Table 1.
Characteristics of training and validation datasets
| Training N = 685 |
Validation 1 N = 669 |
Validation 2 N = 193 |
p Value | |
|---|---|---|---|---|
| Age (years), mean ± SD | 60.1 ± 12.3 | 61.4 ± 12.4 | 61.1 ± 12.5 | 0.15 |
| Female sex, No. (%) | 321 (46.9) | 350 (52.3) | 94 (48.7) | 0.13 |
| Race, No. (%) | 0.001 | |||
| White | 596 (87.0) | 586 (87.6) | 162 (83.9) | |
| African-American | 53 (7.7) | 33 (4.9) | 25 (13.0) | |
| Other | 36 (5.3) | 50 (7.5) | 6 (3.1) | |
| Histology, No. (%) | 0.019 | |||
| Her2 negative breast cancer | 66 (9.6) | 46 (6.9) | 21 (10.9) | |
| Her2 positive breast cancer | 48 (7.0) | 67 (10.0) | 10 (5.2) | |
| Lung adenocarcinoma | 262 (38.2) | 215 (32.1) | 77 (39.9) | |
| Lung squamous cell carcinoma | 40 (5.8) | 37 (5.5) | 12 (6.2) | |
| Melanoma | 180 (26.3) | 185 (27.7) | 47 (24.4) | |
| Renal cell carcinoma | 89 (13.0) | 119 (17.8) | 26 (13.5) | |
| Minimal margin dose, median [IQR] | 20.0 [18.0, 21.0] | 19.0 [17.5, 22.3] | 19.5 [17.0, 22.0] | 0.38 |
| Burden of extracranial disease, No. (%) | <0.001 | |||
| None | 131 (19.1) | 64 (9.6) | 40 (20.7) | |
| Oligometastatic | 276 (40.3) | 165 (24.7) | 84 (43.5) | |
| Widespread | 278 (40.6) | 440 (65.8) | 69 (35.8) | |
| Progressive status of extracranial disease, No. (%) | 282 (41.2) | 438 (65.5) | 85 (44.0) | <0.001 |
| Number of metastases, No. (%) | 0.307 | |||
| One | 327 (47.7) | 324 (48.4) | 91 (47.2) | |
| Two | 158 (23.1) | 146 (21.8) | 36 (18.7) | |
| Three or Four | 138 (20.1) | 136 (20.3) | 37 (19.2) | |
| Five to Seven | 44 (6.4) | 37 (5.5) | 20 (10.4) | |
| Eight or more | 18 (2.6) | 26 (3.9) | 9 (4.7) | |
| Year of SRS | <0.001 | |||
| 2000–2005 | 159 (23.2) | 186 (27.8) | 0 (0.0) | |
| 2006–2010 | 403 (58.8) | 257 (38.4) | 0 (0.0) | |
| 2011–2014 | 123 (18.0) | 226 (33.8) | 193 (100.0) |
SD Standard Deviation, IQR interquartile range, SRS stereotactic radiosurgery without whole brain radiotherapy