Extranodal Tumor Deposits in the Axillary Fat Indicate the Need for Axillary Dissection Among T1–T2cN0 Patients with Positive Sentinel Nodes

Abstract

Background:The ACOSOG Z0011 trial demonstrated the safety of omitting axillary dissection (ALND) in T1-T2cN0 patients with <3 positive sentinel nodes (SLN) undergoing breastconservation therapy. While microscopic extracapsular extension (mECE) >2mm is associated with increased nodal burden, the significance of extranodal tumor deposits (ETDs) in the axillary fat is uncertain.Methods: Consecutive patients with T1-T2cN0 breast cancer undergoing sentinel node biopsy and ALND for SLN metastases from 1/2010-12/2018 were identified. ETDs were defined as intravascular tumor emboli or metastatic deposits in the axillary fat. Clinicopathologic characteristics and nodal burden were compared by ETD status.Results: Among 1114 patients, 113 (10%) had ETDs: 81 (72%) were intravascular tumor emboli and 32 (28%) were soft tissue deposits. Patients with ETDs had larger tumors (median 2.2 vs 2.1cm, p=0.033) and more often had mECE (83% vs 44%, p<0.001). On univariable analysis, presence of ETDs (OR 9.66, and mECE (OR 10.73, were associated with ≥4 additional positive non-sentinel nodes (NSLNs)(all p<0.001). On multivariable analysis, ETDs remained associated with ≥4 positive NSLNs (OR 5.67, p<0.001). ETDs were strongly associated with ≥4 positive NSLNs (OR 11.75, among patients with 1-2 positive SLNs (n=925).Conclusions: Among T1-T2cN0 patients with SLN metastases, ETDs are strongly associated with ≥4 positive NSLNs at ALND. Even among those who may otherwise meet criteria for omission of ALND, the presence of ETDs in axillary fat warrants consideration of ALND.

Pathologic Exploration of the Axillary Soft Tissue Microenvironment and Its Impact on Axillary Management and Breast Cancer Outcomes

“…This varied practice highlights the need for a universal and standardized methodology to quantify ECE and prognostic significance of its extent. Another MSK series applying Z011 criteria, 33 showed that extranodal tumor deposit beyond the LN (which mimics our AXT definition here) is associated with more LN1 similar to the demographics presented in Table 1. However, they had only 113 AXT patients without any subclassification of AXT forms, and the authors clearly stated that they did not aim to correlate AXT with tumor outcomes and did not control for RLNR.…”

“…However, they had only 113 AXT patients without any subclassification of AXT forms, and the authors clearly stated that they did not aim to correlate AXT with tumor outcomes and did not control for RLNR. 33 Our study shows the importance of expanding the focus beyond LN number/morphology and ECE. This is particularly important as the ongoing axillary de-escalation trials focus mainly on LN number/morphology with little to no mention of ECE and AXT.…”

“…However, they had only 113 AXT patients without any subclassification of AXT forms, and the authors clearly stated that they did not aim to correlate AXT with tumor outcomes and did not control for RLNR. 33…”