TABLE III.
Log-Rank Test Comparing Event-Free Survival Rates in Patients with Localized Extraskeletal Osteosarcoma
| Variable | No. of Patients | No. of Events | Three-Year Event-Free Survival Rate* | P Value |
| All patients | 42 | 18 | 0.50 (0.36 to 0.70) | — |
| Patient age | 0.09 | |||
| Fifty years or less | 11 | 2 | 0.75 (0.50 to 1.00) | |
| More than fifty years | 31 | 16 | 0.42 (0.27 to 0.67) | |
| Patient sex | 0.73 | |||
| Female | 23 | 10 | 0.49 (0.30 to 0.78) | |
| Male | 19 | 8 | 0.53 (0.34 to 0.83) | |
| Site of primary tumor | 0.12 | |||
| Axial | 5 | 3 | NA† | |
| Extremity | 37 | 15 | 0.54 (0.39 to 0.75) | |
| Tumor grade | 0.93 | |||
| Low | 2 | 1 | 0.50 (0.13 to 1.00) | |
| High | 40 | 17 | 0.50 (0.36 to 0.71) | |
| Tumor size | 0.26 | |||
| ≤5 cm | 11 | 3 | 0.70 (0.47 to 1.00) | |
| >5 cm | 31 | 15 | 0.43 (0.27 to 0.68) | |
| Tumor depth | 0.03 | |||
| Superficial | 10 | 1 | 0.89 (0.71 to 1.00) | |
| Deep | 32 | 17 | 0.38 (0.23 to 0.63) | |
| Resection margin status | ||||
| R0 | 35 | 13 | 0.57 (0.41 to 0.78) | 0.03 |
| R1 | 7 | 5 | 0.17 (0.03 to 1.00) | |
| Patient history of radiation therapy | 0.08 | |||
| No | 39 | 16 | 0.53 (0.38 to 0.73) | |
| Yes | 3 | 2 | NA† | |
| Treatment type | 0.83 | |||
| Surgery alone | 19 | 7 | 0.55 (0.34 to 0.88) | |
| Surgery and chemotherapy | 5 | 1 | 0.80 (0.52 to 1.00) | |
| Surgery, radiation therapy, and chemotherapy | 8 | 4 | 0.50 (0.25 to 1.00) | |
| Surgery and radiation therapy | 10 | 6 | 0.36 (0.15 to 0.87) |
*
The values are given as the three-year event-free survival rate, with the 95% confidence interval in parentheses.
†
NA = not available. These values are not estimable for axial sites and those with prior radiation therapy because the last event occurred before year 3.