The effectiveness of combined extrahepatic bile duct resection in radically resected cases with intrahepatic cholangiocarcinoma: a SEER-based retrospective cohort study and an external validation.

Objective: To evaluate the effectiveness of the combined extrahepatic bile duct resection (EHBDR) in cases with intrahepatic cholangiocarcinoma (IHCC) in terms of clinicopathological features and long-term survival.

Methods: Radically resected cases with IHCC from 2000 to 2020 were identified from Surveillance, Epidemiology, and End Results (SEER) database. Comparative analyses were performed between resected IHCC patients who received EHBDR and those without EHBDR. Moreover, an external validation was further performed based on a single-center cohort.

Results: A total of 1521 radically resected cases with IHCC (EHBDR: 189) were identified from the SEER database. Comparable age, sex, race, marital status, liver cirrhosis, differentiation status, and adjuvant chemotherapy were acquired between the two groups. EHBDR was associated with a higher incidence of adequate lymphadenectomy ( P <0.001). The incidence of cases with T3-4 or N+ disease was significantly higher in EHBDR group ( P <0.001). Adjuvant radiotherapy was more frequently performed in cases with EHBDR ( P <0.001). EHBDR failed to bring any survival benefit and was associated with a worse prognosis even after matching. Similar findings have also been revealed in the external validation cohort ( n =522, EHBDR: 117). EHBDR was associated with more extended resections, more aggressive tumor biological features, and worse prognosis. In the matched validation cohort, EHBDR was still associated with a higher incidence of early recurrence.

Conclusion: EHBDR was an indicator of the advanced stage and failed to bring any survival benefit. It is the tumor stage that really determines the prognosis. More in-depth analyses focusing on different situations of EHBDR with more detailed clinical data are required.