The prognostic value of the number of metastatic lymph nodes on the long-term survival of intrahepatic cholangiocarcinoma using the SEER database.

Abstract

In the 8th edition of the American Joint Committee on Cancer, the nodal staging of intrahepatic cholangiocarcinoma (ICC) is classified as N0 and N1 in accordance with lymph node (LN) metastases. Recently, several studies have reported that the number of metastatic LNs is associated with prognosis in patients with ICC. However, the majority of these studies were published in Eastern countries, and there are few available data for Western countries. This study aimed to investigate the association between metastatic LN number and prognosis in ICC patients using the Surveillance, Epidemiology, and End Results (SEER) database. Data from 658 ICC patients in the SEER database who underwent hepatectomy with LN dissection from 2000 to 2018 were retrospectively reviewed. Hazard ratios (HRs) according to increasing numbers of metastatic LN were calculated. The patients were then divided into three groups according to their metastatic LN numbers (N0: no metastatic LNs; N+ <4: 1-3 metastatic LNs; N+ ≥4: ≥4 metastatic LNs), and cause-specific survival (CSS) was compared. Metastatic LN number was a prognostic factor of oncologic survival [CSS: HR =1.300; 95% confidence interval (CI): 1.225-1.379; P<0.001]. In survival analysis, an increasing number of metastatic LNs was significantly correlated with poorer oncologic outcomes [CSS: N0 vs. N+ <4 vs. N+ ≥4: 40.856 (95% CI: 38.806-42.919) vs. 22.000 (95% CI: 18.283-25.717) vs. 15.000 (95% CI: 11.520-18.480) months, P<0.001]. In post hoc analysis, a significant difference was found between adjacent groups (N0 vs. N+ <4, P<0.001; N+ <4 vs. N+ ≥4, P=0.004). Patients with ICC in the SEER database were reaffirmed to have worse prognosis with an increasing number of metastatic LNs.