Diagnosis of soft tissue sarcoma
Diagnosing soft tissue sarcoma usually begins with a visit to your family doctor. Your doctor will ask you about any symptoms you have and do a physical exam. Based on this information, your doctor will refer you to a specialist or order tests to check for soft tissue sarcoma or other health problems.
The process of diagnosis may seem long and frustrating. It’s normal to worry, but try to remember that other health conditions can cause similar symptoms as soft tissue sarcoma. It’s important for the healthcare team to rule out other reasons for a health problem before making a diagnosis of soft tissue sarcoma.
The following tests are commonly used to rule out or diagnose soft tissue sarcoma. Many of the same tests used to diagnose cancer are used to find out the stage, which is how far the cancer has progressed. Your doctor may also order other tests to check your general health and to help plan your treatment.
Your health history is a record of your symptoms, risk factors and all the medical events and problems you have had in the past. In taking a health history, your doctor will ask questions about a personal history of:
- symptoms that suggest soft tissue sarcoma
- previous radiation treatment
- genetic conditions
- chronic lymphedema
A physical exam allows the doctor to look for any signs of soft tissue sarcoma. During a physical examination, the doctor will:
- look at and feel the affected area and compare it to the same area on the other side of the body (for example, the other arm or leg) to check for equal size and shape (symmetry)
- check for limited range of motion and muscle atrophy on the affected limb (for example, if there is a lump on the leg, your doctor will check for limping or an abnormal walk)
- check for weakness or numbness, which may mean the tumour is pressing on a nearby nerve
An x-ray uses small doses of radiation to make an image of the body’s structures on film. It is often the first imaging test done to help confirm the presence of a soft tissue sarcoma. An x-ray is also used to find out if the tumour is in the bone or has spread to the lungs.
Ultrasound uses high-frequency sound waves to make images of structures in the body. It is used to find out if a lump is a solid mass or a cyst. Doctors also use ultrasound to help guide a needle into the tumour to collect a sample for biopsy.
A computed tomography (CT) scan uses special x-ray equipment to make 3-dimensional and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.
A CT scan is used to give a more detailed image of the tumour, especially if it is inside the chest or abdomen. It is also used to assess how the tumour is affecting nearby tissues or structures. Doctors will use CT scans to find out if the tumour has spread to the lungs, liver or other structures in the chest, abdomen or pelvis.
Magnetic resonance imaging (MRI) uses powerful magnetic forces and radio-frequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3-dimensional pictures.
MRI is used to give a more detailed image of the tumour. Doctors also use it to check for spread to nearby nerves, blood vessels, muscles or other structures.
During a biopsy, the doctor removes tissues or cells from the body so they can be tested in a lab. The report from the lab will confirm whether or not cancer cells are present in the sample. Different types of biopsies may be used to diagnose soft tissue sarcoma, depending on the size and location of the tumour. Often a biopsy needs to be done by a surgeon that specializes in soft tissue sarcomas. It is very important to plan the biopsy and surgery together as the area from where the biopsy sample was taken is often removed during surgery to remove the tumour.
Fine needle aspiration (FNA) uses a fine needle to draw a sample from a lump. The doctor may use ultrasound, CT scan or MRI to guide the needle to the lump and collect the sample. A FNA can be used instead of surgery to collect samples from areas deep in the body. It is useful in showing whether a lump is a cancerous or non-cancerous tumour, an infection or another disease. FNA can be useful in finding out if a tumour is a metastasis (cancer that has spread to the soft tissue from elsewhere in the body).
Sometimes the doctor can’t collect enough tissue with FNA to confirm a diagnosis. Another type of biopsy may be needed to collect more tissue to confirm that a lump is sarcoma.
Core needle biopsy gets a sample, or core, of tissue rather than just a few cells. It usually collects enough tissue to diagnose the type and grade of soft tissue sarcoma. The doctor may use ultrasound, a CT scan or MRI to guide the needle to the lump and collect the sample.
Incisional biopsy removes only a small part of a lump or abnormal area. It may be used if the tumour is large or when a core needle biopsy is inconclusive or difficult to do.
Excisional biopsy removes the entire lump or abnormal area along with a small amount (margin) of normal tissue around the lump. It is usually only done for small tumours and those that the doctors think are low grade or benign (non-cancerous).
A positron emission tomography (PET) scan uses radioactive materials (radiopharmaceuticals) to look for changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3-dimensional colour images of the area being scanned.
A PET scan may be used to help find out the grade of the tumour or to look for cancer spread, or metastasis.
Some studies have suggested that CT scans give a clearer image and are better for finding cancer that has spread to the lungs. Sometimes PET scans are combined with CT (PET/CT) to create an image that is as clear and detailed as possible.
PET scans may not be available in all centres.
A complete blood count (CBC) measures the number and quality of white blood cells, red blood cells and platelets. Your doctor may order a CBC to check your overall health before treatment starts.
Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are functioning and can help find abnormalities. They are used to stage soft tissue sarcoma.
Abnormal kidney and liver function tests may mean that cancer has spread to these organs. There is a greater risk that this can happen when soft tissue sarcoma develops in the abdomen or retroperitoneum.
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about diagnosis.
Thinning or wasting away of a cell, tissue or body part.
A description of a tumour that includes how different the cancer cells look from normal cells (differentiation), how quickly the cancer cells are growing and dividing, and how likely they are to spread.
Grades are based on different grading systems that are used for specific cancers. Some types of cancer do not have a specific grading system.
The process of examining and classifying tumours based on how cancer cells look and behave under the microscope is called grading.
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