Pathologic, radiologic and PET scan response of gastrointestinal stromal tumors after neoadjuvant treatment with imatinib mesylate.

Aim: The aim of this study is to review the radiologic, PET scan and pathologic response and the outcome of patients with advanced GIST treated with neoadjuvant IM followed by surgical resection.

Materials And Methods: We report a case and review 36 patients reported in MEDLINE with advanced GIST treated with neoadjuvant IM followed by surgical resection.

Results: Thirty-seven patients with a median age of 56 years (range, 32-76 years) at presentation were treated with neoadjuvant IM. Radiologic response accurately predicted pathological response in 31/36 patients, whereas PET scan was accurate in predicting treatment response in only 6/23 patients.

Conclusion: This study demonstrates that the pathologic response of GIST to IM is usually incomplete and does not correlate with the complete response seen on PET scan. This finding suggests that surgical resection will continue to play a vital role in the treatment of patients with advanced disease responding to IM treatment.