Economic and Health System Impact of Implementing the SOUND Trial Approach in Early-Stage Breast Cancer

Axillary management in early-stage breast cancer is increasingly shifting toward de-escalation. While sentinel lymph node biopsy (SLNB) remains standard, evidence suggests axillary ultrasound (AUS) may safely replace SLNB in selected patients. The SOUND trial demonstrated noninferior oncologic outcomes with AUS-based staging among clinically node-negative patients with small (≤ 2 cm), unifocal invasive breast cancers and negative preoperative AUS. However, the economic and health system impact of implementing this strategy in routine practice remains unclear.

We conducted a retrospective cohort analysis of 221 SOUND-eligible patients who underwent breast-conserving surgery with SLNB at four affiliated hospitals between January and June 2023. Costs were modeled using 2025 Medicare reimbursement rates, comparing the observed SLNB pathway with a theoretical AUS-only approach. Estimates included procedural, anesthesia, pathology, and complication-related costs, analyzed from both hospital and patient perspectives.

Total estimated hospital costs were $1192,159.56 for SLNB versus $111,825.65 for AUS-only staging, a 90.6% reduction. Mean patient out-of-pocket costs decreased similarly (from $1078.88 to $101.20 per patient). SLNB added an average of 15.1 min of operative time and increased pathology workload owing to lymph node processing.

In SOUND-eligible patients, axillary staging with ultrasound alone provides substantial reductions in cost, operative time, and resource utilization while supporting a less invasive, value-based approach to breast cancer care. Together with existing evidence, these findings support broader implementation of the SOUND strategy in appropriately selected populations, particularly postmenopausal patients over 50 years undergoing breast-conserving surgery for cT1N0, ER-positive, HER2-negative invasive ductal carcinoma with a negative AUS.