Assessment of safety and patency of 7-mm covered metal stents for preoperative biliary drainage in pancreatic cancer: Prospective multicenter study - Hirotoshi Ishiwatari; Yousuke Kobayashi; Shinya Kawaguchi; Takuji Iwashita; Junichi Kaneko; Jun Ito; Kazuma Ishikawa; Junya Sato; Fumitaka Niiya; Shinya Endo; Tatsunori Satoh; Shinya Uemura; et al. (Endoscopy International Open)