Gastrointestinal stromal tumor (GIST)

 Gastrointestinal stromal tumor (GIST)

 Overview

Gastrointestinal stromal tumors (GISTs) are rare tumors that occur when cells become abnormal and grow out of control. GISTs can start anywhere in your digestive (gastrointestinal) tract, from the esophagus to the anus. More than half start in the stomach, and most others start in the small intestine.

GISTS are very rare in people under 40 years old. Some GISTs occur spontaneously, while others run in families. Talk to your healthcare provider if you have a family history of this condition.

The actual number of people with GIST is not known. However, the condition is rare. Healthcare providers estimate that there are between 4,000 and 6,000 cases per year in the U.S.

GISTs are uncommon tumors that can grow anywhere in your digestive tract , from the esophagus to the anus. Some GISTs are small and not harmful, while others may be larger or cancerous. While some people may have no symptoms, others may feel unwell or have pain or bleeding.

Symptoms

GISTs tend to be fragile tumors that can bleed easily. In fact, they are often found because they cause bleeding into the GI tract. Signs and symptoms of this bleeding depend on how fast it occurs and where the tumor is located.

Brisk bleeding into the esophagus or stomach might cause the person to throw up blood. When the blood is thrown up it may be partially digested, so it might look like coffee grounds. 

Brisk bleeding into the stomach or small intestine can make bowel movements (stools) black and tarry.

Brisk bleeding into the large intestine is likely to turn the stool red with visible blood.

If the bleeding is slow, it often doesn’t cause the person to throw up blood or have a change in their stool. Over time, though, slow bleeding can lead to a low red blood cell count (anemia), which can make a person feel tired and weak.

Bleeding from the GI tract can be very serious. If you have any of these signs or symptoms, see a doctor right away.

Other possible symptoms of GISTs

Other symptoms of GISTs can include:

Abdominal (belly) pain

A mass or swelling in the abdomen

Nausea and vomiting

Feeling full after eating only a small amount of food

Loss of appetite

Weight loss

Problems swallowing (for tumors in the esophagus)

Some tumors grow large enough to block the passage of food through the stomach or intestine. This is called an obstruction, and it can cause severe abdominal pain and vomiting.

Because GISTs are often fragile, they can sometimes rupture, which can lead to a hole (perforation) in the wall of the GI tract. This can also result in severe abdominal pain. Emergency surgery might be needed in these situations.

Although many of the possible symptoms of GISTs (like belly pain and nausea) can be caused by things other than cancer, if you have these symptoms, especially if they last for more than a few days, it's important to see a doctor.

Tests to find GISTs

If your doctor thinks you might have a GIST (or some other type of GI tumor), more tests will be done. Here are some of the tests you might need:

CT or CAT scan: This test uses x-rays to make detailed pictures of the inside of your body. CT scans can often show the size, shape, and place of tumors in the GI tract. This test may also be done to see if cancer has spread.

MRI scan: MRIs use radio waves and strong magnets instead of x-rays to make very detailed pictures of the inside of your body. MRIs can make it easier to see the size and shape of the tumor.

Barium x-ray tests: Different types of x-ray tests can be used to look at the inside of your GI tract. For these tests, you either swallow a chalky liquid, or it is put in through your rectum. The barium in the liquid outlines the inner lining of the GI tract on x-rays. These types of tests aren’t used as much as they were in the past.

PET scan: In this test, you are given a special type of sugar that can be seen inside your body with a special camera. If there is cancer, this sugar shows up as “hot spots” where the cancer is found. This test can help show where a GIST has spread.

Endoscopy: For these tests, the doctor puts a flexible lighted tube with a tiny video camera on the end into the body to see the inner lining of the GI tract. Depending on where the tumor is thought to be, the tube can be put down the throat (for an upper endoscopy) or put into the rectum (for a colonoscopy). If abnormal areas are seen, small samples can be taken out for a biopsy (see below).

Endoscopy can also be used to do a kind of ultrasound test called endoscopic ultrasound (EUS). Ultrasound uses sound waves to make pictures of the inside of the body. For EUS, a small ultrasound probe is on the end of the scope, which allows it to get very close to a tumor. This test can show how far a tumor has grown into the wall of the GI tract. It can also help show if the tumor has reached nearby lymph nodes.

Biopsy

In a biopsy, the doctor takes out small pieces of an abnormal area to check for cancer cells. If cancer is found, lab tests will also be done to find out what type of cancer it is. But not everyone who has a tumor that might be a GIST needs to have a biopsy before treatment.

There are different ways to do a biopsy. It can be done during endoscopy or surgery, or sometimes using a thin, hollow needle to get biopsy samples. The type used will depend on the size of the tumor and where it is in your body. Ask your doctor what kind you will need.

If a GIST is found, tests can be done on the biopsy samples to help tell how quickly the tumor is likely to grow and spread. This might affect your treatment.

Treatment of GIST

A team of specialists meets to discuss the best possible treatment plan for you. This is called a multidisciplinary team (MDT). Treatment of a GIST depends on different things, including:

where the GIST is in the body

the size of the tumor

the grade of the GIST (its mitotic rate)

your general health

if the GIST cells have certain genetic changes.

Your doctor and nurse will talk to you about the best treatment for you. They can talk to you about things to think about when making treatment decisions.

The main treatments for a GIST are surgery and targeted therapy drugs. Chemotherapy is not a helpful treatment for GISTs. Radiotherapy is rarely used.

Risk groups

After surgery to remove a GIST, doctors decide whether it is low-risk or high-risk. They look at where the GIST started, its size and mitotic rate. A tumor that bursts during surgery is also high-risk.

Because high-risk GISTs are more likely to come back your doctor will usually advise treatment with targeted therapy after surgery.

Monitoring

Some small GISTs grow very slowly and may not need treatment. If the GIST is less than 2cm and is not causing symptoms, your doctor might suggest monitoring the tumor. You will have regular endoscopies or scans. If the tumor starts to grow, you can then have surgery.

Targeted therapy

Targeted therapy drugs called tyrosine kinase inhibitors (TKIs) are used to treat GIST. In more than 8 out of 10 GISTs (about 85%), the tumor cells have a change in a protein called KIT. This change (called a mutation) means the GIST cells constantly get signals telling them to grow and multiply. TKIs block these signals. Tests on the cancer cells are done first to find out how helpful these drugs are likely to be. Imatinib is a TKI drug given:

before surgery, to reduce the size of the GIST and make surgery more effective

after surgery, for 3 years, to reduce the risk of GIST coming back (called adjuvant therapy)

to treat a GIST that cannot be operated on or has spread to other parts of the body.

If imatinib stops working or is causing difficult side effects, you may be given sunitinib (Sutent®) or regorafenib (Stivarga®).

Surgery

If the GIST is bigger than 2cm, you may have surgery to remove it. You may have targeted therapy before surgery to shrink the tumour. If the GIST is found to be high-risk, you usually have targeted therapy after surgery.

The surgeon removes the tumour, along with some surrounding healthy tissue. If the tumour has started to grow into other organs close by, the surgeon may also remove these. 

Your surgeon will tell you about any possible effects of the surgery. These depend on the size of the tumour and where it is in the body. If the GIST is in the small bowel, you may have an operation to remove part of the small bowel. This does not usually have any long-lasting side effects. If the GIST is in the stomach, you may have part or most of the stomach removed. A specialist dietitian can give you advice and support.

Surgery may also be used to treat GISTs that come back after treatment. We have more information about surgery for soft tissue sarcoma.

You may be offered some treatments as part of a clinical trial.

If a GIST comes back

If a GIST comes back after treatment it may come back where it first started. This is called a local recurrence. Or it may come back in another part of the body which is called secondary or metastatic cancer.

GIST that comes back is usually treated with targeted therapy. Surgery may also be an option if there is only 1 small new GIST. Your doctor or specialist nurse will talk to you about your treatment options

If GIST comes back in the liver it is called secondary liver cancer. The following treatments may be used:

radiofrequency ablation (RFA) which uses heat to destroy the cancer cells

cryotherapy which uses cold to destroy the cancer cells.

These are called tumour ablation treatments. 

Some people might have a type of radiotherapy called stereotactic ablative radiotherapy (SABR).

Type of Doctor Department : Medical oncologists, gastroenterologists, radiologists and pathologists