External validation of the Besançon nomogram in Asian patients with advanced pancreatic cancer receiving second-line chemotherapy: A multi-institute experience in Taiwan

Background: Determining survival outcome in advanced pancreatic ductal adenocarcinoma (aPDAC) patients receiving second-line (L2) chemotherapy is important for clinical decision-making. The Besançon group from France recently proposed a prognostic nomogram to predict overall survival (OS) for aPDAC patients receiving L2 chemotherapy. The present study aimed to externally validate the performance of the Besançon nomogram in predicting OS in an Asian cohort. Methods: We retrospectively enrolled 349 patients who received L2 chemotherapy for aPDAC between 2010 and 2016 at four institutes in Taiwan. The performance of the Besançon model in this cohort was evaluated with C-index and calibration plots. Results: The median OS time in our patient cohort was 4.5 months (95% confidence interval [CI], 3.0–5.0). Using the Besançon nomogram-predicted risk groups, the median OS times in the low, intermediate, and high-risk groups were 6.7 (95% CI, 5.3–8.2), 3.2 (95% CI, 2.4–3.9), and 1.7 months (95% CI, 0.6–2.7), respectively. The C-index of the predicted six- and 12-month survival probabilities for the Besançon nomogram were 0.766 (95% CI, 0.715–0.816) and 0.698 (95% CI, 0.641–0.754), respectively. The calibration plot showed that the observed six-month survival probability was close to the diagonal line, while that for 12-month survival deviated below the diagonal line compared to the survival probability predicted by the Besançon nomogram. Conclusions: Although the Besançon nomogram tended to over-estimate the 12-month survival probability, our study demonstrated that the nomogram is a reliable and readily applicable model to estimate survival outcomes of aPDAC patients receiving L2 chemotherapy.