Modified staging system of positive lymph nodes based nomogram in intrahepatic cholangiocarcinoma

BACKGROUND: Intrahepatic cholangiocarcinoma (iCCA) presents the similar trend and prevalence of lymph node metastasis to other biliary tract cancer. There is still a necessity and possibility for the current classification of lymph node in the 8th TNM of iCCA, which is the same as the criteria of hepatoma carcinoma (HCC), to further improve the prognostic capacity. We aim to explore the optimal positive lymph nodes cutoff value that could predict the survival outcomes of patients with iCCA and further establish a prognostic nomogram. METHOD: Clinical characteristics were retrospectively collected in 292 patients with iCCA from Sun Yat-sen University Cancer Center (SYSUCC) for preliminary analysis. A retrospective analysis of 107 patients with iCCA in the First Hospital of Dalian Medical University (FHDMU) was performed for verification. R software was used to determine the optimal cutoff value of positive lymph nodes (PLN) and further establish the nomogram with the Cox regression model in the primary cohort. RESULTS: In those patients who were graded into the N1 stage in 8th TNM staging system, the patients with PLN between 1 and 3 showed significantly better overall survival than those patients with more than 4 PLN (P < 0.0001). Moreover, there was a significant correlation between the new PLN classification and adverse clinical characteristic including Micro Invasion (P = 0.001), Lymph Vessel Invasion (P = 0.040), Satellite Sites (P < 0.001), and Tumor Size (P = 0.005). The PLN and ELN were both independent prognostic factors for survival outcomes in the multivariate analysis, and further showed large contribution to the nomogram. The nomogram achieved a satisfied C-index of 0.813 for overall survival (OS), 0.869 for progression-free survival (PFS) in the primary cohort, and 0.787 for OS, 0.762 for PFS in the validation cohort. CONCLUSION: The modified classification of PLN in iCCA could accurately stratify the N1 stage patients in 8th TNM staging system into two groups with significantly different overall survival. The development of this nomogram can offer new evidence to precisely post-operative management of iCCA patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12935-023-03005-6.