Perspective of neo-adjuvant/conversion and adjuvant therapy for pancreatic neuroendocrine tumors

Abstract. The incidence rate of pancreatic neuroendocrine tumors (panNET) is increasing continuously. Curative resection was the primary treatment choice for panNET. However, till now, there were few studies concerning neo-adjuvant/conversion and adjuvant therapy for panNET. In this article, we reviewed the currently widely used medical treatments for advanced panNET. It seemed that peptide receptor radionuclide therapy (PRRT), chemotherapy (temozolomide-based or streptozocin-based) and sunitinib might be more effective to induce tumor shrinkage in panNET and therefore, these treatments could be tried in panNET when neo-adjuvant/conversion therapy was considered. As for adjuvant therapy, it was of great importance to identify patients with high risks of recurrence after curative surgery and previous studies found that high ki-67 index, large tumor size, lymphatic metastasis and perineural/vascular invasion, and so on, were correlated with early recurrence of panNET. Since PRRT and chemotherapy were more cytotoxic, these two kinds of therapies might be worth trying as adjuvant therapies in patients with high risks of recurrence after curative resection of panNET. Admittedly, no studies discussed in this review directly investigated neo-adjuvant/conversion and adjuvant therapy for panNET. Therefore, more prospective studies were still warranted