Bone Cancer (Chondrosarcoma of Cartilage)What is Bone Cancer
Chondosarcoma of Cartilage is characterised by one or more tumours of the cartilage.
Cartilage is a highly specialised avascular form of connective tissue. It consists of chondrocytes and the extracellular matrix that they produce. It is solid and firm but also pliable - rendering cartilage a highly resilient tissue.
Cartilage is a key tissue in the development and maintenance of most bones in the body. During foetal development, the long bones of the body develop from cartilage models. In adults, cartilage forms the articular surface of many joints and the rings of the trachea. There are three different types of cartilage classified on the basis of the extracellular matrix: hyaline, elastic and fibrocartilage.
Who gets Bone Cancer?
This type of bone cancer is uncommon, accounting for only 20% of primary bone malignancies (0.2% of total). Chondrosarcomas are a group of tumours ranging from slow-growing non-metastasising lesions to high grade malignancies and occurs with increasing age. Peak incidence of chondrosarcoma is in the 4th to 6th decades. However, the clear cell and mesenchymal variants can occur in younger patients with sex incidence being a 2:1 male predominance.
Geographically, this bone cancer tumour is found worldwide.
Predisposing Factors
Increasing age, being of the male sex and the presence of a pre-existing enchondroma (benign tumours of hyaline cartilage occurring within the medullary cavity) - although only 10% of chondrosarcomas arise in these pre-existing lesions.
Progression
This type of bone cancer tumour spreads by direct extension into adjacent tissues with characteristic scalloping on x-rays due to the nodular growth patterns of the lesions. When metastases occur, they tend to be to the lungs and other bones.
Other sites can include regional lymph nodes (more common in mesenchymal chondrosarcoma), skin and soft tissues.
Probable Outcomes
A crucial prognostic factor in bone cancer is tumour grade. The majority of conventional chondrosarcomas tend to be of low grade and are thus associated with an improved prognosis. Ten year survival rates are 83% for grade I, 64% for grade II and 29% for grade III.
Tumour size also plays an important role in bone cancer prognosis with smaller lesions behaving less aggressively than larger bone cancer tumours (irrespective of grade). Therefore, early bone cancer diagnosis and bone cancer treatment are associated with an improved prognosis. Unfortunately, these tumours often present as gross, unresectable masses.
How is Bone Cancer Diagnosed?
General investigations into bone cancer may show anaemia or low platelet count if bone marrow is involved. Abnormal alkaline phosphatase levels may also be found.
How is Bone Cancer treated?
Most chondrosarcoma are resistant to chemotherapy, so treatment of these bone cancer tumours revolves around wide surgical excision where clinically possible.
Chemotherapy is advocated in the treatment of the histological variants, mesenchymal and dedifferentiated tumours, but its role in the treatment of conventional chondrosarcoma remains to be defined.
Radiotherapy is used in bone cancer patients where the primary tumour is not resectable.
Improvement in bone cancer symptoms is an important measurement. Specific monitoring may be by serial imaging to detect any recurrence or metastatic spread.
The bone cancer symptoms that may require attention are somatic pain from bone metastases, visceral pain from lung metastases and neurogenic pain if nerve tissue is compressed. Coughing and breathlessness from lung involvement may require specific treatment.
(Source: David Dalley, St Vincent's Hospital).
Bone Cancer References
[1] Flemming DJ, Murphey MD: Enchondroma and chondrosarcoma. Semin Musculoskelet Radiol 2000; 4(1): 59-71
[2] Healey JH, Lane JM: Chondrosarcoma. Clin Orthop 1986 Mar; (204): 119-29
[3] Murphey MD, Flemming DJ, Boyea SR, et al: Enchondroma versus chondrosarcoma in the appendicular skeleton: differentiating features. Radiographics 1998 Sep-Oct; 18(5): 1213-37; quiz 1244-5
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