Prognostic analysis of pathological complete response after neoadjuvant therapy for locally advanced gastric cancer: A national, multicenter, retrospective study.

346 Background: Several research findings indicate that some patients with locally advanced gastric cancer (LAGC) who undergo neoadjuvant therapy followed by curative surgery can achieve pathological complete response (pCR). Whether pCR is equivalent to cure, serves as a good prognostic indicator for long-term survival, and whether patients achieving pCR require subsequent adjuvant therapy are still unknown. Therefore, we conducted a nationwide multicenter retrospective study to investigate the long-term efficacy of patients with LAGC who achieved pCR after neoadjuvant therapy. Methods: Clinical and pathological data were collected from 351 patients with locally advanced gastric cancer who achieved pCR after neoadjuvant therapy between January 2018 and October 2023 at 14 medical centers in China. These patients were matched 1:1 with non-pCR patients based on age, gender, clinical T stage, and N stage. This study evaluated general clinical data, neoadjuvant treatment regimens, cycles, surgical outcomes, and follow-up information including postoperative adjuvant therapy, recurrence, metastasis, and survival status up to November 2023. Results: Negative Serum tumor markers, non-signet ring cell carcinoma and neoadjuvant treatment regimens were closely associated with pCR. Patients achieving pCR were more likely to reach ypN0 status after neoadjuvant therapy compared to non-pCR patients. Survival analysis showed significantly higher overall survival (OS) and disease-free survival (DFS) in pCR patients compared to matched non-pCR patients. Moreover, OS and DFS were significantly higher in ypN0 patients within the pCR group compared to non-pCR patients. However, there was no significant difference in OS and DFS between ypN+ patients in the pCR group and non-pCR patients. Additionally, postoperative adjuvant chemotherapy did not significantly impact OS and DFS in the pCR group. Conclusions: pCR is an independent prognostic factor for OS and DFS. However, survival benefits from pCR are limited to patients achieving ypT0N0 status, while ypT0N+ patients do not benefit from pCR. Furthermore, adjuvant chemotherapy may not improve the prognosis of patients achieving pCR after neoadjuvant therapy.