Clinical significance of extrahepatic bile duct resection for T2 gallbladder cancer using data from the Japanese Biliary Tract Cancer Registry between 2014 and 2018

Purpose: The present study aimed to determine whether concomitant extrahepatic bile duct resection (EHBDR) improves the prognosis of patients with T2 gallbladder cancer (GBC). Methods: Between 2014 and 2018, 4947 patients with GBC were registered in the National Biliary Tract Cancer Registry in Japan. This included 3804 patients (76.9%) who underwent curative-intent surgical resection; 1609 of these patients had pT2 GBC with no distant metastasis. Of the 1609 patients with GBC, 520 underwent EHBDR and 1089 did not. We compared the patients' backgrounds and disease-specific survival rates between the groups. Results: The frequency of lymph node metastasis was significantly higher in the EHBDR group than in the non-EHBDR group (38.2% vs. 20.7%, p <.001). In the entire cohort, however, there was no significant difference in disease-specific survival between the two groups (76% vs. 79%, p =.410). The EHBDR group had a significantly higher incidence of postoperative complications (Clavien–Dindo classification grade = 3) (32.4% vs. 11.7%, p <.001). When we focused on the survival of only T2N1 patients who underwent gallbladder bed resection, the prognosis was significantly improved for the EHBDR group (5-year survival rate: 64% vs. 54%, p =.017). The non-EHBDR group was subcategorized into two groups: D2 dissection and D1 dissection or sampling, and survival curves were compared between these subgroups. Although the EHBDR group tended to have a favorable prognosis compared to the D2 group, this difference was not significant (p =.167). However, the EHBDR group had a significantly greater prognosis than the D1 dissection or sampling group (5 year-survival rate: 64 vs. 49%, p =.027). Conclusions: The EHBDR may improve the prognosis of patients with T2 gall bladder cancer with lymph node metastases; however, its indication should be carefully determined because of the increased risk of postoperative complications.