Usefulness of serum microRNA as a predictive marker of recurrence and prognosis in biliary tract cancer after radical surgery

Abstract

Biliary tract cancer (BTC) is an aggressive type of malignant tumour. Even after radical resection, the risk of recurrence is still high, resulting in a poor prognosis. Here, we investigated the usefulness of serum miRNAs as predictive markers of recurrence and prognosis for patients with BTC after radical surgery using 66 serum samples that were collected at three time points from 22 patients with BTC who underwent radical surgery. Using microarray analysis, we successfully identified six specific miRNAs (miR-1225-3p, miR-1234-3p, miR1260b, miR-1470, miR-6834-3p, and miR-6875-5p) associated with recurrence and prognosis of BTC after radical surgery. In addition, using a combination of these miRNAs, we developed a recurrence predictive index to predict recurrence in patients with BTC after operation with high accuracy. Patients having higher index scores (≥ cut-off) had significantly worse recurrence-free survival (RFS) and overall survival (OS) than those with lower index scores (<cut-off). Furthermore, the index was an independent factor related to RFS and OS by univariate and multivariate analyses using a Cox hazard proportional model. Overall, our results provided compelling evidence for the potential usefulness of specific serum miRNAs as effective predictive tools for recurrence and prognosis in patients with BTC who underwent radical surgery.

Figure 1

The algorithm to identify multiple candidate miRNAs related to prediction of recurrence and prognosis using pre-operative samples.

Figure 2

Comparison of the expression of six candidate miRNAs at the pre-operative time point between the recurrence and nonrecurrence groups in patients with BTC after radical surgery. Four miRNAs were upregulated (A), and two miRNAs were downregulated (B). Two-sided Student’s t tests were used to analyse the differences. *P < 0.05.

Figure 3

Changes in the expression of six candidate miRNAs at three time points in the recurrence and nonrecurrence groups of patients with BTC after radical surgery. Four miRNAs were upregulated (A), and two miRNAs were downregulated (B). The grey line indicates the transition in the miRNA expression value of each patient. Red and blue lines show the transitions of median expression values of miRNAs in patients with BTC in the recurrence and nonrecurrence groups, respectively. ^apre, pre-operative time point. ^bpost, postoperative time point. ^crec, recurrence time point. ^dlast, last observation time point.

Figure 4

Evaluation of our novel indices using a combination of candidate miRNAs as a recurrence prediction marker in patients with BTC after radical surgery. (A) Comparison of recurrence predictive index scores between the recurrence and nonrecurrence groups. (B) Receiver operator characteristic (ROC) curve analysis of recurrence predictive indices in comparison with CEA and CA19-9 values. Area under the curve (AUC) values are shown on the graphs. (C) Association of recurrence predictive indices with recurrence-free survival (RFS). Kaplan-Meier graphs representing the probabilities of RFS in the enrolled patients according to recurrence predictive index scores. Log-rank tests were used to analyse the significance of the differences. **P < 0.001.