Viet Nam The studies of Minimally invasive surgery in treating esophageal cancer by Nguyễn Minh Hải (2003), Triệu Triều Dương (2003), Phạm Đức Huấn (2006), Lê Lộc (2017) with sample size from 20 - 150 patients resulted in: Average operation durat ion: 330 - 395 minutes.