Bone cancer is an abnormal growth of cells that occurs in the bones. There are two main forms: primary cancer starts within the actual bone itself and is quite rare, while secondary is caused by cancer elsewhere in the body spreading to the bones. It should not be confused with leukemia, which is cancer of the bone marrow.
In the body, old cells are continually being broken down and replaced with new ones. If there is an abnormality in the new cell, causing it to grow and replicate much more quickly than normal, a tumor may develop. There are both benign and malignant tumors that grow in the cells. Benign tumors are not cancerous and will not spread to other tissues, while malignant ones will. Benign tumors can often be removed through surgery.
There are several different types of primary bone cancer, named based on what type of bone cell has the cancer and the area of the bone or surrounding tissue where it is found. Each type has different characteristics and is treated differently. Malignant cancers are commonly called sarcomas.
The most common type of bone cancer is osteosarcoma, which starts in cells that are growing new bone tissue. It is most commonly found in the knees, arms, or pelvis. This form of cancer often develops in young people under the age of 30, in males more than females. It is rare in middle age and has a very low incidence in adults in their 60s and 70s. Osteocarcoma usually spreads to other parts of the body, particularly the lungs.
Chondrosarcoma is the second most common type, and it starts in the cartilage cells, so it can develop anywhere this tissue is found. In most cases, this is a slow growing cancer, so it is unlikely to spread to other parts of the body before being treated. Chondrosarcoma is rare in young people, but the risk increases from age 20 up to about 75. Men and women have an equal chance of developing it.
The third most common type of primary bone cancer is Ewing’s Sarcoma. This form tends to start within the cavities of bones, particularly the legs, pelvis and chest wall, but it can grow in other tissues. It is most common in children and adults under the age of 30. The cancer grows very quickly, allowing it to spread to other organs and tissues throughout the body.
Chordomas are found in the base of the skull or the vertebrae that make up the spine. This type of cancer tends to be slow-growing, but if not treated carefully and completely removed, it will come back repeatedly to the same area. It is uncommon in people under 30 and men are about twice as likely as women to develop it.
There is no single factor that can be said to cause bone cancer. While cancers are often diagnosed after an injury to a bone, the injury is not the cause — just an indicator. There are several risk factors for developing this form of cancer, including having a genetic disposition for it, having had benign bone tumors or non-cancerous bone disease, and undergoing previous radiation or chemotherapy treatment, especially when young. Some people will develop primary tumors without having any of these risk factors.
The most common symptom is pain in the affected area. Initially, the pain may be intermittent, but as the tumor grows, it will become worse and occur more often. Swelling may occur around the cancer, usually weeks after the pain has started. Because of the location of the tumor, it is often difficult to feel any actual lump. Detecting this cancer is not easy, and it is often diagnosed through a biopsy of the painful area.