Abstract
            Introduction: Malignant bone tumors account for 6% of childhood malignancies. The peak incidence rate for  bone cancer is in adolescents. Geographic and race differences in incidence rate of bone tumors are important  for correct diagnosis and treatment.  
  Objectives: This study aimed to investigate the demographic features of patients with malignant bone tumors and  prognostic factors.
    Patients and Methods: In a retrospective study, records of all patients diagnosed and treated for malignant bone  tumor from March 1996 to February 2014 were investigated. Data were collected using checklists and analyzed  using SPSS software.
    Results: The most common type of bone tumor was Ewing sarcoma (73.7%) in patients who were over 10 years  old (87.5%). Primary site of disease in most cases of osteosarcoma and Ewing sarcoma was distal femur (50%  and 27.3%, respectively). Most common clinical manifestation was local pain and mass (88.5%). Regarding  metastasis, 72.7% of osteosarcoma patients and 32.4% of Ewing sarcoma patients had metastasis. There was not  statistically relationship between survival rate and gender, age group and stage of disease at diagnosis time. One,  three and five-year survival rate was lower than the previous studies.  
  Conclusion: The incidence of Ewing sarcoma is more then osteosarcoma in West Azerbaijan. In our study there  were no statistically important differences in survival rates of patients with metastasis at diagnosis time and those  without metastasis.