followed by radiation was just as effective as radical mastectomy which had a significant impact on the lives of the many women who experience breast cancer.