Impact of preoperative endoscopy for predicting treatment response and prognosis in patients with gastric cancer after neoadjuvant chemotherapy

Background and study aims Response evaluation criteria in solid tumors (RECIST) have been the gold standard to preoperatively predict treatment response and prognosis in patients with gastric cancer (GC) after neoadjuvant chemotherapy (NAC); however, methods for patients without evaluable lesions by RECIST are not yet confirmed. The aim of this study was to assess the utility of preoperative endoscopy for predicting treatment response and prognosis in patients with GC after NAC. Patients and methods This retrospective study included 105 patients with initially resectable GC who underwent NAC followed by surgical treatment. Preoperative factors for predicting treatment response and survival outcomes were analyzed. Results The number of patients classified as responders using preoperative endoscopic assessment, RECIST, and postoperative pathological evaluation were 25 (23.8 %), 28 (26.7 %), and 18 (17.1 %), respectively. Forty-three patients (41 %) were classified as non-targeted disease only, and their treatment responses were not evaluable by RECIST. Multivariate analysis identified endoscopic response as an independent preoperative factor to predict postoperative histological treatment response (odds ratio = 4.556, 95 % CI = 1.169–17.746, P = 0.029). Endoscopic treatment response was the only independent preoperative predictive factor for overall survival (OS) (hazard ratio = 0.419, 95 % confidence interval (CI) = 0.206–0.849, P = 0.016). Further, endoscopic treatment response was available for 33 patients (76.7 %) with non-targeted disease only, which showed significantly different OS between endoscopic responders (80.0 %) and non-responders (43.5 %) ( P = 0.025). Conclusions Endoscopic evaluation was an independent preoperative factor to predict treatment response and prognosis in patients with GC after NAC. Endoscopic assessment may be especially valuable for patients who could not be assessed by RECIST.