Abstract P3-03-32: Monocentric experience with the sentinel lymph node biopsy prior to neoadjuvant chemotherapy in clinically lymph node negative early breast cancer

Abstract

Background In patients with clinically lymph node negative (cN0) early breast cancer (EBC) treated with neoadjuvant chemotherapy (NACT), the sentinel lymph node biopsy (SLNB) can be performed before or after NACT. We report safety of axillary staging performing the SLNB prior to NACT in cN0 EBC and estimate NACT-induced downstaging to ypN0 in previously NACT-treated cN1 EBC, to make an assumption for avoiding axillary lymph node dissection (ALND) if SLNB was done after NACT. Patients and Methods Monocentric retrospective study of consecutive triple negative (TNBC) and HER-2 amplified BC patients treated with standard NACT. cN0 patients had SLNB before NACT followed by local therapy. Axillary lymph node dissection (ALND) post-NACT was performed in all cN1 and in cN0 cases with a positive or failed SLNB. Using descriptive statistics, we here report SLNB-detection and SLNB-positive rate, SLNB-operative complications, complete tumor regression in the breast (ypT0/is) and disease-free survival (DFS) for cN0 cases and NACT-induced downstaging to ypN0 in previously NACT-treated cN1 EBC. Results We included 245 NACT-treated patients; 119 cN0 and 126 cN1. SLNB-detection rate in cN0 cases was 99,2%; 25 or 21% had ≥ 1 involved SLN, 21.8% experienced SLNB related-complications (e.g. infection, seroma, hematoma) leading to NACT-delay in 3 and interruption in 1 patient. Median start of NACT after SLNB was 7 days (range 1-20 days). In patients with a positive SLNB, there were no additional involved nodes in the ALND. In 5 of these patients, therapy response in a lymph node was described. Complete tumor regression in the breast (ypT0/is) was 52% in SLNB-positive and 59,1% in SLNB-negative cN0 cases. NACT-induced ypN0 was 61% in cN1 cases. At 30 months of median follow-up (range 1-86 months), DFS was 93,2% (4.2% metastatic; no axillary relapse) in cN0 cases. Median DFS was better for patients with complete tumor regression in the breast as compared to those with partial response; 95.6% and 90% respectively. Conclusion In conclusion, performing SLNB before NACT in cN0 cases is a safe and accurate method. While some pN1(sn) could have avoid ALND by NACT-induced axillary down-staging, based on our assumption, long term follow-up is needed to conclude whether SLNB after NACT is safe. Keywords: Breast cancer, neoadjuvant chemotherapy, timing sentinel lymph node biopsy Citation Format: Delameilleure M, Smeets A, Nevelsteen I, Han S, Van Nieuwenhuysen E, Berteloot P, Hoste G, Salihi R, Van Ongeval C, Keupers M, Prevos R, Wildiers H, Punie K, Van Limbergen E, Weltens C, Janssen H, Floris G, Vergote I, Neven P. Monocentric experience with the sentinel lymph node biopsy prior to neoadjuvant chemotherapy in clinically lymph node negative early breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-32.