Table 1. Demographics and Tumor Characteristics of the Surveillance, Epidemiology, and End Results database (training cohort) and Chinese Cohort (validation cohort).
| Variables | Training Cohort (N = 4,109) | Validation Cohort (N = 145) | P** | |||||
|---|---|---|---|---|---|---|---|---|
| No. Patients | % | Hazard Ratio | 95% CI | P* | No. Patients | % | ||
| Sex | 0.063 | 0.009 | ||||||
| Male | 3366 | 81.9 | Reference | 131 | 90.3 | |||
| Female | 743 | 18.1 | 0.907 | 0.818–1.005 | 0.063 | 14 | 9.7 | |
| Age, years | <0.001 | 0.874 | ||||||
| <60 | 1570 | 38.2 | Reference | 48 | 33.1 | |||
| 60–70 | 1533 | 37.3 | 1.112 | 1.016–1.217 | 0.021 | 72 | 49.7 | |
| >70 | 1006 | 24.5 | 1.367 | 1.236–1.511 | <0.001 | 25 | 17.2 | |
| Race | <0.001 | <0.001 | ||||||
| White | 3629 | 88.3 | Reference | 0 | 0 | |||
| Black | 280 | 6.8 | 1.352 | 1.167–1.566 | <0.001 | 0 | 0 | |
| Other | 200 | 4.9 | 1.136 | 0.953–1.353 | 0.154 | 145 | 100 | |
| Histology | <0.001 | <0.001 | ||||||
| Adenocarcinoma | 2884 | 70.2 | Reference | 7 | 4.8 | |||
| Squamous cell carcinoma§ | 1225 | 29.8 | 1.305 | 1.201–1.418 | <0.001 | 138 | 95.2 | |
| Tumor site | <0.001 | <0.001 | ||||||
| Upper | 120 | 2.9 | Reference | 4 | 2.8 | |||
| Middle | 700 | 17.0 | 1.102 | 0.867–1.400 | 0.428 | 100 | 69.0 | |
| Lower | 3008 | 73.2 | 0.865 | 0.689–1.085 | 0.209 | 41 | 28.3 | |
| Overlapping | 124 | 3.0 | 1.080 | 0.795–1.467 | 0.622 | 0 | 0 | |
| Unknown (X) | 157 | 3.8 | 0.531 | 0.383–0.737 | <0.001 | 0 | 0 | |
| Tumor size (cm) | <0.001 | 0.188 | ||||||
| ≤3 | 1240 | 30.2 | Reference | 54 | 37.2 | |||
| ≤5 | 1007 | 24.5 | 1.804 | 1.620–2.008 | <0.001 | 30 | 20.7 | |
| >5 | 807 | 19.6 | 2.034 | 1.818–2.276 | <0.001 | 61 | 42.1 | |
| Unknown (X) | 1055 | 25.7 | 1.177 | 1.053–1.315 | 0.004 | 0 | 0 | |
| Grade | <0.001 | <0.001 | ||||||
| Well differentiated | 259 | 6.3 | Reference | 13 | 9.0 | |||
| Moderately differentiated | 1500 | 36.5 | 1.843 | 1.497–2.269 | <0.001 | 99 | 68.3 | |
| Poorly or Undifferentiated | 1953 | 47.5 | 2.761 | 2.251–3.387 | <0.001 | 33 | 22.8 | |
| Unknown (X) | 397 | 9.7 | 1.193 | 0.932–1.527 | 0.161 | 0 | 0 | |
| Timing of radiation therapy | 0.292 | <0.001 | ||||||
| None | 2640 | 64.2 | Reference | 145 | 100 | |||
| Prior to surgery | 1469 | 35.8 | 1.044 | 0.963–1.132 | 0.292 | 0 | 0 | |
| Pathologic T category | <0.001 | <0.001 | ||||||
| T1 | 1425 | 34.7 | Reference | 22 | 15.2 | |||
| T2 | 778 | 18.9 | 1.898 | 1.683–2.141 | <0.001 | 26 | 17.9 | |
| T3 | 1603 | 39.0 | 2.868 | 2.596–3.167 | <0.001 | 93 | 64.1 | |
| T4 | 303 | 7.4 | 4.777 | 4.128–5.528 | <0.001 | 4 | 2.8 | |
| Pathologic N category | <0.001 | 0.968 | ||||||
| N0 | 2355 | 57.3 | Reference | 79 | 54.5 | |||
| N1 | 1009 | 24.6 | 2.581 | 2.353–2.832 | <0.001 | 42 | 29.0 | |
| N2 | 511 | 12.4 | 3.892 | 3.479–4.354 | <0.001 | 18 | 12.4 | |
| N3 | 234 | 5.7 | 5.197 | 4.479–60.30 | <0.001 | 6 | 4.1 | |
| Pathologic TNM stage | <0.001 | 0.004 | ||||||
| IA | 707 | 17.2 | Reference | 3 | 2.1 | |||
| IB | 666 | 16.2 | 1.801 | 1.503–2.157 | <0.001 | 17 | 11.7 | |
| IIA | 330 | 8.0 | 2.835 | 2.320–3.464 | <0.001 | 21 | 14.5 | |
| IIB | 1053 | 25.6 | 3.748 | 3.201–4.388 | <0.001 | 48 | 33.1 | |
| IIIA | 596 | 14.5 | 5.989 | 5.069–7.076 | <0.001 | 33 | 22.8 | |
| IIIB | 285 | 6.9 | 8.430 | 6.989–10.169 | <0.001 | 13 | 9.0 | |
| IIIC | 472 | 11.5 | 8.913 | 7.512–10.574 | <0.001 | 10 | 6.9 | |
| No. of nodes retrieved | 0.007 | 0.496 | ||||||
| 0–9 | 2230 | 54.3 | Reference | 73 | 50.3 | |||
| 10–14 | 810 | 19.7 | 0.960 | 0.868–1.063 | 0.435 | 37 | 25.5 | |
| 15–24 | 744 | 18.1 | 0.841 | 0.755–0.937 | 0.002 | 29 | 20.0 | |
| >25 | 325 | 7.9 | 0.861 | 0.741–0.999 | 0.049 | 6 | 4.1 | |
§According to the 7th edition of the AJCC cancer staging manual, if a tumor is of mixed histopathologic type or is not otherwise specified, it recorded as squamous cell carcinoma.
*Univariate Cox-Regression analysis.
**Student t-test or Pearson χ2.