Differential Presentations, Clinical Courses, and Survivals of Osteosarcomas of the Proximal Humerus over Other Extremity Locations

Although there are controversies about the prognosis of proximal humeral osteosarcoma, our previous study showed poor survival in those patients. In the present study, we undertook to determine why this site is associated with a poor outcome and to identify the clinicopathologic variables involved. The study cohort consisted of 36 proximal humeral and 341 other extremity American Joint Committee on Cancer (AJCC) stage II osteosarcomas. We examined the clinicopathologic differences between these osteosarcomas. The prognostic significances of factors identified for a proximal humoral location were evaluated by survival analysis of all 377 patients. Patients with a proximal humeral osteosarcoma had the following characteristics: a higher incidence of pathologic fracture (P < 0.01), an osteolytic pattern on plain radiographs (P < 0.01), an unusual pathological subtype (P = 0.01), poor histologic response (P < 0.01), and an increased tumor-volume ratio (TVR) (P < 0.01). Multivariate analysis revealed that a large tumor volume (P < 0.01), an increase in tumor volume (P < 0.01), and a poor histologic response to preoperative chemotherapy (P < 0.01) independently predicted shorter metastasis-free survival. The association between proximal humeral osteosarcoma and poor survival could be the result of unresponsiveness to chemotherapy, which was expressed by a tumor volume increase in our patients.