Esther M. John. PhD, MSPH is Professor of Epidemiology & Population Health and of Medicine (Division of Oncology) and co-leader of the Population Sciences Program of the Stanford Cancer Institute. Dr. John is a cancer epidemiologist and her research focuses on the etiology and prognosis of breast and prostate cancer, to better understand modifiable lifestyle, hormonal and genetic causes and outcomes of these common cancers. She has a special interest in understanding cancer health disparities and cancer in Hispanics and African Americans, two understudied populations.