# Upfront surgery, neoadjuvant chemoradiotherapy, or neoadjuvant chemotherapy for rectal cancer with lateral lymph node metastasis: A multicenter MRI and lateral lymph node dissection study

## TL;DR

This study compares different preoperative treatments for rectal cancer with lymph node metastasis, finding that chemoradiotherapy followed by surgery offers the best local control.

## Contribution

The study provides new evidence on treatment outcomes for rectal cancer with lateral lymph node metastasis using high-resolution MRI and lymph node dissection.

## Key findings

- Chemoradiotherapy followed by surgery showed the highest 3-year local recurrence-free survival (100%).
- Upfront surgery provided good local control but multidisciplinary treatment is recommended for better outcomes.
- Neoadjuvant chemotherapy showed promise for non-MRF patients with 100% 3-year local recurrence-free survival.

## Abstract

The purpose was to clarify the oncological outcomes of rectal cancer (RC) with lateral lymph node metastasis (LLNM) on high‐resolution MRI (HRMRI), considering preoperative treatments.

Two hundred and twelve patients, from 13 hospitals, diagnosed with RC with lateral lymph node dissection (LLND), between 2017 and 2019, were prospectively registered. LLNM was defined as a short‐axis size ≥5 mm. Ultimately, this study included 102 patients. Upfront surgery (Upfront), chemoradiotherapy (CRT), and neoadjuvant chemotherapy (NAC) were performed at each institution's discretion.

Sixty‐six (64.7%) had mesorectal fascia (MRF) involvement, 35 (34.3%) had extramural venous invasion, and 33 (32.4%) had bilateral LLNMs. A positive radial margin (RM1) was observed in nine patients (8.8%), and 35 (34.3%) had pathological LLNM (pLLNM). Overall, 3‐year relapse‐free survival (3yRFS) and local recurrence‐free survival (3yLRFS) were 69.6% and 92.9%. Upfront 3yRFS (N = 54), CRT (N = 23) and NAC (N = 25) constituted 62.9%, 82.6%, and 72.0%; 3yLRFS was 92.4%, 100%, and 88.0%. RM1 and pLLNM were significantly associated with LRFS (RM0 vs. RM1, 3yLRFS 96.7% vs. 50.0%; pLLNM negative vs. positive, 97.0% vs. 84.7%). 3yRFS Upfront non‐MRF (N = 21), post CRT non‐MRF (N = 15), and post NAC non‐MRF (N = 14) were 61.9%, 86.7%, and 100%; 3yLRFS was 90.2%, 100%, and 100%.

Good local control of Upfront LLND for RC with LLNM was shown, but multidisciplinary treatments were required. CRT followed by surgery was preferable for RC with LLNM, but a radiation‐sparing strategy is promising for post NAC non‐MRF.

Kaplan–Meier analyses of RFS (A) and LRFS (B) in non‐MRF groups. RFS, relapse‐free survival; LRFS, local recurrence‐free survival; MRF, mesorectal fascia; Upfront, upfront surgery; CRT, chemoradiotherapy; NAC, neoadjuvant chemotherapy.