The GIST journey:Know what to expect

GIST can be a moving target

You, your care partners, and your care team may all have been shocked by a GIST (gastrointestinal stromal tumor) diagnosis. After all, it is a fairly rare condition with only 4,000-6,000 new cases a year in the US. Because of this, it is not something that is widely known or talked about. However, it is very familiar to researchers and GIST specialists, and there are well‑established GIST treatments.

In fact, GIST is something that you may be living with for a very long time. So, it’s important to remember that the GIST you’re living with today may be different from the GIST you have later. Your treatment needs and personal needs may change, too.

GIST treatment

The GIST treatment process usually starts like this:

• Doctors establish the size and location of the tumor(s)
• Tests will determine how aggressive the disease is
• Doctors check for factors that suggest if the tumor may grow quickly. This is called the mitotic rate
• They may also test for gene mutations that can affect how well some drugs work

Usually, GISTs that are large or cause a lot of symptoms are removed with surgery. However, surgery might not be the best option if the GIST is too large, there are multiple GISTs that affect several organs (metastatic disease), or the person has health issues that can make surgery risky. In those cases, surgery could be delayed or avoided.

The American Cancer Society has more information about how GIST is treated.

The stages of GIST

Like other cancers, people often refer to stages when they talk about GIST. For GIST that starts in the stomach, the stages are:

Stage 1A The tumor is 5 cm or smaller with a low mitotic rate

Stage 1B The tumor is more than 5 cm up to 10 cm with a low mitotic rate

Stage 2 The tumor is 5 cm or smaller with a high mitotic rate. Or larger than 10 cm with a low mitotic rate

Stage 3A The tumor is more than 5 cm up to 10 cm with a high mitotic rate

Stage 3B The tumor is larger than 10 cm with a high mitotic rate

Stage 4 The tumor is any size and it has spread to nearby lymph nodes or other parts of the body, such as the liver. This is also called metastatic cancer. The cancer may have a low or high mitotic rate.

The stages of GIST in other areas are defined differently.

Keeping up with tests is very important

Whether you’ve had surgery or not, committing to follow-up testing is very important. Even if all the cancer was removed, it can come back. And even if you are taking medication as your doctor instructs, a GIST may still grow. Someday you may need more surgery or a different treatment. For some people, this may happen quickly. For others, it may take several years.

• When your GIST was first diagnosed, you may have had tests including PET, CT/CAT, MRI, bone scan, endoscopy (upper, lower, capsule), ultrasound, biopsies, and/or blood tests. You may have some of these tests again later on.
• Many doctors also recommend genetic testing (or genotyping) before choosing a treatment. This is helpful because some drugs target certain genes associated with cancer. And some genetic mutations can affect how well certain drugs work. You may be tested for KIT (exon 9, 11, 13, and 17) and/or PDGFRA (exon 12 and 18).
• As the months and years pass, your main follow-up will include imaging (CT, MRI, PET, FUSION PET‑CT) and blood tests. These will help determine if your GIST has grown or spread. They can also show whether your current treatment is still effective or needs to be changed.

If you’d like to learn more about tests, Lab Tests Online is a great source of information.

Targeting GIST

You may have heard the terms first line, second line, etc. used when talking about drugs. These refer to the usual order of treatments, which are defined by the protocols doctors follow. These protocols were created over years of research. Protocols get updated as new treatments are established. First line treatments are the ones doctors usually start people with when they’re diagnosed with inoperable metastatic disease. For most people living with GIST, imatinib is a first line treatment.

Imatinib is what’s called a targeted therapy. Targeted therapies identify and attack specific targets in the cancer cells to block their growth and spread. These therapies are different from regular chemotherapy which is not targeted.

Your GIST treatment may change over time

Sometimes, if the tumor is too large, imatinib is prescribed before surgery to help shrink or control the tumor. This is called neoadjuvant treatment. In high-risk patients, imatinib may be prescribed after surgery to help prevent a tumor from growing or, if it was completely removed, from returning. This is called adjuvant treatment.

Sometimes, even when you take imatinib as prescribed, a GIST can still grow. This is called cancer progression. It can happen because the tumor is or becomes resistant to the drug (the drug won’t work like it’s supposed to). This resistance to imatinib may happen relatively soon after you start it, or years after you start. Depending on the tumor’s growth, your doctor may add local treatment or increase your dose of imatinib. Do not stop taking imatinib once you’ve started, unless your doctor tells you to.

If the tumor doesn’t respond to imatinib, if side effects are an issue, or if progression continues, the doctor may prescribe other approved medications. These may include sunitinib, regorafenib, and/or ripretinib.*

All the drugs used to treat GIST may have side effects. If you experience any, tell your doctor because he or she may have ways to help you handle them. The American Cancer Society also has many suggestions.

*Avapritinib is a medication approved for people with unresectable or metastatic GIST who have a PDGFRα exon 18 mutation. It is another option and may be prescribed at any time.

New GIST treatments are always being developed

Some people with advanced GIST consider joining a clinical trial for the chance to try a new treatment that is not approved by the FDA for GIST yet. But there may be risks with clinical trials. So, you should learn everything you can about them and speak with your care team before joining.

You can read about new trials for GIST treatments at Life Raft Group’s Clinical Trials website. The National Cancer Institute and The National Institute of Health also offer information about clinical trials.

Also, be sure to sign up for ongoing education, support, and information about future treatments from GISTTogether.

Where can you learn more about GIST?

Here are some sites where you can learn more about GIST:

• American Cancer Society
• Cancer.net
• The GIST page from the Dana‑Farber Cancer Institute
• GIST Support International
• The Life Raft Group
• The Mayo Clinic
• National Cancer Institute