For over forty years, the Gynecologic Oncology Group drove progress in treating endometrial cancer. The first decades of investigation began with a meticulous prospective, surgicopathologic staging study that was the platform for development of all subsequent trials. The resultant statistical model of low risk, intermediate risk, and high-risk groups of patients led to trials where therapeutic modalities were best targeted at disease spread. A clear role for chemotherapy was established. It was realized that greater advances might be achieved with the advent of newer anti-neoplastic agents and these agents were subjected to extensive phase II testing.