Diagnosing soft tissue sarcoma
To diagnose soft tissue sarcoma, a specialist doctor will usually arrange for you to have an ultrasound scan and a biopsy.
How soft tissue sarcoma is diagnosed
If your GP thinks you might have a sarcoma, you should be seen at the hospital within 2 weeks. Your doctor can refer you to see a specialist within 2 days if you are 24 years old or under and have either:
- a lump that is getting bigger
- an uncertain or suspicious ultrasound result.
At the hospital the specialist will examine you. They arrange different tests depending on your symptoms. Your doctor and specialist nurse will explain the tests you need. Tests usually include blood tests, ultrasound, x-rays and scans.
A doctor or nurse may take samples of tissue from the tumour. This is called a biopsy. The type of biopsy depends on where the lump is and its size. If you are having surgery to remove the tumour, you may not have a biopsy before your operation.
If tests show you have a sarcoma your specialist will arrange further tests. These can help find out more about the size and position of the cancer and whether it has spread. This is called staging.
Tests are also done on the cancer cells to find out more about the type of sarcoma. Other tests check if the cancer cells have any genetic changes or are producing any proteins.
Ultrasound scan
An ultrasound uses sound waves to make a picture of an area inside the body.
The type of ultrasound will depend on where the lump is in your body.
If the lump is in the womb or pelvis (area between your hips) you may also have a transvaginal ultrasound scan. This is when they gently insert the ultrasound device into the vagina.
CT scan
A CT scan makes a detailed picture of the inside of the body using x-rays taken by the CT scanner.
Depending on the type of sarcoma you may have a CT scan of the abdomen (tummy) or pelvis. If sarcoma is diagnosed you might also have a CT scan to check your lungs. The lungs are one of the most common places for soft tissue sarcomas to spread to.
Endoscopy
An endoscopy is a test that looks inside the body using a thin, flexible tube called an endoscope.
The tube has a light and video camera at the end so the doctor can see any abnormal areas. It is passed into the body to help doctors see certain areas. For example, it is passed into the mouth to see the gullet (oesophagus), stomach and small bowel.
An endoscopy can be used to investigate gastrointestinal stromal tumours (GISTs). The doctor may also remove a small sample of tissue (biopsy) during an endoscopy.
Sometimes an endoscopy is combined with an ultrasound. This is called an endoscopic ultrasound scan (EUS).
Biopsy
Your doctor or nurse may take samples of tissue from the tumour. This is called a biopsy. It is the only way to tell if the lump is cancer (malignant) or a non-cancerous (benign) tumour.
The samples are sent to a specialist doctor called a pathologist. They have experience in sarcomas. They can tell if the tumour is cancer or not by looking at the cells under a microscope. They do further tests on the sample to try to find out exactly what type of sarcoma it is.
If you are going to have surgery to remove the tumour, you may not have a biopsy before your operation. This may be when the tumour is very small, or it is in the abdomen. Instead, the whole tumour is sent to the laboratory after the operation. The laboratory will do tests to check that it is a sarcoma.
The type of biopsy you have depends on where the lump is, and its size.
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Fine needle aspiration (FNA)
Your doctor uses a very thin needle and a syringe to take small pieces of tissue from the lump. An FNA may be slightly uncomfortable but should not be painful. Before the biopsy is taken, you may have an injection of local anaesthetic to numb the area.
The doctor guides the needle to the right place by feeling the lump near the surface of the body. If they cannot feel the lump, or if it is deep inside the body, they may use an ultrasound or a CT scan to guide the needle.
If an FNA does not collect enough cells to give a clear diagnosis, you will need a different type of biopsy.
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Core needle biopsy
This is the most common type of biopsy. The doctor uses a hollow needle to take small samples of tissue from the lump.
You are usually awake during a core needle biopsy. You may be given a sedative to make you feel relaxed and drowsy. Sometimes the biopsy is done under a general anaesthetic.
Before the biopsy, the doctor injects a local anaesthetic into the skin around the lump to numb the area. The doctor passes the biopsy needle through the skin and into the lump to take the sample.
You may have an ultrasound or a CT scan at the same time. The pictures from the scan help the doctor guide the needle to the right place. They usually take several samples of tissue.
If the biopsy does not collect enough cells to give a clear diagnosis, you will need a surgical biopsy.
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Surgical biopsy
If the lump is small, the doctor may do a small operation to remove the whole lump. This is called an excision biopsy. You may have this done using a local or a general anaesthetic.
Sometimes doctors do a biopsy that removes only a sample of the lump. This type of biopsy is called an incision biopsy. It is done less often than an excision biopsy.
Further tests
If the tests show that you have a soft tissue sarcoma, your doctor may do further tests. These are to find out the size and position of the cancer and whether it has spread to other parts of the body. This is called staging. It helps you and your doctor decide on the best treatment for you.
Chest x-ray
PET or PET-CT scan
A PET scan uses low-dose radiation to check the activity of cells in different parts of the body.
You may have a PET scan and a CT scan together. This is called a PET-CT scan. It can give more detailed information about cancer or abnormal areas seen on other scans.
Testing the cancer cells for genetic changes or proteins
Tests are done on the tissue samples to find out if there are any genetic changes in the sarcoma cells. This is sometimes called cytogenetic testing.
This can help tell your doctor the type of sarcoma you have and if certain treatments would be suitable for you.
The tissue sample is also tested to look for any proteins the cancer cell is producing. This is called immunohistochemistry.
About our information
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References
Below is a sample of the sources used in our soft tissue sarcoma information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk
Gronchi A, Miah AB et al. Soft tissue and visceral sarcomas: ESMO-EURACAN-GENTURIS Clinical practice guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2021; 32, 11, 1348-1365 [accessed May 2022].
Casali PG, Blay JY et al. Gastrointestinal stromal tumours: ESMO-EURACAN-GENTURIS Clinical practice guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2022; 33,1, 20-33 [accessed May 2022].
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