Chondrosarcoma is a malignant tumor that arises from cells that produce cartilage, the rubbery tissue around joints. Therefore, it is a type of sarcoma that is predominantly found in the area around bones.
Sarcomas of the bone are rare and represent about 0.2% of all new cancer cases each year. The two most common forms of bone cancer are osteosarcoma and Ewing's sarcoma. Among the less common are chondrosarcoma, fibrosarcoma, and malignant fibrous histiocytoma, all of which arise from spindle cell neoplasms.
Chondrosarcomas arise from chondroblasts, cells that form cartilage. Cartilage is the matrix found at the tip of the nose and ears. However, cancer that develops from chondroblasts is usually observed on the surface of the pelvis, in the femur of the upper leg, around the shoulder, in the humerus of the upper arm, and in the ribs.
Depending on the type and location of the chondrosarcoma, the tumor can either be high grade and aggressive or low grade and not as invasive. There are two different categories of chondrosarcomas—classic chondrosarcomas and variant chondrosarcomas. Together they have five main types.
Central chondrosarcoma and peripheral chondrosarcoma are both classic chondrosarcomas. Central chondrosarcoma occurs within a bone, and peripheral chondrosarcoma develops on the surface of a bone. Both can develop as a primary tumor or as a secondary tumor to an existing tumor elsewhere in the body. Most, however, are primary tumors. Seventy-six percent of primary chondrosarcomas occur centrally within a bone.
There are three variant chondrosarcomas: clear cell chondrosarcoma, mesenchymal chondrosarcoma, and dedifferentiated chondrosarcoma. Clear cell chondrosarcoma is the most rare form of chondrosarcoma. It is a low grade, slow growing tumor that typically occurs locally in the epiphysis, or end part, of long tubular bones such as the femur and humerus, meaning that it does not normally invade into surrounding soft tissue. As the name implies, cells biopsied from this type of chondrosarcoma appear clear with many large vacuoles.
Mesenchymal chondrosarcoma is another rare variant. However, as opposed to clear cell chondrosarcoma, it is highly malignant and frequently metastasizes, commonly to the lungs, lymph nodes and other bones. This variant has a tendency to develop in flat bones such as vertebra, the pelvis, or the skull, as opposed to long tubular bones. Under a microscope, the cells appear round and contain spindle cell elements and neoplastic cartilage formation.
Dedifferentiated chondrosarcoma is also rare and is the most malignant form of chondrosarcoma. It is characterized by the presence of a mix of low-grade chondrosarcoma and has undergone malignant degeneration, producing a fully malignant soft tissue mass that is no longer identifiable as cartilage. These cancers occur most commonly in the flat bones of individuals over the age of sixty. Despite varied treatments, they are almost always fatal.
Due to the location of chondrosarcoma tumors, the result is often a decrease in the range of motion of limbs, especially tumors occurring on the epiphysis of bones such as those seen in clear cell chondrosarcoma.
Although there are exceptions, chondrosarcomas occur mainly in older adults forty to sixty years old and typically occur more in men than in women. Chondrosarcomas are rarely seen in infants and children. Dedifferentiated chondrosarcomas predominantly arise in the elderly over the age of sixty, equally between males and females. Mesenchymal chondrosarcoma develops in the young adult population between the ages of twenty and forty years old, and it is slightly more common in females. Classic chondrosarcomas usually develop in people over the age of forty. However, when they occur in younger age groups, they have a propensity to be highly malignant, capable of metastasis.
Causes and symptoms
As of 2001, there is little known about what causes chondrosarcomas. However, researchers have discovered
There are many symptoms associated with the onset of chondrosarcomas. They tend to develop slowly in most cases, except when the cancer is aggressive. The following is a list of the main symptoms that may present:
- firm lump
- broken bone
- impeded normal range of motion
- urinary frequency (seen in pelvic chondrosarcomas)
- urinary obstruction (seen in pelvic chondrosarcomas)
The above symptoms are not always indicators of the presence of chondrosarcoma. Any one of these symptoms could be related to another, less serious condition. A doctor should be seen to diagnose the problem properly.
In order to diagnose bone cancer, a doctor will take the patient's history and conduct a thorough physical exam. Blood tests will be performed to rule out other conditions and identify cancer markers.
The most revealing initial exam is an x ray. It can show the location, size, and shape of the tumor. If a malignant tumor is present, the x ray will expose a soft tissue mass with ill-defined edges. This procedure takes less than an hour and can be performed in the doctor's office. Depending on the medical facilities, the results can be returned the same day after being interpreted by a physician, and perhaps a consulting oncologist and radiologist.
If the patient is seeing a primary care provider, the provider may perform the initial diagnostic tests. However, in order to comprehensively diagnose and treat chondrosarcomas, the primary care provider will refer the patient to an orthopaedic oncologist (bone cancer specialist). Radiologists, pathologists and orthopaedic surgeons will also be involved to read x rays, examine tissue samples, and remove the tumor if necessary.
Many other individuals will be involved with the treatment of chondrosarcoma. For example, nurses and dieticians are available to explain side effects of treatment and offer suggestions on eating healthy meals to help fight the side effects. If a limb is totally or partially removed, a physical therapist or vocational therapist will assist the patient in learning how to use a prosthetic limb.
Clinical staging, treatments, and prognosis
After the physician makes the diagnosis, it is important to determine the stage of the cancer. This will help reveal how far the cancer has progressed and how much tissue has been affected.
A new system of staging was adopted in 1980 by the Musculoskeletal Tumor Society. It is based on the fact that differing tissue types associated with the bone behave similarly when cancerous. This classification system uses grade (G), location (T), and lymph node involvement and metastasis (M).
Surgical grade (G) refers to how aggressive the cancer is. For example, G0 represents a benign tumor and G2 represents a highly aggressive tumor. The anatomical location (T) establishes whether or not the tumor is inside the bone (T1) or outside the bone (T2). If metastases are present, then the tumor is classified as M0; and if metastases are not present, the tumor is classified as M1. The following is a list of stages and their indications:
- Stage IA (G1, T1, M0): low grade within the bone, without metastasis
- Stage IB (G1, T2, M0): low grade outside the bone, without metastasis
- Stage IIA (G2, T1, M0): high grade within the bone, without metastasis
- Stage IIB (G2, T2, M0): high grade outside the bone, without metastasis
- Stage IIIA (G1 or G2, T1, M1): inside the bone, with metastasis
- Stage IIIB (G1 or G2, T2, M1): outside the bone, with metastasis
Physicians can employ several courses of treatment to remove chondrosarcomas. The most effective treatment is surgical removal. When performing the surgery, the doctor will remove the tumor and some healthy tissue or bone around it to ensure that the tumor does not recur near the original site. The physician may replace the removed bone with a metal device. In children, the metal device can be lengthened as the child grows, but this will require further surgeries. The fact that most chondrosarcomas tend to be low grade and slow-progressing makes this procedure one that does not necessitate entire limb removal except in extreme cases when the tumor is large.
Even individuals with low-grade chondrosarcoma that have undergone surgery experience a moderate risk of local recurrence. To combat recurrence, chemotherapy (the use of one or more cancer killing drugs) and radiation therapy (the use of high energy rays) have also been used to complement surgery. Employing chemotherapy or radiation therapy individually (without surgery) is much less effective. In fact, chondrosarcomas are generally resistant to chemotherapy alone.
Low stage chondrosarcomas (Stages IA and IB) have greater one and five-year survival rates than the high stages (Stages IIIA and IIIB). High-grade tumors are more aggressive and highly metastatic than lower grade tumors, and therefore they have a lower survival rate. Not only is the grade of the tumor (the estimate of its aggressiveness) important in determining prognosis, but the age of the patient is also crucial. Generally, chondrosarcomas that occur in childhood and infancy have a higher mortality rate than those that occur in adults.
Metastases appear later in the development of chondrosarcomas. The lungs are the sites of primary metastasis. Once metastasis to the lungs has occurred, survival rate decreases.
Coping with cancer treatment
Chemotherapy often results in several side effects, depending on the drug used and the patient's individual tolerance. Patients may have to deal with nausea, vomiting, loss of appetite, and hair loss. Often, chemotherapy and radiation therapy are better handled if the patient is eating well. Nurses and dieticians can aid in choosing healthful foods to incorporate into the patient's diet.
If the chondrosarcoma necessitates limb amputation, the patient will need to learn how to cope with a prosthetic device. Both physical and vocational therapists can help the patient adjust and learn to use prosthetic devices to perform daily activities in new ways.
Since chondrosarcomas are rare forms of cancer, there is still much to be learned. Clearly, surgery is the most effective treatment. New techniques in cryosurgery are being developed in various institutions across the country.
Chemotherapy trials have shown improved results with more intense regimens. Such drugs that are under study include methotrexate, leucovorin, vincristine, bacillus Calmette-Guérin, doxorubicin, or a combination of two or three of these.
Patients should consult with their physicians or contact the American Cancer Society to learn what procedures are currently in clinical trials. In some cases, insurance companies will not cover clinical trial procedures. Patients should talk with their doctor and insurance company to determine which procedures are covered.
Since little is known about what causes chondrosarcomas, there is also little known about how to prevent them. In general, the prevention of cancer can be assisted by avoiding known chemical carcinogens such as alpha-naphthylamine, carbon tetrachloride, and benzene. Another way to avoid developing cancer—especially bone cancer—is to minimize exposure to penetrating radiation such as x rays and radioactive elements. Medical x rays revolutionized the field of medicine and are used to detect and treat many diseases. In most cases, the benefits of medical x rays outweigh the risks.
Cancer treatments, especially surgical amputation, can take a physical and psychological toll on cancer patients and their families. To deal with the psychological impact, many different support groups and psychotherapists are available to help. Some therapists will consider amputation a post-traumatic stress disorder and treat it accordingly. Faith practices are also beneficial for cancer patients in dealing with their condition. Patients should discuss all options with their physician to determine what is available to them.
Once the cancer has been treated, patients should make sure to schedule follow-up appointments with their
Malawer, Martin M. "Sarcomas of Bone." In Cancer Principles and Practice of Oncology, edited by Vincent T. DeVita, Jr., M.D., et al. New York: Lippincott-Raven Publishers, 1997, pp.1789-852.
Rosen, Gerald, M.D. "Neoplasms of the Bone and Soft Tissue."In Cancer Medicine, edited by Robert C. Bast, Jr., M.D., et al. London: BC Decker, Inc., 2000, pp.1870-95.
Lee, Francis, M.D., et al. "Chondrosarcoma of Bone: AnAssessment of Outcome." The Journal of Bone and Joint Surgery (March 1999): 326-38.
Mitchell, A.D., et al. "Experience in the treatment of dedifferentiated chondrosarcoma" The Journal of Bone and Joint Surgery (January 2000): 55-61.
American Cancer Society. <http://www.cancer.org>.
National Cancer Institute. <http://cancernet.nci.nih.gov>.
Sally C. McFarlane-Parrott
—An agent that is capable of causing cancer.
—The end of long tubular bones such as femur in the leg and the humerus in the arm. Initially separated from the main bone by a layer of cartilage that eventually allows the parts to fuse.
—Spindle-shaped cells typically found in connective tissue.
QUESTIONS TO ASK THE DOCTOR
- What diagnostic procedures are best for the location and type of tumor suspected?
- What treatments are best for the location and type of tumor suspected?
- What kinds of side effects will this course of treatment result?
- Are there support services available?
- What treatments are currently in clinical trials?
- What treatments will my health care insurance cover?