Predicting distant metastasis in nasopharyngeal carcinoma using gradient boosting tree model based on detailed magnetic resonance imaging reports

Table 1 Demographic and clinicopathological characteristics of patients, n (%)

Variable	No. of patients
Median age (years)	45 (38-53)
Sex
Male	576 (72.7)
Female	216 (27.3)
WHO histologic type
I	5 (0.6)
II	41 (5.2)
III	746 (94.2)
T classification
T1	204 (25.8)
T2	97 (12.2)
T3	296 (37.4)
T4	195 (24.6)
N classification
N0	182 (23.0)
N1	438 (55.3)
N2	113 (14.3)
N3	59 (7.4)
AJCC stage
I	73 (9.2)
II	175 (22.1)
III	303 (38.3)
IV	241 (30.4)
Chemotherapy
No	107 (13.5)
Yes	685 (86.5)

WHO: World Health Organization; AJCC: American Joint Committee on Cancer.