Reply to Angsuwatcharakon et al.

We greatly appreciate the interest and comments of Angsuwatcharakon et al. in their letter [1] regarding our recent study [2] that identified risk factors for recurrent biliary obstruction following the placement of self-expandable metallic stents (SEMS) in patients with malignant perihilar biliary strictures. We would like to reply to their comments.

Out of the 12 patients with gallbladder cancer enrolled in the study, 6 (50 %) developed recurrent biliary obstruction (RBO) and 6 died without developing RBO. Because the latter six patients were censored at the date of death and not treated as end points (RBO), it is unlikely that the short survival time is the main reason for the increased risk of developing RBO in patients with gallbladder cancer in the initial analysis. Even within the shorter median survival time (147 days) compared with that of patients with bile duct cancer (352 days), the patients with gallbladder cancer had a higher risk of RBO (hazard ratio 8.18) and shorter stent patency durations than those with bile duct carcinoma. These results suggest that malignant perihilar biliary strictures due to gallbladder carcinoma are at very high risk of RBO after the insertion of SEMS, and SEMS should be avoided in such cases. Further multicenter prospective studies are required to confirm the present findings in larger series. On the other hand, the shorter stent patency period shown in the additional analysis, which treated both RBO and patient death as combined end points, clearly indicates the difficulty in managing patients with advanced gallbladder cancer. Appropriate management of malignant perihilar biliary strictures would contribute to improving the prognosis, but the best approach will require further clarification.

• References

• 1 Angsuwatcharakon P, Pradermchai K, Rungsun R. What exactly shortens stent patency in hilar block from gallbladder carcinoma?. Endoscopy 2016; 48: 1049
• 2 Miura S, Kanno A, Masamune A et al. Risk factors for recurrent biliary obstruction following placement of self-expandable metallic stents in patients with malignant perihilar biliary stricture. Endoscopy 2016; 48: 536-545