The purpose of this observational study is to evaluate the impact of different neoadjuvant therapies on patients with locally advanced gastric cancer. The primary question it aims to address is: Which patient populations benefit most from neoadjuvant immunochemotherapy versus neoadjuvant chemotherapy in locally advanced gastric cancer?

This study aims to: 1. Compare pCR rates and TRG between neoadjuvant chemotherapy (two-drug vs. three-drug) and neoadjuvant immunochemotherapy; 2. Explore efficacy differences across subgroups; 3. Provide evidence-based guidance for individualized neoadjuvant treatment.

Inclusion Criteria:

Eligible patients had pathologically confirmed adenocarcinoma, imaging-confirmed resectable LAGC (cT2-4aN0-3M0, AJCC 8th), no distant metastases, and completed protocol-specified neoadjuvant therapy (nICT: PD-1/PD-L1 inhibitors plus two-drug chemotherapy; nCT: two-drug [SOX/XELOX] or three-drug [FLOT/DCF] chemotherapy) with ECOG 0-1.

Exclusion Criteria:

Exclusion criteria included incomplete neoadjuvant therapy, non-radical surgery, other malignancies, active autoimmune diseases/immunosuppressant use, missing key data, or inadequate follow-up (<3 months without documented events).

This study screened 10,334 patients diagnosed with gastric/gastroesophageal junction tumors at a tertiary-grade A cancer hospital from November 2019 to December 2023 , identifying 777 who received neoadjuvant therapy, with 291 meeting inclusion criteria for final analysis. The cohort comprised resectable gastric adenocarcinoma patients undergoing neoadjuvant immunochemotherapy (nICT, n=98) or chemotherapy (nCT, n=193) followed by radical surgery (Figure S1), with follow-up through November 2024.