PGR and neoplasm: The missing grade for Phase I, II, and III (n = 930) were imputed using the Multivariate Imputation by Chained Equations package [27] based on a previously published method, which used ER/PR/HER2 status, node status, race, age, tumor stage, size, p53 mutation status, survival, grade, and study phase as predictor variables [28].