Abstract Ovarian cancer is most often detected in late stage when prognosis is poor; in contrast, prognosis is excellent when detection occurs in early stage. Early detection with regular biomarker tests may reduce disease-specific mortality. Two screening trials with annual CA125 greater than 35 U/mL demonstrated promise. Before undertaking larger trials, statistical analyses of serial CA125 levels showed each woman has her own baseline level; and in ovarian cancer cases, CA125 rose rapidly from her baseline after a change point. Improved early detection of ovarian cancer may result if each woman were tested for the presence of a change-point CA125 profile. Using the serial CA125 from the completed trials, a statistical method was developed to measure the probability a change-point had occurred. Subsequent screening trials implemented the risk of ovarian cancer algorithm (ROCA) in which screening decisions are made based on the risk of having a change point. Development of ROCA is described, and ROCA trials are listed.