AUCa calculated by testing prediction models on SEERb.

AUCa: area under the receiver operating characteristic curves.SEERb: National Cancer Institute's Surveillance, Epidemiology, and End Results.variable selectionc: the variable selection method which has the highest AUC.BSFSd: variable selection using backward stepwise feature selection.GAe: variable selection using genetic algorithms.Globalf: without variable selection.*: median AUC of 15 tests.**: comparing the AUC of prediction models with TNM staging system.&: comparing the AUC of prediction models with 20 variables to that with 14 variables.