What Is Bone Cancer? What Causes Bone Cancer?

Bone cancer can be primary bone cancer or secondary bone cancer. Primary bone cancer started in the bone; the cancer initially formed in the cells of the bone, while secondary cancer started elsewhere in the body and spread to the bone. Examples of primary bone cancer include steosarcoma, Ewing sarcoma, malignant fibrous histiocytoma, and chondrosarcoma.

According to the National Cancer Institute, USA, it is estimated that by the end of 2010 there will have been 2,650 new cases and 1,450 deaths from cancer of the bones and joints. The National Health Service (NHS), UK, informs that primary bone cancer accounts for 1 in every 500 cancers in the United Kingdom. There are approximately 500 cases of bone cancer each year in the UK, making this kind of cancer a fairly rare one.

Primary bone cancer (tumor) - these can be divided into benign tumors - which can have a neoplastic (abnormal tissue growth), developmental, traumatic, infectious, or inflammatory cause - and cancers.

Examples of benign bone tumors include - osteoma, osteoid osteoma, osteochondroma, osteoblastoma, enchondroma, giant cell tumor of bone, aneurysmal bone cyst, and fibrous dysplasia of bone.

Examples of malignant primary bone tumors include: osteosarcoma, chondrosarcoma, Ewing's sarcoma, malignant fibrous histiocytoma, fibrosarcoma, and other sarcomas. Multiple myeloma is a blood cancer which may include one or more bone tumors. Teratomas and germ cell tumors are frequently located in the tailbone.

Osteosarcoma is the most common type of bone cancer. It usually develops in children and young adults. After leukemia and brian tumors, osteosarcoma is the third most common cancer among for children in the UK and the USA.

Ewing sarcoma usually develops in the pelvis, shin bone or thigh bone. 90% of patients develop this type of cancer when they are less than 20 years of age.

Chrondrosacroma usually develops in adults. It starts in the cartilage cells and moves on to the bone.

The outlook for a patient with malignant bone cancer depends mainly on whether it has metastasized (spread to other parts of the body). If the cancer is localized (has not spread), prognosis is usually good.

What are the signs and symptoms of bone cancer?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor notice. For example, pain may be a symptom while a rash may be a sign.

The patient initially experiences pain in the affected area. Over time the pain gets worse and continuous. In some cases the pain is subtle and the patient may not see a doctor for several months. The progression of pain with Ewing sarcoma tends to be faster than in most other bone cancers. Typically, bone cancer pain is deep, nagging and has a permanent character.

There may also be swelling in the affected area.

Often the bone will weaken, resulting in a significantly higher risk of fracture.

The patient may find he/she loses weight unintentionally.

A mass (lump) may be felt in the affected area.

Although much less common, the patient may also experience fever, chills and/or night sweats.

What are the causes of bone cancer?

Nobody knows in general what the causes of bone cancer are. Patients with chronic (long-term) inflammatory diseases, such as Paget's disease are at a significantly higher risk of developing bone cancer later on in life. However, nobody can explain why one person gets bone cancer while another one doesn't. It is not contagious - you cannot catch it from someone else.

The following groups of people may be at a higher risk of developing bone cancer (risk factors):

• Being a child or very young adult - most cases of bone cancer occur in children or young adults aged up to 20.
• Patients who have received radiation therapy (radiotherapy).
• People with a history of Paget's disease.
• People with a close relative (parent or sibling) who has/had bone cancer.
• Individuals with hereditary renoblastoma - a type of eye cancer that most commonly affects very young children.
• People with Li-Fraumeni syndrome - a rare genetic condition.
• Babies born with an umbilical hernia.

How is bone cancer diagnosed?

A GP (general practitioner, primary care physician) may order a blood test to rule out other possible causes for the patient's symptoms. The patient will then be referred to a bone specialist (orthopedic surgeon). The following diagnostic tests may be ordered:

• Bone scan: a liquid which contains radioactive material is injected into a vein. This material collects in the bone, especially in abnormal areas, and is detected by a scanner. The image is recorded on a special film.
• Computerized tomography (CT): the CT scanner uses digital geometry processing to generate a 3-dimensional (3-D) image of the inside of an object. The 3-D image is made after many 2-dimensional (2-D) X-ray images are taken around a single axis of rotation - in other words, many pictures of the same area are taken from many angles and then placed together to produce a 3-D image. It is a painless procedure. CT scans are commonly used to see whether the bone cancer has spread and where it has spread to.
• Magnetic resonance imaging (MRI): the device uses a magnetic field and radio waves to create detailed images of the body, which in this case would be a specific bone or part of a bone. Most MRI machines look like a long tube, with a large magnet present in the circular area. When beginning the process of taking an MRI, the patient is laid down on a table. Then depending on where the MRI needs to be taken, the technician slides a coil to the specific area being imaged. The coil is the part of the machine that receives the MR signal.
• Positron emission tomography (PET): a PET scan uses radiation, or nuclear medicine imaging, to produce 3-dimensional, color images of the functional processes within the human body. The machine detects pairs of gamma rays which are emitted indirectly by a tracer (positron-emitting radionuclide) which is placed in the body on a biologically active molecule. The images are reconstructed by computer analysis.
• X-rays: this type of scan can detect damage the cancer may have caused to the bone. It may also detect new (bone) cells that have started to form around the tumor. An x-ray does not provide enough data for a definitive diagnosis, but can help the surgeon decide whether further tests are recommended.
• Bone biopsy - a sample of bone tissue is extracted and examined for cancer cells. This is the most reliable way to diagnose bone cancer. A core needle biopsy involves inserting a long, thin needle into the bone and removing a sample, while an open biopsy involves making an incision in the target bone area and surgically removing a sample of tissue.

Staging the bone cancer Bone cancer is has different stages which describe its level of advancement.

• Stage I - the cancer has not spread out of the bone. The cancer is not an aggressive one.
  
• Stage II - same as Stage I, but it is an aggressive cancer.
  
• Stage III. Tumors exist in multiple places of the same bone (at least two).
  
• Stage IV. The cancer has spread to other parts of the body.

What is the treatment for bone cancer?

The type of treatment for bone cancer depends on several factors, including what type of bone cancer it is, where it is located, how aggressive it is, and whether it is localized or has spread. There are three approaches to bone cancer:

• Surgery
• Chemotherapy
• Radiotherapy (radiation therapy)

Surgery - the aim is to remove the tumor, all of it if possible, and some of the bone tissue that surrounds it. If some of the cancer is left behind after surgically removing the tumor it may continue to grow and eventually spread. Limb sparing surgery, also known as limb salvage surgery means that surgical intervention occurs without having to amputate the limb. The surgeon may take some bone from another part of the body to replace lost bone (bone graft), or an artificial bone may be put in. In some cases, however, amputation of a limb may be necessary.

Radiation therapy - also known as radiotherapy, radiation oncology and XRT. Approximately 40% of patients of all types of cancer undergo some kind of radiotherapy. It involves the use of beams of high-energy X-rays or particles (radiation) to destroy cancer cells. Radiotherapy works by damaging the DNA inside the tumor cells, destroying their ability to reproduce. Radiotherapy can be used for different reasons:

• Total Cure - to cure the patient by completely destroying the tumor.
• To alleviate symptoms - radiotherapy is often used to relieve pain in more advanced cancers.
• Neo-adjuvant radiotherapy (before surgery) - if a tumor is large, radiotherapy can shrink it, making it easier and less harmful to then surgically remove it.
• Adjuvant radiotherapy - given after surgery. The aim is to eliminate the cancer cells that remained behind.
• Combination therapy (radiotherapy combined with another type of therapy) - in some cases, chemoradiation - radiotherapy combined with chemotherapy - is more effective.

Chemotherapy - the use of chemicals (medication) to treat disease - more specifically, it usually refers to the destruction of cancer cells. Cytotoxic medication prevents cancer cells from dividing and growing. In general, chemotherapy has 5 possible goals:

• Total remission - to cure the patient completely. In some cases chemotherapy alone can get rid of the cancer completely.
• Combination therapy - chemotherapy can help other therapies, such as radiotherapy or surgery have more effective results.
• Delay/Prevent recurrence - chemotherapy, when used to prevent the return of a cancer, is most often used after a tumor is removed surgically.
• Slow down cancer progression - used mainly when the cancer is in its advanced stages and a cure is unlikely. Chemotherapy can slow down the advancement of the cancer.
• To relieve symptoms - also more frequently used for patients with advanced cancer.

What is phantom limb pain?

Also known as phantom limb syndrome - the patient feels sensations, often of pain, in a limb that has been amputated; the limb is no longer there. The brain still receives messages from the nerves that originally carried impulses from the missing arm or leg.