Corrigendum: Expression of Human Epidermal Growth Factor Receptor-2 Status and Programmed Cell Death Protein-1 Ligand Is Associated With Prognosis in Gastric Cancer - Lv, Huifang; Zhang, Junling; Sun, Keran; Nie, Caiyun; Chen, Beibei; Wang, Jianzheng; Xu, Weifeng; Wang, Saiqi; Liu, Yingjun; Chen, Xiaobing (Frontiers in Oncology, 2021)