Soft Tissue Sarcoma and
Gastrointestinal Stromal Tumors (GIST)
Soft Tissue Sarcoma
Soft tissue sarcomas are very rare cancers that can develop anywhere on the body. They make up less than 1% of all adult cancers. They develop from our supportive tissue structures such as fat, muscle, nerve, bone, blood vessels etc. There are more than 50 subtypes of sarcoma. These tumours can grow quite large before giving any symptoms as they tend to push other structures aside as opposed to invade them. These are very complex surgeries often requiring a multi-disciplinary team. It is important that if you have the diagnosis of Sarcoma that you be evaluated in a specialized center such as the Ottawa Hospital. The Ottawa Hospital is one of the three Cancer Care Ontario designated Sarcoma Centers. This means Sarcoma surgery can only be performed and treated at these centers in Ontario.
Gastrointestinal Stromal Tumors (GIST)
Gastrointestinal Stromal Tumors (GIST) are a type of Sarcoma of the GI tract. They arise from the muscular layer of the GI tract. They can occur anywhere from the Esophagus all the way down to the Rectum. The most common site however is the Stomach. These tumors have a tendency to bleed. When very large, often treatment entails a combination of target therapy (specific medication directed at the tumor, called Imatinib) and surgery together to provide potential cure. When smaller, surgical resection alone may suffice. For very small GISTs in the stomach that are ≤2cm and give no symptoms, in some cases. observation is a reasonable option. These tumors are quite rare and should only be treated by specialized surgeons designated for Sarcoma Complex Care, such as the Ottawa Hospital, one of the three designated Sarcoma Centers in Ontario.
Desmoid Tumour
A desmoid tumour is a benign (not cancer) tumour that can be found anywhere in the body but is often in the abdominal wall. They can vary in size. Depending on size, rate of growth and symptoms, the treatment is variable. The majority of desmoids can be observed. Others may require medical therapy, chemotherapy or surgery. This must be discussed with a surgeon and medical oncologist. These tumors are quite rare and should only be treated by specialized doctors designated for Sarcoma Complex Care, such as the Ottawa Hospital, one of the three designated Sarcoma Centers in Ontario.
Dr. Carolyn Nessim actively treats Soft Tissue Sarcoma and GIST patients through the Ottawa Hospital Regional Cancer Center. She is an active collaborator of the Sarcoma Communities of Practice of the Ottawa Regional Cancer Program.
Sarcoma is cared for by a multidisciplinary team including a Surgical Oncologist, Orthopedic Oncologist, Urologist Oncologist, Plastic Surgeon, Medical Oncologist, Radiation Oncologist, Pathologist and Radiologist. The Ottawa Hospital has a dedicated sarcoma team to care for sarcoma patients.
Dr. Nessim is the secretary and Chair of the Research Evaluation Committee of the Trans-Atlantic Australasian Retroperitoneal Sarcoma Working Group (TARPSWG). She is also a member of the GIST Specialist Registry Canada as well as the Desmoid Expert Registry – Desmoid Tumour Foundation of Canada. She helps develop guidelines and research for the treatment of soft tissue sarcoma and GIST and is also a member of the Canadian Sarcoma Research Collaboration (CanSaRC).
Dr. Nessim recently wrote an editorial about Soft Tissue Sarcoma. It can be found here.
Frequently asked questions about Soft Tissue Sarcoma/GIST/Desmoid
Why do I need a biopsy of my tumour?
In many cases a biopsy is required as this gives us the proper diagnosis to appropriately guide your treatment. Given that there are more than 50 subtypes of Soft Tissue Sarcoma, the diagnosis is essential to help guide treatment, as the treatment may vary according to subtype. That being said, some sarcomas do not require biopsy. It is best to wait and see a sarcoma specialist before a biopsy of your tumour is performed.
How will the biopsy be performed?
For Soft tissue sarcomas and desmoids:
This is often performed by a Radiologist under image guidance so that they can specifically target the correct tissue. This is done under local anesthetic and thus causes no pain. A specialized sarcoma pathologist will then analyze the tissue under a microscope to give the diagnosis, which guides treatment.
For most GIST tumours :
This biopsy is often performed by a specialized Gastroenterologist. This is done with the help of an ultrasound probe at the end of a gastroscope (camera that goes through your mouth and into your esophagus/stomach/small bowel) or a colonoscope (camera that goes through your bottom end to enter the rectum/colon), to get the tissue. A specialized sarcoma pathologist will then analyze the tissue under a microscope to give the diagnosis, which guides treatment.
Is a biopsy dangerous and does it cause seeding of the tumour?
This biopsy is very safe when done by specialized Radiologists, as those at The Ottawa Hospital. Several studies have shown that needle track seeding of the tumour is very minimal and should not be a reason to avoid a biopsy, as the benefits of knowing the diagnosis and doing the biopsy outweigh the negligible risk of seeding.
Frequently asked questions about Retroperitoneal Sarcoma
In a retroperitoneal sarcoma, why do I need removal of various organs?
You do not always need removal of various structures with the tumour. However, these are often very large tumours often coming close to your kidney, bowel, stomach, diaphragm, spleen, pancreas or bladder. To ensure full removal of the tumour, often some of these structures must be removed “en bloc” (all in one piece) with the tumour. This is what will give you the best chance of cure. The decision to remove these organs with the tumour is often decided at the time of the operation in the operating room. Organs will only be removed if it is felt that this is essential to ensure full removal of the cancer.
Will I need radiation therapy before or after surgery?
In some cases, radiation therapy may be required prior to surgery. This will be discussed with your Radiation Oncologist.
Will I need Chemotherapy after surgery?
Although many sarcomas have limited benefit from chemotherapy after surgery, there are some subtypes and situations that can benefit. This will therefore be discussed with your medical oncologist if you have one of these subtypes.
Frequently asked questions about GIST
Is a GIST a Stomach cancer?
GIST is NOT a stomach cancer like the traditional stomach cancer that you have potentially heard or read about (refer to section on Gastric cancer on this site). GISTs can be found anywhere along the GI tract from the Esophagus down to the rectum. They are not WITHIN the GI tract but more so a cancer of the muscular layer (WALL) of the GI tract. The most common site of a GIST is the stomach.
Will I need treatments other than surgery?
The mainstay of treatment for potential cure is surgical removal of the GIST. In some cases, of very large or high risk GISTs, a medical therapy called Imatinib is often required to prevent the GIST from coming back in the same spot or somewhere else in your body or may be required to shrink the tumour prior to surgery. If you have a high risk GIST this will be discussed with your surgeon and medical oncologist.
Will I need Radiation therapy?
No. These tumours are almost never treated with radiation therapy.
Frequently asked question about Desmoids
Is a desmoid tumour a cancer?
Desmoids are a benign tumour and therefore not a cancer. They can however, grow to a large size causing symptoms and thus may require an active treatment.
Can my desmoid shrink?
Yes, in fact 10-15% of desmoid tumors may spontaneously shrink without any treatment at all. The majority of desmoids stay small and stable and can simply be observed with repeated imaging to ensure they stay small and without symptoms.
What if my desmoid grows or is causing me pain?
If your desmoid grows or is causing pain then there are multiple treatment strategies including medications, chemotherapy or surgery. This will be discussed in detail with you by your surgeon and medical oncologist and the multi-disciplinary team for the best management strategy for your desmoid.
Why do I need a colonoscopy when I am diagnosed with a desmoid tumour?
In very rare cases, desmoid tumours are associated with a genetic mutation called Familial Adenomatous Polyposis (FAP). Patients with this mutation have a tendency to develop desmoid tumours and have more than 100 polyps in their colon with a high risk of getting a colon cancer. We therefore check that you have a normal colonoscopy and do not have polyps in your colon to ensure you do not have FAP as this would require a genetic counselor for further management.