Prognostic factors among 130 patients with osteosarcoma. One hundred thirty patients with high grade osteosarcoma were enrolled in a randomized prospective multidisciplinary treatment that included intraarterial chemotherapy, local irradiation, limb salvage surgery, and prophylactic whole lung irradiation. The patients were evaluated to stage the prognostic factors. In a multivariate analysis, a minimal level of serum lactic acid dehydrogenase less than 300 IU/L showed a significant prognostic value. The history of trauma before diagnosis of disease, local irradiation of the affected site, histologic response to preoperative multidisciplinary therapy, and prophylactic whole lung irradiation were associated with significantly better prognosis in the log rank test. Patient age, site of the primary tumor, presentation of fracture, pathologic subtype, signs and symptoms, serum alkaline phosphatase level, and erythrocyte sedimentation rate were not found to be prognostic factors. The 9-year survival rate of the whole group was 55%.