Pancreatic neuroendocrine tumor (PNET) refer to tumors originating from the islet of Langerhans and shows various prognosis based on the presence or absence of symptoms due to hormone secretion, the Ki-67 cell proliferation index, and the histologic grade, and according to the degree of disease progression defined by the tumor-node-metastasis (TNM) stage classification. The purpose of medical treatment for PNET is to control symptoms or inhibit tumor growth. Somatostatin analogues can be administered for the purpose of controlling symptoms caused by the secretion of specific hormones, and are accepted as effective drugs for inhibiting the progression of G1/G2 tumors based on World Health Organization (WHO) classification with a Ki-67 cell proliferation index less than 20%. Among the molecularly targeted agents, everolimus and sunitinib can be considered in patients with WHO G1/G2 PNET showing progression after somatostatin analog therapy. Cytotoxic chemotherapy is generally administered to patients with large tumor volume and rapidly progressing metastatic NET, and etoposide/cisplatin combination therapy has been considered as a standard treatment. For the patient group of Grade 3 PNET (well differentiated) newly classified by the WHO 2017 classification, guidelines for standard treatment have not yet been established. As it has been reported, studies are needed to evaluate the treatment response rate of somatostatin analogues or molecularly targeted therapies for the patient with Grade 3 PNET. It is important to consider a multidisciplinary approach with all possible treatment options including medical treatment, radical resection of primary or metastatic lesions, liver-directed therapies, and peptide receptor radionuclide therapy for the patients with PNET.
Morphological imaging and CT histogram analysis to differentiate pancreatic neuroendocrine tumor grade 3 from neuroendocrine carcinoma