Table 1.
Patient characteristics
| Variable | Development cohort
|
Validation cohorts
|
|||
|---|---|---|---|---|---|
| MAASTRO Clinic (n=548) | NKI (n=174) | P* | MSKCC (n=130) | P* | |
| Mean age (y) | 66 (SD 10) | 63 (SD 10) | <.001 | 67 (SD 11) | .510 |
| Gender | .144 | <.001 | |||
| Male | 379 (69.2%) | 110 (63.2%) | 63 (48.5%) | ||
| Female | 169 (30.8%) | 64 (36.8%) | 67 (51.5%) | ||
| WHO-PS | <.001 | .013 | |||
| 0 | 192 (35.0%) | – | 48 (36.9%) | ||
| 1 | 287 (52.4%) | 139 (79.9%) | 78 (60.0%) | ||
| ≥2 | 63 (11.6%) | 35 (20.1%) | 4 (3.1%) | ||
| Missing | 6 (1.0%) | – | – | ||
| Mean FEV1 (%) | 76 (range 21–139) | 78 (range 37–133) | .292 | ||
| Missing | 71 (13.0%) | 34 (19.5%) | |||
| BMI | 24.9 (SD 4.3) | NA | – | NA | |
| Missing | 179 (32.7%) | ||||
| Nicotine use | NA | – | <.001 | ||
| No/former smoker | 304 (55.5%) | 100 (76.9%) | |||
| Current smoker | 202 (36.9%) | 30 (23.1%) | |||
| Missing | 42 (7.7%) | – | |||
| Clinical T stage | .053 | <.001 | |||
| T1 | 74 (13.5%) | 28 (16.1%) | 27 (20.8%) | ||
| T2 | 172 (31.4%) | 67 (38.5%) | 42 (32.3%) | ||
| T3 | 60 (10.9%) | 27 (15.5%) | 27 (20.8%) | ||
| T4 | 216 (39.4%) | 52 (29.9%) | 31 (23.8%) | ||
| Missing | 26 (4.7%) | – | 3 (2.3%) | ||
| Clinical N stage | <.001 | ||||
| N0 | 95 (17.3%) | 13 (7.5%) | |||
| N1 | 15 (2.7%) | 7 (4.0%) | |||
| N2 | 267 (48.7%) | 123 (70.7%) | |||
| N3 | 167 (30.5%) | 31 (17.8%) | |||
| Missing | 4 (0.7%) | ||||
| Clinical overall stage | <.001 | NA | |||
| IIIA | 199 (36.3%) | 115 (66.1%) | |||
| IIIB | 349 (66.1%) | 58 (33.3%) | |||
| Missing | 1 (0.6%) | ||||
| Histology | <.001 | ||||
| Adenocarcinoma | 81 (14.8%) | 35 (20.1%) | |||
| SCC | 164 (29.9%) | 54 (31.0%) | |||
| Large cell carcinoma | 190 (34.7%) | 78 (44.8%) | |||
| Other | 93 (17.0%) | 7 (4.0%) | |||
| Unknown | 20 (3.7%) | – | |||
| Median GTV (mL) (range) | 51 (0–725) | 99 (0–1822) | <.001† | 54 (0.3–1057) | .360† |
| Missing | 41 (7.5%) | 5 (2.9%) | – | ||
| PLNS | .603 | <.001 | |||
| 0 | 104 (19.0%) | 36 (20.7%) | 6 (4.6%) | ||
| 1 | 107 (19.5%) | 36 (20.7%) | 14 (10.8%) | ||
| 2 | 113 (20.6%) | 32 (18.4%) | 39 (30.0%) | ||
| 3 | 69 (12.6%) | 31 (17.8%) | 36 (27.7%) | ||
| ≥4 | 125 (22.9%) | 39 (22.4%) | 35 (26.9%) | ||
| Missing | 30 (5.5%) | – | |||
| Chemotherapy | – | .009 | |||
| No | 66 (12.0%) | – | 12 (9.2%) | ||
| Sequential | 280 (51.1%) | – | 51 (39.2%) | ||
| Concurrent | 202 (36.9%) | 174 (100%) | 67 (51.5%) | ||
| Mean OTT (d) | 32 (SD 8) | 31 (SD 2) | .763 | 43 (SD 8) | <.001 |
| Mean EQD2 (Gray) | 60.8 (SD 7.1) | 70.1 (SD 0) | – | 60.1 (SD 8.8) | .313 |
Abbreviations: BMI = body mass index; EQD2 = equivalent radiation dose at 2 Gy; FEV1 = forced expiratory volume in 1 second; GTV = gross tumor volume; MSKCC = Memorial Sloan Kettering Cancer Center; NKI = Netherlands Cancer Institute; OTT = overall treatment time radiation therapy; PLNS = number of positive lymph node stations; SCC = squamous cell carcinoma; SD = standard deviation; WHO-PS = World Health Organization performance status.
*
P values assessed using t test (continuous variables) or χ2 test (categorical variables).
†
P values assessed using Mann-Whitney test (nonparametric distribution).