OS and PFS. Kaplan-Meier analysis of OS (upper panel) and PFS (lower panel). OS was defined as survival from all causes and was calculated from date of last RT. End points for PFS included death from any cause, local failure, and distant disease failure. Survivors were followed for a median of 6.2 years (range, 1.6-22.8). Median OS was 16.5 years. Five-year and 10-year OS estimates were 94% and 79%, respectively. Presenting stage was highly significant for PFS (P < .001), local failure (P < .001), and distant failure (P = .003).