European validation of the Yonsei Gastric Cancer Prognosis Prediction Model after gastrectomy: Validation with the Netherlands Cancer Registry

Recently, a novel model predicting 5-year survival after gastrectomy was developed, the Yonsei Gastric Cancer Prognosis Prediction Model, to overcome limitations of the tumor-node-metastases (TNM) staging system. This study aimed to validate this model in a European cohort. All patients who underwent gastrectomy for gastric cancer were selected from the Netherlands Cancer Registry (2005–2015). Patients with 30-day mortality, co-existing cancer, neoadjuvant therapy, or missing data were excluded. The prediction model included gender, age, resection type, pT-stage, pM-stage, number of retrieved lymph nodes, number of metastatic lymph nodes, and tumor histology. The model was validated and compared to the 7th TNM staging system using calibration plots and the concordance index (c-statistic with 95% confidence interval (CI)). From the 5748 patients who underwent gastrectomy, 2253 were included in this study. Mean age was 72.1 years, most patients had advanced gastric cancer (88%), and in 1102 patients (49%) no proper TNM staging could be performed since