Bone Tumors

Osteosarcoma

Osteosarcoma is the most common bone tumor in children and young adults. Classic osteosarcomas are high grade and begin to grow within the bone. It often starts in the ends of the bones where new bone tissue forms as a young person grows. Bones in the thigh, upper arm, and shin are the most common site, but osteosarcoma can occur anywhere in the body. It often develops during the period of rapid growth during adolescence, when a teenager matures into an adult. The average age at diagnosis is 15 years. Boys and girls have a similar incidence of this tumor until late adolescence, at which time boys are more commonly affected. Osteosarcoma cells can be many different shapes and sizes. Only rarely does osteosarcoma run in families. A defective tumor suppressor gene (which allows tumors to grow) has been linked to an increased risk of this disease and is also associated with familial retinoblastoma, a childhood cancer of the eye. Children with familial retinoblastoma have a high risk for osteosarcoma in adolescence.

Treatment

In general, chemotherapy (treatment with anticancer drugs) is given to shrink the main tumor. It is called neoadjuvant chemotherapy as it is often given before the tumor is removed by surgery. Neoadjuvant chemotherapy for osteosarcoma became the standard of care at the beginning of the era when surgeons began removing the tumors and saving the diseased limbs. New prosthesis to replace the limb required time to manufacture since they were custom-made to the patient's size. Thus, chemotherapy was used to deliver treatment while the prosthesis was being made. Physicians found that three or four cycles of chemotherapy with multiple drugs given before surgery may help kill off more tumor cells so that it is easier to surgically remove the remaining tumor. Radiation therapy (treatment with targeted x-rays) is rarely used to treat osteosarcoma but may be recommended to control pain in late stage disease or if the cancer is centralized in the spine.

The second stage of treatment is to remove the main tumor through surgery. After the tumor is surgically removed, pathologists study it to reveal a percentage necrosis rate, or the amount of dead tumor cells. The higher the percentage necrosis rate, the more dead tumors cell, and this figure represents, in essence, a "report card" to guide the medical/pediatric oncologist on how to tailor additional therapy. Studies have shown that the necrosis rate is highly predictive of overall survival. Some recent studies indicate that altering the type of chemotherapy drug given after surgery may not improve survival of patients with low necrosis rates. Medical/pediatric oncologists are testing different strategies to combat aggressive tumors including therapies that target individual cancer cells and varying dosing schedules of standard drugs.

The third stage of treatment consists of between five to eight months of additional chemotherapy. The entire treatment process may take close to one year to complete.

Recurrence: Osteosarcomas have less than a five percent chance of recurring in the original location of the disease after surgical resection. It is most common for an osteosarcoma to metastasize (spread) to the lungs. Less commonly, osteosarcoma can spread to other bones.

Patients treated for osteosarcoma will have the area of the original tumor examined radiographically with x-rays or other imaging techniques at three to six month intervals for three to five years. At the same time, CT scans of the lungs will be performed at regular intervals since early discovery of lung lesions (tumor cells that have spread to the lungs) allows for easier removal by surgery. Bone scans are performed periodically to watch for spread to other bones. If the area where the tumor was removed was reconstructed with a metal prosthesis, this area will be followed with regular x-rays yearly for the remainder of the patient's life. The orthopedic surgeon will monitor the healing of the reconstruction or the durability of the metal prosthesis and provide suggested exercises to increase the function of the affected limb.

Drug therapy with doxorubicin (Adriamycin) can potentially affect the heart. Patients with osteosarcoma who have received this drug as part of their therapy will need to have echocardiograms and electrocardiograms performed at least every three years. Certain types of exercise are better for the survivor's heart and should be discussed as part of follow-up care. In addition, hearing should be checked within the year of completing therapy and then three to five years later because some of the common drugs can cause minor or more severe hearing loss.

Ewing's sarcoma

Ewing's sarcoma is the second-most common cancerous bone tumor affecting children and young adults. It gets its name from Dr. James Ewing, the doctor who first described the tumor in the 1920s. Ewing's sarcoma may arise anywhere in the body, but it usually originates in the long bones of arms and legs, the pelvis or the chest. Though more rare, it may also develop in the skull or flat bones of the trunk. While it is most often a bone tumor, Ewing's sarcoma can develop in the soft tissue near bones as well. Under the microscope, Ewing's sarcoma is characterized by small, round, blue cells. Primitive neuroectodermal tumors (PNET) are very rare molecularly-related tumors that often arise outside of the bone and are treated the same as Ewing's sarcoma.

While Ewing's sarcoma can occur anytime during childhood, it most commonly develops during puberty when bones are growing rapidly. This type of cancer is uncommon in African-American, African, and Chinese children.

Treatment options for Ewing's sarcoma include surgery, chemotherapy and radiation therapy. Several cycles of chemotherapy, treatment with anticancer drugs, is usually suggested as the first stage of therapy to shrink the primary or main tumor. Chemotherapy drug regimens may include adriamycin, vincristine, cyclophosphamide, etoposide and ifosfamide.

Unlike osteosarcomas, Ewing's sarcomas are sensitive to radiation, which can be used treat the primary site of the disease. Radiation occasionally is used as an alternative treatment to surgery in areas where it is unlikely that all tumor cells will be removed, such as the spine, or if it is too difficult to restore function after surgery, such as the pelvis.

Generally, if the cancer can be removed, surgery is recommended since radiation therapy may have profound side effects, especially in young children. Patients treated with surgery alone or surgery and radiation have less of a chance that their cancer will recur than if they were treated with radiation alone. Additional chemotherapy is given following surgery or radiation therapy to destroy any tumor cells that may have spread to other parts of the body.

Follow-Up: Ewing's sarcoma patients will be monitored with x-rays of the original tumor every three to six months for three to five years. Similarly, patients will have regular CT scans of the lungs and periodic bone scans to detect recurrence as early as possible. For the rest of their life, patients will have yearly x-rays of the area of the original tumor to monitor any reconstructive devices and healing of the limb. Exercises may be suggested to increase the function of the affected limb.

Chondrosarcoma

Chondrosarcoma is the most common bone tumor occurring in adults. It occurs most often in the pelvis but can occur in any bone and usually in people aged 50 years and older. The most effective treatment strategy used for this disease is surgery. Chemotherapy and radiation have proven ineffective. Given the complexity of pelvic surgery and the importance of removing as much tumor as possible, patients should seek the opinion of surgeons with special training in orthopedic oncology. Chondrosarcoma patients are monitored closely for disease that has spread to the lungs. Future research may show that image-guided surgery, using remote control computers and robots, may increase accuracy and help avoid critical nerves in pelvic surgery.

Osteosarcoma

Classic osteosarcomas are high grade and start within the bone. With time they can destroy the bone and break out into the surrounding soft tissues.

Some high grade osteosarcomas are a result of receiving prior radiation for a different cancer. Patients with Paget's disease are also at higher risk of developing osteosarcoma in the bone that is affected by the Paget's disease.

In general, treatment for osteosarcoma in adults is similar to treatment for the disease in children. In the first stage of treatment, chemotherapy (treatment with anticancer drugs) is given to shrink the main tumor. It is called neoadjuvant chemotherapy as it is often given before the tumor is removed by surgery. Neoadjuvant chemotherapy for osteosarcoma became standard of care at the beginning of the era when surgeons began removing the tumor and saving the diseased limbs. New prosthesis to replace the limb required time to manufacture since they were custom-made to the patient's size. Thus, chemotherapy was used to deliver treatment while the prosthesis was being made. Physicians found that three or four cycles of chemotherapy with multiple drugs given before surgery may help kill off more tumor cells so that it is easier to surgically remove the remaining tumor. Radiation therapy (treatment with targeted x-rays) is rarely used to treat osteosarcoma but may be recommended to control pain in late stage disease or if the cancer is centralized in the spine.

The second stage of treatment is to remove the main tumor through surgery. After the tumor is surgically removed, pathologists study it to reveal a percentage necrosis rate, or the amount of dead tumor cells. The higher the percentage necrosis rate, the more dead tumor cells, and this figure represents, in essence, a "report card" to guide the medical/pediatric oncologist on how to tailor additional therapy. Studies have shown that the necrosis rate is highly predictive of overall survival. Some recent studies indicate that altering the type of chemotherapy drug given after surgery may not improve survival of patients with low necrosis rates. Medical oncologists are testing different strategies to combat aggressive tumors including therapies that target individual cancer cells and varying dosing schedules of standard drugs.

The third stage of treatment consists of between five to eight months of additional chemotherapy. The entire treatment process may take close to one year to complete.

Osteosarcomas have less than a five percent chance of recurring in the original location of the disease after surgical resection. It is most common for an osteosarcoma to metastasize (spread) to the lungs. Less commonly, osteosarcoma can spread to other bones.

There are several subtypes of osteosarcomas that vary in appearance under the microscope or in their rate of growth or likelihood of metastasis. Surface osteosarcomas include parosteal, periosteal, and high grade surface osteosarcomas. Parosteal osteosarcomas are low grade and grow on the surface of the bone. These tumors are easily removed by surgery but it is important to be sure the entire tumor is removed as these cancers have a high chance of recurrence if not removed properly. Chemotherapy is not necessary to treat these tumors. Periosteal osteosarcomas are very rare and also occur on the surface of the bone. They are intermediate in grade and are treated with surgery and possibly chemotherapy. High grade surface osteosarcomas are treated the same as a classic osteosarcoma with chemotherapy and surgery.

A telangiectatic osteosarcoma is a high grade osteosarcoma that is filled with large blood-filled spaces and has a different appearance on x-rays and under the microscope.

Other bone tumors occurring in adults include

Malignant fibrous histiocytoma or MFH (which is similar to osteosarcoma and treated similarly), fibrosarcoma, adamantinoma (which occurs in the tibia), and chordoma (occurring in the sacrum or base of the skull).

All bone tumors in adults are treated with surgery. Most also are treated with chemotherapy pre-operatively and often post-operatively depending on the grade and degree of spread of the tumor. Radiation has proven ineffective in most adult bone tumors.

The most common primary malignant bone tumor in adults is multiple myeloma, which is not a sarcoma. This tumor can involve the bone marrow and multiple different bony sites and is treated with chemotherapy and radiation. Surgery is reserved for stabilizing a bone to prevent fracture.