By Val Stockdale, RT (Orthopaed)

As we all know, bones support and protect internal organs, act as levers and braces for muscles to move, and produce and store blood cells in the bone marrow.

What is the cause of bone cancer?
The actual cause of bone cancer is unknown. It often arises in areas of rapid growth. Possible causes include inherited mutations, trauma, and radiation but, in most cases, no specific cause is found. Bone tumours may be benign or malignant.

Bone cancer was once prevalent in people who painted radium on watch faces to produce a glow-in-the-dark dial. They used to "tip" the brush with their tongue to produce fine work, absorbing minute amounts of radium that deposited in the bone. Radium paint was abandoned in the middle of the 20th century.

Osteochondromas are the most common benign bone tumour, occurring in people between the ages of 10 and 20. and found most commonly in the knees, upper legs and upper arms. Most benign bone tumours go away on their own and are monitored by periodic x-rays. These bone tumours do not spread, are not life threatening, and are cured by surgery.

Malignant bone tumours occur as a primary bone tumour or as metastasis spread from another area of the body. Malignant bone tumours include osteosarcomas, Ewing's disease, fibrosarcoma, and chondrosarcoma. The incidence of bone cancer is increased in families with familial cancer syndromes. In children, the incidence is about five cases per million children. The most common cancers that spread to the bone are cancer of the breast, lung, prostate, kidney and thyroid, and usually affect older people.

The main type of cancers that are true bone cancers are called sarcomas. Sarcomas are cancers that start in the bone, muscle. fibrous tissue, blood vessels and fat tissue. They can develop anywhere in the body.