An update on the development of concepts, diagnostic criteria, and challenging issues for neuroendocrine neoplasms across different digestive organs

High expression of insulinoma-associated protein 1 (INSM1) distinguishes colorectal mixed and pure neuroendocrine carcinomas from conventional adenocarcinomas with diffuse expression of synaptophysin

Complementary to synaptophysin and chromogranin A, insulinoma-associated protein 1 (INSM1) has emerged as a sensitive marker for the diagnosis of neuroendocrine neoplasms. Since there are no comparative data regarding INSM1 expression in conventional colorectal adenocarcinomas (CRCs) and colorectal mixed adenoneuroendocrine carcinomas/neuroendocrine carcinomas (MANECs/NECs), we examined INSM1 in a large cohort of conventional CRCs and MANECs/NECs. In conventional CRC, we put a special focus on conventional CRC with diffuse expression of synaptophysin, which carry the risk of being misinterpreted as a MANEC or a NEC. We investigated INSM1 according to the immunoreactive score in our main cohort of 1,033 conventional CRCs and 21 MANECs/NECs in comparison to the expression of synaptophysin and chromogranin A and correlated the results with clinicopathological parameters and patient survival. All MANECs/NECs expressed INSM1, usually showing high or moderate expression (57% high, 34% moderate, and 9% low), which distinguished them from conventional CRCs, which were usually INSM1 negative or low, even if they diffusely expressed synaptophysin. High expression of INSM1 was not observed in conventional CRCs. Chromogranin A was negative/low in most conventional CRCs (99%), but also in most MANECs/NECs (66%). Comparable results were observed in our independent validation cohorts of conventional CRC (n = 274) and MANEC/NEC (n = 19). Similar to synaptophysin, INSM1 expression had no prognostic relevance in conventional CRCs, while true MANEC/NEC showed a highly impaired survival in univariate and multivariate analyses (e.g. disease-specific survival: p < 0.001). MANECs/NECs are a highly aggressive variant of colorectal cancer, which must be reliably identified. High expression of INSM1 distinguishes MANEC/NEC from conventional CRCs with diffuse expression of the standard neuroendocrine marker synaptophysin, which do not share the same dismal prognosis. Therefore, high INSM1 expression is a highly specific/sensitive marker that is supportive for the diagnosis of true colorectal MANEC/NEC.

Updates in histopathological classification and tissue biomarkers of digestive neuroendocrine neoplasms: What the clinician should know

Histopathological classifications of neuroendocrine neoplasms (NEN) change regularly and the latest WHO classification published in 2022, which concerns all NEN in the body, attempts to standardize classifications in the different locations. Differentiation and proliferation mainly assessed by Ki-67 index are still the cornerstone of those classifications. However, many markers are now used for diagnostic (to check neuroendocrine differentiation, to identify the site of origin of a metastasis, to help separating high-grade neuroendocrine tumors/NET and neuroendocrine carcinoma/NEC), prognostic or theranostic purposes. NENs are often heterogeneous and this can lead to difficulties in classifications, biomarker and prognostic assessment. These different points are discussed successively in this review, insisting especially on the frequent digestive, gastro-entero-pancreatic (GEP) localizations.

Patterns of emergency department visits before diagnosis with digestive neuroendocrine neoplasms

OBJECTIVE

To evaluate the patterns of emergency department visits before diagnosis with digestive neuroendocrine neoplasms (NENs).

METHODS

Linked administrative databases from the province of Alberta, Canada, were examined, and patients diagnosed with digestive NENs from 2004 to 2019 were reviewed. Incidents of emergency department visits in the 3 months before histological diagnosis were reviewed. Multivariable logistic regression analyses were used to examine factors associated with at least one emergency department (ED) visit as well as factors associated with more than one ED visit. The impact of pre-diagnosis ED visits on overall survival was further assessed in a multivariable Cox regression model, which included (in addition to ED visits), age at diagnosis, sex, histology, Charlson comorbidity index, and stage.

RESULTS

A total of 2120 patients were considered eligible for the study, and they were included in the analysis (including 1041 patients (49.1%) with at least one ED visit in the 3 months before diagnosis). The following factors were associated with a higher likelihood of an ED visit prior to diagnosis: younger age (OR with increasing age: 0.983; 95% CI: 0.977-0.989), higher comorbidity index (OR: 1.332; 95% CI: 1.215-1.460), female sex (OR: 1.292; 95% CI: 1.084-1.540), and stage IV (OR: 1.515; 95% CI: 1.106-2.075). Likewise, the following factors were associated with more than one ED visit within 3 months before diagnosis: younger age (OR with increasing age: 0.985; 95% CI: 0.979-0.992), higher comorbidity index (OR: 1.280; 95% CI: 1.167-1.405), and female sex (OR: 1.516; 95% CI: 1.230-1.868). Using multivariable Cox regression modeling, the following factors were associated with worse overall survival (higher risk of death): older age (HR: 1.050; 95% CI: 1.043-1.056), higher comorbidity index (HR: 1.280; 95% CI: 1.209-1.356), stage IV (HR: 3.163; 95% CI: 2.562-3.905), neuroendocrine carcinoma histology (HR: 1.645; 95% CI: 1.350-2.003), pre-diagnosis ED visit (HR: 1.784; 95% CI: 1.529-2.083).

CONCLUSION

Almost one-half of patients with NENs visit the ED within 3 months before diagnosis. ED visits were associated with younger age, female sex, advanced disease, and higher comorbidity. Moreover, pre-diagnosis ED visit(s) were associated with worse overall survival in the current cohort.

European Neuroendocrine Tumor Society (ENETS) 2023 guidance paper for digestive neuroendocrine carcinoma

This ENETS guidance paper, developed by a multidisciplinary working group, provides up-to-date and practical advice on the diagnosis and management of digestive neuroendocrine carcinoma, based on recent developments and study results. These recommendations aim to pave the road for more standardized care for our patients resulting in improved outcomes. Prognosis is generally poor for digestive NEC, most are advanced at diagnosis and median survival in metastatic disease is 11-12 months. Surgery can be of benefit for localized disease after extensive preoperative imaging. Carboplatin in combination with etoposide is recommended as first-line treatment for metastatic disease. Irinotecan with fluoropyrimidines has the best evidence as second-line treatment. Immunotherapy plays a minor role in biomarker-unselected patients. Molecular profiling if available is encouraged to identify new targets. More prospective clinical trials are highly needed to fulfil the unmet needs in this field, especially on new predictive and prognostic biomarkers and to improve survival of patients with advanced disease.

The Landscape and Clinical Application of the Tumor Microenvironment in Gastroenteropancreatic Neuroendocrine Neoplasms

Simple Summary

The tumor microenvironment (TME) plays a role in promoting tumor progression. Elucidating the relationship between the TME and tumor cells will benefit current therapies. Therefore, this review summarizes the most recent relationship between the TME and tumor characteristics, discusses the differences in the TME at various sites along the digestive tract, and compares the TMEs of neuroendocrine tumors and neuroendocrine carcinomas. Microbial ecological changes in the TME were reviewed. The clinical application of the TME was summarized from bench to bedside. The TME can be used as a tumor drug target for diagnostic value, prognosis prediction, and efficacy evaluation, further revealing the potential of immune checkpoints combined with antiangiogenic drugs. The clinical application prospects of adoptive cell therapy and oncolytic viruses were described. The potential therapeutic approaches and strategies for gastrointestinal neuroendocrine neoplasms are considered.

Abstract

Gastroenteropancreatic neuroendocrine neoplasms feature high heterogeneity. Neuroendocrine tumor cells are closely associated with the tumor microenvironment. Tumor-infiltrating immune cells are mutually educated by each other and by tumor cells. Immune cells have dual protumorigenic and antitumorigenic effects. The immune environment is conducive to the invasion and metastasis of the tumor; in turn, tumor cells can change the immune environment. These cells also form cytokines, immune checkpoint systems, and tertiary lymphoid structures to participate in the process of mutual adaptation. Additionally, the fibroblasts, vascular structure, and microbiota exhibit interactions with tumor cells. From bench to bedside, clinical practice related to the tumor microenvironment is also regarded as promising. Targeting immune components and angiogenic regulatory molecules has been shown to be effective. The clinical efficacy of immune checkpoint inhibitors, adoptive cell therapy, and oncolytic viruses remains to be further discussed in clinical trials. Moreover, combination therapy is feasible for advanced high-grade tumors. The regulation of the tumor microenvironment based on multiple omics results can suggest innovative therapeutic strategies to prevent tumors from succeeding in immune escape and to support antitumoral effects.