Adjuvant Imatinib for Gastrointestinal Stromal Tumor

Risk stratification and staging are essential when determining treatments for localized gastrointestinal stromal tumors (GISTs), explains Anthony P. Conley, MD. A staging system may be used to ascertain the prognosis of the disease at a particular point in time. Staging criteria for GISTs considers tumor size and location, mitotic count, and any evidence of lymph node involvement or metastasis. Once this is established, the point of disease origin, such as of small bowel or gastric origin, further stratifies risk.

The goal of care is complete resection for patients who have operable or localized GIST, says Conley. Risk stratification is particularly essential after surgery, as it helps determine individuals who are going to benefit from surgery alone or require additional therapy to prevent tumor recurrence.

Patients who undergo surgical resection have a high risk of recurrence, says Robert H. I. Andtbacka, MD. Prior to the availability of the tyrosine kinase inhibitor imatinib, there were no good therapeutic options for these patients, he adds. Studies have shown that imatinib improves recurrence free survival. The current recommended starting dose of imatinib is 400 mg daily. However, not every patient should receive adjuvant imatinib, says Andtbacka. Patients with very small tumors of gastric origin with low mitotic count have a low risk of recurrence and may not require adjuvant therapy.