OUP accepted manuscript

Molecular imaging Theranostics of Neuroendocrine Tumors

Neuroendocrine neoplasms (NEN) are rare and heterogeneous tumors, originating mostly from the gastro-entero-pancreatic (GEP) tract followed by the lungs. Multidisciplinary discussion is mandatory for optimal diagnostic and therapeutic management. Well-differentiated NEN (NET) present a high expression of somatostatin receptors (SSTR) and can be studied with [68Ga]-DOTA-peptides ([68Ga]Ga-DOTANOC, [68Ga]Ga-DOTATOC, [68Ga]Ga-DOTATATE) PET/CT to assess disease extension and the eligibility for peptide receptor radionuclide therapy (PRRT). SSTR-analogues labelled with 90Y or 177Lu have been used since mid-90s for NET therapy. PRRT is now considered an effective and safe treatment option for SSTR-expressing NET: following the approval of 177Lu-DOTATATE by FDA and EMA, PRRT is now part of the therapeutic algorithms of the main scientific societies. New strategies to improve PRRT efficacy and to reduce its toxicity are under evaluation (eg, personalization of treatment schemes, the selection of the most suitable patients, improvement of response assessment criteria, optimization of treatment sequencing, feasibility of PRRT-retreatment, combination of PRRT with other treatments options). Recently, several emerging radiopharmaceuticals showed encouraging results for both imaging and therapy (eg, SSTR-analogues labelled with 18F, SSTR-antagonists for both diagnosis and therapy, alpha-labelling for therapy, radiopharmaceuticals binding to new cellular targets). Aim of this review is to focus on current knowledge and to outline emerging perspectives for NEN's diagnosis and therapy.

Management of Appendix Neuroendocrine Neoplasms: Insights on the Current Guidelines

Appendiceal neuroendocrine neoplasms (ANENs) usually present as incidental findings at the time of appendectomy for acute appendicitis. They are rare, accounting for only 0.5-1% of intestinal neoplasms; they are found in 0.3-0.9% of all appendectomy specimens. They are usually sporadic tumors. There are several histological types including well-differentiated neuroendocrine tumors (NETs), poorly differentiated neuroendocrine carcinomas (NECs), and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs). Histologic differentiation and the grade of well-differentiated NETs correlate with clinical behavior and prognosis. Management varies based on differentiation, aggressiveness, and metastatic potential. There is debate about the optimal surgical management for localized appendiceal NETs that are impacted by many factors including the tumor size, the extent of mesoappendiceal spread, lymphovascular invasion and perineural involvement. In addition, the data to guide therapy in metastatic disease are limited due to the paucity of these tumors. Here, we review the current advances in the management of ANENs within the context of a multidisciplinary approach to these tumors.