Most patients have no known causes or risk factors, however there are some known associations:
1. Ionizing radiation is a known risk but is implicated in <3% of cases.
2. Pre-existing Benign lesions
- 2% of patients with Paget’s disease develop ostesarcoma later in life, and these patients do very poorly.
- Osteochondromas, enchondromas and fibrous dysplasia can all give arise to osteosarcoma, but this is very rare, chondrosarcomatous degeneration being more common.
3. Genetic syndromes associated with defects in cell function.
Genetic Syndromes Associated with osteogenic sarcoma:
|Rothmund Thompson syndrome||
Osteosarcomas are cytogenetically highly disrupted tumours with multiple cellular processes involved. Nonetheless, two mechanisms have been quite well established.
Tumour-suppressor gene located at 17p13.1.
Commonly disrupted in osteosarcoma; p53 deficient mice develop osteosarcomas.
Involved in multiple cell processes that control growth and replication as well DNA damage detection and repair and apoptosis. Loss of this central regulator seems important for tumour development
The gene for retinoblastoma protein is found at 13q14.2 and is associated with osteosarcoma (with or without a prior history of retinoblastoma).
Osteosarcomas show Rb gene deletions and rearrangements, altered mRNA expression levels and abnormal retinoblastoma proteins.
Non-germ line mutations of p53 and Rb occur in osteosarcoma