# Outcomes of targeted axillary radiation therapy with omission of axillary dissection in early breast cancer patients with one or two positive sentinel lymph nodes and extracapsular extension

## TL;DR

This study investigates whether omitting axillary dissection in early breast cancer patients with limited lymph node involvement and extracapsular extension is as effective as traditional surgery.

## Contribution

The study explores targeted axillary radiation therapy as an alternative to axillary dissection in patients with extracapsular extension in one or two sentinel lymph nodes.

## Key findings

- Omitting axillary dissection did not result in inferior disease-free survival compared to completion dissection.
- Local recurrence was rare (0.5%) and systemic recurrence occurred in 11.3% of patients.
- Five-year disease-free survival rates were 86% overall, with no significant difference between groups.

## Abstract

Axillary dissection has been shown to be equivalent to axillary radiotherapy in the AMAROS trial; however, extracapsular invasion of sentinel lymph nodes was not considered among the evaluated variables. The clinical significance of extracapsular extension (ECE) in one or two positive sentinel lymph nodes remains under investigation. This study aims to evaluate the impact of targeted axillary radiation therapy while omitting completion axillary lymph node dissection (ALND) in the presence of extracapsular extension.

A retrospective study was conducted between 2016 and 2023 involving cT1–2N0 breast cancer patients who did not receive neoadjuvant chemotherapy and underwent either breast-conserving surgery or mastectomy, with extracapsular extension present in one or two positive sentinel lymph nodes.

Our study included 213 patients treated between 2016 and 2023, with a median follow-up of 48.07 months (range: 9.07–103.10 months). ECE was ≤ 2 mm in 201 patients (94.4%) and > 2 mm in 12 patients (5.6%). A total of 112 patients (52.6%) underwent completion ALND. Systemic recurrence occurred in 24 patients (11.3%), while local recurrence occurred in one patient (0.5%). The 5-year disease-free survival (DFS) rates were 86% in the completion axillary clearance (AC) group and 89% in the non-AC group. The estimated DFS rates for the entire study at 1, 3, and 5 years were 97%, 89%, and 86%, respectively.

Within this single-institution study of early breast cancer patients with predominantly luminal A subtype and mostly limited ECE (≤ 2 mm) treated with targeted axillary radiation, omission of ALND did not result in inferior DFS compared to completion ALND. However, these findings are preliminary, hypothesis-generating, and limited by the retrospective design, short follow-up, and specific patient population studied. Prospective studies are needed to confirm these observations.

Retrospectively registered after the approval of Baheya Ethical Committee, IRB no. 202,304,030,017.