What Is a Sarcoma? Bone and Soft Tissue Types Explained
A sarcoma is a cancer that begins in connective tissue, the material that supports, connects and surrounds other parts of the body. That includes bone, cartilage, muscle, fat, blood vessels and nerve sheaths. The main division is between bone sarcomas, which start in bone, and soft tissue sarcomas, which start in the other supporting tissues.
Sarcomas are uncommon. Cancers that arise in the lining of organs, such as the breast, lung or bowel, are called carcinomas and are far more frequent. The US National Cancer Institute describes soft tissue sarcoma as a broad term for cancers that start in soft tissues such as muscle, fat, tendons, nerves and blood vessels. This page gives general background only and is not a substitute for advice from a doctor.
Why there are so many kinds
The body has many types of connective tissue, and a sarcoma is named after the tissue it resembles. Pathologists have described dozens of subtypes, which is part of why sarcoma is considered a group of related diseases rather than one illness. Subtypes can behave very differently. Some grow slowly and others spread more quickly, and they can respond differently to treatments.
This variety is also a challenge for research. Because each subtype is rare, studies often involve small numbers of people, and specialist centres are important for collecting experience.
Bone sarcomas
Bone sarcomas arise within bone. The three best known are:
- Osteosarcoma, which forms bone-like material and is most often diagnosed in teenagers and young adults, although it can occur at other ages.
- Ewing sarcoma, which occurs in bone or soft tissue and is most common in children and young adults.
- Chondrosarcoma, which arises from cartilage-producing cells and is more often diagnosed in adults.
Not every bone cancer is a sarcoma. Cancer that spreads to bone from elsewhere, such as the breast or prostate, is a different situation and is treated according to where it started.
Soft tissue sarcomas
Soft tissue sarcomas can occur almost anywhere, but are often found in the arms, legs, trunk and the back of the abdomen. Some commonly named types are:
| Type | Tissue it resembles |
|---|---|
| Liposarcoma | Fat |
| Leiomyosarcoma | Smooth muscle |
| Rhabdomyosarcoma | Skeletal muscle |
| Synovial sarcoma | Resembles tissue near joints, though not always arising there |
| Angiosarcoma | Blood or lymph vessels |
| Undifferentiated pleomorphic sarcoma | Cells that do not clearly resemble one tissue |
| Gastrointestinal stromal tumour (GIST) | Supportive cells in the digestive tract |
| Alveolar soft part sarcoma | A rare type of unclear tissue origin |
Alveolar soft part sarcoma (ASPS) is a very rare subtype, and there is a separate overview of it in What Is ASPS?. Because the origin of its cells is still uncertain, it is described by its microscopic pattern instead of a tissue it resembles.
How rare are sarcomas?
Sarcomas make up a small share of all cancers in adults, often quoted as around one percent, and a larger share of cancers in children and young people. Exact figures differ by country, by year and by how subtypes are counted, so the best place to check current numbers is a national cancer registry or cancer charity. In the UK, the NHS provides overview pages on soft tissue sarcoma, and in the US the National Cancer Institute does.
Is every lump a sarcoma?
No. Most soft tissue lumps are not cancer. Lipomas (harmless fatty lumps) and cysts are far more common. A sarcoma diagnosis can only be made after tests, usually imaging and a tissue sample examined under a microscope.
What causes sarcoma?
In most cases, no clear cause is found. Some risk factors are known: certain inherited genetic conditions, earlier radiation therapy to an area, long-term swelling of a limb (lymphoedema) in the case of one rare form, and exposure to some chemicals in a few instances. These account for a minority of cases, and most people who develop a sarcoma have none of them. Statements that a lifestyle choice or injury caused a sarcoma are generally not supported by evidence.
Frequently asked questions
Is sarcoma a type of bone cancer?
Sometimes. Bone sarcomas such as osteosarcoma and Ewing sarcoma start in bone, but most sarcomas begin in soft tissues like muscle, fat or blood vessels.
Is sarcoma common?
No. Sarcomas are rare compared with cancers such as breast, lung or bowel cancer. Because they are rare, it can take time for the right specialist care to be identified.
Is sarcoma hereditary?
Usually not. A small number of cases are linked with inherited genetic conditions, but most occur without a family history.
Can children get sarcoma?
Yes. Some types, such as rhabdomyosarcoma and Ewing sarcoma, are more common in children and young people than in older adults.
Where to learn more
Reliable, regularly updated information is available from the National Cancer Institute’s soft tissue sarcoma pages and the NHS soft tissue sarcoma page. Anyone with a personal concern about a lump or symptoms should speak with a doctor. For a general look at a specific rare type on this site, read What Is ASPS?, and for how the subject has been covered in the press see the media summary.