Pathological Complete Response After Neoadjuvant Imatinib in a Recurrent Duodenal Gastrointestinal Stromal Tumor (GIST).

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal neoplasms of the gastrointestinal (GI) tract. Although surgery is the treatment of choice in resectable disease, neoadjuvant therapy is indicated in advanced, metastatic, and recurrent tumors. Decreasing tumor burden may facilitate resection and reduce surgical morbidity. We describe a case of a 66-year-old male with a recurrent duodenal GIST, after surgery and adjuvant imatinib five years before. Following neoadjuvant therapy with imatinib for 12 months, the patient underwent a cephalic pancreaticoduodenectomy, without complications. The final histopathology showed a pathological complete response (pCR) with no residual neoplasm. A pathological complete response to imatinib in a recurrent disease is extremely rare. Molecular testing should be performed before neoadjuvant therapy to identify response-predictive mutations. In recurrent/metastatic disease, systemic therapy is the standard treatment for all patients. Surgery should be considered in a tailored approach in patients with good responses to systemic therapy before developing therapeutic resistance.