Comparison of the Prognostic Value of Platelet-Related Indices in Biliary Tract Cancer Undergoing Surgical Resection

Abstract

Purpose: Platelet-related indices, including mean platelet volume (MPV) and plateletocrit (PCT), have been reported as new prognostic factors of overall survival (OS) in many cancers, but not yet in biliary tract cancer (BTC). We intended to assess these indices in predicting OS in BTC patients with the aim to build a new prognostic model for patients with BTC after surgical resection.

Materials and methods: Survival analysis and time receiver operating characteristic analysis were applied to screen the platelet indices. Univariate and multivariate Cox analyses were used to identify independent prognostic factors and develop a new prognostic model. Harrell's C-statistics, calibration curves, and decisive curve analysis were used to assess the model.

Results: MPV and platelet distribution width (PDW)/PCT showed the best prognostic accuracy among the platelet indices. In multivariable analysis, factors predictive of poor OS were presence of nodal involvement, Non-radical surgery, poor tumor differentiation, carbohydrate antigen 19-9 > 100 U/mL, MPV > 8.1 fl, and PDW/PCT > 190. The new model was found to be superior to the TNM staging system and our new staging system showed higher discriminative power.

Conclusion: MPV and PDW/PCT have high prognostic value in BTC patients, and the novel staging system based on these two indices showed good discrimination and accuracy compared with the American Joint Committee on Cancer 7th TNM staging system.

Keywords: Biliary tract neoplasms; Mean platelet volume; PDW/PCT; Platelet; Prognosis.

Fig. 1

Time-AUC curves of the platelet indices for overall survival prediction. AUC, area under curve; MPV, mean platelet volume; PCT, plateletocrit; PDW, platelet distribution width; PLR, platelet-to-lymphocyte ratio; PLT, platelet count; Time-AUC, areas under time-dependent ROC curves.

Fig. 2

Nomogram for predicting the 1-, 3-, 5-year, and median survival in patients with biliary tract cancer lines are drawn upward to determine the points for each variable. Total points represent the sum of points corresponding to each variable. Another line is drawn downward to determine the survival probability for total points. CA19-9, carbohydrate antigen 19-9; MPV, mean platelet volume; PCT, plateletocrit; PDW, platelet distribution width.

Fig. 3

Kaplan-Meier curves for OS in different subsets of patients with BTC. BTC patients (A), GBC patients (C), ICC patients (E), and ECC patients (G) were stratified by the novel staging system. BTC patients (B), GBC patients (D), ICC patients (F), and ECC patients (H) were stratified according to the AJCC TNM staging system. AJCC, American Joint Committee on Cancer; BTC, biliary tract cancer; GBC, gallbladder cancer; ECC, extrahepatic cholangiocarcinoma; ICC, intrahepatic cholangiocarcinoma; OS, overall survival.

Fig. 4

Decisive curve analysis of the nomogram. (A) 3-Year survival of the training cohort. (B) 5-Year survival of the training cohort. (C) 3-Year survival of the validation cohort. (D) 5-Year survival of the validating cohort. The horizontal black line denotes no survival, while the gray curve represents all survival.