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.