ABSTRACT
BACKGROUND: A conditional survival nomogram was developed at a single high-volume center to predict 5-year overall survival for esophageal cancer patients after neoadjuvant chemoradiation and esophagectomy. The aim of this study was to externally validate the nomogram in a cohort of patients with esophageal adeno- or squamous cell carcinoma from another high-volume center. METHODS: Consecutive patients with an esophageal adeno- or squamous cell carcinoma who had undergone esophagectomy after being treated with preoperative chemoradiation between 2004 and 2016 were selected from a prospectively maintained institutional database. The level of discrimination for prediction of 5-year overall survival was quantified by Harrell's C statistic. Calibration of the conditional survival nomogram was visualized by plotting predicted 5-year survival and observed 5-year survival for comparison. RESULTS: Of the 296 patients examined, the probability of 5-year overall survival directly after surgery was 45% and increased to 51%, 68%, 78%, and 89% for each additional year survived. The predicted 5-year overall survival differed from the observed survival, with a calibration slope of 0.54, 0.55, 0.59, 0.73, and 1.09 directly after surgery and 1, 2, 3, and 4 years of survival after surgery, respectively. The nomogram's discrimination level for 5-year survival was moderate, with a C statistic of 0.65 compared to the 0.70 reported in the original study. CONCLUSION: The nomogram model has moderate predictive discrimination and accuracy, supporting its applicability to external cohorts to predict conditional survival. Further validation studies should empirically assess the model for predictive performance.