Abstract GS4-05: Preservation of axillary lymph nodes compared to complete dissection in T1-T2 breast cancer patients presenting 1-2 metastatic sentinel lymph nodes. A multicenter randomized clinical trial. Sinodar One

• Published in: Cancer research (Chicago, Ill.) Ill.), 2022-02, Vol.82 (4_Supplement), p.GS4-05-GS4-05
• Main Authors: Gentile, Damiano, Gatzemeier, Wolfgang, Barbieri, Erika, Sagona, Andrea, Bottini, Alberto, Errico, Valentina, Testori, Alberto, Scorsetti, Marta, Canavese, Giuseppe, Tinterri, Corrado
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS21-GS4-05

Introduction: Sentinel lymph node (SLN) staging is currently used to avoid complete axillary lymph node dissection (ALND) in breast cancer (BC) patients. The SLN is the only site of axillary metastasis (MTS) in ≥60% of cases. Recently, a randomized controlled trial (Z0011) comparing SLN biopsy (SLNB) alone with SLNB followed by ALND in patients with 1-2 SLNs+ demonstrated no significant statistical difference in relapse and overall survival (OS) rates among the two different groups. However, this study had some limitations: small tumor size (≤2cm in 70% of cases), frequent presence of only microMTS in SLN (40%), prevalent use of “whole breast” adjuvant radiotherapy (>90%). Given these considerations, the SINODAR-ONE study started in April 2015. Objectives: The aims are to assess whether ALND omission in BC patients with 1-2 SLNs+ is associated with worse survival and/or increased rate of regional/distant relapse. Thus evaluating whether SLNB is or is not inferior to ALND. Primary endpoint is OS. Secondary endpoints are disease-free survival (DFS) referring to distant MTS and loco-regional recurrence. Methods: Patients received either mastectomy or conservative surgery plus radiotherapy. They all underwent SLNB and were randomly divided into two arms of treatment: standard (SLNB plus ALND) or experimental treatment (only SLNB). According to multidisciplinary evaluation, patients could undergo additional adjuvant radiotherapy, chemo- and/or hormonal therapy, or no further therapy. Eligibility criteria: age 40-75 years; primary invasive T1-T2 tumor; axillary nodes cN0; no more than 2 macro-metastatic SLNs; no distant MTS; no neo-adjuvant therapy; no previous invasive BC. Exclusion criteria: in situ, inflammatory, contralateral BC; micro-metastatic SLNs; pregnancy or breast feeding; comorbidity impeding adjuvant therapy. All analyses were performed both on all patients according to the Intention-To-Treat principle and excluding those patients who did not receive the axillary treatment randomly assigned. Statistical analysis: OS and DFS were calculated using the Kaplan-Meier Product Limit Estimator and differences between arms were assessed with the log-rank test. Results: The enrollment of patients ended in April 2020 with a total of 889 cases (443: standard arm; 446: experimental arm). In April 2021, we conducted a preliminary analysis on 889 patients. We found the two groups homogeneous for epidemiologic characteristics (age and menopausal status), tumor cha