Discussion
malignant extrahepatic biliary strictures
This randomized controlled trial compared the sensitivity of two intraductal brush cytology devices and showed that the dense brush was not superior to the conventional brush in diagnosing malignant extrahepatic biliary strictures. Following the recommendation from the DSMB, this study was interrupted after the interim analysis for reasons of futility.Several studies have investigated the sensitivity of brush cytology devices in identifying malignant extrahepatic biliary strictures. The modest sensitivity (44–50%) in our study is in line with results from two systematic reviews that reported sensitivity rates of 42% (± 3.2%) and 45% (95%-CI 40–50%), respectively. [In addition, three retrospective studies showed conflicting results on the increased sensitivity of dense brush cytology devices. Two of these studies did show higher sensitivity for the dense brush when compared to conventional brush cytology devices, although Bank et al. did not observe a higher sensitivity [The results of this randomized study should be interpreted in light of some limitations. First, this study was ended prematurely as recommended by the DSMB for reasons of futility. As a consequence, the sample size calculated for this study was not accomplished, thereby implicating the robustness of the conclusions that can be drawn from our data. Second, it is impossible to draw any conclusions regarding the equality of both brushes since this trial was designed as a superiority trial. In addition, because block randomization was not used in this study, the number of patients allocated to each group appears unequal (In conclusion, this randomized controlled trial showed that the dense brush is not superior to the conventional brush in terms of sensitivity in diagnosing malignant extrahepatic biliary strictures. As a consequence, this study was prematurely terminated for reasons of futility. Future studies should focus on the application of new techniques to evaluate biliary brush specimens (e.g., DNA mutation analysis) and on the value of advanced endoscopic procedures to obtain biliary samples (e.g., intraductal biopsies).