ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Childhood Osteosarcoma. Use the menu to see other pages. Think of that menu as a roadmap to this complete guide.
Sarcoma is cancer that develops in the tissues that support and connect parts of the body. These include bone, fat, muscle, and soft tissue. Cancer begins when healthy cells change and grow out of control. They form a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant. This means that it can spread to other parts of the body, called metastasis. A benign tumor means the tumor will not spread.
Osteosarcoma is a cancer of the bone that destroys tissue and weakens the bone. It develops from immature bone cells that normally form new bone tissue.
Places where osteosarcoma begins
Osteosarcoma most often starts in a leg bone around the knee joint, either at the femur, which is the lower end of the thigh bone, or the tibia, which is the upper end of the shin bone. The next most common place osteosarcoma begins is in the humerus. This is the upper arm bone close to the shoulder.
However, osteosarcoma can develop in any bone in the body. Rarely, it occurs as a tumor in the body’s soft tissue, outside the bone.
Types and subtypes of osteosarcoma
There are 2 types of osteosarcoma.
Central tumor, also called a medullary tumor
Surface tumor, also called a peripheral tumor
Each type has different subtypes. The type and subtype of osteosarcoma is determined by looking at the tumor cells through a microscope.
The most common subtype is called conventional central osteosarcoma. The other subtypes are much less common. They each account for less than 5% of all osteosarcomas.
Subtypes of medullary osteosarcoma include:
Conventional central osteosarcoma, such as osteoblastic, chondroblastic, fibroblastic, and mixed types
Intraosseous well-differentiated, or low-grade, osteosarcoma
Small cell osteosarcoma
Subtypes of peripheral osteosarcoma include:
Parosteal, well-differentiated or low-grade, osteosarcoma. Also called juxtacortical osteosarcoma.
Periosteal osteosarcoma that is low grade to intermediate grade
High-grade surface osteosarcoma
Grade is the most important factor in treatment decision-making, since low-grade tumors only recur in the same area, called locally, while high-grade tumors metastasize to other parts of the body and can recur anywhere in the body. Most osteosarcoma in children are high grade. This section covers osteosarcoma that is diagnosed during childhood. Visit the bone cancer and soft-tissue sarcoma sections on Cancer.Net to learn more about other types of sarcoma.
Looking for More of an Introduction?
If you would like more of an introduction, explore these related items. Please note that these links take you to other sections on Cancer.Net:
- ASCO Answers Fact Sheet: Read a 1-page fact sheet that offers an introduction to osteosarcoma. This fact sheet is available as a PDF, so it is easy to print out.
- Cancer.Net Patient Education Video: View a short video led by an ASCO expert in childhood cancer that provides basic information and areas of research.
The next section in this guide is Statistics. It helps explain the number of people who are diagnosed with osteosarcoma and general survival rates. Use the menu to choose a different section to read in this guide.