Table 3. Annual trends of the characteristics of the separate cohort that utilized hypofractionation.
| Variables | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Age (years) | ||||||||||||
| 20–29 | 33 (2.9) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 66 (3.8) | 0 (0.0) | 33 (1.7) | 0 (0.0) | 99 (3.6) | 0 (0.0) | 50 (1.2) | 100 (2.6) |
| 30–39 | 198 (17.1) | 66 (8.3) | 198 (17.6) | 231 (15.9) | 165 (9.4) | 330 (16.1) | 231 (11.7) | 165 (6.9) | 363 (13.3) | 396 (10.8) | 400 (9.5) | 250 (6.5) |
| 40–49 | 627 (54.3) | 396 (50.0) | 264 (23.5) | 693 (47.7) | 924 (52.8) | 792 (38.7) | 957 (48.3) | 990 (41.7) | 825 (30.1) | 1,287 (35.1) | 1,550 (36.9) | 1,600 (41.6) |
| 50–59 | 165 (14.3) | 264 (33.3) | 429 (38.2) | 297 (20.5) | 396 (22.6) | 561 (27.4) | 396 (20.0) | 693 (29.2) | 957 (34.9) | 1,254 (34.2) | 1,050 (25.0) | 1,150 (29.9) |
| 60–69 | 132 (11.4) | 66 (8.3) | 165 (14.7) | 132 (9.1) | 33 (1.9) | 231 (11.3) | 264 (13.3) | 396 (16.7) | 297 (10.8) | 429 (11.7) | 1,000 (23.8) | 550 (14.3) |
| ≥70 | 0 (0.0) | 0 (0.0) | 66 (5.9) | 99 (6.8) | 165 (9.4) | 132 (6.5) | 99 (5.0) | 132 (5.6) | 198 (7.2) | 297 (8.1) | 150 (3.6) | 200 (5.2) |
| Combined age (years) | ||||||||||||
| <70 | 1,155 (100.0) | 792 (100.0) | 1,056 (94.1) | 1,353 (93.2) | 1,584 (90.6) | 1,914 (93.5) | 1,881 (95.0) | 2,244 (94.4) | 2,541 (92.8) | 3,366 (91.9) | 4,050 (96.4) | 3,650 (94.8) |
| ≥70 | 0 (0.0) | 0 (0.0) | 66 (5.9) | 99 (6.8) | 165 (9.4) | 132 (6.5) | 99 (5.0) | 132 (5.6) | 198 (7.2) | 297 (8.1) | 150 (3.6) | 200 (5.2) |
| Axillary surgery | ||||||||||||
| ALND | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 33 (5.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| Excision | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 33 (4.8) | 0 (0.0) | 0 (0.0) | 33 (1.7) | 0 (0.0) | 0 (0.0) |
| SNB | 330 (100.0) | 165 (100.0) | 264 (100.0) | 627 (100.0) | 627 (95.0) | 594 (100.0) | 660 (95.2) | 825 (100.0) | 1,254 (100.0) | 1,881 (98.3) | 2,200 (100.0) | 2,250 (100.0) |
| RT | ||||||||||||
| No | 627 (54.3) | 330 (41.7) | 561 (50.0) | 330 (22.7) | 561 (32.1) | 594 (29.0) | 825 (41.7) | 792 (33.3) | 1,320 (48.2) | 2,244 (61.3) | 2,000 (47.6) | 2,100 (53.8) |
| Yes | 528 (45.7) | 462 (58.3) | 561 (50.0) | 1,122 (77.3) | 1,188 (67.9) | 1,452 (71.0) | 1,155 (58.3) | 1,584 (66.7) | 1,419 (51.8) | 1,419 (38.7) | 2,200 (52.4) | 1,800 (46.2) |
| Region of surgery I | ||||||||||||
| Non-Seoul | 264 (50.0) | 264 (57.1) | 330 (58.8) | 693 (61.8) | 627 (52.8) | 726 (50.0) | 759 (65.7) | 1,089 (68.8) | 990 (69.8) | 957 (67.4) | 1,200 (54.5) | 1,000 (55.6) |
| Seoul | 264 (50.0) | 198 (42.9) | 231 (41.2) | 429 (38.2) | 561 (47.2) | 726 (50.0) | 396 (34.3) | 495 (31.2) | 429 (30.2) | 462 (32.6) | 1,000 (45.5) | 800 (44.4) |
| Region of surgery II | ||||||||||||
| Non-capital | 363 (31.4) | 132 (16.7) | 231 (20.6) | 462 (31.8) | 561 (32.1) | 594 (29.0) | 726 (36.7) | 792 (33.3) | 1,089 (39.8) | 1,221 (33.3) | 1,450 (34.5) | 1,100 (28.2) |
| Capital area | 792 (68.6) | 660 (83.3) | 891 (79.4) | 990 (68.2) | 1,188 (67.9) | 1,452 (71.0) | 1,254 (63.3) | 1,584 (66.7) | 1,650 (60.2) | 2,442 (66.7) | 2,750 (65.5) | 2,800 (71.8) |
| Region of surgery III | ||||||||||||
| Non-metropolitan | 198 (17.1) | 33 (4.2) | 66 (5.9) | 99 (6.8) | 165 (9.4) | 198 (9.7) | 264 (13.3) | 231 (9.7) | 363 (13.3) | 561 (15.3) | 450 (10.7) | 300 (7.7) |
| Metropolitan | 957 (82.9) | 759 (95.8) | 1,056 (94.1) | 1,353 (93.2) | 1,584 (90.6) | 1,848 (90.3) | 1,716 (86.7) | 2,145 (90.3) | 2,376 (86.7) | 3,102 (84.7) | 3,750 (89.3) | 3,600 (92.3) |
| Size of hospital of surgery | ||||||||||||
| <800 beds | 396 (34.3) | 231 (29.2) | 462 (41.2) | 528 (36.4) | 891 (50.9) | 825 (40.3) | 660 (33.3) | 693 (29.2) | 1,254 (45.8) | 1,320 (36.0) | 1,750 (41.7) | 1,500 (38.5) |
| ≥800 beds | 759 (65.7) | 561 (70.8) | 660 (58.8) | 924 (63.6) | 858 (49.1) | 1,221 (59.7) | 1,320 (66.7) | 1,683 (70.8) | 1,485 (54.2) | 2,343 (64.0) | 2,450 (58.3) | 2,400 (61.5) |
| RT technique | ||||||||||||
| 3D | 528 (100.0) | 462 (100.0) | 561 (100.0) | 1,122 (100.0) | 1,188 (100.0) | 1,452 (100.0) | 1,155 (100.0) | 1,518 (95.8) | 1,287 (90.7) | 825 (58.1) | 1,700 (77.3) | 950 (52.8) |
| IMRT | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 66 (4.2) | 132 (9.3) | 594 (41.9) | 500 (22.7) | 850 (47.2) |
| RT fractionation | ||||||||||||
| No RT | 627 (54.3) | 330 (41.7) | 561 (50.0) | 330 (22.7) | 561 (32.1) | 594 (29.0) | 825 (41.7) | 792 (33.3) | 1,320 (48.2) | 2,244 (61.3) | 2,000 (47.6) | 2,100 (53.8) |
| 1–14 | 33 (2.9) | 0 (0.0) | 0 (0.0) | 66 (4.5) | 0 (0.0) | 33 (1.6) | 66 (3.3) | 33 (1.4) | 132 (4.8) | 66 (1.8) | 50 (1.2) | 100 (2.6) |
| 15–20 | 66 (5.7) | 33 (4.2) | 0 (0.0) | 66 (4.5) | 198 (11.3) | 132 (6.5) | 33 (1.7) | 330 (13.9) | 264 (9.6) | 792 (21.6) | 1,000 (23.8) | 1,000 (25.6) |
| ≥21 | 429 (37.1) | 429 (54.2) | 561 (50.0) | 990 (68.2) | 990 (56.6) | 1,287 (62.9) | 1,056 (53.3) | 1,221 (51.4) | 1,023 (37.3) | 561 (15.3) | 1,150 (27.4) | 700 (17.9) |
Data are presented as number (%), unless otherwise indicated. ALND, axillary lymph node dissection; SNB, sentinel node biopsy; RT, radiation therapy; 3D, three-dimensional; IMRT, intensity-modulated RT.