2144 - The Optimal Neoadjuvant Modality in Locally Advanced Gastric Cancer in the Era of Immune-Drugs: A Multicenter Retrospective Analysis

03:00pm - 04:00pm ET

Poster Hall - Exhibit Hall A

Screen: 27

POSTER

Presenter(s)

Quanming Liu, MD, PhD - Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, Beijing

Q. Liu¹, J. Wu², W. Yan², Z. Xiong², H. Yuan², and N. Li^1,2; ¹National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China, ²Cancer Hospital Chinese Academy of Medical Sciences Shanxi Hospital, Taiyuan, China

Purpose/Objective(s):

Optimal neoadjuvant strategies for locally advanced gastric cancer (LAGC) remain contentious. The purpose of this study was to compare the survival prognosis and safety of LAGC receiving three different neoadjuvant modalities.

Materials/Methods:

In this multicenter retrospective cohort, 670 patients with LAGC (Jan 2012 - Dec 2022) receiving neoadjuvant therapy followed by curative-intent gastrectomy were analyzed. Three cohorts were compared: neoadjuvant chemotherapy alone (NAC, n=339), neoadjuvant chemoimmunotherapy (NACI, n=233), and neoadjuvant chemoradiotherapy (NACRT, n=98). Primary endpoints were overall survival (OS) and disease-free survival (DFS); secondary endpoints included local-regional control (LC), distant metastasis-free survival (DMFS), pathological complete response (pCR) and toxicity (CTCAE v5.0). Survival analyses used Kaplan-Meier/log-rank tests; Cox regression assessed hazard ratios (HRs); the categorical endpoints were analysis by Chi-square or Fisher's exact tests based on expected frequencies; significance was P<0.05.

Results:

The NACRT group achieved significantly higher pCR rates (26.5% vs. 7.4% [NAC] and 16.3% [NACI]; P<0.001). With median follow-up of 40.7 months, NACRT demonstrated superior 5-year OS (80.4% vs. 57.3% [NAC] and 50.8% [NACI], P<0.001) and 5-year DFS (63.9% vs. 50.0% [NAC] and 44.0% [NACI]; P<0.05). 5-year distant metastasis-free survival (DMFS) favored NACRT (77.9% vs. 59.3% [NAC], P=0.004). Grade =3 toxicity was comparable (15.3% NACRT vs. 12.1% NAC vs. 12.5% NACI; P=0.69).

Conclusion:

Neoadjuvant chemoradiotherapy significantly improves survival outcomes versus neoadjuvant chemotherapy or chemoimmunotherapy in LAGC, with higher pCR and 5-year OS/DFS rates without increased severe toxicity. Despite improved pCR with chemoimmunotherapy, survival benefits were absent. Chemoradiotherapy should be prioritized in LAGC management, with future trials exploring CRT-immunotherapy synergy.