الفهرس 
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Abstract
Osteosarcoma (OS) is the most common primary malignant bone tumor across all age groups. It has a bimodal age distribution, a major peak coinciding with the adolescent growth spurt and a minor peak in the elderly. The most frequent predilection sites for osteosarcoma are the metaphyseal regions of the distal femur, proximal tibia, and proximal humerus respectively.
Since the introduction of the current management protocol, comprising surgical resection, adjuvant and neoadjuvant chemotherapy, the 5-year survival rates for osteosarcoma have improved. However, OS still has a fatal outcome mainly because of drug resistance, local recurrence, and occurrence of metastasis.
OS is a widely heterogenous neoplasm characterized by a highly complex and chaotic genome. Both inter-tumoral and intra-tumoral heterogeneity are observed. Despite the recent development in understanding the molecular biology of osteosarcoma, no specific genetic abnormality which can be used for either diagnostic or therapeutic purposes is yet defined.