A sarcoma is a cancer that starts in the tissues that support and connect the body: fat, muscle, tendons, blood vessels, nerves, cartilage or bone. It is a malignant and uncommon tumor. There are dozens of types, and what most affects how one behaves is the grade of the tumor and whether the first operation is done well.
How is a sarcoma different from other cancers?
By the tissue it starts in. Most cancers, such as breast, colon or lung cancer, are carcinomas: they start in the cells that line organs. Sarcomas start in connective tissue, the tissue that gives the body its shape and support.
That is why they can appear almost anywhere. Soft tissue sarcomas are most common in the arms, legs, abdomen and retroperitoneum, the area behind the abdominal cavity (US National Cancer Institute).
What types of sarcoma are there?
They fall into two main groups. Soft tissue sarcomas are the most common in adults, and within them the name says which tissue the cells seem to come from:
- Liposarcoma, from fat tissue. It is one of the most common in the retroperitoneum.
- Leiomyosarcoma, from smooth muscle, the muscle in the walls of blood vessels, the uterus or the bowel.
- Undifferentiated pleomorphic sarcoma, when the cells do not look like any specific tissue.
- Synovial sarcoma, which usually appears near joints, often in young people.
- Angiosarcoma, from blood or lymph vessels.
- Rhabdomyosarcoma, from skeletal muscle, more typical in children.
- Gastrointestinal stromal tumor (GIST), which starts in the wall of the digestive tract and has its own treatment.
The other group is bone sarcomas, such as osteosarcoma, chondrosarcoma or Ewing sarcoma.
What is the grade of a sarcoma and why does it matter?
The grade shows how different the tumor cells look from normal cells and how fast they divide. A low-grade sarcoma grows slowly and rarely spreads; a high-grade one grows faster and is more likely to spread.
Together with size, location and whether the tumor has spread, grade weighs most in the prognosis and in the decision to add radiotherapy or chemotherapy to surgery. We explain survival figures by type and grade in life expectancy with sarcomas.
What symptoms does a sarcoma cause?
The most common symptom of a soft tissue sarcoma is a painless lump that keeps growing, often in an arm or a leg. Those in the abdomen can grow very large without causing discomfort, until their size causes pain, a feeling of fullness or digestive problems.
Most lumps in or under the skin are benign, such as lipomas. It is worth seeing a doctor if the lump is growing, is large, lies deep or comes back after being removed.
How is it diagnosed and treated?
With imaging, usually an MRI, and a biopsy that confirms the type and grade. The biopsy should be planned by the same team that will operate, because the needle track is removed later together with the tumor.
The main treatment is surgery: removing the whole tumor, without opening it and with a margin of healthy tissue around it. Depending on the type and grade, radiotherapy or chemotherapy is added before or after surgery.
Why does it matter so much who does the first operation?
Because it has the greatest influence on the prognosis. A sarcoma removed with insufficient margins, or opened during the operation, is more likely to grow back in the same place and leads to much more aggressive repeat surgery.
That is why the European guideline (ESMO, 2021) recommends that patients with a suspected sarcoma be assessed at a reference center, ideally before the biopsy and the first operation. This matters even more for abdominal and retroperitoneal sarcomas: parts of other organs often have to be removed at the same time, and sometimes vessels have to be reconstructed, which requires a team with oncovascular experience. If the sarcoma has already been operated on and has come back, salvage surgery is still an option in selected cases.
Frequently asked questions
Is a sarcoma malignant?
Yes. Sarcoma is the name for malignant tumors of connective tissue. Benign tumors of the same tissues, such as lipomas, have other names and are not sarcomas.
Is a sarcoma the same as cancer?
Yes, it is a type of cancer. It differs from the most common ones, carcinomas, in that it starts in connective tissue (fat, muscle, vessels, nerves, cartilage or bone) rather than in the tissue lining the organs.
What is the most common sarcoma?
In adults, soft tissue sarcomas are much more common than bone sarcomas, and among them liposarcoma, leiomyosarcoma and undifferentiated pleomorphic sarcoma stand out.
Can a sarcoma be cured?
Yes, especially when it is localized and removed completely with adequate margins in the first operation. The grade and size of the tumor are the factors that weigh most.
If you have been diagnosed with a sarcoma or one is suspected, an assessment is most useful before the first operation. We review your scans and tell you whether the proposed surgery is right for you: request a second opinion.
References
- US National Cancer Institute. Adult Soft Tissue Sarcoma Treatment (PDQ®), patient version.
- Gronchi A, Miah AB, Dei Tos AP, et al. Soft tissue and visceral sarcomas: ESMO-EURACAN-GENTURIS Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2021;32(11):1348-1365.
This information is for general education and does not replace your doctor's assessment.