Optimal response population after neoadjuvant therapy for patients with locally advanced gastric cancer: A multicenter study.

Objective: Pathologic complete response (pCR) following neoadjuvant therapy (NAT) for gastric cancer (GC) is rare but associated with a favorable prognosis. This study aims to reassess the optimal response population (ORP) following NAT by evaluating the prognostic outcomes associated with various T and N stages, utilizing multicenter data from China.

Methods: Patients who underwent NAT following radical gastrectomy at 10 tertiary hospitals in China between 2008 and 2021 were included. The ORP was introduced to explore the disease-free survival (DFS), overall survival (OS), recurrence patterns, and influencing factors following propensity score matching (PSM).

Results: A total of 1,076 patients were enrolled in this study (median follow-up period: 60 months). We defined ORP as a pCR or tumor infiltration of the mucosal or submucosal layer without lymph node metastasis (pCR or ypT1N0) after NAT. The ORP group comprised 136 patients (12.6%), while the non-ORP group comprised 940 patients (87.4%). After applying a 1:4 PSM, we obtained an ORP group of 136 patients and non-ORP group of 544 patients. Survival analysis demonstrated that both the 3-year OS (before PSM: 89.0% vs. 55.0%, P<0.001; after PSM: 89.0% vs. 55.4%, P<0.001) and DFS (before PSM: 85.8% vs. 49.7%, P<0.001; after PSM: 85.8% vs. 50.6%, P<0.001) were significantly superior in the ORP group compared to that in the non-ORP group. Remarkably, adjuvant chemotherapy did not impact the prognosis of patients in the ORP group (3-year OS: 89.0% vs. 89.7%, P=0.988; 3-year DFS: 84.9% vs. 89.7%, P=0.700).

Conclusions: This study reevaluates patients with ORP following NAT, providing a more comprehensive and accurate depiction of the potential beneficiary group and survival outcomes in patients with locally advanced GC.