Table 1. Characteristics of the matched study population in the primary analysis.
| Group A: with IGRT | Group B: without IGRT | |||
|---|---|---|---|---|
| number (%)# or mean (SD)# | number (%)# or mean (SD)# | Standardized difference (rounded) | ||
| Age | < 65 | 334 (77.14) | 331 (76.44) | 0.016 |
| ≥ 65 | 99 (22.86) | 102 (23.56) | ||
| Gender | female | 17 (3.93) | 16 (3.7) | 0.012 |
| male | 416 (96.07) | 417 (96.3) | ||
| Residency | non-north | 295 (68.13) | 290 (66.97) | 0.025 |
| north | 138 (31.87) | 143 (33.03) | ||
| T-stage | T1–T2 | 71 (16.4) | 71 (16.4) | 0 |
| T3–T4 | 362 (83.6) | 362 (83.6) | ||
| N-stage | positive | 392 (90.53) | 393 (90.76) | 0.008 |
| negative | 41 (9.47) | 40 (9.24) | ||
| RT delivery | 3DCRT | 7 (1.62) | 6 (1.39) | 0.019 |
| IMRT | 426 (98.38) | 427 (98.61) | ||
| Institution | high-volume | 223 (51.5) | 226 (52.19) | 0.014 |
| low-volume | 210 (48.5) | 207 (47.81) | ||
| Period | 2008–2009 | 40 (9.24) | 40 (9.24) | 0 |
| 2010–2013 | 393 (90.76) | 393 (90.76) |
Abbreviations:
#
rounded to the second decimal place;
IGRT, image-guided RT; 3DCRT, 3D conformal RT; IMRT, intensity-modulated RT; SD, standard deviation.