Primary bone cancer -- cancer that actually starts in bone tissue -- is relatively rare. Bone cancer can occur in any of the bones of the body, but it occurs most often in the long bones of the arms and legs.
While it can occur at any age, the most common types occur in children and young adults.
Types of Bone Cancer
Primary bone cancer, which means cancer that actually starts in bone tissue, is relatively rare. About 2,400 cases are diagnosed every year. Primary bone cancer can occur in any of the 206 bones of the adult human body, but it occurs most often in the long bones of the arms and legs. Although bone cancer can occur at any age, the most common types occur in children and young adults.
Bone cancers form in the cells that make hard bone tissue. Cancers that arise in the cells produced in the bone marrow, such as leukemia, multiple myeloma, and lymphoma, are not considered bone cancers, although they do affect the bone and may require orthopedic management.
Benign (noncancerous) bone tumors are more common than malignant (cancerous) ones. Although benign tumors do not spread, and are rarely life threatening, both types may grow and compress healthy bone tissue and absorb or replace it with abnormal tissue.
Osteosarcoma is the most common type of primary bone cancer, making up 35 percent of bone cancer cases. This cancer affects primarily children and young adults between the ages of 10 and 25. Osteosarcoma often starts in the ends of bones, where new tissue forms as children grow. It arises most often in the knee.
Chondrosarcomas, one of the most common types of bone cancer in adults over age 50, form in cartilage -- usually around the pelvis, knee, shoulders, or upper part of the thighs. These cancers make up 26 percent of all bone cancer cases.
Ewing's sarcoma occurs most often in the middle part of bones, arising most often in the hip, ribs, upper arm, and thighbones. Like osteosarcoma, this cancer affects primarily children and young adults between the ages of 10 and 25. Ewing's sarcoma is responsible for 16 percent of bone cancer cases.
Rarer Bone Cancers
The following types of bone cancer are rare, and occur primarily in adults:
Fibrosarcomas usually appear in the knee or hip area. They can arise in older patients after radiation therapy for other cancers.
Adamantinomas usually occur in the shinbone.
Chordomas are found most often in the sacrum -- the lower part of the spine, also known as the tailbone.
Metastatic Bone Cancer
Metastatic bone cancer -- cancer that starts somewhere else in the body and then spreads to the bone -- is much more common than primary bone cancer. Although any type of cancer can spread to the bone, the most common types are those of the breast, lung, kidney, thyroid, and prostate. Bone metastases most often arise in the hip, femur (thighbone), shoulder, and spine. Like other types of cancer, those that start in the bone can also spread to other parts of the body. The remainder of this overview focuses on the primary bone cancers osteosarcoma and Ewing's sarcoma.
The most common symptom of bone cancer is pain, which is caused either by the spread of the tumor or by the breaking of bone that is weakened by a tumor. Stiffness or tenderness in the bone may also occur. Sometimes there are other symptoms, such as fatigue, fever, swelling, and stumbling.
But these symptoms can also be caused by other conditions. Only a doctor can tell for sure whether or not a patient has bone cancer.
As with most illnesses, the first part of the diagnosis of suspected bone cancer is a discussion with the doctor about the patient's personal and family medical history. Then the doctor performs a complete medical examination and conducts various tests.
One key test is an examination of a patient's blood for alkaline phosphatase, an enzyme that can be found at particularly high levels in the blood when bone-forming cells are very active. This kind of high activity occurs normally when a young child's bones are growing, or when a broken bone is mending. Otherwise, it might be an indication that a tumor is creating abnormal bone tissue. Since alkaline phosphatase may rise in response to other causes, high levels don't necessarily indicate whether a patient has bone cancer, but they do signal the need for further evaluation.
A physician will usually order imaging tests such as an x-ray, which will allow the doctor to see any unusual bone growths. This may be followed by a bone scan, to see if there are other abnormal areas in the skeleton. Before a bone scan, a small amount of "tracer" material is injected into a vein. After a few hours, this tracer material, which is slightly radioactive, collects in places where there is new bone growth. A CT (computed tomography) or MRI (magnetic resonance imaging) scan is often ordered to show the exact size and shape of the suspected bone tumor, and to determine if it has invaded surrounding tissue or the bone marrow space.
Finally, a biopsy of the suspicious bone tissue is needed to make a definite diagnosis. If the tumor is small enough, the doctor may remove the entire tumor, then analyze samples of it under a microscope to see if it is cancerous. This procedure is called an "excisional biopsy." In other cases, the doctor may make a small opening in the skin and remove just a small part of the tumor for analysis -- an "open biopsy." Or the doctor may do a needle biopsy, in which a sample of the tumor is removed through the skin using a needle. It is important that the biopsy be performed by an experienced and skilled surgeon, because an improperly performed biopsy may limit treatment options later.
A pathologist examines the biopsy samples to determine whether or not the tissue is cancerous, and if it is, to identify the exact type of cancer. Determining the exact type of cancer is critical, because not all types of bone cancer respond to the same types of treatment.
Though surgical resection remains the mainstay of treatment in musculoskeletal tumors it is uncommon for a patient with a high grade sarcoma to be treated by surgery alone. Adjuvant modalities like chemotherapy and radiotherapy play an essential part in the integrated management of these patients. A majority of bone tumors would receive chemotherapy while some like Ewing's sarcoma would benefit from additional radiotherapy.
Surgery is used to remove the bone cancer itself. When operating to remove bone tumors, surgeons remove some of the surrounding bone and muscle to be sure that they are removing as much cancerous tissue as possible. If the operation is on an arm or leg, the surgeon will try , as much as possible, to preserve the limb and maintain its fnctionality. Sometimes the bone that is removed will be replaced with bone from another part of the body, bone from the tissue bank or with an artificial replacement.
Radiation therapy is sometimes given together with surgery, to destroy tumors or to reduce the size of the tumor. Radiation therapy may also be used to kill remaining cancer cells after surgery, or treat tumors that cannot be surgically removed -- sometimes in combination with chemotherapy.
Chemotherapy is often used to treat primary bone cancers, in conjunction with surgery. Chemotherapy is commonly given before surgery to facilitate surgery and also after surgery to kill any cancer cells that remain in the body after the main tumor is removed surgically.
Once tissue diagnosis is made, chemotherapy is advised. Chemotherapy is given both before and after surgery. Adriamycin, cisplatinum, ifosfamide and etoposide are the effective drugs against osteosarcoma.
Ewing's family of Tumors
Like in osteosarcoma, multiagent chemotherapy improves overall survival. Ifosfamide, etoposide, vincristine, adriamycin, cyclophosphamide and actinomycin-D are the agents used. Radiation had earlier been the preferred method of local control but the role of surgery is now being established. Recent reports indicate that surgery combined with chemotherapy and with or without radiation may have better local control rates than chemotherapy with radiation alone.