What is soft tissue sarcoma?
Sarcoma is a form of cancer that occurs in bones or soft tissues. Soft tissues include the following:
- blood vessels
- fibrous tissue
- lower layers of the skin (not the outer layer)
- the lining of the joints
Many types of abnormal growths can develop in soft tissues. If a growth is a sarcoma, it is either a malignant tumor or a cancer. Malignant means that parts of the tumour may break down and spread into the surrounding tissues. These escaped cells travel through the body and reside in the liver, lungs, brain, or other important organs.
Soft tissue sarcoma is relatively rare, particularly when compared to carcinomas, another type of malignant tumor. Sarcomas can cause death, especially if they are diagnosed when a tumour is already large or has spread to other tissues.
Soft tissue sarcoma is most commonly present in the arms or legs, as well as in the trunk, internal organs, head and neck, and behind the abdominal cavity.
There are many different types of soft sarcoma. A sarcoma is classified according to the tissue where it grew up:
- Malignant tumors in fat are called liposarcomas.
- In the smooth muscles surrounding the internal organs, cancerous sarcomas are known as léiomyosarcomes.
- Rhabdomyosarcoma is a malignant tumour of the skeletal muscle. Skeletal muscle can be found in your arms, legs and other body parts. This kind of muscle makes it possible to move.
- Gastro-intestinal stromal tumours (GISTs) are malignant tumours that start in the digestive tract (GI).
Although these are also found in adults, rhabdomyosarcomas are the most common soft tissue sarcomas in children and youth.
Other soft tissue sarcomes that are very uncommon include:
- Kaposi sarcomas
- malignant schwannomas
- neurogenic sarcomas
- synovial sarcomas
- malignant mesenchymomas
- alveolar soft part sarcomas
- epithelioid sarcomas
- clear cell sarcomas
- pleomorphic undifferentiated sarcomas
- spindle cell tumors
What are the symptoms of a soft tissue sarcoma?
Initially, soft tissue sarcomas can cause no symptoms. A pain-free mass under the skin of the arm or leg can be the first indication of soft tissue sarcoma. If a soft tissue sarcoma develops in your stomach, it may not be found until it is very broad and pressing onto other structures. You may experience pain or difficulty breathing because of a tumour growing in your lungs.
Another possible symptom is blockage in the intestinal tract. This may happen if a soft tissue tumour develops in the stomach. The tumor pushes too hard against your bowels and prevents food to flow easily. Other symptoms include blood from stool or vomit or black, tarry stool.
What causes soft tissue sarcomas?
In general, the cause of soft tissue sarcoma remains unidentified.
The exceptional is Kaposi’s sarcoma. Kaposi’s sarcoma is a cancer of the wall of the blood vessels or lymphatics. This cancer is responsible for violet or brown skin lesions. It is caused by an infection by the human herpes virus 8 (HHV-8). It is common in people with reduced immune function, such as those infected with HIV, but it may also occur without HIV infection.
Who is at risk for developing a soft tissue sarcoma?
Genetic risk factors
Certain inherited or acquired DNA mutations, or faults, may make you more likely to develop a soft tissue sarcoma:
- Basal cell nevus syndrome raises the risk for basal cell skin cancer, rhabdomyosarcoma and fibrosarcoma.
- Inherited retinoblastoma causes some sort of eye cancer in children, but this may also increase the risk of further soft tissue sarcoma.
- Li-Fraumeni syndrome raises the risk of several types of cancer, often through radiation exposure.
- Gardner’s disease causes cancers of the stomach or intestines.
- Neurofibromatosis may result in tumours of the nerve sheath.
- Tuberous sclerosis can lead to rhabdomyosarcome.
- Werner’s syndrome can lead to numerous health issues, including an increased risk of all soft tissue sarcomas.
Exposure to a number of toxins, such as dioxins, vinyl chloride, arsenic and herbicides If they contain phenoxyacetic acid at high doses, they may increase your risk of developing soft tissue sarcoma.
Radiation exposure, particularly via radiotherapy, can be a risk factor. Radiotherapy often deals with more frequent cancers such as breast cancer, prostate cancer or lymphoma. However, this effective therapy may increase your risk of developing some other forms of cancer, including soft tissue sarcoma.
How is soft tissue sarcoma diagnosed?
Physicians are generally only able to diagnose soft tissue sarcoma when the tumour becomes large enough to be noticed, as there are very few early symptoms. When cancer causes recognizable symptoms, it may already have spread to other tissues and organs of the body.
If your physician suspects soft tissue sarcoma, he or she will obtain a complete family history to see if others in your family may have had rare forms of cancer. You will also be required to undergo a physical examination to verify your overall health. This can help you figure out which treatments would work best for you.
Your physician will investigate the location of the tumor with the help of imaging scans such as simple X-rays or a CT scan. CT scans can also require the use of an injected dye to make the tumour more visible. Your physician may also request an MRI, PET or ultrasound scan.
At the end of the day, a biopsy is required to confirm the diagnosis. The test typically consists of inserting a needle into a tumor and taking a small sample.
In some cases, your physician may use a scalpel to cut a portion of the tumour to make it easier to examine. At other times, especially if the tumour puts pressure on a major organ like your intestines or lungs, your physician will remove the entire tumor and surrounding lymph nodes.
Tumour tissues will be examined microscopically to determine if the tumor is benign or malignant. While a benign tumor does not invade other tissues, a malignant tumor can.
Other tests carried out on a tumor sample from a biopsy include the following:
- immunohistochemistry, which investigates antigens or sites on tumor cells to which certain antibodies may bind.
- cytogenic analysis, which investigates changes in the chromosomes of tumor cells.
- fluorescence in situ hybridization (FISH), a test for specific genes or short DNA fragments.
- flow cytometry, which is a test to examine the number of cells, their health, and the presence of tumor markers on the cell surface.
Staging the cancer
If you have a biopsy that confirms cancer, your doctor will evaluate and stage the cancer by examining the cells under the microscope and comparing them with normal cells of this type of tissue. Staging is based on tumor size, tumor grade (probability that it spreads, ranked from grade 1 [low] to grade 3 [high]), and if the cancer has propagated to lymph nodes or other locations. Here are the various stages:
- Stage 1A: tumor less than or equal to 5 cm, grade 1, and the cancer did not spread to lymph nodes or far away sites.
- Stage 1B: the tumor measures more than 5 cm, grade 1, and The cancer did not spread to lymph nodes or far away sites.
- Stage 2A: The tumor is 5 cm or less, grade 2 or 3, and the cancer did not spread to the lymph nodes or far away.
- Stage 2B: the tumor is over 5 cm, grade 2, and It did not spread to lymph nodes or remote sites.
- Stage 3A: the tumor is longer than 5 cm, grade 3, and the cancer did not spread to lymph nodes or remote sites OR the tumor is of any size and the cancer spread to nearby lymph nodes, but not to other sites.
- Stage 4: tumor of any size and rank, and has spread to the lymph nodes and/or other sites.
What are the treatments for a soft tissue sarcoma?
Soft tissue sarcoma is rare, and it is best to look for treatment in an establishment that is familiar with your type of cancer.
Treatment depends on the location of the tumor and the exact cell type from which the tumor arises. (for example, muscle, nerve, or fat). If the tumor has metastatic, or spread to other tissues, it also affects treatment.
Surgery is the most common initial treatment. Your physician will remove the tumor and part of the surrounding healthy tissue and test to see if certain tumor cells can still be left in your body. If the tumor is at other known sites, your physician may also remove these secondary tumors.
Your physician may also need to remove the surrounding lymph nodes, which are tiny organs of the immune system. Lymph nodes are often the earliest places of tumor cell propagation.
Before, physicians often had to amputate a limb that had tumors. Now, the use of state-of-the-art surgery, radiotherapy and chemotherapy can often save a limb. However, significant tumors affecting the main blood vessels and nerves may still require amputation of limbs.
The risks associated with surgery include:
- damage to nearby nerves
- reactions to anesthesia
Chemotherapy is also used for the treatment of certain soft tissue sarcomas. Chemotherapy involves the use of toxic medications to kill cells that divide and multiply quickly, such as tumor cells. Chemotherapy also damages other cells that divide quickly, such as bone marrow cells, intestinal mucosa or hair follicles. There are numerous side effects associated with this damage.
However, if the cancerous cells extend beyond the original tumor, chemotherapy may actually kill them before they start forming new tumors and harm vital organs.
Chemotherapy does not kill every soft tissue sarcoma. However, chemotherapy treatments are effective in treating one of the most common sarcomas, rhabdomyosarcomas. Medicinal products such as doxorubicin (Adriamycin) and dactinomycin (Cosmegen) may also treat soft tissue sarcomas. There are numerous other medications that are specific to the type of tissue in which the tumor originated.
In radiotherapy, beams of high-energy particles like X-rays and gamma rays damage the DNA of cells. Cells that divide quickly, like tumor cells, are far more likely to die from this exposure than normal cells, but some normal cells will also die. Sometimes physicians combine chemotherapy and radiotherapy to make everyone more efficient and kill more tumor cells.
Side effects associated with chemotherapy and radiotherapy include:
- weight loss
- hair loss
- nerve pain
- other side effects associated with each type of medication regimen.
What are the potential complications of soft tissue sarcoma?
Complications from the tumor depends on the position and size of the tumor. The tumor can exert pressure on major structures such as:
- blood vessels
The tumor can invade and harm neighboring tissues as well. If the tumor metastasizes, which means that the cells detach and find themselves in other places such as the following, new tumors can develop in these organs:
In these areas, tumors can cause severe and potentially fatal damage.
The long-term survival of a soft tissue sarcoma varies according to the specific type of sarcoma. The prospects also depend on the status of the cancer at the time of the first diagnosis.
Stage 1 cancer will probably be much more treatable than stage 4 cancer, and has a higher survival rate. A tumor that is small, has not spread into the surrounding tissue, and is located in a readily accessible area, such as the forearm, will be easier to treat and remove completely with surgery.
A tumor that is large, surrounded by numerous blood vessels (making surgery challenging), and metastasized to the liver or lungs is much more difficult to treat.
Chances for recovery are dependent on:
- the position of the tumor.
- the cell type
- stage and grade of the tumor
- removal of the tumor surgically.
- your age
- your health
- Tumor is recurrent or new
After initial diagnosis and treatment, you will need to see your doctor frequently for checkups, even if the tumor is in remission, meaning that it is not detectable or not growing. X-rays, CT scans and MRIs may be required to verify whether a tumor has reappeared at its original site or at other locations in your body.