The cause of bone tumors is unknown. They often arise in areas of rapid growth. Possible causes include inherited mutations, trauma, and radiation, but in most cases no specific cause is found. Bone tumors may be benign or malignant. Osteochondromas are the most common benign bone tumors, and occur most often in people between the ages of 10 and 20. Some benign bone tumors go away on their own and do not require treatment. These benign tumors are monitored periodically by x-ray. Malignant bone tumors occur as a primary bone tumor or as metastasis (cancer spread from another area of the body). Primary bone tumors are rare (less than 1% of all malignant tumors) and are most common in young men. Malignant bone tumors include osteosarcomas, Ewing's sarcoma, fibrosarcoma, and chondrosarcoma. The most common cancers that spread to the bone are cancer of the breast, lung, prostate, kidney, and thyroid. These forms of cancer usually affect older people. Bone cancer was once prevalent among individuals who painted radium on watch faces (to produce glow-in-the-dark dials). The painter would 'tip' the brush with their tongue (in order to produce fine work) and absorb minute amounts of radium, which deposited in the bone and caused cancer. The practice of using radium paint was abandoned in the middle of the 20th century. The incidence of bone cancer is also increased in families with familial cancer syndromes. The incidence of bone cancer in children is approximately 5 cases per million children each year. | 
Orthopaedic Oncology
