What is bone cancer?

Bone cancer refers to a malignant bone tumour that affects human bone tissue, degenerates cells and destroys the surrounding healthy tissue. Doctors distinguish between the three most common forms of bone cancer, osteosarcoma, chondrosarcoma and Ewing's sarcoma. The cancer cells can be deposited in other organs via the lymphatic system or the bloodstream and form metastases there. The earlier bone cancer is detected, the better the chances of cure.

The most common types of bone cancer

Doctors distinguish between the following three types of malignant bone cancer, which are the most common:

• osteosarcoma: occurs in the bone (mainly the long bones in the upper arms or thighs) and is more common than average in male adolescents between the ages of 10 and 20.
• ewing's sarcoma: occurs in the bone marrow (mainly in the shaft of the long bone in the pelvic bone or leg) and is equally common in boys and girls and occurs mainly between the ages of 10 and 15.
• chondrosarcoma: occurs in the cartilage (mainly in the pelvis, thigh or shoulder region) and is particularly common in adults between the ages of 30 and 50.

There is also the so-called primary bone cancer. This is a rather rare type of cancer that develops directly in the bone tissue. Only about 700 patients are diagnosed with primary bone cancer in Germany every year, which is about one per cent of all malignant cancers.

Bone metastases, on the other hand, occur more frequently. This includes tumour diseases that have developed from other cancer foci in the body, which is why it is also called secondary bone cancer. These tumours mainly include lung, breast, prostate, kidney and thyroid cancers that metastasise to the bones. Secondary bone cancer usually develops over several years and occurs mainly in the second half of life.

How does bone cancer develop?

The exact causes of bone cancer are still unknown to doctors. The fact that malignant bone cancer is particularly common in childhood and/or during puberty is explained by growth-related and hormonal factors. These could also play a role in the development of bone cancer. In addition, there are the following risk factors that can cause bone cancer to develop:

• a genetic disposition,
• a history of Paget's disease in the bones,
• radiation therapy or chemotherapy that was necessary because of another cancer,
• a retinoblastoma (retinal tumour) significantly increases the risk of a bone tumour

What are the symptoms of bone cancer?

Bone cancer usually manifests itself through the following rather unspecific symptoms, which can vary greatly depending on the type of tumour, tumour size and the location of the tumour:

• Pain in the affected area where the bone cancer has formed,
• Skin swelling, which can be accompanied by pain on movement.

Patients suffering from osteosarcoma often complain of painful swellings, which can even affect the mobility of the affected limbs. Since the bone loses its strength due to the malignant tumour, even a normal load can lead to a bone fracture. Patients should therefore have such spontaneous bone fractures, which occur without any major external force, medically clarified.

If it is a Ewing's sarcoma, on the other hand, pain and swelling can occur in the affected area, as well as a strong feeling of illness, which can be accompanied by fever. These symptoms can resemble inflammation of the bone marrow. Chondrosarcoma, on the other hand, is more likely to go unnoticed, causing hardly any symptoms.

How is bone cancer diagnosed?

If bone cancer is suspected, the doctor will first take the patient's medical history and then carry out an X-ray examination. If the initial suspicion is then confirmed, further imaging procedures such as an MRI (magnetic resonance imaging) and/or a CT (computerised tomography) will be ordered. If the doctor also suspects that the tumour has already spread to other parts of the body, a scintigraphy, an imaging procedure in nuclear medicine, can also be carried out. A blood test can also provide information about whether certain enzymes are elevated. This is especially the case with osteosarcoma or Ewing's sarcoma.

To finally confirm the diagnosis, a biopsy must be taken to determine whether the bone tumour is benign or malignant. To do this, a tissue sample is taken from the bone with a needle and examined in the laboratory.

How is bone cancer treated?

Bone cancer is treated according to the type of tumour, its size and spread. In general, the oncologist has the following treatment options at his or her disposal:

• Surgery: in which whole bone parts and, under certain circumstances, the surrounding tissue are removed and stabilised by incorporated foreign materials such as screws and plates. In rare cases, amputation may also be necessary.
• Chemotherapy: can be used in combination with surgery, for example, and usually aims to reduce the size of the tumour so that it can be removed surgically.
• Radiation: is an important part of the therapy for Ewing's sarcoma.

What is the prognosis for bone cancer?

The chances of a cure for bone cancer depend on the type of tumour, the size and spread of the tumour, and its stage. Even after successful treatment, however, it can never be completely ruled out that the tumour will not form again (recurrence). As with other types of cancer, the chances of cure increase depending on how early the cancer was diagnosed and treated. If osteosarcoma is diagnosed early enough, the chances of a cure are good. If the osteosarcoma has not yet metastasised, the chance of survival five years after diagnosis is over 60 percent. If, on the other hand, metastases have already formed, the prognosis is far less favourable. The same applies to Ewing's sarcoma. With this type of bone cancer, however, the chance of survival five years after diagnosis is lower than with osteosarcoma. Chondrosarcoma, on the other hand, has a particularly poor prognosis. The chance of survival five years after diagnosis is less than 50 per cent.