Pelvis and extremity osteosarcoma with similar tumor volume have an equivalent survival.

Background And Objectives: The poor prognosis of pelvic osteosarcoma is well recognized, but the cause of this prognosis has not been well defined.

Methods: We analyzed the clinicopathologic characteristics of pelvic osteosarcoma, and their prognostic significances in a cohort of 41 patients, treated either surgically by ablation or non-surgically. In a separate case-controlled study, the 20 surgically treated osteosarcoma patients were matched with 38 patients with extremity osteosarcoma by tumor volume and age.

Results: The 5-year overall survival rates of the surgically and the non-surgically treated pelvic osteosarcoma were 55.8 +/- 13.0% and 4.8 +/- 4.7%, respectively (P < 0.01). Non-surgically managed pelvic osteosarcoma group were found to have a larger tumor volume (P = 0.02), bladder displacement and sacroiliac joint involvement (P < 0.01). The 5-year metastasis free survival rates in the surgically treated pelvic and extremity osteosarcoma were no different (41.4 +/- 12.8% vs. 48.6 +/- 8.4%), and histologic responses to chemotherapy were similar in two groups.

Conclusions: No significant difference in survival or histologic response was found between the surgically treated pelvic and the extremity osteosarcoma with suitable tumor volume. Outcome of pelvis osteosarcoma corresponds to the poor survival of extremity osteosarcoma of high initial tumor burden.