Gastrointestinal Stromal Tumor: Comprehensive Patient Guide

What Are Gastrointestinal Stromal Tumors (GISTs)?

Gastrointestinal stromal tumors, or GISTs, are rare cancers that form in the digestive tract, most commonly in the stomach or small intestine. They originate from interstitial cells of Cajal, which help coordinate muscle contractions in the gastrointestinal tract. GISTs vary widely in size, location, and aggressiveness. Early detection can improve outcomes, but many patients are diagnosed after experiencing symptoms such as abdominal pain, bloating, nausea, fatigue, gastrointestinal bleeding, or anemia. Some tumors are discovered incidentally during imaging for other conditions.

GISTs are staged based on tumor size, location, mitotic rate (how quickly tumor cells divide), and spread to lymph nodes or distant organs. Genetic testing is also important. Mutations in the KIT or PDGFRA genes are common and directly influence treatment choices. Accurate diagnosis and staging are essential for developing an effective treatment plan.

How GISTs Are Diagnosed and Staged

Diagnosis usually begins with imaging tests such as CT scans or MRIs to locate the tumor and assess its size and spread. Endoscopy may be performed for tumors in the stomach or small intestine, allowing direct visualization and tissue sampling. A biopsy confirms the diagnosis, and molecular testing identifies mutations that predict responsiveness to targeted therapies.

Laboratory tests may also be performed to evaluate overall health and organ function. Early discussion with your oncologist about genetic testing is important because it can guide treatment selection and clinical trial eligibility.

“They are not common tumors; they are tumors of the supporting structure of the gastrointestinal tract, kind of like the scaffolding. And again, they are, by and large, benign entities, but they certainly have significant malignant potential. So when we see them, and we see them often enough in patients because they are often found as lumps and bumps during an endoscopy, further characterization is definitely warranted,” Dr. Rosario Ligresti, the chief of Gastroenterology and Interventional Endoscopy at Hackensack Meridian Health, explained in an interview with CURE.

Key Imaging and Testing Methods for GIST Diagnosis

Stage 1 GIST: Localized, Low-Risk Tumors

• Frontline: Surgery is the primary treatment for Stage 1 GISTs and may be curative. Surgeons aim to remove the tumor with a margin of healthy tissue while preserving organ function. For patients with high-risk features (such as large tumor size or high mitotic rate) adjuvant therapy with Gleevec (imatinib) for up to 3 years may reduce recurrence risk.
• Second-Line: If patients cannot tolerate Gleevec or if disease recurs, Sunitinib (Sutent) may be considered.
• Third-Line and Beyond: Regorafenib is used for tumors resistant to both Gleevec and Sunitinib, and clinical trials may offer access to emerging therapies.

Stage 2 GIST: Intermediate-Risk Tumors

• Frontline: Surgery remains central. Adjuvant Gleevec is typically recommended for patients with features that suggest higher recurrence risk. Treatment decisions are guided by tumor size, mitotic rate, and location.
• Second-Line: Sunitinib can be used if the tumor progresses despite Gleevec therapy.
• Third-Line and Beyond: Regorafenib or investigational agents in clinical trials may be options. Patients may also discuss dose adjustments or combination approaches with their oncologist.

Stage 3 GIST: High-Risk, Localized Tumors

• Frontline: Surgery combined with adjuvant Gleevec is standard. Preoperative (neoadjuvant) Gleevec may be considered if the tumor is large or in a location where surgery could be complex, to shrink it and make removal easier.
• Second-Line: Sunitinib is used if disease progresses or the tumor becomes resistant to Gleevec.
• Third-Line and Beyond: Regorafenib or other targeted agents may be considered. Participation in clinical trials is encouraged for patients with resistant or aggressive tumors.

Metastatic GIST: Treatment for Advanced Disease

• Frontline: For tumors that have spread to distant organs, Gleevec is the first-line therapy. Most patients achieve disease control rather than cure, with long-term management focused on controlling tumor growth.
• Second-Line: Sunitinib is the standard option for tumors that progress on Gleevec or in patients who cannot tolerate it.
• Third-Line and Beyond: Regorafenib is used for further disease control. Clinical trials may provide access to newer targeted therapies, combination treatments, or immunotherapy approaches.

Common Side Effects of Targeted GIST Therapies

Targeted therapies can cause side effects, which vary in severity.

• Gleevec (imatinib): fatigue, fluid retention, nausea, diarrhea, muscle cramps, skin rash.
• Sunitinib (Sutent): fatigue, high blood pressure, diarrhea, hand-foot skin reactions, mouth sores.
• Regorafenib: fatigue, hypertension, diarrhea, hand-foot skin reactions, liver enzyme changes.

Patients are encouraged to report side effects promptly. Dose adjustments, supportive medications, or lifestyle strategies can help manage symptoms. Open communication with your care team can improve quality of life and allow continued therapy.

Practical Tips and Questions for Patients With GIST

• Ask your oncologist about the tumor’s genetic profile and how it affects treatment.
• Discuss the risks and benefits of adjuvant therapy after surgery.
• Keep a symptom diary to track side effects and communicate them clearly at appointments.
• Consider seeking a second opinion at a specialized center if the tumor is high risk or metastatic.
• Ask about clinical trials, which may offer access to newer therapies.

“Even if you had curative surgery, number one, you need surveillance. Number two, some patients need treatment to decrease risk of recurrence. And number three, it’s best to also have genetic follow-up, to make sure there is no inherited risk for yourself and also for other family members,” Dr. Weijing Sun, associate director at the University of Kansas Cancer Center, said in an interview with CURE.

Conclusion: Personalized Treatment Improves Outcomes for GIST Patients

GIST treatment is highly personalized. Surgery is the mainstay for localized tumors, while targeted therapies like Gleevec, Sunitinib, and Regorafenib play a critical role in high-risk or metastatic disease. Genetic testing informs treatment selection, and careful monitoring can help manage side effects. Patients are encouraged to maintain open dialogue with their oncologist, ask questions about new therapies, and explore supportive care resources to maintain quality of life throughout treatment.

Editor’s Note: This guide is designed to be a starting point. Your personal experience will be unique. By using this information as a foundation for your discussions, you can partner with your oncologist to make the best decisions for your health.

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