External Validation of an Eastern Asian Nomogram for Survival Prediction After Gastric Cancer Surgery in a European Patient Cohort

Several nomograms for survival prediction after curative gastric cancer surgery have been published over the recent years. Previous validation studies failed to prove applicability of Eastern Asian nomograms in Western patients. Here we present data on a validation analysis of a newly developed Korean nomogram in a German patient cohort. Among a total of 2771 patients having been treated in the Department of Surgery of the Technische Universitaet Muenchen from 1982 to 2008, 908 patients were eligible to undergo this analysis. Patients were treated according to Japanese Gastric Cancer guidelines and followed up on a regular basis for at least 60 months postoperatively. Baseline characteristics were compared using chi(2)-testing. Survival analyses were computed with the Kaplan-Meier method and multivariate regression analysis models. The C-statistics and Hosmer-Lemeshow chi-square statistics were computed for comparisons of the nomogram's predictive ability. All baseline characteristics were significantly different (P<0.0001) between Korean and German patients except Union Internationale Contre le Cancer-stages (P = 0.427). Multivariate regression analysis revealed the same predictive factors for overall survival in the German and Korean cohorts, respectively, with the exception of tumor size > 10cm and an exclusive correlation of whole stomach spread and pN1-stage for German patients only. The C-index was 0.76, representing an adequate value for predictability of the Korea nomogram in German patients. The Hosmer-Lemeshow statistic implied applicability of the nomogram in the TUM-cohort. A newly developed multicenter Korean nomogram for survival prediction after curative gastric cancer surgery may be applicable for estimating survival prognosis in Western (European) patients.