Sarcomas are rare cancers that develop in the supporting or connective tissues of the body such as muscle, bone, nerves, cartilage, blood vessels and fat.
There are around 3200 new cases of sarcoma diagnosed each year in the UK.
Sarcomas account for about 11% of childhood cancers and about 14% of cancers in teenagers.
Most sarcomas (about 55%) affect the limbs, most frequently the leg. About 15% affect the head and neck area or are found externally on the trunk, while the remainder will be found internally in the retroperitoneum (abdominal area).
Types of sarcoma
Sarcomas fall into three broad categories;
- Soft tissue cancers
- Primary bone cancers
- Gastro-intestinal stromal tumours (a type of soft tissue sarcoma found in the stomach and intestines commonly known as GIST)
There are around 70 different sub-types of sarcoma within these broad categories. These sub-types are determined by the tissue of origin (the tissue in the body where the tumour originally formed), genetic characteristics or by other molecular analysis undertaken by expert pathologists.
The most common sub-types are:
- Gastrointestinal stromal tumour (GIST)
- Kaposi’s sarcoma (KS)
- Malignant peripheral nerve sheath tumour (MPNST)
- Desmoid tumour
- Ewing’s sarcoma
- Giant cell tumour (GCT)
If you have just been diagnosed, it will help you build your understanding of your disease as you read websites and other information to know:
- The sub-type (histotype) you have (see above)
- The ‘grade’ of the tumour – this is determined by a pathologist examining the tumour under a microscope and is an indicator for how aggressive the cancer may be
- The ‘stage’ the disease has reached – this is a process of clinical examination and imaging (CT and MRI scans) undertaken by the doctors to help decide the best treatment plan for you. This information might not be available immediately
- After surgery, whether margins around the removed tumour were ‘negative’ (this means that the tumour has been completely cut away and there is no evidence of the cancer left in you)
Causes of Sarcoma
The causes of most sarcomas are unknown. There are some hereditary conditions which have a susceptibility to sarcoma but the number of cases is very small. Patients who had retinoblastoma (an eye cancer) as a child have a genetic defect which also gives them a pre-disposition to sarcoma in later life. People with neurofibromatosis type 1 (a condition that causes the growth of benign and malignant tumours) may have a tendency to develop sarcoma.
There is also evidence from the USA that prolonged or intensive exposure to certain chemicals (such as Agent Orange, used in the Vietnam War) may be a cause.
Occasionally, patients who have had radiotherapy for another cancer are diagnosed with sarcoma. Such radiation induced sarcomas (often angiosarcoma) can occur many years after the treatment for the first cancer. It is a matter of concern that the success in treating cancers such as breast cancer with radiation may create a small rise in cases of sarcoma.
Accurate data about the actual diagnosed number of cases of sarcoma is hard to find. This is because cancer is reported against ‘site of origin’ (the area of the body where the cancer is found). Sarcomas can appear almost anywhere on or in the body and many are only found following investigations for a condition which seems unconnected with cancer. They are often reported as a cancer associated with a specific part of the body rather than as a sarcoma. This confusion is being resolved in the UK through research being undertaken by the National Cancer Intelligence Network (NCIN).
Despite the many different sub-types of sarcoma, the general pattern of treatment is similar. (There are a few exceptions, most notably with sarcomas in children).
Surgery is commonly viewed as the best option for a ‘cure’. Chemotherapy will usually be used with bone sarcomas before and after surgery, although it is less often used with soft tissue sarcoma. The case for chemotherapy following surgery is uncertain with soft tissue sarcoma but may be suggested with sub-types known to respond well to chemotherapy.
There are circumstances when radiotherapy offers benefits, usually after surgery but occasionally at other times too.
Gastrointestinal stromal tumours respond poorly to traditional chemo- or radiotherapies but can be treated with the new drug Glivec (imatinib).
The treatment plan developed by your doctors will be specific for you. You may meet other patients with a similar diagnosis but who are having different treatment but this is usual and nothing to be worried about.
This may be undertaken by a specialist sarcoma surgeon or by a specialist from another discipline in those cases where tumours are affecting their area of speciality such as the stomach. Some specialist sarcoma surgeons also have a background in orthopaedic or plastic/reconstructive surgery. Surgery should be undertaken under the supervision of a sarcoma specialist multi-disciplinary team, even when the surgeon is not a regular member of that team.