139 External Validation of 7th and 8th Editions of the AJCC TNM Staging Classification System for Anal Canal Cancer: A Multi-Institutional Quality Assurance Study. (October 2019) - Wang, Michael; Doll, Corinne; Ghosh, Sunita; Fairchild, Alysa; Usmani, Nawaid; Tankel, Keith; Nijjar, Tirath; Severin, Diane; Mulder, Karen; Urgoiti, Gloria Roldan; Mathen, Peter; Joseph, Kurian