# Survival benefit from adjuvant chemoradiotherapy in local advanced gastric cancer without accurate D2 confirmation: a real-world retrospective study (TJ-ARK01)

## TL;DR

This study shows that adjuvant chemoradiotherapy improves survival in a specific subgroup of gastric cancer patients with low lymph node involvement and HER2-negative tumors.

## Contribution

Identifies a distinct subgroup of gastric cancer patients who benefit from chemoradiotherapy based on lymph node ratio and HER2 status.

## Key findings

- Adjuvant chemoradiotherapy improved 5-year DFS and OS compared to chemotherapy alone.
- Patients with a lymph node ratio ≤ 0.5 and HER2-negative tumors had better outcomes with chemoradiotherapy.
- Molecular biomarkers and nodal burden can refine treatment strategies beyond histology.

## Abstract

The role of adjuvant chemoradiotherapy (CRT) is controversial following D2 dissection in advanced gastric cancer. Also, the extent of “D2 surgery” varied geographically due to the diversity in surgical techniques of radical lymphadenectomy and pathological accuracy in detecting positive lymph nodes detection. The purpose was to explore the role of adjuvant chemoradiation for gastric cancer and focus on patient stratification strategy. We retrospectively collected information of patients underwent surgery in Tongji Medical Cancer Center from January 2013 to December 2017 (2,489 in total). Propensity score match was applied to the chemotherapy (CT) group enrollment with well-balanced clinicopathological distributions. In total, 162 and 166 eligible patients were recruited into CT and CRT groups, nearly 75% diagnosed with advanced stage. The median follow-up duration was 61.3 months (4.0 to 109.0 months), 201 recurrence events occurred and 194 deaths events occurred. The 5-year disease-free-survival (DFS) rates were 32.0% in CT group and 44.0% in CRT group (P = 0.031), while 5-year overall survival (OS) rates were 36.0% in CT group and 50.0% in CRT group (P = 0.043). In the subgroup analysis, all patients were regrouped as subgroup 1 (positive lymph node (LN) ratio 0–50%) and subgroup 2 (positive LN ratio 51%–100%). There was a prolongation in 5-year DFS rates in subgroup 1 (40.0% in CT group, 61.0% in CRT group, P = 0.012) and in 5-year OS rates (48% in CT group, 64.0% in CRT group, P = 0.047). Further, patients with negative HER-2 expression had longer 5-year DFS (38% in CT, 49% in CRT, P = 0.115) and 5-year OS (36% in CT, 43% in CRT, P = 0.047). While previous studies found that the survival benefits were gained from chemoradiotherapy (CRT) inpatients of intestinal-type gastric cancer with lymph node metastasis, our findings highlight a distinct subgroup—patients with a lymph node ratio (LNR) ≤ 0.5 and HER2-negative tumors—for whom adjuvant chemoradiation may offer significant improvements in disease-free survival (DFS). This contrast underscores the potential role of molecular biomarkers (HER-2 status) and quantitative nodal burden (LNR) in refining therapeutic strategies, shifting the paradigm from histology-driven approaches to precision-based patient selection.