Down-Staging Depth Score As A Better Surrogate Endpoint For Long-Term Outcomes In Locally Advanced Gastric Cancer After Pre-Operative Chemo-Radiotherapy

Abstract

To explore a surrogate endpoint for long-term outcomes in locally advanced gastric cancer after pre-operative chemoradiotherapy (CRT). Materials/Methods: From April 2012 to April 2019, 95 patients enrolled in 4 prospective studies (ClinicalTrial.gov NCT01291407, NCT02296658, NCT03427684 and NCT04062058) with locally advanced gastric cancer who received preoperative concurrent radio-chemotherapy were included. All patients were stage T3 / 4, N +. The local control (LC), distant metastasis-free (DMFS), disease-free (DFS) and overall survival (OS) were evaluated. The clinicopathological factors related with the long-term prognosis were analyzed by uni-and multi-variant analysis. Down-staging depth score (DDS), a novel method of evaluating CRT response, was used for predicting long-term outcomes. Results: The median follow-up for survivors was 30 months. The AUC value of ROC curve predicted by DDS was 0.728, which was better than that of pCR, histological response and ypN0 (AUC Z 0.634, 0.640 and 0.643). DDS cutoff value was 4. DDS and surgery were correlated with DMFS, DFS and OS (p Z 0.009, 0.013, 0.032 and 0.001, 0.000, 0.000). pCR and ypN0 were associated with OS (p Z 0.026, 0.049). Multivariate analysis showed that DDS was an independent DFS prognostic factor (p Z 0.021). Conclusion: Preoperative CRT was effective for local advanced gastric cancer. DDS, a simple, short-term indicator, seemed to be a better surrogate endpoint for DFS in gastric cancer patients with preoperative CRT