Photodynamic therapy (PDT), radiofrequency ablation (RFA) with biliary stents in palliative treatment of unresectable extrahepatic cholangiocarcinoma a systematic review and meta-analysis - Mohan, Babu P; Chandan, Saurabh; Khan, Shahab R; Kassab, Lena L; Ponnada, Suresh; Artifon, Everson L. A; Otoch, José Pinhata; Mcdonough, Stephanie; Adler, Douglas G (Journal of clinical gastroenterology, 2022)