Risk Stratification for Sentinel Lymph Node Positivity in Older Women With Early-Stage Estrogen Receptor-Positive/Human Epidermal Growth Factor Receptor 2 Neu-Negative Invasive Breast Cancer.

Abstract

Purpose: Guidelines recommend omission of sentinel lymph node biopsy (SLNB) for axillary staging in select patients age 70 years and older with early-stage estrogen receptor-positive (ER+), human epidermal growth factor receptor 2 neu-negative (HER2-) invasive breast cancers (BCs). However, many women meeting criteria for SLNB omission continue to receive this procedure. This study aims to stratify patients into risk cohorts for nodal positivity that can be incorporated into deimplementation strategies to reduce low-value SLNB procedures.

Methods: A retrospective cohort analysis using the National Cancer Database was performed on patients age 70 years and older with ER+/HER2-, cT1-2, cN0, cM0 BC who underwent breast surgery from 2018 to 2021. Patients who received neoadjuvant therapies were excluded. Recursive partitioning analysis (RPA) was used to develop two models to estimate nodal positivity: (1) a clinical model for preoperative use to decide whether to perform SLNB and (2) a pathologic model for postoperative use to guide adjuvant decisions in cases of SLNB omission.

Results: The study included 68,867 patients who received SLNB; 13.4% had a tumor-involved lymph node. RPA on the basis of clinical covariates demonstrated <8% risk of nodal positivity for patients with cT1mi-cT1b and grade 1-2 tumors. RPA on the basis of pathologic covariates found <10% risk of nodal positivity for patients with pT1 tumors without lymphovascular invasion (LVI). Patients with cT2 or pT2 without LVI and nonductal/nonlobular histology had <5% risk of nodal positivity.

Conclusion: This study demonstrates a low risk of nodal positivity for patients with cT1 or pT1 tumors. Our RPA-defined subgroups offer a novel approach to predict nodal positivity in patients age 70 years and older with early-stage, ER+/HER2- invasive BC that can be incorporated in deimplementation strategies to reduce low-value axillary surgery.