Prognosis And Nomogram For Predicting Postoperative Survival Of Distal Cholangiocarcinoma After Surgical Resection

Objectives:Distal cholangiocarcinoma is a rare malignancy tumor involving the distal common bile duct with poor prognosis.The 5-year survival for patients with distal cholangiocarcinoma is about 20%-40%.Surgical resection is suggested for patients with no distant metastasis.Patients with M0 stage distal cholangiocarcinoma patients after surgical resection from Surveillance,Epidemiology,and End Results database were retrospectively analyzed to develop a nomogram to estimate prognosis of distal cholangiocarcinoma.Material and Methods:This study retrospectively analyzes 612 patients with M0 stage distal cholangiocarcinoma patients after surgical resection from SEER database between 2010 and 2015.Significant prognostic factors for overall survival were analyze by using R 4.02.Kaplan-Meier method was used to plot survival curves and log-rank test was performed for prognostic factors.A receiver operating characteristic(ROC)curve was drawn and the area under the AUC was calculated to evaluate the accuracy of three lymph node metastasis system.Cox proportional hazards regression models were used to determine prognostic factors and later developed a nomogram by those factors.C-index was used to evaluate the accuracy of the nomogram and AJCC 7th TNM system.Results: According to our study,the median survival time of 612 patients with distal cholangiocarcinoma without distant metastasis was 19 months(95%CI: 0.555--0.635).The 1-year,2-year,and 3-year overall survival rates were 76.3 %(95%CI: 0.730-0.798),50.8%(95%CI: 0.468-0.552),35.8%(95%CI: 0.317-0.404).In survival analysis,postoperative prognosis of stage M0 distal cholangiocarcinoma were associated with AJCC 7th TNM staging(P=0.0056),AJCC 7th TNM T staging(P=0.02),AJCC 7th TNM N staging(P<0.001),AJCC 8th TNM N staging(P<0.001),positive lymph node rate(P<0.001),tumor size(P<0.001),and histological grade(P=0.0001).By comparing the area of receiver operating characteristic curve(AUC),it was concluded that the positive lymph node rate(AUC=0.592)was the optimal way to evaluate lymph node metastasis.In Cox multivariate analysis,histological grade,tumor size and positive lymph node rate were independent prognostic factors of patients with M0 stage distal cholangiocarcinoma.For patients with lymph node metastasis,adjuvant radiotherapy or chemotherapy after surgery is an independent prognostic factor.Nomogram was developed including histological grade,tumor size,positive lymph node rate,and adjuvant therapy after surgery.The C-index of this model was 0.644(95%CI :0.61-0.67),higher than the 7th edition of TNM staging 0.549(95%CI :0.520-0.578).Calibration curves showed the optimal agreement in predicating OS between nomogram and actual observation.Conclusion:Our study develops a Nomogram including histological grade,tumor size,positive lymph node rate,and adjuvant therapy for patients with M0 stage distal cholangiocarcinoma after surgery.This nomogram forms the decision-making reference for the follow-up action and treatment so that can help clinicians to predict the prognosis of patients with distal cholangiocarcinoma without metastasis.