Table 3. Prognostic factors and rates of progression-free survival following postoperative radiation therapy.
| Prognostic factor | Total | Recurrences (%) | 1-y PFS, % | 5-y PFS, % | p | |
|---|---|---|---|---|---|---|
| Modality | SRS + S | 8 | 5 (62.5) | 100 | 20 | 0.28 |
| SRT + S | 34 | 19 (55.9) | 97 | 40.6 | ||
| Prescribed dose | cGy < 6,000 | 11 | 7 (63.6) | 100 | 0 | 0.009 |
| cGy > 6,000 | 16 | 6 (37.5) | 93.8 | 69.6 | ||
| Time to RT | < 6 mo | 28 | 16 (57.1) | 92 | 42.6 | 0.3 |
| > 6 mo | 9 | 5 (55.6) | 100 | 0 | ||
| Age | < 45 y | 10 | 4 (40) | 100 | 74.1 | 0.03 |
| > 45 y | 32 | 20 (62.5) | 93.2 | 24.6 | ||
| Subtype | Chondroid | 9 | 4 (44.4) | 100 | 34.3 | 0.45 |
| Classical | 33 | 20 (60.6) | 96.8 | 38.8 | ||
| Tumor diameter | < 3.5 cm | 19 | 13 (68.4) | 100 | 29.6 | 0.15 |
| > 3.5 cm | 19 | 8 (42.1) | 94.4 | 35.9 | ||
| Sex | Male | 24 | 12 (50) | 100 | 28.4 | 0.49 |
| Female | 18 | 12 (66.7) | 94.1 | 25.3 | ||
| Tumor type | Primary | 26 | 11 (42.3) | 100 | 51.27 | 0.045 |
| Recurrent | 16 | 13 (81.3) | 93.7 | 23.56 |
Abbreviations: RT, radiation therapy; SRS + S, stereotactic radiosurgery following surgery; SRT + S, stereotactic radiation therapy following surgery.