Background: The negative prognostic role of pathologic fracture in osteosarcoma is not determined, as previous case-control and retrospective cohort studies have produced contradictory results.
Methods: We conducted both cohort (n = 384) and case-control (n = 111) studies on 37 pathologically fractured localized osteosarcoma of extremity.
Results: In cohort study, patients with a fracture showed a tendency of poorer survival, but the difference did not reach the level of significance (5-year metastasis-free survival rates; 48% for cases vs. 61% for controls; P = 0.06). A case-control study on 37 fractured and 74 control recruited from 347 patients matched for tumor size and location showed no survival difference between the cases and controls (P = 0.12).
Conclusions: Reported negative prognostic effect of a pathologic fracture is likely to be due to confounding by tumor size and location. The present study suggests that the presence of a pathologic fracture has no prognostic relevance.