Results of a new Swedish study have shown that a surgeon needed to perform at least 15 esophagectomies in cancer patients in order to achieve stable survival results in the first months after the operation. In fact, after 15 surgeries the all-cause 30-day mortality decreased by more than half.
http://www.cancernetwork.com/gastrointestinal-cancer/learning-curve-exists-esophageal-cancer-surgery#sthash.Q3KIEX0r.dpuf
Learning Curve Exists for Esophageal Cancer Surgery