Bone cancer is the term used to define the cancers of the bone. They are generally of two types:
- Primary bone cancer: This is the bone cancer that arises from the bones. There are 206 bones in a human body and primary bone cancer can arise from any of them. However, the long bones of the arms and the legs are the common site of primary bone cancer.
- Secondary bone cancer: This form of bone cancer is far more common compared to primary bone cancer. The term secondary is used to denote the fact that the primary tumor is elsewhere in the body and it has metastasized to the bones to form the secondary tumor.
According to the latest statistics, around 2,300 new cases of primary bone cancer are detected in the US every year. They account for less than 1% of all the cancers. In UK, one in every 500 new cancer cases is primary bone cancer.
Primary bone cancer can be further divided into two groups. They are:
- Benign tumors of the bone: These may be neoplastic in nature, or may be developmental, or may develop following some trauma, infection or inflammation. Examples of benign bone tumors include osteoma, osteochondromas, osteoblastoma, giant cell tumor of the bone, aneurysmal bone cyst
- Malignant bone tumors: These include osteosarcoma, chondrosarcoma, Ewing's sarcoma, fibrosarcoma, etc.
Let us look at some of the common malignant primary cancers of bone and the rate of survival of patients affected by them.
It is important to remember that bone cancers usually respond well to conventional therapy and survival rates are good if the cancer has not spread to other parts of the body. On an average, 40% of all men and 50% of all women affected by primary bone cancers survive beyond five years. However, the five years survival rate depends up on:
- Grade of the tumor: Chances of survival increases when the tumor is of a low grade.
- Stage of the tumor: Tumors localized to bone of origin are more likely to be cured completely. As the staging of tumor increases, the prognosis becomes worse.
Osteosarcoma is the most common malignant primary bone cancer. It is usually found in children and young adults and frequently affects bones of face and jaw or the long bones of leg. It is the third most common tumor in children after leukemia and brain tumors. The five year survival rate of patients with osteosarcoma is around 60%. However, when the tumor has metastasized to the lungs, the 5 year survival rate is just 10%.
Ewing's sarcoma strikes adolescents and young adults before they are 20 years of age in 90% cases. It generally involves long bones of legs, and the pelvic bone. The five year survival rate of patients diagnosed with Ewing's sarcoma is 70%. The rate falls down to 30% in patients with lung metastasis and is just 5% in case of brain metastasis.
Chondrosarcoma is a type of bone cancer usually affecting adults. It starts in the cartilage cells and then grows to involve the bone. In patients with low grade chondrosarcoma, ten years survival rate is as high as 80%. However, if the tumor is of a high grade the survival rate falls and the five years survival rate is only 30%.
Although these statistics stand for a vast majority of patients, it is important to remember that no two patients and their cancer are similar in nature. Every patient is unique. Therefore, it is difficult to predict how a particular patient will respond to treatment and what will be his prognosis.
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