Abstract PS2-05-14: Omitting Sentinel Lymph Node Dissection After Neoadjuvant Treatment in Early Breast Cancer: Interim Results from the VENUS Randomized Clinical Trial

Abstract Introduction: Sentinel lymph node dissection (SLND) omission after neoadjuvant therapy (NAT) in early-stage breast cancer has not yet been studied, because most SLND omission trials do not allow recruitment of patients who undergo NAT. The VENUS trial (ClinicalTrials.gov NCT05315154, ReBEC RBR-8g6jbf, Ethics approved: CAAE:06805118.2.0000.5404) is an ongoing study that aims to evaluate the safety of omitting sentinel lymph node dissection in clinically and ultrasound node-negative early breast cancer (BC). The trial permits neoadjuvant treatment (NAT). Objectives: Evaluate the characteristics of patients enrolled in the VENUS trial until September 25th 2025, who underwent NAT and compare them to the other patients enrolled, in order to determine if it is safe to maintain the recruitment of women with early-stage breast cancer and neoadjuvant treatment indication. Methods: Descriptive interim exploratory analysis of the patients enrolled on the VENUS trial until September 25th 2025. The VENUS trial is a multicenter, prospective, non-inferiority, phase 3 clinical trial that includes women with T1/T2, N0 (clinical/ultrasound), M0 breast cancer, randomized to SLND or no axillary surgery (NAS). Initial treatment could be NAT or upfront surgery, and the axillary ultrasound must be negative before and after the neoadjuvant treatment (analysis groups: NAT-SLND, NAT-NAS, up-front-SLND, up-front-NAS). This interim analysis focuses on patient and tumor characteristics, SLND positivity, and axillary recurrence. Results: So far, 788 women were enrolled, with 287 randomized to SLND and 273 to NAS. Patients' epidemiological characteristics (body mass index, race and menopausal status) were similar in all randomization groups, but those who underwent NAT were younger (NAT-SLND and NAT-NAS mean ages were 53.4 and 53.7 years old versus up-front-SLND and up-front-NAS of 59.7 and 62.7 years old, p=0.01). Among all randomized patients, 45 (8%) underwent NAT, of which 25 had SLND performed and 20 no axillary surgery. They had more aggressive tumor profiles (37.7% HER2 positive tumors and 33.3% triple-negative tumors) and tumors' mean size of 28 mm. SLND positivity seems to be lower after NAT compared to upfront surgery (4.2% vs. 19.9%, p=0.1048), though this difference did not reach statistical significance. No axillary recurrences were observed during the 22-month follow-up. Conclusions: This interim analysis suggests that SLND positivity is lower after NAT and that omitting SLND in this context may be oncologically safe, with no axillary recurrences observed over 22 months of follow-up. However, the small NAT sample limits statistical power, and continued data collection is needed to confirm safety and feasibility. At this stage, continuing the inclusion of patients with indication for NAT in the VENUS trial appears justified. Recruitment will proceed through December 2025. Citation Format: M. P. L. Kraft, G. M. Duarte, D. M. Araújo, R. M. Jales, J. Y. Shinzato, R. Z. Torresan, C. Cardoso Filho, F. P. Brenelli, S. B. Esteves, H. K. Mantovani, G. M. Tavares, A. S. Detoni, E. C. Pessoa, C. K. C. Pessoa, I. de Oliveira Júnior, R. Freitas Júnior, R. M. S. Rahal, V. M. Budel, L. R. Budel, A. P. S. Damin, L. R. Soares, R. D. J. A. de Andrade, F. P. Cavalcante, M. Antonini, R. S. Machado, D. L. Ferreira Filho, K. B. F. Diocesano, S. Vieira, A. Mattar, T. Giuzio, L. Z. Sarian. Omitting Sentinel Lymph Node Dissection After Neoadjuvant Treatment in Early Breast Cancer: Interim Results from the VENUS Randomized Clinical Trial [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS2-05-14.