Most bone tumours encountered in clinical practice are secondaries (i.e. metastases from primary cancer that started elsewhere), and it is a layman’s misnomer to refer to these as ‘bone cancer’. The doctor reserves this term to those tumours of bone which arise in the bone ab initio. The point is of importance as the methods and data outlined below do not apply to bone secondaries/metastases.
Primary bone tumours include osteogenic sarcoma (arising from the true bone forming cell) Ewing’s sarcoma (arising from a primitive pluripotential cell), chondrosarcoma (arising from the cartilage forming cell line)and other rare forms of sarcoma (e.g. malignant fibrous histiocytoma).
Primary bone lymphoma will not be considered here , nor the sarcomas which are more commonly associated with soft tissues such as bone and connective tissue – see Soft Tissue Sarcoma Section.
Osteogenic sarcoma occurs with two peak incidences in life: the first is in adolescence (when the bones are actively growing) and the second is in late life when it is not infrequently associated with Paget’s disease of bone. Exposure to radiation predisposes to the later development of osteogenic sarcoma, and some patients with familial syndromes (par excellence those with hereditary retinoblastoma – but see introductory remarks concerning soft tissue sarcomas for others) are predisposed.
Ewing’s sarcoma tends to present in youth and is very unusual over the age of 40 years.
Both osteogenic sarcoma and Ewing's sarcoma are less common in people of African extraction.
Chondrosarcomas, whilst certainly afflicting the young, are overall more common in later life again two peaks of age incidence.
