A sarcoma is a cancer that starts in the connective tissues of the body. A soft tissue sarcoma is a cancer that originates from the soft connective tissues of the body such as fat, muscle, nerves, blood vessels and fibrous tissues. As these structures are present everywhere in the body, soft tissue sarcomas can arise from all parts of the body but occur more commonly in the arms and legs.
Sarcomas are given different names depending on the type of cell they originate from. A sarcoma arising from fat cells is called a liposarcoma, from the muscle is called a leimyosarcoma, from the blood vessel is called an angiosarcoma etc. Other types include synovial sarcoma, malignant peripheral nerve sheath tumour, Desmoid tumour and solitary fibrous tumour.
Soft tissue sarcomas can occur in children, teenagers and young adults but are more common in people aged above 30.Sarcomas arising from the bones are discussed separately. Below is a picture of a soft tissue sarcoma of the leg.
Age
As in any cancer, age is a risk factor in the development of a soft tissue sarcoma. Sarcoma is more common in people older than the age of 60 but can occur in any age. Sarcomas can also occur in children.
Genetic Conditions
A small number of soft tissue sarcomas arise in patients who have genetic conditions such as Li Fraumeni syndrome, Neurofibromatosis, Gardner’s syndrome. Not all people with these syndromes develop a soft tissue sarcoma but are at an increased risk.
Previous Radiotherapy
Treatment with radiotherapy in the past increases the risk of development of a soft tissue sarcoma. This risk is small and is usually most 5-10 years after the radiotherapy treatment.
It is important to note that this risk is small in patients having radiotherapy and has to be balanced against the benefit the radiotherapy gives.
Previous Chemotherapy
Having chemotherapy in the past increases the risk slightly for developing a soft tissue sarcoma. Again, this risk is small and should not deter anyone having chemotherapy for that reason and have to balance benefits and risks when considering such treatments.
Chemicals
Exposure to chemicals such as dioxins, insecticides, vinyl chloride, increases the risk of developing soft tissue sarcoma.
A soft tissue sarcoma may not produce any symptoms at all when it is small but usually manifests itself as the size increases. The common symptoms associated with such a tumour include
Lump
Feeling or seeing a lump that grows in size is a common symptom of a soft tissue sarcoma. The lump can be painless or painful and may grow either slowly or rapidly.
Most lumps that grow on the body are not sarcomas, but a sarcoma needs to be suspected if the lumps are large or painful. Sarcomas that occur in the abdomen can become large before they are discovered.
Other Symptoms
Sarcomas can cause symptoms such as pain due to the tumour itself or the tumour compressing another structure such as a nerve. Sarcomas present in the abdomen can cause symptoms such as abdominal pain, constipation or diarrhoea. Sarcomas present in the lungs can cause cough and breathlessness. Sarcoma arising from the Uterus(womb) can cause vaginal bleeding. Patients with advanced sarcomas can have symptoms of tiredness, loss of appetite and weight loss.
A range of investigations are done to identify and confirm the presence of a soft tissue sarcoma. When a patient presents with a lump, the following tests are done to assess further. A thorough examination and routine blood tests will be done by the doctor prior to these tests.
Ultrasound Scan
An ultrasound scan is usually the starting test that is done to assess the lump that has been found. The scan will be able to assess the size, location and possible area of origin of the lump. In some situations, the doctor may request a CT or MRI scan directly without doing an ultrasound scan.
MRI Scan
An MRI scan is a very important test in determining the nature of the lump being investigated. It is more sensitive than CT scan in assessing sarcoma of the limbs, head and body areas and is the preferred investigation when assessing sarcomas. MRI scan is done to assess the sarcoma at its site of origin. MRI scan is the best test in this situation to help identify the growth or lump and will be able to tell if the lump is a cancer or not.
CT Scan
A CT scan can also be used to assess or investigate a lump when sarcoma is suspected. A CT scan is more helpful than an MRI in assessing soft tissue sarcoma arising from organs such as liver lung etc or in situations when an MRI is not available. CT scan is done either on its own or with PET to scan the whole body to look for spread of cancer to other areas.
PET/CT Scan
Use of PET/CT scan is not a routine staging investigation in soft tissue sarcomas. PET CT scans are good at assessing some types of sarcomas and not all and hence is not done routinely. This test is more useful in select situations such as investigating for a recurrence of the sarcoma or very occasionally for assessment of response to treatment.
Biopsy
A core biopsy is usually done to determine the nature of the lump or mass. The core biopsy involves taking a small piece of the lump with a needle and examining it under the microscope. A full diagnosis is made after a biopsy. Frequently, special staining of the biopsied material is needed to determine the exact nature of the mass. A biopsy of a suspected soft tissue sarcoma should be taken very carefully and by an experienced doctor in treating or diagnosing this condition. A right location has to be selected for the procedure so that the area is removed at the time of operation later if a sarcoma is diagnosed. A biopsy from the wrong place may make future surgery more complex or complicated.
If the lump is small, an excision biopsy is done where the entire lump or growth is removed, and a diagnosis is made by looking at it under the microscope.
The stage of a cancer is a term used to describe the size and location of the cancer in the body. Knowing the stage of the cancer helps the doctors to decide on the most appropriate treatment. Soft tissue sarcoma is staged based on the TNM staging system or the number system.
Staging with either system is based on the size and extent of the tumour, the spread of the cancer into the lymph nodes and spread of cancer into other parts of the body.
TNM stands for tumour, node and metastases. T stands for tumour and N stands for nodes and spread of cancer into lymph nodes around the cancer. M stands for metastases and spread of cancer to distant areas in the body.
TNM Staging
T Stage
| T1 | Here the cancer is 5cm or less in size. This is divided into T1a where The cancer is superficial and T1b where it is deep in the tissues |
| T2 | The cancer is more than 5cm in size and is divided into superficial T2a And deep T2b |
N Stage
| N0 | There is no involvement of lymph nodes by the cancer |
| N1 | The cancer has spread into the surrounding lymph nodes |
M Stage
| M0 | There is no spread of cancer into distant parts of the body |
| M1 | There is spread of cancer into distant parts of the body |
Grade of Cancer
The cancer is given a grade depending on its look under the microscope. It is called as well differentiated or grade 1 when the cancer resembles the original cell of origin the most and grade 3 or poorly differentiated when the cancer cells don’t resemble the original cell at all. Grade 2 or moderately differentiated cancer is in between grade 1 and grade 3.
Soft tissue sarcomas are treated based on the stage of the cancer at diagnosis. The treatment options include surgical resection, radiotherapy and chemotherapy.
Surgical Resection
Surgical resection involves surgical removal of the sarcoma. The type of surgery done can be a wide excision, where the tumour along with a margin of normal area around the tumour is removed. A margin of normal tissue is taken to ensure completeness of removal of tumour.
When a wide excision is done in a limb like an arm or a leg, it is also called as a limb sparing surgery as the entire limb is not removed.
For most patients, a wide excision is possible. However, in patients where this is not possible, an amputation of the limb may be necessary to remove the tumour. An amputation of the limb involves removal of the whole limb. Following removal of the cancer, reconstructive surgery may be needed to replace the removed tissue with other tissues such as muscle, bone etc or a prosthesis.
In most patients with soft tissue sarcoma, surgical resection is the first treatment option followed by others. However, in some situations when surgery is not feasible, radiotherapy is used first, followed by surgery. This option is used more commonly in sarcomas arising in the abdomen.
If an amputation is required, a prosthesis can be arranged to continue to enable function of the limb.
A prosthesis is an artificial limb or joint or any other structure that enables to give the same function of the amputated limb or other body part that was removed at surgery. The doctor doing the amputation will discuss and finalise options for the prosthesis prior to doing the amputation.
Surgery can sometimes be considered in patients with advanced sarcoma that has spread to other parts of the body from its site of origin. This is usually in patients in whom the spread is limited to one or two areas and not extensive. Following surgery for soft tissue sarcoma, particularly after surgery of a limb such as an arm or a leg, rehabilitation or physiotherapy is needed to obtain the best function possible in that operated limb.
Radiotherapy
Radiotherapy is commonly used as a treatment option in patients with soft tissue sarcoma. Usually radiotherapy is used as adjuvant treatment which means it is given after a definitive treatment such as surgery. The treatment is given to the area where the tumour was prior to the surgery. The purpose of adjuvant radiotherapy in this condition is to kill off any remaining cancer cells still present in that area. Usually radiotherapy given in this setting is for 6-7 weeks (30-33 treatments), with treatment given 5 days a week. Radiotherapy is given for patients with high grade and intermediate grade sarcomas as well as some low-grade sarcomas.
In some patients, radiotherapy is given before definitive surgery. This method is called as neo adjuvant radiotherapy. This type of treatment is considered in patients with abdominal sarcomas or sarcomas in other sites which are large and difficult to remove surgically and are removed once they shrink in size after radiotherapy.
Different techniques of radiotherapy can be used in the treatment of sarcomas. 3D-CRT, IMRT, IGRT and other techniques are used. For more details on radiotherapy, please see section on radiotherapy in cancer FAQ’s. Side effects of radiotherapy in soft tissue sarcomas include tiredness, redness of the skin, soreness of the skin, stiffness of the joints if they are in the treatment area and swelling of the limbs can occur as long-term side effects in some patients.
Radiotherapy to the abdomen can cause side effects such as abdominal discomfort or pain, loose motions, constipation
Chemotherapy
Chemotherapy is used less in patients with soft tissue sarcoma compared to other cancers as its benefit is limited in most types of soft tissue sarcomas. Chemotherapy is used in conditions such as Rhabdomyosarcomas, liposarcomas and synovial sarcomas where the response of these tumours to chemotherapy is better.
Chemotherapy used before definitive surgery is called as neo adjuvant chemotherapy. This option is used to shrink down a large tumour that is difficult to remove directly. Chemotherapy used after definitive surgery or radiotherapy is called as adjuvant chemotherapy and is used in some types of soft tissue sarcomas to reduce the risk of recurrence.
Chemotherapy is more commonly used in patients with advanced or metastatic disease (stage 4) that is not curable. Here, the purpose of chemotherapy is to control the cancer and symptoms and increase survival. Common drugs used in this setting include Doxorubicin, Ifosfamide, Taxanes, Gemcitabine, Trabectedin and Eribulin. For more details on chemotherapy, see section on chemotherapy in cancer FAQ’s.
Biological or Targeted Therapy
Biological treatment or targeted treatment involves use of drugs that target specific sites either on the cancer cells or on mechanisms that enable the cancer to grow. A number of these biological drugs are available for treatment of soft tissue sarcomas.
Pazopanib, Imatinib, Sunitinib, Sirolimus are some of the drugs used in soft tissue sarcomas. For details of biological therapy, see section on Biological therapy in cancer FAQ’s.
