Sarcomas are an uncommon group of cancers that arise in the body’s supporting, or connective, tissues — the framework of bone, cartilage, muscle and fat that holds the body together and lets it move. Because that framework runs everywhere, a sarcoma can appear almost anywhere. It begins when cells in one of these tissues start to divide and multiply without the usual controls.
Rarity shapes the whole experience of sarcoma. Soft tissue sarcomas account for only a small fraction of all cancers in Australia — of the order of a couple of thousand new cases across the country each year — so a typical GP may encounter only a handful across an entire career, and the great majority of lumps they assess prove to be harmless. That rarity is precisely why anything suspicious is sent to a specialist unit, where the same tumours are seen every week and the team knows what to look for.
Sarcomas fall into two broad families, grouped by the tissue in which they begin.
Soft tissue sarcoma
Soft tissue sarcomas develop in the soft, supporting tissues of the body: fat, muscle, blood vessels, lymphatic vessels, nerves, tendons and cartilage. There are more than 50 types. The most common include:
- Undifferentiated pleomorphic sarcoma (UPS) — most common in people aged 50 to 70
- Leiomyosarcoma — starts in smooth muscle, often in the limbs, abdomen or uterus
- Liposarcoma — starts in fat cells, often in the trunk, limbs or abdomen
- Angiosarcoma — starts in blood vessels or lymphatic vessels
- Malignant peripheral nerve sheath tumour — starts in the lining of nerves, often deep in the arms, legs or trunk
- Fibroblastic sarcoma — develops in the fibrous tissues, often in the limbs, skin or trunk
- Rhabdomyosarcoma — develops in skeletal muscle, most common in children under 10
- Synovial sarcoma — develops in cells around joints and tendons
Bone sarcoma
Primary bone sarcoma starts in the bone itself. This is different from bone metastases — cancer that has spread to the bone from somewhere else, such as the breast or lung. The two are treated quite differently, which is one reason accurate diagnosis matters so much.
Bone sarcomas are more common in children and teenagers than in adults. The main types are:
- Osteosarcoma — the most common primary bone cancer. It usually occurs at the ends of the long bones, especially around the knee
- Ewing sarcoma — common sites include the pelvis, the chest wall and the middle of the long bones in the legs; it can also form in soft tissue
- Chondrosarcoma — starts in the cells that make cartilage, and often affects the upper arm, legs, pelvis, ribs or shoulder blade
What does this mean for you?
The name of your tumour — its exact type and grade — determines everything that follows: which tests you need, whether surgery comes first or after other treatment, and what follow-up looks like. Working that name out precisely is the purpose of the tests described in the next step.