Question

Discuss the adjuvant therapy for GIST.

Hint:

Adjuvant imatinib therapy significantly improves the survival rate in high-risk GIST patients after surgical resection and is typically given for 3-5 years postoperatively.

Answer 1

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Adjuvant therapy for GISTs aims to reduce the risk of recurrence after surgery, particularly in patients with high-risk tumors.
Step 1: Surgical Resection:
The primary treatment for localized GISTs is complete surgical resection. Ensuring clear surgical margins is essential to minimize the risk of recurrence. In cases of inoperable or metastatic GISTs, systemic therapy is indicated.
Step 2: Adjuvant Imatinib (Gleevec):
Imatinib is a tyrosine kinase inhibitor and is the cornerstone of adjuvant therapy for GISTs. It works by inhibiting the KIT protein, which is commonly mutated in GISTs. The use of imatinib after surgical resection significantly reduces the risk of recurrence in high-risk patients.
1. Duration of Therapy: Adjuvant imatinib is typically administered for 3 to 5 years following surgery, depending on the risk of recurrence and the size and mitotic index of the tumor.
2. Risk Stratification: Patients with tumors greater than 5 cm, high mitotic rate, or aggressive features are considered high-risk and benefit the most from adjuvant imatinib.
Step 3: Alternative Therapies:
For patients with imatinib-resistant GISTs, alternative tyrosine kinase inhibitors such as sunitinib or regorafenib may be considered. These drugs can be used in patients with metastatic disease or those who experience progression while on imatinib.
Step 4: Monitoring:
Patients undergoing adjuvant therapy should be regularly monitored with imaging and clinical assessments to detect early signs of recurrence or disease progression.