What Are Gastrointestinal Stromal Tumors?
Gastrointestinal stromal tumors (GISTs for short) are tumors that form in your GI tract. Most start in your stomach or small intestine. Some GISTs are tiny -- about the size of a pencil eraser. These usually grow slowly and may never need treatment. Others grow and spread faster. Often, doctors can remove these tumors with surgery.
When GISTs can’t be removed or have spread, targeted medicine may help you live longer and better.
GISTs start with changes in a type of gene called an oncogene. It tells cells when to divide and grow. Most people with GISTs have a change in an oncogene called KIT that tells cells to divide and grow when they don’t need to. A small subset of GISTs contains other mutations in the homologous kinase platelet derived growth factor receptor alpha (PDGFRA).
Changes in other genes can cause GISTs, too. Most people don’t inherit these gene changes from their parents. And they’re not caused by anything you did. No one knows for sure why they happen.
The ones you have depend on the size of your tumor and where it is. Some small GISTs never cause symptoms. Your doctor may find them when you have a test for something else. Larger tumors can cause bleeding. You might vomit blood or see it in your stool. You could also have:
- A full feeling after a few bites, or not wanting to eat at all
- Belly pain or a lump you can feel
- Blood in your stool
- Trouble swallowing
- Weight loss you can’t explain
Getting a Diagnosis
Your doctor needs to learn more about your symptoms to figure out what’s going on. You’ll answer questions about your medical history and have a physical exam. If your doctor thinks you might have a GIST, you might have some tests that help find the tumor and let your doctor know if it’s spread to other parts of your body.
Some tests you may have include:
Computed tomography (CT) scan. This gives detailed pictures of the soft tissues where GISTs start. It can show the tumor’s size, location, and if it’s spread to your liver or other organs. An MRI can do this as well.
Positive emission tomography (PET) scan. You get a shot that contains a small amount of radioactive sugar. Cancer cells take up more sugar than normal cells, so tumors light up. PET scans are good at finding large, fast-growing tumors, but not so good at finding small ones.
Upper endoscopy. This test uses a thin, lighted tube with a tiny camera on the end (called an endoscope). Your doctor passes it down your throat through your mouth. It shows your throat, stomach, and part of your small intestine.
Endoscopic ultrasound (EUS). This combines endoscopy with ultrasound. It’s a test that uses sound waves to see what’s going on inside your body. You might have had an ultrasound when you were pregnant or had gallbladder trouble. In an endoscopic ultrasound, the ultrasound probe is on the tip of an endoscope. This gives your doctor close-up images of the tumor.
Biopsy tests. The only way to know for sure you have a GIST is to look at a small sample of the tumor in a lab. This is called a biopsy. It checks for certain proteins or changes in KIT and other genes, including one called PDGFRA that activates other proteins that have to do with how a cell grows and divides.
Questions for Your Doctor
You and your doctor are equal partners in your care. So it’s important to get answers to all your questions. Don’t be afraid to ask about anything -- no matter how small. Here are some questions to think about:
- Why do you think my tumor is a GIST?
- Where is the tumor?
- How big is it?
- Is it growing fast?
- Has the tumor spread?
- What are my treatment options? How will those treatments make me feel? How well do they work?
- Have you ever treated this type of cancer before?
- Will I have a say in all decisions about my care?
- What is the prognosis?
- Is it curable?
- How will I be monitored?
- Are there any clinical trials available?
- How much will treatment cost? Will my insurance cover it? If you don’t know, who else can I talk to?
The tests you take while you’re diagnosed will also give your doctor insight into what treatment might work best for you. Surgery is the main treatment for most GISTs. It can often cure small tumors. But if your tumor is very large or close to other organs, you might need medicine to shrink the tumor before surgery. Or your surgeon may need to remove part of another organ to reach the cancer.
It’s important to find a surgeon who knows about GISTs. It takes special skill to remove them so the cancer doesn’t spread.
Many types of cancer are treated with chemotherapy, radiation, or both. These treatments don’t work well for GISTs. There is medication that can treat GISTs if surgery is not the best choice for you. Which medication you’ll take will depend on the characteristics of your tumor.
If Gleevec doesn’t work for you or stops working, you might take Sutent.
If the tumor is inoperable or has metastasized, you may be prescribed a kinase inhibitor called which works by blocking proteins that cause cancer. Options include avapritnib (Ayvakit) and ripretinib (Qinlock).
Taking Care of Yourself
You can do things before, during, and after your treatment that can make you stronger in body and spirit. Here are some tips to get you started:
Don’t smoke. (Avoid secondhand smoke, too.) This lowers your chance of future cancers, heart attack, and stroke. It’s hard to quit, but don’t give up. Most people try six or seven times before they kick the habit for good.
Keep moving. Exercise is a must for everyone with cancer -- even during treatment. It lifts your spirits, fights fatigue, burns off extra pounds, and has been shown to help you live longer. Try to get at least 30 minutes of exercise most days (more is better). Combine heart-healthy exercises like brisk walking or biking with weight training. A trainer or physical therapist can show you the ropes.
Eat well. Focus on fruits, vegetables, healthy oils like olive oil, chicken, and fresh fish. Limit red meat, sugar, and processed foods.
Get support. It’s important to take care of your emotional health, too. Trained counselors and support groups offer safe places to talk about how you feel. Or, you might want to turn to friends and family or your health care team.
What to Expect
Your GIST may never go away completely. If so, you may take imatinib as long as possible. Watch for side effects like:
GISTs can also come back after treatment. You’ll need follow-up tests for a few years to make sure you’re OK. If you’re taking a targeted medicine, you’ll have CT scans to see if it’s still working.