Subjects

Two hundred forty-seven distal MBO patients aged from 40 to 90 years admitted to the hospital between July 2015 and December 2019 were evaluated for this study. All patients were admitted to the hospital for the first time due to distal MBO (Bismuth-Corlette I). They had not previously received any antitumor treatment (chemotherapy, radiotherapy, or immunotherapy). Eligible patients were randomly assigned to receive either the biliary stent implantation loaded with radioactive ¹²⁵I seeds (radioactive biliary stent, RBS) or conventional biliary stent (CBS). Research staff at the study site opened the sequentially numbered opaque envelope that contained the biliary stent assignment. An individual unassociated with the clinical portion of the study prepared the envelopes. Randomization sequence was created using Stata 9.0 (StataCorp., College Station, TX) statistical software. The sample size determination formula was used to calculate the sample size. The outcome was the incidence of biliary tract infection. The infection rate was 20% in the RBS group and 10% in the CBS group.10 Two-side test was required, α=0.05, the ratio of sample size was 1:1(the number of cases was equal), β=0.1, the degree of assurance was 1% to 90%, and the minimum sample size required was 193.9. A signed informed consent was obtained from each patient. This study was approved by the Ethics Committee (200901B003).