Work

Exploring the treatment gap and outcome risks in patients with node-positive, high-risk, HR-positive, HER2-negative early breast cancer: analyses of real-world data

Year: 2026

Type: article

Abstract: BACKGROUND: Two-year treatment with abemaciclib plus endocrine therapy (ET) is approved and guideline-recommended for patients with node-positive (N+), high-risk, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer (EBC). This study assessed real-world utilization of adjuvant abemaciclib and risk of recurrence and death in abemaciclib-eligible patients [N+ high-risk disease: N1 or N1 with micrometastases (N1mi) plus grade 3 or tumor size ≥5 cm, N2, or N3] treated with ET alone. MATERIALS AND METHODS: This retrospective analysis used the United States-based Flatiron Health data (January 2023-June 2024) to assess abemaciclib utilization among eligible patients with N+ high-risk features (N+ high-risk) and characteristics of patients who did or did not receive abemaciclib. A second analysis using a Flatiron Health data subset (January 2011-June 2024) compared risk of recurrence [invasive disease-free survival (IDFS)] and overall survival (OS) in patients with N+ high-risk features to patients with lower-risk features (non-high-risk) receiving ET alone, overall and by nodal subgroups. Outcomes in early triple-negative breast cancer (eTNBC) were described for context. RESULTS: Of 3170 patients with N+ high-risk EBC, 60.0% did not receive abemaciclib. Of those eligible with N1/N1mi tumors, 69.1% did not receive abemaciclib, despite 73.5% having grade 3 disease. In outcomes analyses, 5-year IDFS rates were similar for N+ high-risk (n = 696; 70.9%) and eTNBC (n = 515; 74.3%) and lower than non-high-risk (n = 5654; 91.2%). OS trends were consistent with IDFS. Five-year IDFS rates were 75.7%, 68.3%, and 59.6% for N1/N1mi, N2, and N3 subgroups, respectively, with similar trends for OS. Five-year risks of recurrence and death approximately doubled in N1/N1mi high-risk versus N1/N1mi non-high-risk. CONCLUSIONS: While adjuvant abemaciclib is approved for N+, high-risk, HR-positive, HER2-negative EBC, utilization remains suboptimal in eligible patients, despite high recurrence and mortality risks similar to eTNBC. These data indicate the need for education about risk identification and implementation of optimal therapy.

Source: ESMO Open

DOI: 10.1016/j.esmoop.2025.106021