BONE CANCER

Cancer that begins in the bones is primary bone cancer. Cancer may also spread to the bone from other sites and is known as secondary bone cancer.

What causes Bone Cancer?

Most people with bone cancers do not have any apparent risk factors. However the following can factors can be attributed towards bone

*Inherited genes: A very small number of bone cancers appear to be hereditary. Children with this inherited form of retinoblastoma also have an increased risk for developing osteosarcoma. Families with several members that have developed osteosarcome without inherited changes in any of the known genes.

*Radiation: Bone exposure to radiation may also increase the risk of developing bone cancer.

*Paget's Disease: Bone sarcomas are believed to develop in severe cases of Paget disease, usually when many bones are affected.

*Multiple Exostoses: Patients with multiple osteochondromas(multiple swellings of the bone)have an increased risk for chondrosarcomas.

*Bone Marrow Transplantation: Osteosarcoma has been reported in a few patients who have undergone bone marrow (stem cell) transplantation.

Types of Bone Tumours

Primary Bone Tumors:There are several different types of bone tumors. Some primary bone tumors are benign (not cancerous), and others are malignant (cancerous).

Benign Bone Tumors: Benign bone tumors do not spread to other tissues and organs and are not life threatening. Types of benign bone tumors include osteoid osteoma, osteoblastoma, osteochondroma, enchondroma, chondromyxoid fibroma.

Osteosarcoma: Osteosarcoma (also called osteogenic sarcoma) is a cancerous tumor of the bone and is the most common primary bone cancer.

Chondrosarcoma: Chondrosarcoma is a cancer that develops from the cartilage of bones.

Ewing Tumor:This is a cancer of cartilage cells and is the second most common primary bone cancer. Chondrosarcoma is a cancer that develops from the cartilage of bones.

Malignant Fibrous histiocytoma:This is a cancer of cartilage cells and is the second most common primary bone cancer. Chondrosarcoma is a cancer that develops from the cartilage of bones.

Fibrosarcoma and Malignant Fibrous histiocytoma:This is a cancer of cartilage cells and is the second most common primary bone cancer. Chondrosarcoma is a cancer that develops from the cartilage of bones.

Giant Cell tumor of the bone:This is a cancer of cartilage cells and is the second most common primary bone cancer. Chondrosarcoma is a cancer that develops from the cartilage of bones.

Chordoma:This is a cancer of cartilage cells and is the second most common primary bone cancer. Chondrosarcoma is a cancer that develops from the cartilage of bones.

Symptoms

Pain is the most common symptom of bone cancer. However, symptoms may vary depending on the location and size of the cancer. Tumors that occur in or near joints may cause swelling or tenderness in the affected area. Bone cancer can also interfere with normal movements and can weaken the bones, occasionally leading to a fracture. Other symptoms may include fatigue, fever, weight loss, and anemia

Diagnosis

X-rays: The bone at the site of the cancer may appear irregular instead of solid. The cancer can also appear as a hole in the bone. Sometimes a tumor is present around the defect in the bone that may extend into nearby tissues

Computed tomography (CT) : CT scans can also be used to precisely guide a biopsy needle into a suspected metastasis.

Magnetic resonance imaging (MRI): MRI scans are often the best test for outlining a bone tumor.

Chest x-ray: This test may be done to determine whether bone cancer has spread to the lungs.

Radionuclide bone scan: This procedure helps show if a cancer has spread to other bones, and it can find metastases earlier than regular x-rays.

Positron emission tomography (PET or PET scan)

Staging

AJCC Staging System

One system that is used to stage all bone cancer is the American Joint Commission on Cancer (AJCC) system. T stands for features of tumor (its size), N stands for spread to lymph nodes, M is for metastasis (spread) to distant organs, and G is for the grade of the tumor.

T Stages of Bone Cancer

T0: No evidence of the tumor
T1: Tumor is 8 cm (around 3 inches) or less
T2: Tumor is larger than 8 cm
T3: Tumor has "skipped" to another site or sites on the same bone

N Stages of Bone Cancer

N0: No spread to regional (nearby) lymph nodes
N1: The cancer has spread to nearby lymph nodes

M Stages of Bone Cancer

M0: No distant metastasis
M1: Distant metastasis (spread of the cancer to tissues or organs far away from the original bone tumor)

M1a: The cancer has spread only to the lung
M1b: The cancer has spread to other sites


Grades of Bone Cancer

G1-G2: Low grade
G3-G4: High grade

TNM Stage Grouping

Stage IA: T1, N0, M0, G1-G2: The tumor is confined to the bone and is less than 8 cm. It is also low grade.

Stage IB: T2, N0, M0, G1-G2: The tumor is confined to the bone and is larger than 8 cm. It is also low grade.

Stage IIA: T1, N0, M0, G3-G4: The tumor is confined to the bone and is less than 8 cm. It is also high grade.

Stage IIB: T2, N0, M0, G3-G4: The tumor is confined to the bone and is larger than 8 cm. It is also high grade.

Stage III: T3, N0, M0, Any G: The tumor is confined to the bone but has spread to other sites on the bone. (It can be any grade.)

Stage IVA: Any T, N0, M1a, Any G: The tumor has spread to the lung.

Stage IVB: Any T, N1, Any M, Any G: The tumor has spread to lymph nodes and distant sites, OR
Any T, Any N, M1b, Any G: The tumor has spread to distant sites other than the lung.

Treatment:

Treatment options depend on the type, size, location, and stage of the cancer, as well as the person’s age and general health.

Surgery is often the primary treatment. Although amputation of a limb is sometimes necessary, pre- or post-operative chemotherapy has made limb-sparing surgery possible in many cases. When appropriate, surgeons avoid amputation by removing only the cancerous section of the bone and replacing it with an artificial device called a prosthesis

Chemotherapy and radiation may also be used alone or in combination. Because of the tendency for Ewing’s sarcoma to metastasize rapidly, multidrug chemotherapy is often used, in addition to radiation therapy or surgery on the primary tumor

Surgery for bone cancer includes the diagnostic biopsy and the surgical treatment. It is very important that the biopsy and surgical treatment be planned together.

The surgical treatment can be limb-salvage (limb-sparing) surgery (removing the cancer without amputation) or amputation (removing the cancer and all or part of an arm or leg).

Limb-salvage surgery: The challenge for the surgeon is to remove the entire tumor while still preserving the nearby tendons, nerves, and vessels. The bone that is removed is replaced with a bone graft or with an endoprosthesis (meaning internal prosthesis) made of metal and other materials.

Amputation: If the patient has a large tumor that extends into the nerves and/or the blood vessels, it may not be possible to save the limb.

Surgical treatment of metastasis: Bone cancers are not curable without surgery, and this includes the treatment of the metastases. Surgical treatment to remove bone cancer metastases to the lungs must be planned very carefully. However, some lung metastases may not be able to be removed because they are too big or are too close to important structures in the chest (such as large blood vessels) that interfere with the surgery. Patients whose general condition is not good (due to poor nutritional status or problems with the heart, liver, or kidneys) may not be able to withstand the stress of anesthesia and surgery to remove metastases.

Curettage

This procedure involves scooping out the tumor from the bone, without removing a section of the bone. For cryosurgery, liquid nitrogen is poured into the cavity of the bone from which the tumor was removed. This extremely cold material kills tumor cells by freezing them. The cavity in the bone remaining after curetting can be filled by bone grafts or by a polymethylmethyacrylate (PMMA).

Radiation therapy uses high-energy rays or particles to kill cancer cells. External beam radiation therapy uses radiation delivered from outside the body that is focused on the cancer. However, bone cancers are not easily killed by radiation. Radiation therapy does not play a major role in the treatment of most types of bone tumors. Radiation therapy may be useful, however, in some cases where the tumor cannot be completely removed by surgery.

Chemotherapy is the use of drugs for treating cancer. Chemotherapy is useful for bone cancer that has spread through the bloodstream to the lungs and/or other organs. Except for Ewing sarcoma and osteosarcoma, chemotherapy is seldom used for bone cancer unless it has spread. The drugs mainly used to treat bone cancer include:

doxorubicin (Adriamycin)

cisplatin or carboplatin

etoposide

ifosfamide

cyclophosphamide

Usually, several drugs (2 or 3) are given together. For example, a very common combination is doxorubicin and cisplatin. Another combination is ifosfamide and etoposide.


source: http://www.webhealthcentre.com/healthcorners/cancer_bone.aspx