Table 4. ORs for omitting RT and hypofr RT.
| Variables | RT omit vs. RT | Conv RT vs. hypofr RT | |||||||
|---|---|---|---|---|---|---|---|---|---|
| RT omit | RT | OR (95% CI) | P | Conv RT | Hypofr RT | OR (95% CI) | P | ||
| Treatment period | |||||||||
| 2009–2014 | 3,003 | 5,313 | 4,686 | 495 | |||||
| 2015–2020 | 9,281 | 9,577 | 1.15 (1.13–1.16) | <0.001 | 5,711 | 3,419 | 1.12 (1.1–1.13) | <0.001 | |
| Combined age (years) | |||||||||
| <70 | 11,357 | 14,229 | 10,067 | 3,716 | |||||
| ≥70 | 877 | 661 | 1.18 (1.15–1.22) | <0.001 | 330 | 198 | 1.1 (1.07–1.13) | <0.001 | |
| Axillary surgery | |||||||||
| No | 7,032 | 8,366 | 5,931 | 2,104 | |||||
| Yes | 5,252 | 6,524 | 1.04 (0.99–1.1) | – | 4,466 | 1,810 | 1.14 (1.06–1.23) | 0.001 | |
| Region of surgery† I | |||||||||
| Non-Seoul | 7,035 | 8,157 | 5,947 | 2,688 | |||||
| Seoul | 5,249 | 6,733 | – | – | 4,450 | 1,226 | 0.98 (0.97–1) | 0.008 | |
| Region of surgery† II | |||||||||
| Non-capital | 4,057 | 4,664 | 3,138 | 1,361 | |||||
| Capital area | 8,227 | 10,226 | 0.95 (0.93–0.96) | <0.001 | 7,259 | 2,553 | 1.04 (1.03–1.06) | <0.001 | |
| Region of surgery† III | |||||||||
| Non-metropolitan | 1,109 | 1,819 | 1,090 | 597 | |||||
| Metropolitan | 11,175 | 13,071 | 1.16 (1.14–1.19) | <0.001 | 9,307 | 3,317 | 0.98 (0.96–1) | 0.082 | |
| Size of hospital of surgery‡ | |||||||||
| <800 beds | 5,032 | 5,478 | 1.06 (1.04–1.07) | <0.001 | 4,003 | 1,243 | 0.99 (0.97–1) | 0.016 | |
| ≥800 beds | 7,252 | 9,412 | 6,394 | 2,671 | |||||
| RT technique | |||||||||
| 3D | – | – | 10,314 | 1,921 | |||||
| IMRT | – | – | – | – | 83 | 1,993 | 2.12 (2.08–2.15) | <0.001 | |
Data are presented as number, unless otherwise indicated. †, region of RT for hypofr RT analysis; ‡, size of hospital of RT for hypofr RT analysis. OR, odds ratio; RT, radiation therapy; conv, conventional fractionation; hypofr, hypofractionated; CI, confidence interval; 3D, three-dimensional; IMRT, intensity-modulated RT.