Recurrence Pattern Analysis And Nomograms To Predict Disease-Free Survival After Curative Resection Of Pancreatic Ductal Adenocarcinoma

Objective:To analyze recurrence patterns and create a nomogram to predict disease-free survival(DFS)following radical resection of pancreatic ductal adenocarcinoma(PDAC).Methods:Clinical data of 165 patients with PDAC who underwent curative resection in the Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College from September 2015 to September 2018 were analyzed retrospectively.Kaplan-Meier survival curve and Cox proportional hazard multivariate analysis were used to determine independent risk factors for DFS in patients with PDAC,and created a nomogram to predict 24 months and 28 months of DFS.The Bootstrap method was used for internal validation,and the calibration curve analyses and concordance index(C-index)were used to evaluate the performance of the model.We classified patients into two risk groups by using this nomogram,and the differences between groups were tested using the Log-rank method.Results:A total number of 165 patients were included,with a recurrence rate of 65.5%and a median DFS of 11.7 months.The median DFS of patients with postoperative recurrence was 6.1 months(95%CI,4.8-7.4 months).Postoperative multiple metastasis was the earliest occurred recurrence pattern(median DFS was 3.7 months[95%Cl,3.2-4.2 months]),followed by liver metastases(median DFS was 5.5 months[95%CI,3.0-8.1 months]).The univariate and multivariable analyses showed age≥65years(HR,1.927;95%CI,1.281～2.900;P=0.002)、T3 stage(HR,1.693;95%CI,1.103～2.600;P=0.016)、lymph node ratio≥0.15(HR,1.588;95%CI,1.048～2.407;P=0.029)、poor tumor differentiation(HR,1.793;95%CI,1.086-2.961;P=0.022)、preoperative CA19-9>37U/ml(HR,1.658;95%CI,1.045～2.629;P=0.032)were considered as risk factors for DFS of patients with PDAC,and constructed a nomogram with these variables.Calibration curves for predicted D F S at 24 and 28 months show that the predicted values of the nomograms are consistent with the actual observations,and C-index was 0.664(95%CI,0.944～1.056).Conclusion:Significant attention should be paid in the prevention and treatment of liver metastasis and local recurrence after curative resection of PD AC.The established nomogram can effectively predict the DFS of patients at 24 months and 28 months after radical resection of PDAC,and can effectively distinguish the risk of recurrence after surgery.