Table 2. Cox regression analysis of sarcoma-related survival in patients with radiation-induced sarcoma (cases) and sporadic sarcomas (controls).
| Univariate analysis |
Multivariate weighted Cox regressiona
|
||||
|---|---|---|---|---|---|
| Prognostic factor | N=337 | P-value | P-value | HR | 95% CI for HR |
| Radiation-induced sarcoma | 0.001 | 0.84 | 0.58–1.22 | ||
| Yes | 98 (29%) | 0.362 | |||
| No | 239 (71%) ref | ||||
| Gender | 0.540 | ||||
| Female | 189 (56%) | ||||
| Male | 148 (44%) | ||||
| Age at sarcoma diagnosis (years) | 0.02 | 1.30 | 0.94–1.79 | ||
| <60 | 175 (52%) ref | 0.109 | |||
| ⩾60 | 162 (48%) | ||||
| Time period of diagnosis | |||||
| Before 1990 | 84 (25%) ref | ||||
| 1990–1999 | 117 (35%) | 0.941 | |||
| From 2000 | 136 (40%) | 0.224 | |||
| Histological subtype | |||||
| Malignant fibrous histiocytoma | 138 (41%) ref | ||||
| Osteosarcoma | 102 (30%) | 0.333 | |||
| Others | 97 (29%) | 0.132 | |||
| Tumour size | 1.57 | 0.97–2.55 | |||
| <5 cm | 66 (20%) ref | 0.002 | |||
| ⩾5 cm | 265 (80%) | 0.067 | |||
| Unknown | 6 | ||||
| Microscopic tumour necrosis | 1.88 | 1.27–2.78 | |||
| Yes | 213 (67%) | 0.002 | |||
| No | 103 (33%) ref | <0.001 | |||
| Unknown | 21 | ||||
| Bone or soft-tissue tumour | |||||
| Bone | 110 (33%) ref | ||||
| Soft tissue/viscera | 223 (67%) | 0.821 | |||
| Unknown | 4 | ||||
| Site | 1.71 | 1.18–2.47 | |||
| Extremity/trunk wall | 232 (69%) ref | <0.001 | 0.004 | ||
| Head/abdomen/axial/thoracic | 106 (31%) | ||||
| Metastases at diagnosis | 2.93 | 1.95–4.41 | |||
| Yes | 59 (18%) | <0.001 | <0.001 | ||
| No | 278 (82%) ref | ||||
| Complete surgical remission | 4.48 | 3.08–6.52 | |||
| Yes | 210 (62%) ref | <0.001 | <0.001 | ||
| No | 126 (38%) | ||||
| Unknown | 1 | ||||
Abbreviations: CI=confidence interval; HR=hazard ratio; ref=reference; RIS=radiation-induced sarcoma.
Significant values are given in bold.
a
In the multivariate analysis 307 patients are included.