There are two different types of bone cancer. The first is primary bone cancer, which is cancer that starts in the bone. The second is secondary bone cancer, which occurs when cancer in another body part has spread, or metastasised, to the bones. People with breast cancer, lung cancer or prostate cancer are especially prone to bone metastases. Cancer can metastasise to several different parts of the bone.
Just as cancer can originate at other body parts and metastasise to the bone, bone cancer also can metastasise to other body parts. Primary bone cancer which has not spread is referred to as localised bone cancer, and generally has a much higher survival rate than bone cancer which has spread to other sites on the body.
The prognosis for primary bone cancer and secondary bone cancers differ. Additionally the prognosis for primary bone cancers differ, depending on what stage at diagnosis and the treatment.
Types of Primary Bone Cancer
The body has more than 200 bones, and any individual bone or set of bones within the body can be affected by bone cancer. However, there are several common types of bone cancer which tend commonly to affect specific bones within the body. Osteosarcoma, which primary strikes children and young adults, is most commonly found in the knee bones or surrounding areas. Osteosarcoma begins to develop in new tissue, called osteoid, in growing bones.
A second common type of bone cancer, Ewing's sarcoma, again primarily strikes children and young adults. Doctors believe Ewing's sarcoma develops in immature nerve tissue in the bone. Ewing's sarcoma primarily affects bone in the upper leg and pelvis.
Approximately 20 per cent of all bone cancers are referred to as Chondrosarcoma, which generally originates in the pelvis, ribs, or upper thigh, although it can also be found below the knees or elbows. Chondrosarcoma, which primarily affects adults, usually begins in cartilage, although it can also originate within a bone or along the surface of a bone. Chondrosarcoma primarily targets adults between the ages of 40 and 75. Rare cases diagnosed in young people are referred to as mesenchymal-chondrosarcoma.
Chordoma, malignant fibrous histiocytoma--which typically originates in the legs and arms--and firbosarcoma are also mostly seen in adults and rarely in children.
Factors Affecting Prognosis for Primary Bone Cancer
There are several factors affecting prognosis for primary bone cancer. Localised bone cancers generally have a better prognosis than metastatic bone cancer. The most important factors are the type and location of the bone cancer; the stage of the disease; whether the disease is in one site or many; whether it has metastasised to other sites or other body parts; the grade of the cancer (how much the cells deviate from normal, the speed at which the cells multiply), and the patient's general health and response to treatment.
Other important factors include how long the patient had symptoms, including fatigue and pain at the site of the cancer, and how much of the cancer can be removed by surgery or killed by chemotherapy.
5 Year Survival Rates for Localized Primary Bone Cancer
While the survival rates vary, progress is being made to greatly improve the survival rates for the most common types of bone cancer.
For example, experimental therapies tested in 2007 by Holcombe E. Grier of Dana-Farber Cancer Institute and Boston Children's Hospital, demonstrated that Ewing's sarcoma patients with localised bone cancer--cancer in one particular site--had as much as a 72 per cent survival rate, up from the 61 per cent with previous treatments.
The survival rate for osteosarcoma can be as high as 70 per cent to 75 per cent for localised primary bone cancer.
Long term survival rate for those with chondrosarcoma is generally between 50 per cent and 75 per cent.
Survival Rates for Primary Bone Cancer That Has Metastasized
Once primary bone cancer metastasises to other parts of the body, survival rates diminish greatly. This occurs because the cancer can no longer be treated or eliminated by removing the tumour and cancer cells within the bone.
Survival rates vary dramatically depending on where the cancer metastasises to. Metastases to the nerves or blood vessels may be treated by amputating the affected limbs. Metastases to the lungs or breast is far more serious and carries relatively low 5-year survival rates, which vary depending on the extent of the metastases.
Survival Rates for Secondary Bone Cancer
Survival rates for secondary bone cancer depend on the extent of the metastases to the bone, other sites of metastases and the type of primary cancer. Generally, widespread metastases to the bone has a poor prognosis and very low survival rates. In addition, metastases to the bone often has symptoms which adversely affect daily living, including pain at the metastases site and/or elevated calcium levels in the bloodstream, leading to symptoms including delusions, kidney stones or even death.