Bone cancer

What is bone cancer?

Primary bone cancer, where the tumour develops from bone cells, is very rare - about 500 cases are diagnosed in the UK each year (only about one in every 500 cancers).

There are several different types, depending on the type of bone cells involved:

• Osteosarcoma, which often affects the large bones of the leg or upper arm, is the most common form
• Chondrosarcoma, formed from the cells that normally produce cartilage
• Ewing's sarcoma, usually in the pelvis, thigh or shin
• Spindle cell sarcoma

Bone cancer causes

Unlike most cancers, bone cancer tends to affect the young. Osteosarcoma usually appears in children and young adults, while Ewing's sarcoma is most common between the ages of 10 and 20.

Other risk factors include:

• Previous radiotherapy treatment, especially at a young age. Some chemotherapy drugs also increase the risk of osteosarcoma
• As many as one in eight people who develop a tumour of the eye will go on to develop an osteosarcoma, possibly because of a genetic susceptibility to both conditions and the additional effect of anti-cancer treatments
• Genetic conditions linked to bone tumours including Li-Fraumeni syndrome, HME, inherited breast cancer and congenital umbilical hernia (Ewing's sarcoma is three times more common in children with this condition)
• Paget's disease, a bone disease that generally occurs in older people and increases the risk of osteosarcoma, as does another bone condition called chondroma
• Bone cancer has often been linked to injuries to a limb, but it's questionable and may simply be that the injury draws attention to a tumour that was already growing

Many primary cancers can spread to bones, in particular breast, prostate, lung, thyroid and kidney cancer.

Because the cancer is formed from the primary cells, such as breast or lung cells, it has to be treated with drugs, radiotherapy or other treatments that would usually be used to target the primary cancer. If you're affected by secondary bone cancer, always check information on the primary cancer first.

Bone cancer symptoms

The symptoms of bone cancer depend where the tumour grows (about half occur in or near the knee). By the time a lump or swelling is detectable, the cancer may have been present for some time.

Pain, especially at night, is a common problem and may cause a limp if the leg is affected, because weight-bearing is uncomfortable or the cancer interferes with the way the joints work.

There may also be generalised symptoms such as weight loss, sweats, fever and lethargy or tiredness. Sometimes, bone cancer is discovered incidentally - when an x-ray is taken after an accident, for example - or occasionally when the bone breaks due to weakness caused by the cancer.

Diagnosing bone cancer

X-rays that suggest cancer may show areas of bone destruction, new bone growth, swelling and changes in the surrounding soft tissues. Further tests may include a bone scan (involving the injection of a radioactive substance to show up the bones clearly), MRI and other scans.

Ultimately, a biopsy is necessary to obtain sample of cells that can be studied under the microscope. Specialists usually carry out bone biopsies by placing a needle through the skin into the bone and drawing out some cells.

Bone cancer treatments

Treatment will depend on an assessment of what type of cancer is present and how far it has spread. This is called staging and involves a combination of the grade of the cancer (a measure of how abnormal the cells look under the microscope and therefore how aggressive) and whether it has spread either locally or to another organ in the body.

Bone cancer that hasn't spread outside the bone may be treated with surgery and may not require chemotherapy. More abnormal bone cancer that has spread will be more difficult to treat, and chemotherapy as well as surgery is usually recommended.

In general, treatment of bone cancer has a good outlook, especially if it's in the early stages and can be completed during surgery. About two-thirds of people with primary bone cancer can be cured. But if the cancer is more advanced or has spread, the prognosis may not be so good, with five-year survival rates of only 10-20 per cent. It's vital that you talk to your specialist to get a picture of how successful treatment is likely to be in your individual case.

Treatment usually consists of surgery often combined with chemotherapy to shrink the tumour and make it less likely to recur. Because surgery involves removing bone, it can be quite drastic. Where possible, the surgeon will try to replace the diseased bone with a graft of bone from elsewhere in the body or an implant, but sometimes amputation is necessary.

Some bone cancers, such as Ewing's sarcoma, respond well to chemotherapy and other treatments such as radiotherapy.

Newer biological therapies based on natural body chemicals such as interferon are also being used. These may work, for example, by encouraging the body's immune system to attack the cancer cells. A number of different research trials are looking at different combinations of these treatments in an effort to improve results.

After initial treatment, regular follow-ups are essential to check for recurrences and to manage the consequences of treatment, such as the use of an artificial limb.