The second group of sarcoma is bone cancer. It is very rare with approximately 2,000 new cases diagnosed in the United States each year. The incidence is slightly higher in males than females and no race has a higher incidence than another, although, Ewings sarcoma is even more rare among African and American blacks. Due to the rarity and severity of bone cancer, a bone cancer specialist such as an Orthopedic Oncologist should be consulted in the treatment of the disease. Visit the Musculoskeletal Tumor Society website to find a sarcoma surgeon.
Bones consist of three types of tissue: compact tissue (the hard outer portion of the bone), cancellous tissue (spongy tissue inside the bone containing the bone marrow), and subchondral tissue (the smooth bone tissue of the joints). Cartilage surrounds the subchondral tissue to form a cushion around the joints.
Bone tumors can be benign (non-cancerous) or malignant (cancerous). Benign bone tumors are rarely life threatening and do not spread within the body; however, they can grow and compress healthy bone tissue. Cancer that develops in the bone is called primary bone cancer. It is differentiated by secondary bone cancer which spreads to the bone from another part of the body. Primary bone cancer is rare with approximately 2,500 new cases diagnosed each year in the United States (this figure includes bone cancer which is not sarcoma).
The most common type of primary bone cancer is osteosarcoma. Because it occurs in growing bones, it is most often found in children. Another type of primary bone cancer is chondrosarcoma which is found in the cartilage. This cancer occurs more often in adults.
Scientists are uncertain what causes bone cancer however they have been able to identify some factors which may put a person at risk. Children, and young adults who have had undergone radiation therapy or chemotherapy for other diseases, are at increased risk for bone cancer. Additionally, adults with Paget's disease which is a disease characterized by abnormal growth of new bone cells have an increased risk of osteosarcoma. There are also some hereditary conditions which can increase the risk of bone cancer.
Symptoms of bone cancer can vary depending on the size and location of the tumor. Pain is the most common symptom. Tumors arising in or around the joints often cause swelling and tenderness. Tumors can also weaken the bones thus causing fractures. Some other symptoms can be weight loss, fatigue and or anemia.
The first step in diagnosing primary bone cancer is a complete medical history and physical examination performed by a physician. The doctor may order a blood test to determine the level of an enzyme called alkaline phosphatase. Approximately 55% of patients with primary bone cancer will have elevated levels of alkaline phosphatase. However, it isn't a completely reliable indicator for bone cancer since growing bones in children will cause the enzyme to be elevated.
X-rays are also used to locate a tumor. If an x-ray suggests a tumor is present then a doctor may require further testing such as a CT scan, Magnetic Resonance Imaging (MRI), or an angiogram. Finally, a biopsy must be performed to determine if cancer is present. A biopsy is a procedure used to remove sample tissue from the tumor. A surgeon, usually an orthopedic oncologist, performs the procedure using a needle or making an incision. During a needle biopsy the surgeon makes a small hole in the bone and removes sample tissue with a small instrument. During an incisional biopsy, the surgeon cuts into the tumor and removes sample tissue. A Pathologist (a doctor specializing in identifying disease) then studies the cells and tissues under a microscope to determine whether the tumor is cancerous.
The treatment of bone cancer depends on the size, location, type and stage of the cancer. Surgery is often the primary treatment. While amputation of a limb is sometimes necessary, using chemotherapy either before or after surgery has allowed physicians to save the limb in many cases. Radiation may also be used alone or in combination with the other treatments.
New and more effective treatments are being developed in clinical trials at many hospitals and cancer centers in the United States. The most common types of bone sarcomas are described below.
This is a cancer of that usually grows within a bone or on its surface. It is most typically found in middle-aged adults. Chondrosarcoma is usually a slow-growing tumor and the most common sites are the pelvis, shoulder and the upper part of the arms and legs.
The treatment for chondrosarcoma relies heavily on surgical removal, since there is limited response to radiation and/or chemotherapy. One of the reasons for aggressive treatment is that 10% of low-grade tumors have been reported to develop a much more aggressive biologic behavior, a process called dedifferentiation.
Ewing’s Sarcoma Family of Tumors (EWST)
Note: This section is used with permission from the author, Edward Y. Cheng, M.D., Mairs Family Professor, Department of Orthopaedic Surgery, University of Minnesota Cancer Center, KWRISF Board member and was originally in the Journal of the American Academy of Orthopaedic Surgeons, October 2004. For the the full article, including figures, click here.
This is a cancerous (malignant) tumor. It usually begins growing initially in a bone. Occasionally, it also begins in the soft tissues (extraosseous Ewing’s sarcoma). Doctors don’t know the exact cell of origin. Recently, doctors have defined the disease to include a family of tumors. This includes the Ewing’s sarcoma of bone or soft tissue, primitive neuroectodermal tumor (PNET), and Askin tumor of chest wall. Sometimes these tumors are called small blue cell (round cell) tumors. They are named for the way they look under a microscope.
Compared with other cancers, all malignant bone tumors are rare. Among malignant bone tumors in children and young adults, Ewing’s sarcoma is the second most common. It occurs in 1.7 per million to 2.7 per million children who are younger than 15 years old. There is no known cause.
First a doctor uses imaging studies to diagnose a bone tumor. These include X-rays and MRI (magnetic resonance imaging), CT (computed tomography) and bone scans. The doctor confirms the diagnosis by taking a piece of tissue to look at under a microscope (biopsy). This may be done in an operating room or X-ray department.
Then, special tests can help the doctor diagnose Ewing’s sarcoma. The hallmark is an abnormality in the cell’s chromosomes. Genetic material is mismatched. Chromosomes #11 and #22 are affected.
More tests (blood tests, lung CT scan, bone scan, and bone marrow biopsy) are needed to show the extent of disease. This process is known as “staging”. Tests can show if cancer has spread to other sites. This can include the lungs or bone marrow. The part of the body where the first tumor develops is called the “primary” site. Any parts of the body where it spreads are called “metastatic” sites.
There are no known risk factors for developing Ewing’s sarcoma. There is no known genetic link. There is no means of prevention either. The tumor does not develop as a result of any dietary, social or behavioral habits. Parents of affected children should know that there is nothing they could have done to prevent the tumor.
There is usually pain and/or swelling at the affected site. But the tumor may be present for many months before it becomes large enough to cause pain and swelling. Injuries are not a known cause—but injury may draw attention to a tumor. A bone weakened by disease may break after a minor injury. Ewing’s sarcoma usually affects the long bones. These include the thighbone (femur), shinbone (tibia) and upper arm (humerus) bone. The bones of the pelvis may also be affected.
Doctors in many specialties help treat Ewing’s sarcoma. These include orthopaedic surgical oncologists, pediatric or adult medical oncologists, radiation oncologists, pathologists and radiologists. Most patients are treated at major hospital institutions or cancer centers. The main treatments are:
- Chemotherapy. This is used to kill the primary tumor and any unknown microscopic spread.
- Surgery. This is used to remove the primary tumor, and occasionally metastatic lesions. If necessary, surgery can also rebuild the limb or body part.
- Radiation.This is used to lower the chance of the primary tumor coming back (recurring) or may be used instead of surgery at sites where surgery is too risky or complicated.
Ewing’s sarcoma is usually diagnosed as a primary bone tumor without evidence of spread elsewhere. Even if tests to do not show spread, the treatment strategy assumes that a very small amount of spread (micrometastatic disease) has already happened.
Chemotherapy uses multiple medications. The most common agents are vincristine (Oncovin®), dactinomycin (actinomycin D®), cyclophosphamide (cytoxan®), and doxorubicin (adriamycin®). Recent evidence shows the addition of ifosfamide (Ifex®) and etoposide (VePesid®, VP-16) helps. The chemotherapy is given through an indwelling central venous catheter. This is placed just before treatment is started. Chemotherapy is done in cycles. It uses combinations of the various drugs. The time between cycles lets the blood cell count recover. This includes white blood cells and platelets. The drugs depress them. The patient will lose their hair. Various medications can lessen other side effects. These include nausea, mouth sores and fevers.
It generally takes close to one year to finish all the cycles of chemotherapy, with surgery and/or radiation. A doctor will look at the effect of chemotherapy. He or she will evaluate the number of cells killed in the tumor after it has been removed. This happens following several cycles of chemotherapy that may shrink the tumor, (figures 2 and 3). Many advances in chemotherapy have been made through knowledge gained by placing patients in clinical trials. Your doctor can tell you more. A physician may request permission to enroll a patient in a specific clinical trial.
Both surgery and radiation are effective treatments for the primary tumor. Many surgeons remove the tumor when doing so will not cause a major loss of function of the body part involved. Many doctors use radiation treatment only when a tumor cannot be removed completely or without the patient losing function.
The surgeon can reconstruct the bone, joint or soft tissue site. He or she may use use bone grafts, artificial joints, or a combination. The goal is to restore the body part so the patient can do their normal everyday activities. Strenuous or athletic activities are likely to cause too much stress or wear on the reconstruction.
Some patients may need more operations to keep the limb functioning for the rest of their life. Reconstruction of a bone in a growing child is a special challenge. As the child grows, multiple procedures are needed to lengthen the reconstructed bone. Surgery and/or radiation can be done either before or during chemotherapy. Most centers will halt the chemotherapy sessions sometime during the first half of the treatments to complete the surgery/radiation. Chemotherapy is restarted once the wound site has healed enough. This is usually about 2 weeks to 3 weeks after surgery.
Depending on the site involved, the patient may need to limit weight bearing on the limb. Ongoing rehabilitation with physical therapy is needed to optimize function.
In many cases, doctors can avoid amputation by surgically removing the primary tumor. Rebuilding the bone and joints is then needed. It’s important to consider the risks and complications associated with the surgery. Infections, problems with prosthesis and wound healing are the most frequent concerns.
When radiation treatment is used, daily treatments are given over the course of many weeks. While the discomfort of surgery may be avoided, there are risks, however, associated with the radiation including:
- skin damage
- muscle scarring and loss of joint flexibility
- damage to nearby organs
- loss of bone growth in growing children
- secondary cancers caused by radiation
- chronic swelling of an extremity
- slow wound healing
Recently, more doctors are using surgery to remove the tumors when possible. Most physicians work as a team to tailor their recommendations of surgery and/or radiation to a patient’s specific situation.
Treatment outcome and success
The outcome for patients with Ewing’s sarcoma has improved a lot. This is thanks to improvements in chemotherapy, diagnostic imaging and reconstructive techniques. In general, two-thirds of patients without any demonstrable spread will survive at least five years after diagnosis with standard treatment. When tumors come back, it usually happens within the first few years after treatment. The absence of known spread is the most important factor in favor of being more likely to survive. Other factors include having excellent response to chemotherapy, primary tumors in the extremities instead of pelvis, and complete removal of the tumor.
This type of bone cancer is also most commonly found in adults, particularly during middle age. A typical site is the thigh bone. Fibrosarcoma cancers arise in the fibroblast-type cells (any cell from which connective tissue is developed) in the body. These cells form scars as well as perform other important connective functions. This sarcoma contains much connective tissue.
Malignant fibrous histiocytoma
This is a very rare type of bone cancer that occurs in adults. It is usually found in the arms and legs, especially around the knee joint.
Most cancers in the bone have spread (metastasized) to the bone from another area in the body (the “primary” site, e.g., lung, breast, kidney) or are related to a cancerous tumor of blood cells (e.g, myeloma). On rare occasion, however, a cancer can begin in the bone itself from cancerous cells that make bone tissue. A malignant tumor that forms bone tissue from the cancerous cells is called an osteosarcoma. Although cancers that begin in the bone (primary bone cancer) are much less common that those that metastasize to the bone, among the primary bone cancers, osteosarcoma is the most common type.
Osteosarcoma is a rare tumor and only about 2000 new cases are diagnosed in the USA per year and this comprises < 1% of all new cancer cases in the USA annually. The vast majority of these tumors develop in patients with bones that are growing rapidly, namely adolescents or young adults. However, a smaller concentration of osteosarcomas also affects the elderly age group, in part due to another disease, Paget’s disease, that occurs in the elderly and may turn into an osteosarcoma. The higher prevalence of osteosarcoma in the young age group is intuitive if one thinks of cancer as an error in cellular growth resulting in uncontrolled growth. During the pubertal growth spurt, a higher number of bone cells are multiplying and it is more likely that an error in the cellular duplicating machinery might occur at that time.
Just as osteosarcomas tend to occur in the rapidly growing adolescent, the tumors tend to occur in those bony sites growing most rapidly, namely the distal femur (figure 1), proximal tibia, and proximal humerus. Tumors may also start growing in the spinal column or the pelvis. Obviously, depending upon the extent of the tumor, these anatomic sites are much more difficult to operate upon completely eradicate the mass. Learn more about Osteosarcomas...