Prognostic implications of morphological subtypes in a surgical cohort of perihilar cholangiocarcinoma: the overriding impact of nodal status.

Background: The morphological classification of perihilar cholangiocarcinoma (pCCA) may influence survival outcomes following curative resection. This study aimed to evaluate the impact of different morphological subtypes on long-term survival.

Methods: We conducted a retrospective analysis of 167 patients with pCCA who underwent curative resection between 2013 and 2018. Patients were classified into three morphological subtypes: intraductal growth (IG-type), periductal infiltrating (PI-type), and mass-forming/mixed (MF-type).

Results: Among the 167 resected patients, the PI-type was most prevalent (53.3%), followed by the IG-type (25.7%) and MF-type (21.0%). Within this surgical cohort, the IG-type was associated with the most favorable prognosis, exhibiting a significantly longer median OS (21.0 months) compared to the PI-type (15.9 months) and MF-type (14.5 months). Multivariable analysis identified positive RM and LNM as the independent predictors of both poor OS and RFS. A critical interaction was observed: in LNM-negative patients, achieving an R0 resection conferred a significant survival benefit across all morphological subtypes. However, in LNM-positive patients, survival was uniformly poor, and the prognostic impact of RM status was completely attenuated.

Conclusion: Among patients with resectable pCCA, morphological subtype is associated with distinct prognostic profiles. However, the ultimate determinants of survival outcome are the RM status and the status of LNM. Achieving an R0 resection is paramount in LNM-negative disease, whereas LNM positivity dictates a poor prognosis regardless of margin status. This underscores the dominant roles of margin status and nodal involvement in risk stratification and in guiding decisions for adjuvant therapy.