Cancer is a group of many related diseases. All cancers begin in cells
, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor
Tumors can be benign or malignant.
Benign tumors are not cancer.
Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer.
They are generally more serious. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original (primary) tumor to form new tumors in other organs. The spread of cancer is called metastasis.
Benign bone tumors are more common than malignant ones. Both malignant and benign bone tumors compress healthy bone tissue, however, benign tumors will not spread, will not destroy bone tissue, and very rarely threaten life.
These tumors - osteoid osteoma, osteoblastoma, osteochondroma, enchondroma and chondromyxoid - are generally cured by surgery.
Also, quite often, bone cancer is the result of metastasis
- meaning, a cancer from elsewhere has migrated to the bone. These cancers show the original cancerous cells and not those associated with bone cancer. In these cases, the cancer is treated by following the original course of treatment for the initial tumor.
However, there are malignant cancers of the bone although they are quite low, composing only around 1% of those diagnosed. Because bones are composed of osteoid
(hard or compact), cartilaginous
(tough, flexible), fibrous
(threadlike) tissue, and bone marrow
(soft, spongy tissue in the center of most bones) the types differ. Following are the most common types of bone cancer:
- this cancer, one of the primary and most common bone tumors, arises from osteoid tissue in the bone and is most often found in the knee and upper arm. It is most often found in young people (aged 10-30) but also can be exhibited in older people (aged 60-70.)
- this type begins in cartilaginous tissue, which is found at the end of bones and lines the joints. These tumors are most often found in the pelvis, upper leg, and shoulder. Occasionally, chondrosarcoma will develop in the trachea, larynx, or chest wall. Sometimes a chondrosarcoma contains cancerous bone cells. In that case, doctors classify the tumor as an osteosarcoma.
Also, chondrosarcomas have different features, which can lead to a different prognosis:
- these begin as typical chondrosarcomas but then some parts of the tumor change into cells like those of an osteosarcoma or fibrosarcoma.
Clear Cell Chondrosarcoma
- this type grows slowly and rarely spreads to other parts of the body.
- these can grow rapidly but are sensitive to treatment with radiation and chemotherapy.
The Ewing Sarcoma Family of Tumors (ESFTs)
- these normally appear in the bone but can be found in soft tissue such as muscle, blood vessels and fibrous tissues. ESFTs occur most commonly along the backbone and pelvis and in the legs and arms.
Malignant Fibrous Histiocytoma
- this type often starts in "soft tissue" (connective tissue) rather than in bones. However, when it develops in bones, normally it affects the legs or arms and grows quickly while also spreading to other parts of the body, like the lungs and lymph nodes.
Giant Cell Tumor Of Bone
- This cell tumor develops in both benign and malignant forms. The benign form is most common. Giant cell bone tumors typically affect the leg or arm bones of young and middle-aged adults.
- This tumor normally occurs in the base of the skull and bones of the spine and grows slowly. While they do not normally spread to other parts of the body,they will come back in the same area if they are not removed completely.
In addition to these bone tumor types, non-hodgkin lymphoma and multiple myeloma either start in the bones or directly impact them.