Categorical data in all raw data were based on the following rules：

Sex(1=Male, 2=Female)
T(1 = pathological stage T1, 2 = pathological stage T2, 3 = pathological stage T3, 4 = pathological stage T4)
N(0=without regional lymph node metastasis，1=with 1-3 regional lymph node metastases, 2=with more than 4 regional lymph node metastases)
M(0=without distant metastasis, 1=with distant metastasis)