To date, empirical literature has generally been considered lacking in relation to neuroendocrine carcinomas (NECs), the highly malignant subgroup of neuroendocrine neoplasms. NECs are often found in the lungs or the gastroenteropancreatic (GEP) system and can be of small or large cell type. Concentrating on GEP-NECs, we can conclude that survival times are poor, with a median of only 4–16 months depending on disease stage and primary site. Further, this aggressive disease appears to be on the rise, with incidence numbers increasing while survival times are stagnant. Treatment strategies concerning surgery are often undecided and second-line chemotherapy is not yet established. After an analysis of over 2600 articles, we can conclude that there is indeed more empirical literature concerning GEP-NECs available than previously assumed. This unique review is based on 333 selected articles and contains detailed information concerning all aspects of GEP-NECs. Namely, the classification, histology, genetic abnormalities, epidemiology, origin, biochemistry, imaging, treatment and survival of GEP-NECs are described. Also, organ-specific summaries with more detail in relation to disease presentation, diagnosis, treatment and survival are presented. Finally, key points are discussed with directions for future research priorities.

Peptide receptor radionuclide therapy (PRRT) is a relatively new mode of internally targeted radiotherapy currently in clinical trials. In PRRT, ionizing radioisotopes conjugated to somatostatin analogues are targeted to neuroendocrine tumors (NETs) via somatostatin receptors. Despite promising clinical results, very little is known about the mechanism of tumor control. By using NCI-H727 cells in an in vivo murine xenograft model of human NETs, we showed that ¹⁷⁷Lu-DOTATATE PRRT led to increased infiltration of CD86+ antigen presenting cells into tumor tissue. We also found that following treatment with PRRT, there was significantly increased tumor infiltration by CD49b+/FasL+ NK cells potentially capable of tumor killing. Further investigation into the immunomodulatory effects of PRRT will be essential in improving treatment efficacy.

The aim of this study was to determine overall survival and recurrence-free survival after resection of bronchopulmonary carcinoids by means of predominantly minimally invasive surgery and lung-sparing resections. In addition, we aimed to identify prognostic factors for overall survival. Retrospective review of consecutive patients operated for bronchopulmonary carcinoids between January 2009 and October 2020 identified from a prospectively collected database. A total of 236 patients representing 240 cases of bronchopulmonary carcinoids were included. Of these, 212 (88.3 %) were typical carcinoids, while 28 (11.7 %) were atypical carcinoids. A Video-Assisted Thoracoscopic Surgery (VATS) approach was used in 75 % of cases. There was no 30-day mortality. The median follow-up was 5.6 years for overall survival and 4.7 years for recurrence-free survival. 5- and 10-year overall survival rates were 89 % and 71 %, while 5- and 10-year recurrence-free survival rates were 84 % and 71 %. Patients with atypical carcinoids had significantly reduced overall survival and recurrence-free survival rates (HR 3.4; 95 % CI 1.5-7.6; p = 0.003 and HR 5.4; 95 % CI 2.6-11.4; p < 0.001). Independent predictors of overall survival included atypical carcinoid (HR 2.7; 95 % CI 1.2-6.0; p = 0.018) and age > 60 years (HR 2.9; 95 % CI 1.2-7.3; p = 0.021). Surgery for bronchopulmonary carcinoids by means of predominantly VATS and lung-sparing resections provides favorable long-term survival. Atypical carcinoids and age > 60 years are independent predictors of poor overall survival.

Background: The incidence of small intestinal (SI) and pancreatic neuroendocrine tumors (siNETs and pNETs) seems to have increased. The increased frequency of incidental findings might be a possible explanation. The study aimed to examine (1) changes in incidence and the stage at diagnosis (2010–2011 vs. 2019–2020), (2) changes in the initial indication for diagnostic workup and 3) the differences in stage between incidentally discovered vs. symptomatic disease during the entire study period. Methods: We performed a retrospective study, that includes consecutive siNET and pNET patients referred to the Copenhagen ENETS center of excellence in 2010–2011 and 2019–2020. Results: The annual incidence of siNET per 100,000 increased from 1.39 to 1.84, (p = 0.05). There was no change in the stage at diagnosis, and in both periods approximately 30% of patients were incidentally diagnosed (p = 0.62). Dissemination was found in 72/121 (60%) of symptomatic vs. 22/50 (44%) of incidentally discovered SI tumors in the entire cohort, (p = 0.06). The annual incidence of pNET increased from 0.42 to 1.39 per 100,000, (p < 0.001). The proportion of patients with disseminated disease decreased from 8/21 (38%) to 12/75 (16%), (p = 0.02) and the number of incidental findings increased from 4/21 (19%) to 43/75 (57%), (p = 0.002). More symptomatic patients had disseminated disease compared to patients with incidentally discovered tumors (15/49 (31%) vs. 5/47 (11%), (p = 0.01)). Conclusion: The incidence of siNET and pNETs increased over the past decade. For siNETs, the stage of disease and the distribution of symptomatic vs. incidentally discovered tumors were unchanged between the two periods. Patients with pNETs presented with more local and incidentally discovered tumors in the latter period. Patients with incidentally discovered siNETs had disseminated disease in 44% of the overall cases. The vast majority of incidentally found pNETs were localized.

Neoplastic tissue exhibits high glucose utilization and over-expression of glucose transporters (GLUTs) and hexokinases (HKs), which can be imaged by ¹⁸F-Fluorodeoxyglucose-positron emission tomography (FDG-PET). The aim of the present study was to investigate the expression of glycolysis-associated genes and to compare this with FDG-PET imaging as well as with the cellular proliferation index in two cancer entities with different malignant potential. Using real-time PCR, gene expression of GLUT1, HK1 and HK2 were studied in 34 neuroendocrine tumors (NETs) in comparison with 14 colorectal adenocarcinomas (CRAs). The Ki67 proliferation index and, when available, FDG-PET imaging was compared with gene expression. Overexpression of GLUT1 gene expression was less frequent in NETs (38%) compared to CRAs (86%), P = 0.004. HK1 was overexpressed in 41% and 71% of NETs and CRAs, respectively (P = 0.111) and HK2 was overexpressed in 50% and 64% of NETs and CRAs, respectively (P = 0.53). There was a significant correlation between the Ki67 proliferation index and GLUT1 gene expression for the NETs (R = 0.34, P = 0.047), but no correlation with the hexokinases. FDG-PET identified foci in significantly fewer NETs (36%) than CRAs (86%), (P = 0.04). The gene expression results, with less frequent GLUT1 and HK1 upregulation in NETs, confirmed the lower metabolic activity of NETs compared to the more aggressive CRAs. In accordance with this, fewer NETs were FDG-PET positive compared to CRA tumors and FDG uptake correlated with GLUT1 gene expression.