Table III.
Factors associated with overall survival in 24 patients.
| Univariate analysis | Multivariate analysis | |||||
|---|---|---|---|---|---|---|
| Factor | n (%) | MST, months | P-value | HR (95% CI) | P-value | HR (95% CI) |
| Age, years | ||||||
| <65 | 13 (54.2) | 47 | 0.3912 | 1.000 | – | – |
| ≥65 | 11 (45.8) | 27 | 1.964 (0.412–10.545) | – | ||
| Gender | ||||||
| Male | 14 (58.3) | 27 | 0.7355 | 1.000 | – | – |
| Female | 10 (41.7) | 47 | 0.801 (0.212–3.001) | – | ||
| Performance Status | ||||||
| 0 | 14 (58.3) | 27 | 0.5065 | 1.000 | – | – |
| 1 | 10 (41.7) | 47 | 0.636 (0.151–2.398) | – | ||
| Primary tumor location | ||||||
| Colon | 18 (75.0) | 45 | 0.6331 | 1.000 | – | – |
| Rectum | 6 (25.0) | 21 | 1.414 (0.295–5.256) | – | ||
| Left-sided colon | 11 (45.8) | 45 | 0.5105 | 1.000 | – | – |
| Other | 13 (54.2) | 21 | 1.562 (0.385–5.691) | – | ||
| Ablative SBRT | ||||||
| Yes | 8 (33.3) | 56 | 0.0182 | 1.000 | 0.4688 | 1.000 |
| No | 16 (66.7) | 12 | 8.673 (1.387–169.233) | 1.121×10−8 (0–25.088) | ||
| BED10, Gy | ||||||
| <100 | 13 (54.2) | 21 | 0.0060 | 1.000 | 0.1802 | 1.000 |
| ≥100 | 11 (45.8) | 56 | 0.092 (0.005–0.544) | 3.133×10−9 (0–9.697×10−39) | ||
| Maximum diameter of the GTV, mm | ||||||
| ≤30 | 9 (37.5) | 27 | 0.4843 | 1.000 | – | – |
| >30 | 15 (62.5) | 45 | 1.715 (0.409–11.580) | – | ||
| ≤50 | 17 (70.8) | 47 | 0.3458 | 1.000 | – | – |
| >50 | 7 (29.2) | 45 | 2.066 (0.416–8.634) | – | ||
| PTV margin, mm | ||||||
| <8 | 11 (45.8) | 21 | 0.2071 | 1.000 | – | – |
| 8 | 13 (54.2) | 45 | 0.445 (0.113–1.573) | – | ||
| Interval between the initial treatment and radiotherapy, months | ||||||
| ≥35 | 11 (45.8) | 21 | 0.0028 | 1.000 | 0.4246 | 1.000 |
| <35 | 13 (54.2) | 56 | 0.079 (0.004–0.456) | 0.353 (0.010- 3.807) | ||
| Presence of metastasis at the initial diagnosis | ||||||
| Yes | 8 (33.3) | 45 | 0.3683 | 1.000 | – | – |
| No | 16 (66.7) | 27 | 1.984 (0.475–13.384) | – | ||
| History of local therapya for metastasis | ||||||
| Yes | 16 (66.7) | 45 | 0.4530 | 1.000 | – | – |
| No | 8 (33.3) | N/A | 0.564 (0.084–2.313) | – | ||
| History of chemotherapy | ||||||
| Yes | 21 (87.5) | 45 | 0.3970 | 1.000 | – | – |
| No | 3 (12.5) | N/A | 2.903 (0.147–20.092) | – | ||
| History of radiotherapy | ||||||
| Yes | 4 (16.7) | 15 | 0.1113 | 1.000 | 0.1131 | 1.000 |
| No | 20 (83.3) | 45 | 0.201 (0.033–1.545) | 0.154 (0.013–1.629) | ||
| Presence of extra diseases outside the field of radiotherapy | ||||||
| Yes | 5 (20.8) | 56 | 0.6227 | 1.000 | – | – |
| No | 19 (79.2) | 27 | 1.438 (0.354–7.363) | – | ||
| Number of liver metastases | ||||||
| 1 | 18 (75.0) | 47 | 0.0323 | 1.000 | 0.1246 | 1.000 |
| >1 | 6 (25.0) | 21 | 5.294 (1.160–27.017) | 3.845 (0.689–30.348) | ||
a
Local therapy included surgery, radiofrequency ablation, and radiotherapy. MST, median survival time; SBRT, stereotactic body radiation therapy; HR, hazard ratio; CI, confidence interval; BED, biologically effective dose; GTV, gross tumor volume; PTV, planning target volume; N/A, not applicable.