A real-world US study of recurrence risks using combined clinicopathological features in HR-positive, HER2-negative early breast cancer.

To assess invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS) in hormone receptor-positive, HER2-negative early breast cancer with combined clinicopathological criteria from monarchE, a phase III study of abemaciclib. US electronic health records were used to compare outcomes between high-risk (≥4 lymph nodes, or 1-3 lymph nodes and grade 3, tumor ≥5 cm or Ki-67 ≥20%) versus nonhigh-risk groups using Kaplan-Meier methods and Cox regression models. The high-risk group (n = 557) was at higher risk for IDFS and DRFS events than the nonhigh-risk group (n = 3471).