Treating Gastrointestinal Stromal Tumors

Most small GISTs need to be treated. Some very small tumors (less than 2 centimeters across) that are not causing any symptoms might never cause problems. In these low-risk tumors, doctors might watch the tumor over time with endoscopy. As long as it is not growing, you might not need further treatment.

Surgery is the main treatment for most small tumors. The need for more treatment after surgery depends on the risk of the GIST coming back. Tumors that are small and are not growing quickly typically have a low risk of coming back, so often no further treatment is needed.

The risk of a GIST coming back after surgery is higher if:

• The tumor is larger
• It did not start in the stomach
• The tumor is ruptured or breaks apart during surgery
• The cancer cells are dividing quickly (have a high mitotic rate)

If the cancer has an intermediate or high risk of coming back and the tumor has certain changes in the KIT and PDGFRA genes, treatment with the targeted drug imatinib (Gleevec) is often recommended after surgery. For tumors that are highly likely to come back, many doctors now recommend at least 3 years of imatinib.

Tumors that are larger or in places that make them harder to remove completely might require more extensive surgery. Because this could cause health problems both in the short and long term, surgery is not typically the first treatment.

Targeted therapy

If biopsy test results show that the tumor has certain changes in the KIT or PDGFRA genes, treatment with the targeted drug imatinib (Gleevec), or in some cases avapritinib (Ayvakit), is usually done first to try to shrink the tumor. If a targeted drug is given, it is continued at least until the tumor stops shrinking.

GIST tumors with gene changes other than KIT or PDGFRA might be treated with other targeted drugs. For example, GIST tumors with changes in the NTRK gene might be treated with other targeted drugs like larotrectinib (Vitrakvi) or entrectinib (Rozlytrek).

If the tumor shrinks enough after targeted therapy, surgery might be done if the doctor thinks surgery is safe. Targeted therapy will likely be continued after surgery to lower the chance of the cancer coming back.

If the tumor doesn’t shrink enough to make surgery possible, targeted therapy is often continued for as long as it seems to help and side effects are manageable.

If it's no longer working, sometimes higher doses can be helpful. If not, or if the side effects are too severe, other targeted drugs might be tried to shrink the tumor. These include other targeted drugs, such as sunitinib (Sutent), regorafenib (Stivarga) or ripretinib (Qinlock).

Treatment options for unresectable GISTs depend on why they are unresectable and, if they have spread, how extensive the spread is.

Surgery is not often the first treatment for these tumors, so before starting treatment, it’s important to confirm that the tumor is a GIST with a biopsy.

Targeted therapy

If biopsy test results show that the tumor has certain changes in the KIT or PDGFRA genes, the targeted drug imatinib (Gleevec) is typically used first. Imatinib is continued for as long as the tumor doesn’t grow and the side effects are tolerable. If the tumor starts to grow again, higher doses of imatinib might be tried.

The targeted drug avapritinib (Ayvakit) might be used instead if the cancer cells have certain changes in the PDGFRA gene.

If the tumor does not respond, or if the side effects are too severe, other targeted drugs might be tried to shrink the tumor. These include: 

• Sunitinib (Sutent)
• Regorafenib (Stivarga)
• Ripretinib (Qinlock)
• Sorafenib (Nexavar)
• Dasatinib (Sprycel)
• Nilotinib (Tasigna)
• Pazopanib (Votrient)

Other treatments

If the cancer has spread to only 1 or 2 sites in the abdomen, such as the liver, the doctor might advise removing or destroying the tumors with treatments like ablation and embolization. If this is the case, be sure to talk with your doctor about whether the goal of treatment is to try to cure the cancer, help you live longer, or prevent or reduce symptoms, as well as its possible benefits and risks.

Standard chemotherapy drugs are usually not very effective. Taking part in a clinical trial of a newer treatment might be a good option for some people.

When a cancer comes back after treatment, it is called a recurrence. If the cancer recurs in or near the place it started, it is called a local recurrence. If it recurs at other sites, such as the lungs or liver, it is called a distant (metastatic) recurrence.

Treatment options for recurrent GISTs depend on the location and extent of the recurrence.

Targeted therapy

For most recurrences, treatment with the targeted drug imatinib (Gleevec) is often the first option to try to shrink any tumors, as long as it is still effective and the patient can tolerate taking it. If the starting dose of imatinib doesn't work, the dose can be increased.

If the tumor does not respond, or if the side effects are too severe, other targeted drugs might be tried to shrink the tumor. These include: 

• Sunitinib (Sutent)
• Regorafenib (Stivarga)
• Ripretinib (Qinlock)
• Sorafenib (Nexavar)
• Dasatinib (Sprycel)
• Nilotinib (Tasigna)
• Pazopanib (Votrient)

Other treatments

If the cancer comes back as one or more well-defined tumors, removing or destroying the tumor might be an option. Doctors are still not certain if removing GISTs that come back after treatment helps people live longer, so it's important to discuss the risks and benefits of this treatment with your doctor and family.

Radiation therapy might also be an option to help treat symptoms such as pain, especially in tumors in the bones.

Because these cancers are often hard to treat, you might want to consider taking part in clinical trials of newer treatments as well.