Breast Cancer, HR+/HER2- Early-Stage

Hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer constitutes approximately 70% of all breast cancer cases. Although early-stage patients generally have favorable outcomes following standard surgery and adjuvant endocrine therapy, long-term follow-up data reveal a distinct "bimodal" or "long-tail" recurrence pattern, with risks persisting for decades. Recent landmark trials (e.g., NATALEE, MonarchE) have established that combining CDK4/6 inhibitors with endocrine therapy significantly improves invasive disease-free survival (iDFS) in high-risk populations. However, the stringent enrollment criteria of these randomized controlled trials may not fully capture the heterogeneity of real-world patients. Reliance on binary cut-off values (e.g., nodal status alone) risks misclassifying biologically high-risk individuals with low anatomical burden, leading to either undertreatment or overtreatment. There is an urgent clinical need for a multidimensional, individualized risk assessment tool to guide escalated therapy decisions.