Who Can Truly Skip the Sentinel Node? A Paired Two-Stage Virtual Tumor-Board Study Among Patients Meeting the 2025 ASCO Clinicopathologic Criteria

Background/Objectives: Sentinel lymph-node biopsy (SLNB) may be omitted in selected patients with clinically node-negative, early-stage breast cancer; however, the extent to which nodal information still influences contemporary adjuvant-treatment planning remains uncertain. This study aimed to determine whether disclosure of SLNB pathology changed multidisciplinary systemic-treatment and/or radiotherapy recommendations among patients fulfilling study-defined criteria derived from the 2025 American Society of Clinical Oncology omission pathway. Methods: In this single-center, retrospective, record-based paired decision-impact study, routine clinical records of consecutive postmenopausal women aged ≥ 50 years who underwent breast-conserving surgery and SLNB between 1 January 2015 and 30 June 2026 were reviewed after closure of the prespecified clinical-record window. Each anonymized case was assessed by a six-member virtual tumor board in two stages: first with SLNB pathology concealed and subsequently, after a six-week washout period, with nodal findings disclosed. The primary outcome was a definitive change in chemotherapy, CDK4/6-inhibitor, and/or radiotherapy recommendation. Paired transitions, interobserver agreement, decision confidence, and pre-SLNB factors associated with management-changing information were evaluated. Results: Among 412 eligible patients, occult sentinel-node deposits were identified in 46 (11.2%; 95% confidence interval [CI], 8.5–14.6%), including isolated tumor cells in seven, micrometastases in 13, and macrometastases in 26. Nodal disclosure produced at least one definitive management change in 28 patients (6.8%; 95% CI, 4.7–9.6%), corresponding to 14.7 SLNB procedures per management-changing recommendation. Twenty-six changes represented treatment escalation. Radiotherapy recommendations changed in 22 patients, CDK4/6-inhibitor recommendations in 13, and chemotherapy recommendations in seven, with overlap between domains. The expanded decision-impact endpoint was reached in 43 patients (10.4%; 95% CI, 7.8–13.8%). Management changed in 0.5% of patients with pN0 disease, none with isolated tumor cells, 46.2% with micrometastases, and 76.9% with macrometastases (p < 0.001). Increasing clinical tumor size was associated with management-changing information (adjusted odds ratio per 5 mm increase, 1.58; 95% CI, 1.07–2.37; p = 0.023). Conclusions: SLNB pathology left definitive adjuvant-treatment recommendations unchanged in more than 90% of selected patients but altered management in approximately one in 15, predominantly through radiotherapy-field selection and CDK4/6-inhibitor consideration. These findings support selective, multidisciplinary implementation of SLNB omission while emphasizing that decision changes do not necessarily represent proven oncological benefit.