Table 1.
Baseline characteristics in treatment groups with and without a bolus
| Characteristics | Radiotherapy delivered with a bolus (n = 101) | Radiotherapy delivered without a bolus (n = 213) | Total (n = 314) | p-value (Z-test) (*independent t-test) |
|---|---|---|---|---|
| Histological grade n (%) | ||||
| 1 | 7 (6.9) | 19 (8.9) | 26 (8.3) | 0.55 |
| 2 | 36 (35.6) | 91 (42.7) | 127 (40.4) | 0.23 |
| 3 | 58 (57.4) | 100 (46.9) | 157 (50.0) | 0.08 |
| Unknown | 0 (0) | 3 (1.4) | 3 (1.0) | 0.23 |
| Size (mm) n (%) | ||||
| 1–20 | 15 (14.8) | 43 (20.2) | 58 (18.5) | 0.25 |
| 21–50 | 66 (65.3) | 131 (61.5) | 197 (62.7) | 0.51 |
| >50-80 | 20 (19.8) | 39 (18.3) | 59 (18.8) | 0.75 |
| Lymph node involvement n (%) | ||||
| 0 | 33 (32.7) | 80 (37.6) | 113 (36.0) | 0.40 |
| 1–3 | 63 (62.4) | 110 (51.6) | 173 (55.1) | 0.01 |
| 4–9 | 5 (4.9) | 22 (10.3) | 27 (8.6) | 0.11 |
| ≥10 | 0 (0) | 1 (0.5) | 1 (0.3) | 0.49 |
| Closest margin n (%) | ||||
| Closest margin distance (median/mean) (range) (mm) | 3/5.1 (0–37) | 5/8.2 (0–45) | 5/7.0 (0–45) | 0.002* |
| Deep margin distance (median/mean): mm (range) | 3/5.8 (0–37) | 5/8.7 (0–45) | 5/8.3 (0–45) | 0.002* |
| Lymphovascular space invasion n (%) | ||||
| Yes | 45 (44.6) | 80 (37.5) | 124 (39.5) | 0.24 |
| No | 51 (50.5) | 126 (59.2) | 177 (56.4) | 0.15 |
| Unknown | 4 (4.0) | 5 (2.3) | 7 (2.2) | 0.42 |
| Equivocal | 1 (1.0) | 2 (0.9) | 3 (1.0) | 0.97 |