177PD - Prospective, multicenter registry trial to evaluate the clinical feasibility of targeted axillary dissection (TAD) in patients (pts) with breast cancer (BC) and core biopsy proven axillary involvement (cN+)

Abstract

BackgroundAs part of de-escalating strategies of the axillary treatment in lymph node (LN) positive BC pts, TAD was introduced (Caudle et al., JCO 2016). Despite this very interesting approach, some important aspects regarding the clinical feasibility after neoadjuvant chemotherapy (NACT) were missing if a safe procedure was to be guaranteed. The correct evaluation of pathologic complete response (pCR) has a prognostic impact in high risk BC pts (Katherine, CreATE X). This study aimed to investigate the clinical feasibility of clip placement in positive axillary LNs followed by NACT and TAD in BC patients. MethodsThe Senta trial is a prospective, multicentric registry study (N=598). Prior to NACT, pts with invasive BC received an ultrasound guided core biopsy with clip insertion into the suspicious axillary LN. After NACT, pts underwent axillary surgery according to the investigators discretion, with or without sentinel LN (SLN) biopsy. TAD included removal of the clipped LN and SLN biopsy (SLNB). The pathology of the clipped LN before and after NACT, other LNs, and the SLN were compared. The primary endpoint (EP) was the detection rate (DR) of the clipped LN after NACT. Secondary EP was the false negative rate (FNR) of TAD. ResultsBetween January 2017 and October 2018, 598 cN+ BC pts from 50 different German breast units had biopsy proven axillary LN involvement and received clip insertion into the affected LN. The complete data set from 378 pts was available. After NACT, the clipped N was detected in 78.6% of the patients (target lymph node biopsy = TLNB), and 58.9% of the whole cohort received SLNB as well. The SLN and TLN were identical in 48.0%. An axillary dissection was performed overall in 68%. The FNR of TLNB was 8.0% (CI 95%, 3.0–12.0) for the whole cohort. TAD followed by axillary LN dissection had a FNR of 4.4% (2 of 45, CI 95%, 0.02–9.0). ConclusionsPreliminary results demonstrated a high DR supporting the feasibility of this approach, however, the FNR of TAD (4.4%) was higher than reported earlier (FNR = 2.0%, Caudle et al.). This is of great importance for postneoadjuvant treatment decisions in case of non-pCR and should be discussed. Clinical trial identificationNCT03102307; release date: April 5, 2017. Legal entity responsible for the studyKliniken Essen-Mitte. FundingHas not received any funding. DisclosureM. Reinisch: Honoraria (self): Pfizer, Novartis, Eli Lilly, Roche; Advisory / Consultancy: Roche, Daiichi Sankyo, Hexal, Eli Lilly, Novartis; Travel / Accommodation / Expenses: Pfizer, Celgene, Novartis. J. Heil: Advisory / Consultancy: Roche, Siemens Healthcare Diagnostics; Research grant / Funding (self): BARD; Honoraria (self): Roche, Siemens Healthcare Diagnostics, BARD; Travel / Accommodation / Expenses: Celgene. C. Seiberling: Travel / Accommodation / Expenses: Teva. C. Ankel: Advisory / Consultancy, Travel / Accommodation / Expenses: PFM medicals. V. Hanf: Honoraria (self): Novartis. J. Holtschmidt: Travel / Accommodation / Expenses: Roche. S. Kuemmel: Advisory / Consultancy: Genentech, Genomic Health, Novartis, AstraZeneca, Amgen, Celgene, Somatex, Daiichi Sankyo, Puma Biotechnology, PFM Medical, Pfizer, MSD Oncology; Travel / Accommodation / Expenses: Roche, Daiichi Sankyo. All other authors have declared no conflicts of interest.