Definition: Bone & Soft Tissue Sarcomas
What is Bone?
To better understand the different kinds of bone and soft tissue cancers and how they spread, it may be helpful to examine the anatomy of the bone. Bone is living tissue that makes up the body’s skeleton.
There are three types of bone tissue, including the following:
- Compact tissue—the harder, outer tissue of bones.
- Cancellous tissue—the sponge-like tissue inside bones.
- Subchondral tissue—the smooth tissue at the ends of bones, which is covered with another type of tissue called cartilage. Cartilage is the specialized, gristly connective tissue that is present in adults, and the tissue from which most bones develop in children.
Together, compact and cancellous tissues are called the periosteum. Beneath the hard outer shell of the periosteum there are tunnels and canals through which blood and lymphatic vessels run to carry nourishment for the bone. Muscles, ligaments, and tendons may attach to the periosteum.
There are 206 bones in the human skeleton, not including teeth and sesamoid bones (small bones found within cartilage). Bone is the supporting framework for the body, and provides protection for internal organs. Bones also act as levers and braces for muscles to produce movement, and provide the medium (marrow) for the development and storage of blood cells. Because of the complexities of a bone’s function, there are many disorders and diseases that can affect bone.
Although scientists are not certain what causes bone or soft tissue cancers, risk factors for these cancers are often linked to having had other diseases, treatments for other diseases, or age. These cancers occur more frequently in children and young adults, particularly those who have had radiation or chemotherapy treatments for other conditions. Adults with Paget disease, a non-cancerous condition characterized by abnormal bone turnover, may be at increased risk for osteosarcoma. A few bone and soft tissue cancers are genetically transmitted. For example, children with hereditary retinoblastoma (an uncommon cancer of the eye) are at a higher risk of developing osteosarcoma.
What Are the Different Types of Bone & Soft Tissue Cancer?
There are many types of sarcomas, but the most common are:
Osteosarcoma is a type of bone cancer that develops in undifferentiated cells and occurs at the ends of long bones, especially around the knee. Approximately 900 new cases of osteosarcoma are reported each year in the U.S., occurring most often in children, adolescents, and young adults. Osteosarcoma may metastasize, or spread, into nearby tissues, tendons or muscles as well as metastasize through the bloodstream to other organs or bones.
Chondrosarcoma is the second most common type of bone cancer, occurring in about 26 percent of all bone cancer cases, according to the American Cancer Society. Although chondrosarcoma can affect all skeletal areas of the body, it primarily occurs in cartilage rich areas around the pelvis, upper femur, humerus, and spine.
Ewing sarcoma forms in the cavity of the bone, most often in the extremities and can involve muscle and the soft tissues around the tumor site. Ewing sarcoma cells also can spread (metastasize) to other areas of the body, including the bone marrow, lungs, kidneys, heart, adrenal gland, and other soft tissues. Ewing sarcoma usually appears in children and teenagers, and is uncommon in adults over 30. This type of bone tumor accounts for 16 percent of bone cancers, reports the American Cancer Society.