Abstract PO4-16-10: Overall survival in sentinel node biopsy and axillary dissection: a real-world data

Abstract Background: Information about the status of the axilla (presence or absence of lymph node disease) is important for breast cancer (BC) treatment decision-making. Axillary dissection (AD) has been gradually substituted by sentinel node biopsy (SLNB) in clinical node negative patients and intraoperative evaluation became a routine. Most of the patients with a positive node in an intraoperative evaluation were submitted to AD, and when a negative intraoperative evaluation but a positive paraffin evaluation was found a new axillary surgery was a routine. Both approaches were gradually abandoned with the publication of the ACOSOG Z011 study showing no difference in local recurrence or overall survival (OS). Objective: To evaluate the number of patients with BC who meet the criteria of Z011 trial and could be spared of AD and compare the outcomes of the SLNB only and those that had AD. Methods: Patients with BC that were submitted to upfront surgery and had at least one positive node in SLNB were included in these retrospective analyses at Pérola Byington Hospital database, diagnosed between 1992 and 2019. Clinical and pathological characteristics were extracted from the database and patient medical records. T-test or chi-square test was used to individually analyze the association of each variable between the groups. Multivariate analysis was used to calculate odds ratio (OR) and 95% confidence intervals (CI) for independent variables correlated with positive AD. Cox regression was used for survival analysis, and survival curves were plotted using the Kaplan-Meier method, analyzing the difference between curves using the Log-rank test. R software version 4.1.1 was used for all analyses, with a p-value 0.05 considered statistically significant. Results: A total of 729 patients were analyzed, with a mean age of 54.1 (±11.6) years at diagnosis. Most patients (n=633, 86.8%) underwent AD after a positive SLNB and 40,3% of the patients that were submitted to AD the only positive node was the sentinel node. After AD, 63,3% of these patients had 1 or 2 lymph nodes positive and met the Z011 criteria trial. The mean number of lymph node in AD was 12.2. Most patients (72.7%) were diagnosed at clinical stage II, 62% had nuclear grade 2 tumors, 52.9% had Luminal B subtype, and 63% were postmenopausal. Furthermore, 58.5% of patients underwent breast-conserving surgery, and 5.2% of patients experienced recurrence. The chance of AD was observed 2,2 times for the luminal B (OR 2.163, 95% CI 1.104-4.239, p=0.025), 2,1 times HER2-positive with receptor positive (OR 2.125, 95% CI 1.160-3.893, p=0.015), and 2,8 times for triple-negative (OR 2.806, 95% CI 1.013-7.757, p=0.047) compared to Luminal A. Patients that were submitted to AD had worse outcome when compared to SLNB, the overall survival showed a 94.4% higher risk of death with a median survival of 11 years (HR 1.944, 95% CI 1.20-3.14, p=0.006). Conclusion: These retrospective analyses showed 63,3% of the patients that had a positive node in a SLNB could be spared from AD (based on Z011 trial). Patients submitted to AD had worse outcome and these findings needs to be clarified. Citation Format: Renata Pares, Andre Mattar, Juliana de Lima, Marcelo Antonini, Francisco Pimentel Cavalcante, Luiz Henrique Gebrim. Overall survival in sentinel node biopsy and axillary dissection: a real-world data abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-16-10.