An evaluation of the feasibility of an expanded indication of endoscopic submucosal dissection for ulcer positive early gastric cancer: a case-control study from two medical centers

Jian-Peng Gao, Meng-Jiao Li, Tie-Nan Feng, Chao Liu, Zheng-Lun Zhu, Ben-Yan Zhang, Min Yan, Zheng-Gang Zhu