Malignant bone tumors are a group of lesions that vary in their tissue makeup and behavior.
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Malignant Bone Tumors Malignant bone tumors are a group of lesions that vary in their tissue makeup and behavior and range from locally aggressive tumors that usually do not metastasize to high grade sarcomas with a poor prognosis. They affect all age groups and all bony sites. Diagnosis of the specific type of malignant bone tumor is critical since the treatment for each type varies. Treatment is extremely aggressive in nature usually involving one or more of the following: chemotherapy, radiation therapy, surgery (resection) and bone marrow (stem cell) transplants.
Osteosarcoma (Osteogenic Sarcoma) The most common primary malignant lesion of bone identified by its ability to form bone or bone tissue. There are a few different types of osteosarcoma which behave differently due to their biological makeup. Central osteosarcoma is the classical form usually occurring in adolescents located at the proximal or distal ends of long bones. These sarcomas are rated from low grade to high grade, with low grade being far less aggressive. Juxtacortical (both parosteal and periosteal) are usually considered low grade sarcomas. Telangiectatic osteosarcoma is rare, high grade and behaves as aggressively as classical osteosarcoma.
Osteosarcomas can occur in patients with other skeletal diseases such as Paget's disease, in bone previously treated with radiation for another type of tumor, or in any bone within a radiation field. Osteosarcoma incidence peaks in two age groups: 10-20 years and 50-60 (the older age group is often related to the patient with Paget's disease or those who received radiation). It is more common in males and occurs in areas of rapid growth. The most common site is the distal femur, proximal tibia, proximal humerus and proximal femur, although any bone may be involved.
The tumor is usually noted after trauma brings attention to a painful mass. Patients present with pain, local tenderness, a bony hard mass and decreased function of the body part. If the lesion has been untreated for a long period of time the patient may have symptoms of weight loss, fever, chills, lack of appetite and severe night pain not relieved by aspirin. Sometimes there is an increase in the blood level of alkaline phosphatase. X-rays show a destructive lesion as well as bone formation, a classical 'sun burst' streaming pattern. The outcome of patients without metastases at diagnosis is now quite good due to chemotherapy. Some patients have metastases at diagnosis, usually the lungs but may be in other bones, which worsens the prognosis.
Treatment for osteosarcoma involves chemotherapy and surgery. Chemotherapy is given before and after the surgical procedure in an attempt to reduce the size of the tumor making resection easier, and prevent the spread of cancer cells to other sites of the body. The chemotherapy protocol takes almost one year in total to complete. Previously, amputation was the only surgical treatment option to remove the tumor. Now there are limb-saving procedures which involve resection of the entire tumor as well as a margin of normal tissue (usually muscle and bone) around the lesion with replacement and reconstruction using an allograft (cadaver donor bone) or metal prosthesis. Adequate bone healing can take nine months to one year. Rehabilitation requires casting for a few months followed by bracing and crutches (for lower extremity tumors) for almost one year. Physical therapy is necessary to regain motion and strength, but the progression is slow. It is important to realize that the affected limb will not look the same nor return to normal function. Patients return to normal daily routines but there are restrictions on physical activities. Prolonged walking, sitting, running, and heavy lifting should be avoided with lower extremity allografts. With upper extremity allografts, heavy lifting, pushing/pulling objects and repetitive use of the arm should be avoided. Patients with upper or lower extremity allografts should avoid contact sports.
Sometimes amputation may be the only surgical option due to the tumor size, location and/or invasion of surrounding vessels. Amputation insures complete removal of the tumor, and in most cases, the patient rapidly returns to a functional level. Final prosthetic fittings begin within one month after surgery if the residual limb (stump) is healed. Unlike the allograft patient, the functional limitations of the amputee are left to the imagination and determination of the patient.
If local recurrence or distant metastases occur, the combination of chemotherapy drugs is changed and surgical resection and radiotherapy is considered which involves intermittent periods of hospitalization.
Chondrosarcoma A malignant cartilaginous tumor so named because it makes cartilage as it grows. It occurs most often in adults between 40-60 years of age. This tumor affects the pelvis, hip, proximal femur and sometimes the shoulder and knee. Patients usually complain of a dull, persistent, aching arthritic pain with a tender mass which may slowly increase in size distorting the normal shape of the bone and extremity. Pathologic fracture is rare, but patients may experience pain caused by the large soft tissue mass putting pressure on surrounding nerves and muscles. In some patients, a preexisting enchondroma is present. A full metastatic staging workup is necessary.
Central chondrosarcomas may be low, medium or high grade. The low grade lesions are less likely to spread. Dedifferentiated chondrosarcoma and high grade chondrosarcoma are most likely to spread (metastasize) to other areas. Clear cell chondrosarcoma and intermediate or middle grade chondrosarcomas are less likely to spread to other areas. Juxtacortical and low grade chondrosarcomas are least likely to metastasize. X-rays have a classic look which show a large, centrally placed lesion with significant expansion of the cortex with speckled calcifications characteristic of the the cartilaginous producing process. Sometimes the calcifications look like a 'popcorn pattern'. Examination of high grade chondrosarcoma tissue shows clumps of jelly-like cartilage while lower grade tumors have a firmer consistency.
Treatment for chondrosarcoma is almost entirely surgical. Chemotherapy is not used unless the patient presents with lung metastases at diagnosis. Radiation is not used unless the lesion is very large or in a difficult area such as the spine or pelvis. When possible, limb-sparing procedures are used as long as wide margins can be achieved with reconstruction using metallic or allograft replacement. Low grade lesions may be treated with aggressive curettage and close observation. For high grade lesions with a large soft tissue mass, amputation may be necessary.
Malignant Fibrous Tumors of Bone (MFT) Much rarer than the bone and cartilage forming malignant tumors. The two major types include the fibrosarcoma and malignant fibrous histiocytoma (MFH). They can be grouped together and therefore considered the same in bone.
MFT of Bone usually occurs secondary to other illness such as Paget's disease, giant cell tumor, fibrous displasia, osteomyelitis or bones that have had radiation therapy. These tumors occur in both sexes and in all age groups but are found most often between the ages of 40-60. They are usually located in the long bones of the lower extremities, especially the distal femur and proximal tibia. These lesions are very destructive, thus pathologic fractures are common. X-rays show the destructive (lytic), poorly defined lesions, usually with breakthrough into the cortex causing a soft tissue mass. Low grade tumors have a more well-defined margin than the high grade tumors. The appearance of the tissue cells (malignant fibroblastic stroma and collagen fibers) varies with the grade or degree of tumor aggressiveness. Malignant bone and cartilage tissue are not found in this lesion. Treatment is mainly wide surgical resections. The treatment and outcomes are very similar to an aggressive osteosarcoma. Radiation may have little effect but are sometimes employed in recurrent lesions.
Adamantinoma A very rare malignant bone tumor and gets its name from a jaw tumor because both tissue types are very similar. The difference between lesions in the jaw and those in the long bones is that adamantinoma of long bones can metastasize. It occurs in all sexes and all ages, especially between the years of 20-50. Ninety percent of the lesions occur in the tibia, but it has also been found in the humerus, ulna, femur and other bones. Symptoms include a mild pain or dull ache that has been present for years. Usually a firm, tender mass can be found in the tibial area with thin and shiny skin over the tumor mass. On x-ray, the adamantinoma is clearly outlined, varies in length, has a bubbly appearance and causes the width of the bone to increase. The tissue type is fibrous which replaces the marrow and cortex. The lesion may also have some cystic (fluid-like) areas and hemorrhage (bleeding). Histologic diaganosis can be tricky and it is sometimes difficult to distinguish from other tumors. Treatment is by surgical wide resection of the lesion with allograft reconstruction. Amputation may be necessary due to tumor location and/or recurrence.
Chordoma Another rare tumor of bone believed to come from remnants of embryonic tissue left behind in the sacrum and lower spine. It usually occurs between the ages of 40-70 years, slightly more frequent in males. Sacral chordomas are relentless, slow growing tumors. Patients may have long histories of mild discomfort in the lower spine and tenderness with prolonged sitting. A large soft tissue mass may be felt in the middle of the sacrum or during a rectal examination. Usually neurologic symptoms occur which include constipation because the lesion grows and pushes forward on the rectum; low back pain radiating down the legs because the lesion is pushing against, pinching or engulfing the nerve roots of the sacrum, and loss of sacral nerve sensation causing lower leg weakness, loss of bowel and bladder control, and loss of sexual function because of the the tumor's involvement with the sacral nerves. On x-ray, the chordoma has a typical appearance because of its location in the middle of the sacrum and its destruction of bone with poorly defined margins.
Treatment involves surgical resection of the tumor which is technically difficult due to the location in the sacrum and the proximity (closeness) of vital organs and nerves. Radiation therapy is sometimes given preoperatively, followed by resection with possible intraoperative radiation, internal radiation implants (brachytherapy) postoperatively, and/or proton beam therapy as additional therapy. Chemotherapy has minimal effect on chordomas. Heat ablation has recently been tried for therapy with positive results. Some patients are referred to pain specialists until the neurologic symptoms subside.
Despite the location and difficulty in obtaining complete eradication of a chordoma most patients have a good long-term survival prognosis. Alterations in life style may be necessary depending upon the effect of neurologic loss from the tumor or treatments. Tumors may recur and require more surgery or radiation. Most patients cope well with varying degrees of loss of bowel or bladder control or sexual function. Occasional patients have persistent pain which can be controlled with a variety of new treatment modalities.
Ewing's Sarcoma A rare, highly malignant bone tumor made of small round cells of unknown origin. It is distinguished from other round cell tumors such as malignant lymphoma of bone, myeloma, neuroblastoma, rhabdomyosarcoma, small cell osteosarcoma and metastatic small cell carcinoma of the lung. Ewing's sarcoma is rare in black populations and usually occurs between the ages of 10-20. Males are affected more frequently than females. Any bone may be involved, but the pelvis and lower extremities are the most common sites. The patient usually presents with pain, swelling, a mass and occasionally fevers, weight loss and fatigue for a few months. Blood tests may reveal anemia (low red blood cell count, low hemoglobin or hematocrit) or show an increase in the sedimentation rate (detects inflammatory, neoplastic/cancer, infectious and necrotic/cell breakdown decay processes). Pathologic fractures may be present. X-rays show a destructive lesion in the bone, a soft tissue mass, and destruction of the cortex which elicits a host response/new bone giving an 'onion skin' look around the tumor. Tumor tissue examined under the microscope shows the closely packed, small round cells.
Treatment for Ewing's sarcoma involves chemotherapy and surgical resection. Radiation therapy has also been used but with caution in young children with growth plate involvement to prevent significant growth deformity. The prognosis (outlook for survival) is now quite good due to advances in chemotherapy. Lung metastases may occur in 20-25% of patients at diagnosis or subsequently and are managed with different chemotherapy, radiation, resection or at times, stem cell transplants.
Malignant Lymphomas of Bone May occur at any age but usually in the middle to older age groups. The most common sites are the pelvis, ribs and femur. There are no distinct patient symptoms, although many patients do present with pathologic fracture. It is important to have blood tests taken to rule out leukemia. Lymphomas of bone are similar to Ewing's sarcoma and on x-ray appear as distinctive lesions not well defined with breakage of the cortex and soft tissue mass. The tumor cells are large and round varying in size and shape. Treatment consists of radiation with surgical fixation of pathologic fractures if necessary, and adjuvant chemotherapy.
Multiple Myeloma A malignant tumor of plasma cells, is a common malignant bone tumor that usually develops in middle age. It is a disorder affecting the entire bone marrow, occurring at multiple sites throughout the skeleton, but may present as a single bone lesion referred to as a plasmacytoma. Any bone can be involved but the spine, ribs, skull, pelvis and proximal long bones are the most common sites. Patients complain of pain in their bones with history of fever, fatigue, weight loss and anemia. X-rays may show a fracture, widespread osteoporosis or small puncture holes in the skeleton which can turn into large areas with thinning of the cortex. Skeletal surveys (plain x-rays of many bones) are done since bone scans may not always show all the tumor site.
Patients with myeloma often do not need a biopsy, but if done, the tissue contains sheets of plasma cells. Blood tests are very helpful to establish the diagnosis. Ninety percent of patients have anemia and a high sedimentation rate. Calcium levels may be elevated in patients with extensive bony disease. The blood test immunoelectrophoresis (IEP), which profiles the immunoglobins, demonstrates an abnormal 'g component' (myeloma protein) in ninely percent of patients. Immunoelectrophoresis studies on the urine is positive in over sixty percent of patients. Diagnosis is confirmed by doing a bone marrow biopsy. Normal bone marrow contains only a small amount of plasma cells. Thus, over eight percent of plasma cells is suspicious for myeloma and over twenty percent confirms diagnosis.
Treatment includes radiation because myelomas respond very well to the therapy and the pain caused by these lesions is relieved. Fractured or weakened areas of bone are treated surgically with internal fixation (metal hardware such as pins, rods, plates, screws and possible cement or bone grafting). New forms of chemotherapy and bone marrow transplantation are also being used.
Metastatic Bone Tumors of the skeleton Malignant bone tumors caused by the spread (metastatic disease) of another type of cancer, greatly outnumber the primary (original site) malignant bone tumors. Most of these bone metastases are from prostate, breast, thyroid, lung or kidney cancers. The most common sites for skeletal (bony) metastases are the bones containing blood-forming marrow such as the spine, ribs, skull, pelvis, and the ends of long bones especially the femur and humerus. Rarely metastases to the hands or feet occur. In children, metastatic skeletal tumors are usually due to neuroblastoma, leukemia or Ewing's sarcoma. In teenagers or young adults, lymphoma is the primary disease. Metastases after age 30 are usually adenocarcinoma (a type of cancer that involves the cells lining the walls of different organs in the body). Metastatic tumors from the kidney or thyroid are usually very vascular (made of blood vessels) whereas tumors from prostate, breast and lung are less so. With many patients, the primary tumor is not identified, so staging studies and biopsy are necessary to rule out a primary malignant bone tumor. Sometimes a primary site is never identified. In patients with a history of cancer, a bone scan will show any additional sites of skeletal involvement.
Most patients with bony metastases present with pain in the area of the lesion with decreased mobility and motion. Staging studies are usually done to determine the extent of the metastatic disease and plan the most appropriate treatment. Pain control and surgical internal fixation to provide bone stability are the major goals of treatment. Chemotherapy, use of hormones and palliative radiation therapy, that is radiation to treat the symptoms not cure, are other options used to care for patients with metastatic disease.
It is important to note that many patients have a significant amount of quality time for themselves and their families despite living with metastatic disease. Recent advances in cancer management has made that possible. These patients living with metastatic disease have a phenomenal amount of inner strength and hope.