Chondrosarcoma is a cancer of cartilage cells. It is the second most common primary bone cancer. This cancer is rare in people younger than 20. After age 20, the risk of getting a chondrosarcoma goes up until about age 75. Women get this cancer as often as men. Chondrosarcomas can develop in any place where there is cartilage. Most develop in bones such as the pelvis, leg bone or arm bone. Occasionally, chondrosarcoma will develop in the trachea, larynx, and chest wall. Other sites are the scapula (shoulder blade), ribs, or skull.
Benign (non-cancerous) tumors of cartilage are more common than malignant ones. These are called enchondromas. Another type of benign tumor that has cartilage is a bony projection capped by cartilage called an osteochondroma. These benign tumors rarely turn into cancer. There is a slightly higher chance of cancer developing in people who have many of these tumors, but this is still not common.
Chondrosarcomas are classified by grade, which measures how fast they grow. The grade is assigned by the pathologist (a doctor specially trained to examine and diagnose tissue samples under a microscope) after looking at the tumor under the microscope. The lower the grade, the slower the cancer grows. When a cancer is slow growing, the chance that it will spread is lower and so the outlook is better. Most chondrosarcomas are either low grade (grade I) or intermediate grade (grade II). High grade (grade III) chondrosarcomas, which are the most likely to spread, are less common.
Distinct Clinical Features
Some chondrosarcomas have distinctive features under a microscope. These variants of chondrosarcoma can have a different prognosis (outlook) than usual chondrosarcomas.
• Dedifferentiated chondrosacromas start out as typical chondrosarcomas but then some parts of the tumor change into cells like those of an osteosarcoma or fibrosarcoma. This variant of chondrosarcoma tends to occur in older patients and is more aggressive than usual chondrosarcomas.
• Clear cell chondrosarcoma is a rare variant that grows slowly. It rarely spreads to other parts of the body unless it has already come back several times in the original location.
• Mesenchymal chondrosarcomas can grow rapidly, but like Ewing tumor, are sensitive to treatment with radiation and chemotherapy.
Treatment of chondrosarcoma is wide surgical excision. There is a very limited role for chemotherapy or radiation. Biopsies must be planned with future tumor excision in mind. Patients with adequately resected low grade chondrosarcomas have an excellent survival rate.