CDK4/6 Inhibitors Combined With Endocrine Therapy for Neoadjuvant Treatment

Inclusion criteria

• ✓. ER-positive and/or PR-positive defined as: ≥10% of tumor cells showing positive staining;
• ✓. HER2-negative defined as: standard immunohistochemistry (IHC) result of 0/1+; or IHC 2+ with negative in situ hybridization (ISH) (confirmed by the central pathology laboratory); 3. At least one evaluable lesion per RECIST 1.1, with clinical staging meeting:
• ✓. T1c-2N0M0 with high-risk factors (Grade 3, or Grade 2 with Ki67 ≥20%);
• ✓. T3N0M0;
• ✓. Any TN+M0; 4.Eastern Cooperative Oncology Group (ECOG) performance status score of 0-1; 5.Willing to participate in the study and voluntarily sign informed consent; 6.Agree to undergo ctDNA testing during treatment; 7.Adequate organ and bone marrow function defined as:
• ✓. Absolute neutrophil count (ANC) ≥1,500/mm³ (1.5 × 10⁹/L) (without granulocyte colony-stimulating factor \[G-CSF\] treatment within 14 days);
• ✓. Platelet count (PLT) ≥100,000/mm³ (100 × 10⁹/L) (without corrective therapy within 7 days);
• ✓. Hemoglobin (Hb) ≥9 g/dL (90 g/L) (without corrective therapy within 7 days);