Optimizing Postoperative Management in Deficient Mismatch Repair/Microsatellite Instability-High Gastric or Gastroesophageal Junction Adenocarcinoma: A Multicenter Retrospective Study.

Authors

Hua Liu, Hongmei Xu, Yakun Wang, Zimin Liu, Jia Wei, Zhiwei Chang, Yi Li, Jialin Lu, Boya Wang, Zhiruo Zhou, Wenfei Li, Lin Cong, Yu Sun, Xiaotian Zhang

Published in

Journal of gastric cancer. Volume 26. Issue 3. Pages 378-391.

Abstract

The benefit of chemotherapy in locally advanced gastroesophageal cancer with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) remains uncertain. This study aimed to identify optimal postoperative management strategies for dMMR/MSI-H gastric or gastroesophageal junction (EGJ) adenocarcinoma.
Patients with pathologically confirmed stage II-IVA dMMR/MSI-H gastric or EGJ adenocarcinoma who underwent D2 gastrectomy between 2015 and 2022 were retrospectively enrolled from 4 centers. Postoperative management strategies included observation, chemotherapy, immune checkpoint inhibitors (ICIs), or ICIs combined with chemotherapy (ICI-chemo). The primary endpoint was 2-year event-free survival (EFS), and the secondary endpoints were EFS and overall survival (OS).
A total of 156 patients were included in the analysis. The highest 2-year EFS was observed in the ICI-chemo group (87.5%), followed by the observation group (86.7%) and the ICI monotherapy group (86.5%), whereas chemotherapy alone yielded the lowest rate (75.7%). Patients with earlier-stage disease had significantly lower risks of progression (hazard ratio [HR], 0.29; 95% confidence interval [CI], 0.16-0.53) and death (HR, 0.30; 95% CI, 0.14-0.64). EFS improved progressively from chemotherapy to observation and further to ICI-containing regimens across stages. In stage III-IVA disease, ICI monotherapy significantly improved OS compared with chemotherapy (HR, 0.28; P=0.038), with a favorable trend observed for ICI-chemo (HR, 0.32).
Pathological stage is an independent prognostic factor in resectable dMMR/MSI-H gastric and EGJ adenocarcinoma. Adjuvant chemotherapy alone demonstrated limited benefit, whereas ICI-based regimens were associated with improved outcomes, supporting their use in high-risk patients.

PMID:
42411163
Bibliographic data and abstract were imported from PubMed on 07 Jul 2026.

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