High expression of hypoxia-inducible factor 1-alpha predicts poor prognosis in pancreatic ductal adenocarcinoma: a meta-analysis and database validation protocol - Zoa, Alexis; Yang, Yingjie; Huang, Wenjin; Yang, Jing; Wang, Jiangping; Wang, Haibo; Dong, Minghua; Tian, Yuantong (Translational Cancer Research, 2022)