Surrogate indicators of survival in patients who received neoadjuvant chemotherapy for type 4 and large type 3 gastric cancer in JCOG0501.

Abstract

381 Background: Pathological response rate (pRR) is a common endpoint for assessing the efficacy of neo-adjuvant chemotherapy (NAC) in patients with advanced gastric cancer (GC). We performed supplementary analysis to investigate if pRR can be a surrogate endpoint using data from JCOG0501. Methods: Patients with type 4 and large type 3 resectable GC were randomized either surgery plus adjuvant S-1 (arm A) or NAC (S-1 plus cisplatin) plus surgery plus S-1 (arm B) in JCOG0501. Histological type (sig vs non-sig) was evaluated using preoperative biopsy specimen. Cox proportional hazards model was utilized to assess the effects of covariates for overall survival (OS). Pathological response was defined as Grade1b-3 according to the Japanese Gastric Cancer Association grading. Results: Among 286 (147 in arm A and 139 in arm B) patients who underwent surgery, 132 patients with complete pathological data in arm B were evaluated. Macroscopic tumor response (PR) was observed in 47 patients (36%) and pathological response (Grade 0/1a/1b/2/3) was 15/40/30/44/3, respectively. As shown in the table, pathological response was significantly better OS after adjusting other factors (HR, 0.51 [95% CI 0.30-0.87], p = 0.014). Conclusions: pRR may be used as a surrogate endpoint for future clinical trials in type 4 and large type 3 GC. Clinical trial information: C000000279. [Table: see text]