Relationship between age and survival.

Patients are stratified into five age groups, according to the Surveillance, Epidemiology, and End Results (SEER) program age standards for survival [17]. (A) Boxplot of OS for patients by age group. Age < 55 (n = 449 patients, 12.8%), 55 ≤ age < 65 (n = 829 patients, 23.7%), 65 ≤ age < 75 (n = 1308 patients, 37.3%), 75 ≤ age < 85 (n = 771 patients, 22.0%), 85 ≤ age (n = 146 patients, 4.2%). (B) Kaplan-Meier survival by disease progression shows disease burden greatly diminishing five years after surgery.