Primary malignant bone tumors are rare and primarily affect children. Out of 1,000 new cases per year, more than two in three occur in under-18s. In children, 80% of bone cancers are osteosarcomas, which affect the long bones in the knee, femur and tibia. Boys are more affected than girls.
The second most common type of malignant bone tumor is Ewing’s sarcoma. 95% of 100 cases per year are caused by a gene change: translocation between chromosomes 11 and 22.
Secondary bone cancers are a lot more common than primary bone cancers because 60% of cancers cause bone metastases. They generally appear in the first three years following diagnosis of a primary cancer; often lung, breast, kidney, prostate and thyroid cancer. Bone metastases more commonly occur in the spine and pelvis, although they can affect any bone in the body.
In most cases, intense pain points to the presence of bone metastases. The pain increases gradually and intensifies at the end of the night. While the pain of benign tumors remains moderate and can be relieved by conventional painkillers, the pain caused by primary or secondary malignant tumors is harder to alleviate.
Other warning signs include a suspect lump, a sudden fracture, decreased sensitivity, reflexes and muscle strength, and paralysis. These warning signs tend to be combined with significant weight loss, tiredness and sometimes a fever.
Diagnosis generally occurs at a localized stage for 42% of primary bone cancers, while 15% of cancers are diagnosed when they have reached stage IV (with metastases). A blood and/or urine test will highlight anomalies, an inflammatory syndrome and specific tumor markers. A standard x-ray and a bone scan may be supplemented by imaging using MRI or a PET scan.
Bone cancer treatment tends to be local and general (chemotherapy, hormone therapy and targeted therapy) in order to prevent any complications. At a local level, surgery removes the tumor and the bone is strengthened using a prosthesis. A bone graft and blood transfusions are also sometimes needed.
Drugs also help reduce the risk of fractures and pain. The prognosis for osteosarcomas has considerably improved over the past few years.
These malignant bone tumors can be cured without the cancer ever reoccurring. On average, the cancer reappears 30 months after diagnosis. Complications occur in 4-10% of local reoccurrences. Amputation of the limb cures the cancer in one in two cases.
La Ligue contre le cancer, Le cancer des os