The monarchE trial was the only adjuvant trial that assessed the benefits of adding 2 years of adjuvant abemaciclib to endocrine therapy (ET) in high-risk hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), early breast cancer (EBC) patients.1 This trial randomized 5,637 patients in 1:1 into the abemaciclib + ET group or the ET alone group.1 In the primary analysis, 2-year abemaciclib demonstrated significant risk reductions in invasive disease-free survival (IDFS) (HR=0.664; 95% CI: 0.578-0.762) and distant relapse-free survival (DRFS) (HR=0.659; 95% CI: 0.567-0.767) in the overall intention-to-treat (ITT) population.1 In a subsequent subgroup analysis, the dataset was divided into 2 age subgroups, i.e., patients aged <65 years (n=4,787) and ≥65 years (n=850).1 The median follow-up of monarchE was 42 months