Table 2. Risk factors of cervical regional lymph node involvement in the training and testing data sets.
| Risk factors | SEER database | Our medical center | ||||||||
| Training data (n=15124) | Internal testing data (n=6482) | External testing data (n=1031) | ||||||||
| Node positive | Node negative | p value | Node positive | Node negative | p value | Node positive | Node negative | p value | ||
| Age (year) | <.001 | <.001 | 0.11 | |||||||
| <55 | 1374(75.83) | 8014(60.20) | 572(74.19) | 3509(61.44) | 298(81.20) | 509(76.66) | ||||
| ≥55 | 438(24.17) | 5298(39.80) | 199(25.81) | 2202(38.56) | 69(18.80) | 155(23.34) | ||||
| Race | <.001 | <.001 | ||||||||
| Other1 | 233(12.31) | 1301(9.77) | 99(12.84) | 556(9.74) | 367 | 664 | ||||
| white | 1536(84.77) | 10967(82.38) | 652(84.57) | 4739(82.98) | / | / | ||||
| black | 53(2.92) | 1044(7.84) | 20(2.59) | 416(7.28) | / | / | ||||
| Sex | <.001 | <.001 | <.001 | |||||||
| Male | 495(27.32) | 2171(16.31) | 202(26.20) | 943(16.51) | 91(24.80) | 95(14.31) | ||||
| Female | 1317(72.68) | 11141(83.69) | 569(73.80) | 4768(83.49) | 276(75.20) | 569(85.69) | ||||
| Tumor size (mm) | 7.18±2.46 | 5.29±2.93 | <.001 | 7.07±2.58 | 5.30±2.95 | <.001 | 6.26±2.37 | 5.09±2.33 | <.001 | |
| Extension | <.001 | <.001 | 0.0095 | |||||||
| intrathyroidal extension | 1428(78.81) | 12766(95.90) | 603(78.21) | 5478(95.92) | 333(90.73) | 634(95.48) | ||||
| minimal extension | 353(19.48) | 515(3.87) | 152(19.71) | 223(3.90) | 27(7.36) | 25(3.77) | ||||
| gross extension | 31(1.71) | 31(0.23) | 16(2.08) | 10(0.18) | 7(1.91) | 5(0.75) | ||||
| Multifocality | <.001 | <.001 | 0.0001 | |||||||
| Solitary tumor | 754(41.61) | 8930(67.08) | 322(41.76) | 3851(67.43) | 261(71.12) | 542(81.63) | ||||
| Multifocal tumor | 1058(58.39) | 4382(32.92) | 449(58.23) | 1860(32.57) | 106(28.88) | 122(18.37) | ||||
Notes: All data was presented as the number of cases and composition ratio (%) or mean ± standard deviation. 1Including American Indian/AK Native, Asian/Pacific Islander. PTMC = papillary thyroid microcarcinoma; SEER = Surveillance, Epidemiology, and End Results.