Impact of metformin on survival outcome of esophageal squamous cell carcinomas patients undergoing surgical resection: a multicenter retrospective study

Huang-He He, Jun-Hui Fu, Zhe-Xue Hao, He-Fang Wu, Qiang Zhong, Fan Wang, Hang-Hui Liu, Xiang-Sen Gu, Bin Wang, Hao-Da Huang, Zhuo-Yi Li, Jian-Xing He