HR+ / HER2− Breast Cancer: Treatment Guidelines
Complete evidence-based treatment algorithms for hormone receptor-positive breast cancer — neoadjuvant ICI, adjuvant CDK4/6i, metastatic biomarker-directed therapy, ADCs, surgery/RT de-escalation, and brain mets.
monarchE OS HR
0.842
7-yr: First CDK4/6i OS benefit
INAVO120 PFS
15.0 mo
vs 7.3 mo (HR 0.43)
KEYNOTE-756 pCR
24.3%
vs 15.6% (Pembro + NACT)
HER2-Low/Ultralow
~85%
HR+ MBC T-DXd eligible
HR+ / HER2− Breast Cancer: Epidemiology, Biology, and Treatment Framework
HR+ Prevalence
~70%
Of all breast cancers
5-yr OS (Stage I-III)
>90%
Early stage HR+
Late Recurrence Risk
~15%
Years 5–20 (Luminal A)
ESR1 Mx (After AI)
30–40%
Acquired AI resistance
Luminal A Phenotype
- Grade 1–2, Ki-67 ≤20%, ER-high (>10%), PR+
- Low Oncotype DX (RS 0–25) or MammaPrint Low
- Excellent prognosis; ET alone often sufficient
- Late recurrence risk extends beyond 5 years
Luminal B Phenotype (High-Risk)
- Grade 3, Ki-67 >20–30%, ER-low (1–10%)
- High Oncotype DX (RS ≥26) or MammaPrint High
- Node-positive (N1–N3)
- Benefits from CDK4/6i ± chemotherapy
Clinical Decision Support
Integrated calculators to support treatment decisions in HR+ breast cancer management. Oncotype DX RS interpretation: 0–15 = ET alone; 16–25 = context-dependent; 26–100 = chemo + ET.
Clinical reference only. These guidelines are intended to support, not replace, clinical judgment. Treatment decisions should be individualised based on patient-specific factors, local protocols, and multidisciplinary team input. Always apply clinical judgment and consult local institutional guidelines where applicable. Data reflect published literature as of April 2026.