[Treatment Strategy for Non-Functional Pancreatic Neuroendocrine Tumors (P-NETs) at Kurume University Hospital].

Pancreatic neuroendocrine tumors (P-NETs) are relatively rare. Approximately 50-90% of non-functioning P-NETs are malignant, and the only curative treatment is surgical resection. Liver and lymph node metastases often occur. In Japan, the mTOR inhibitor everolimus is now covered by the national health insurance for treatment of P-NETs, including advanced and unresectable tumors. We present a case of P-NETs with liver metastases seen at our hospital and discuss our treatment strategy for this disease. Patients with tumors≤1 cm receive follow-up observation. For G1 and G2 (other than G3) tumors, if their size is >1 cm when first discovered, resection of the primary lesion along with lymph node dissection (as for pancreatic cancer) is performed. In G1 and G2 tumors with synchronous distant metastases, the primary lesion is first resected, and depending on the pathological findings, chemotherapy (LAR plus everolimus) may be administered. After 4 courses of chemotherapy, the response is assessed, and if further resection is possible, resection is performed. When there are synchronous liver metastases, if partial resection and local treatment (such as RFA) are possible, the primary lesion and synchronous lesions are resected. If a major hepatic resection procedure such as a segmentectomy or lobectomy is possible, the primary lesion is resected, followed by chemotherapy. After 4 courses of chemotherapy, the response is assessed, and if further resection is possible, hepatic resection is performed. G3 tumors are usually highly malignant, advanced, and often associated with metastases at the time of diagnosis. Chemotherapy may be an option for treating patients with G3 tumors.