A case of successful conversion from everolimus to surgical resection of a giant pancreatic neuroendocrine tumor

BACKGROUND Although pancreatic neuroendocrine tumors generally have a far better prognosis relative to pancreatic cancer, the varied manifestations lead to treatment-related challenges. Everolimus therapy is generally recommended for patients with advanced pancreatic neuroendocrine tumors; however, its efficacy in a neoadjuvant setting remains unclear. Here we present a case of a giant pancreatic neuroendocrine tumor with a portal tumor thrombus that became resectable after everolimus therapy. CASE PRESENTATION A 62-year-old woman was admitted to our hospital for surgical resection of a giant pancreatic neuroendocrine tumor in the left upper abdomen. Unfortunately, she was ineligible for surgery because the tumor had extended near the hepatic hilus in the portal vein, and she was administered everolimus (10 mg/day). After 2 years of this therapy, the extent of portal vein involvement had decreased, despite the lack of significant changes in the tumor size, and the hepatic hilus became free of disease. She was subsequently referred to us for resection via distal pancreatectomy with portal vein reconstruction because the tumor had begun to grow slowly. Pathological review identified a grade 2 neuroendocrine tumor with no lymph node metastasis. The patient's postoperative course was uneventful, and she has remained recurrence-free for 27 months, despite a lack of additional treatment. CONCLUSIONS Our experience suggests that everolimus could be useful for neoadjuvant therapy in cases of locally advanced pancreatic neuroendocrine tumor.