Overview

Sarcoma is cancer that develops in the tissues that support and connect the body, including bone, fat, muscle, as well as soft tissue. Cancer begins when normal cells begin to change and grow uncontrollably, forming a mass called a tumor. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). Specifically, osteosarcoma is a cancer of the bone that destroys tissue and weakens the bone. Osteosarcoma starts in immature bone cells that normally form new bone tissue. It occurs rarely as a tumor in the soft tissues of the body, outside the bone.

Osteosarcoma most often starts in the bones around the knee joint: at the lower end of the femur (thigh bone) or the upper end of the tibia (shin bone). The second most common place is in the humerus (upper arm bone) close to the shoulder. However, osteosarcoma can develop in any bone in the body.

Osteosarcoma is described as either a medullary (central) tumor or a peripheral (surface) tumor. Each has a number of subtypes. The type and subtype of osteosarcoma is identified by looking at the tumor cells through a microscope. The most common subtype is conventional central osteosarcoma. The other subtypes are much less common, each accounting for less than 5% of all osteosarcoma cases.

Medullary osteosarcoma subtypes include:

• Conventional central osteosarcoma
  
  
• Telangiectatic osteosarcoma
  
  
• Intraosseous well-differentiated (low-grade) osteosarcoma
  
  
• Small cell osteosarcoma

Peripheral osteosarcoma subtypes include:

• Parosteal (juxtacortical) well-differentiated (low-grade) osteosarcoma
  
  
• Periosteal (low-grade to intermediate-grade) osteosarcoma
  
  
• High-grade surface osteosarcoma

This section covers osteosarcoma that is diagnosed during childhood. Learn more about other types of bone cancer and soft-tissue sarcoma.

Statistics

In 2009, an estimated 900 people total, including 400 people younger than 20, will be diagnosed with osteosarcoma. About 2.7% of all childhood cancers are osteosarcoma. Osteosarcoma is about 50% more common in boys than girls. It most often affects teenagers and young adults in their 20s. The five-year relative survival rate (the percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) depends on the type and subtype of the cancer, the cancer’s response to treatment, and the degree to which the cancer has spread. For children, the overall five-year survival rate is 71%.

Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with osteosarcoma. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.

Statistics adapted from the American Cancer Society’s publication, Cancer Facts & Figures 2009.

Find out more about basic cancer terms used in this section.