What is the appropriate management of nonfunctioning pancreatic neuroendocrine tumours disclosed on screening in adult patients with multiple endocrine neoplasia type 1?

Hereditary Syndromes Associated with Pancreatic and Lung Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PanNETs) and lung NETs (LNETs) represent a rare but clinically significant subgroup of neoplasms. While the majority is sporadic, approximately 17% of PanNETs and a subset of LNETs develop in the context of monogenic familial tumor syndromes, especially multiple endocrine neoplasia type 1 (MEN1) syndrome. Other inherited syndromes associated with PanNETs include MEN4, von Hippel-Lindau (VHL) syndrome, neurofibromatosis type 1 (NF1), and tuberous sclerosis complex (TSC). These syndromes are highly penetrant and their clinical manifestations may vary even among members of the same family. They are attributed to genetic mutations involving key molecular pathways regulating cell growth, differentiation, and angiogenesis. Pancreatic NETs in hereditary syndromes are often multiple, develop at a younger age compared to sporadic tumors, and are associated with endocrine and nonendocrine tumors derived from multiple organs. Lung NETs are not as common as PanNETs and are mostly encountered in MEN1 syndrome and include typical and atypical lung carcinoids. Early detection of PanNETs and LNETs related to inherited syndromes is crucial, and specific follow-up protocols need to be employed to optimize diagnosis and management. Genetic screening is recommended in childhood, and diagnostic screening starts often in adolescence, even in asymptomatic mutation carriers. Optimal management and therapeutic decisions should be made in the context of a multidisciplinary team in specialized centers, whereas specific biomarkers aiming to identify patients denoted to follow a more aggressive course need to be developed.

[Neuroendocrine tumors of the pancreas]

CLINICAL/METHODOLOGICAL ISSUE

Neuroendocrine tumors (NET) of the pancreas fall into the group of gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN). The assignment of imaging morphological criteria to this heterogeneous group of complex tumors is often difficult.

STANDARD RADIOLOGICAL METHODS

Diagnostic ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography-CT (PET/CT) are available for the detection of pancreatic NET (also referred to as NEN) and for the diagnosis of spread and the search for metastases.

METHODOLOGICAL INNOVATIONS

In particular, nuclear medicine examination methods with somatostatin analogues are of high value, since they make tumors visible with high sensitivity via radioactively labeled receptor ligands.

PERFORMANCE

CT and MRI have high detection rates of pancreatic NET. Further developments, such as diffusion imaging, have further improved these traditional cross-sectional imaging diagnostics. However, nuclear medicine methods are an important component in detection and are superior to CT and MRI.

ACHIEVEMENTS

It is important for the radiologist to be familiar with NET of the pancreas, as it is an important differential diagnosis-also with regard to prognosis-of other pancreatic lesions.

PRACTICAL RECOMMENDATIONS

Because NET are often hypervascularized, a biphasic examination technique after contrast administration is mandatory for cross-sectional imaging. PET/CT with somatostatin analogues should be performed for further diagnosis.

Gastroenteropancreatic Neuroendocrine Tumors-Current Status and Advances in Diagnostic Imaging

Gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN) is a heterogeneous and complex group of tumors that are often difficult to classify due to their heterogeneity and varying locations. As standard radiological methods, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET/CT) are available for both localization and staging of NEN. Nuclear medical imaging methods with somatostatin analogs are of great importance since radioactively labeled receptor ligands make tumors visible with high sensitivity. CT and MRI have high detection rates for GEP-NEN and have been further improved by developments such as diffusion-weighted imaging. However, nuclear medical imaging methods are superior in detection, especially in gastrointestinal NEN. It is important for radiologists to be familiar with NEN, as it can occur ubiquitously in the abdomen and should be identified as such. Since GEP-NEN is predominantly hypervascularized, a biphasic examination technique is mandatory for contrast-enhanced cross-sectional imaging. PET/CT with somatostatin analogs should be used as the subsequent method.

A New Medical Therapy for Multiple Endocrine Neoplasia Type 1?

Pancreatic neuroendocrine tumours (pNETs) are a major manifestation of multiple endocrine neoplasia type 1 (MEN1), and the most significant cause of morbidity and mortality in this disorder. There is some evidence that the early use of somatostatin analogues can retard progression, especially of small non-functioning tumours, but there are no other prophylactic therapies for patients, and the treatment of metastatic disease is similar to that for sporadic pNETs. A recent study has shown that in cell line and animal models, MEN1 mutations lead to an upregulation of the enzyme dihydroorotate dehydrogenase (DHODH), which is involved in increasing precursor metabolites for the synthesis of pyrimidines. In these studies, blockade of this pathway by various means, including the DHODH inhibitor leflunomide, attenuates cell growth and tumour progression, suggesting a critical dependence on DHODH specifically in MEN1-mutated tissue. Preliminary clinical studies in three patients with MEN1 and pNETs have indicated some therapeutic potential of this drug, which has previously been used for some years in patients with rheumatoid arthritis. It is suggested that further clinical trials of this re-purposed drug are indicated to evaluate its potential for the treatment of patients with MEN1 and pNETS. This article describes the clinical problem of MEN1 and pNETs, and reviews the recent publication reporting on these initial results.

May the robotic approach expand the indications for redo surgery in recurrent pNETs in Multiple Neuroendocrine Neoplasia type 1?

Pancreatic neuroendocrine tumors (pNETs) represent the leading cause of disease-specific mortality in patients with Multiple Neuroendocrine Neoplasia type 1 (MEN1). Although surgery is the recommended treatment for non-functional pNETs >2 cm, the management of recurrent lesions between 1 and 2 cm is controversial. Robotic surgery was used on a 29-year-old female with MEN1 and previous distal splenopancreatectomy that presented with a 1 cm recurrent pNET. The advantages offered by this approach facilitating a precise resection of the tumor and minimizing the postoperative morbidity may favor the decision towards redo surgery for local recurrences <2 cm, expanding current indications.

Clinical Profile and Mutations Associated with Multiple Endocrine Neoplasia-Type1 (MEN1) and Their First-Degree Relatives at Risk of Developing MEN1: A Prospective Study

Multiple Endocrine Neoplasia type-1 (MEN1) is an autosomal dominant disorder with a combined occurrence of tumours of parathyroid glands, pancreatic islets, and anterior pituitary. About 90% of these patients carry mutations in the MEN1 gene, though the spectrum is not well defined in India. Forty clinically suspected cases of MEN1 were enrolled prospectively over six years; 32 patients (23 index-cases and nine affected relatives) with≥2 classical endocrine tumours of MEN1 were considered definite, and eight were categorised as 'MEN1-like'. Details of their clinical presentation, treatment and mutational analysis including MEN1 gene, 3' and 5' untranslated regions (UTR) of MEN1, CDKN1B, and CaSR genes were collated. Asymptomatic first-degree relatives were also screened. Among the 32 definite MEN1 patients, all had primary hyperparathyroidism, 22 (68.7%) had gastroentero-pancreatic neuroendocrine tumours, and 21 (66%) had pituitary adenoma. Of the 23 definite index-cases, 13 (56.5%) carried mutations in the MEN1 gene. Five of nine affected first-degree relatives (55.5%), and four of 10 asymptomatic relatives (40%) also had MEN1 mutations. Seven of 10 MEN1 mutation-negative definite index-cases harboured p.V109G polymorphism in the CDKN1B gene. All eight MEN1-like cases were negative for mutations and large deletions in MEN1, mutations in 3' and 5' UTR of MEN1, CaSR and CDKN1B genes. The study has helped to clearly document the pattern of mutations among Indian MEN1 patients. However, the absence of MEN1 mutation in ~44% of cases and the presence of p.V109G polymorphism in CDKN1B gene raise the question whether such polymorphisms could independently contribute to pathogenesis.

Multiple Endocrine Neoplasia Type 1: Latest Insights

Multiple endocrine neoplasia type 1 (MEN1), a rare tumor syndrome that is inherited in an autosomal dominant pattern, is continuing to raise great interest for endocrinology, gastroenterology, surgery, radiology, genetics, and molecular biology specialists. There have been 2 major clinical practice guidance papers published in the past 2 decades, with the most recent published 8 years ago. Since then, several new insights on the basic biology and clinical features of MEN1 have appeared in the literature, and those data are discussed in this review. The genetic and molecular interactions of the MEN1-encoded protein menin with transcription factors and chromatin-modifying proteins in cell signaling pathways mediated by transforming growth factor β/bone morphogenetic protein, a few nuclear receptors, Wnt/β-catenin, and Hedgehog, and preclinical studies in mouse models have facilitated the understanding of the pathogenesis of MEN1-associated tumors and potential pharmacological interventions. The advancements in genetic diagnosis have offered a chance to recognize MEN1-related conditions in germline MEN1 mutation-negative patients. There is rapidly accumulating knowledge about clinical presentation in children, adolescents, and pregnancy that is translatable into the management of these very fragile patients. The discoveries about the genetic and molecular signatures of sporadic neuroendocrine tumors support the development of clinical trials with novel targeted therapies, along with advancements in diagnostic tools and surgical approaches. Finally, quality of life studies in patients affected by MEN1 and related conditions represent an effort necessary to develop a pharmacoeconomic interpretation of the problem. Because advances are being made both broadly and in focused areas, this timely review presents and discusses those studies collectively.

A Direct Comparison of Patients With Hereditary and Sporadic Pancreatic Neuroendocrine Tumors: Evaluation of Clinical Course, Prognostic Factors and Genotype-Phenotype Correlations

INTRODUCTION

Pancreatic neuroendocrine tumors (PNETs) in hereditary syndromes pose a significant challenge to clinicians. The rarity of these syndromes and PNETs itself make it difficult to directly compare them with sporadic PNETs. Despite research suggesting differences between these two entities, the same approach is used in hereditary and sporadic PNETs.

METHODS

We included 63 patients with hereditary PNET (GpNET) and 145 with sporadic PNET (SpNET) in a retrospective observational study. Clinical and genetic data were collected in two Polish endocrine departments from January 2004 to February 2020. Only patients with confirmed germline mutations were included in the GpNET cohort. We attempted to establish prognostic factors of metastases and overall survival in both groups and genotype-phenotype correlations in the GpNET group.

RESULTS

Patients with GpNET were younger and diagnosed earlier, whereas their tumors were smaller and more frequently multifocal compared with patients with SpNET. Metastases occurred more frequently in the SpNET group, and their appearance was associated with tumor size in both groups. GpNET patients had longer overall survival (OS). OS was affected by age, age at diagnosis, sex, grade, stage, tumor diameter, occurrence and localization of metastases, type of treatment, and comorbidities. In the MEN1 group, carriers of frameshift with STOP codon, splice site, and missense mutations tended to have less advanced disease, while patients with mutations in exon 2 tended to have metastases more frequently.

CONCLUSIONS

Direct comparisons of GpNET and SpNET demonstrate significant differences in the clinical courses of both entities, which should force different approaches. A larger group of patients with GpNET should be assessed to confirm genotype-phenotype correlations.

CT-Radiomic Approach to Predict G1/2 Nonfunctional Pancreatic Neuroendocrine Tumor

RATIONALE AND OBJECTIVES

Tumor grading of nonfunctional pancreatic neuroendocrine tumors (NF-pNETs) determines the choice of clinical treatment and management. The pathological grade of pancreatic neuroendocrine tumors is usually assessed on postoperative specimens. The goal of our study is to establish a tumor grade (G) prediction model for preoperative G1/2 NF-pNETs using radiomics for multislice spiral CT image analysis.

MATERIALS AND METHODS

This retrospective study included a primary cohort of 59 patients and an independent validation cohort of 40 consecutive patients; their multislice spiral CT images were collected from October 2012 to October 2016 and October 2016 to June 2018, respectively. All 99 patients were diagnosed with clinicopathologically confirmed NF-pNETs. Most significant radiomic features were selected using the minimum redundancy and maximum relevance algorithm. Support vector machine classifier with a radial basis function-based predictive model was subsequently developed for clinical use.

RESULTS

A total of 585 radiomics features were extracted from every phase for each patient. Six of these radiomics features were identified as most discriminant features for G1 and G2 tumors and used to construct the tumor grade prediction model. The prediction model resulted in the area under the curve values of 0.968 (95% CI: 0.900-0.991) and 0.876 (95% CI: 0.700-0.963) for the training cohort and validation cohort, respectively. Sensitivity and specificity were 96.4% and 83.9%, and 90.9% and 88.9% for the training and validation cohorts, respectively. The decision curves indicated that if the threshold probability is above 0.1, using the rad-score in the current study on G1/2 NF-pNETs is more beneficial than the treat-all-patients scheme or the treat-none scheme.

CONCLUSION

Radiomics developed with a combination of nonenhanced and portal venous phases can achieve favorable predictive accuracy for histological grade for G1/G2 NF-pNETs.

Long-term outcomes in MEN-1 patients with pancreatic neuroendocrine neoplasms: an Israeli specialist center experience

PURPOSE

The decreased life expectancy of MEN-1 patients is mainly related to pancreatic neuroendocrine tumors (pNETs). At best, limited data is available on the natural history of MEN-1-associated pNETs, as these tumors are rare and have a wide range of biologic behavior. Our study aims to explore the clinical course of patients with MEN-1-associated pNETs and the long-term outcomes.

METHODS

This longitudinal study was conducted on the MEN-1 cohort treated at our referral center over a 22-year period (1996-2018). Relevant clinical data were retrospectively analysed.

RESULTS

Among the 33 MEN-1 patients included in our study, pNETs were identified in 21 subjects with a penetrance of 48% by the age of 50. Non-functioning and functioning pNETs were diagnosed in sixteen (76%) and five (24%) patients, respectively. Two-thirds of the patients had multifocal tumors. The median number of pancreatic macroscopic lesions per individual was 4.0 ± 3.9 (range 1-8) with a mean size of 1.3 ± 2.1 cm (range 0.5-10). The metastatic rate according to the dominant pNET lesion reached 100%, 62% and 6% for tumors sized > 4 cm, 2.1-4 cm, and 1-2 cm, respectively. Over the study period, one or more therapeutic interventions for pNETs were required in 20 out of the 21 patients. pNET-related metastatic complication was the main cause of death within this MEN-1 cohort. The overall survival rate for the pNETs patients was 86% during a mean follow-up period of 8.0 ± 4.6 years.

CONCLUSIONS

In our MEN-1 cohort, non-functioning pNETs were the most frequent type of pancreaticoduodenal tumor, and the tumor size correlated with the risks of metastasis and death. Increased awareness, early diagnosis, and a multidisciplinary approach may improve the associated morbidity and mortality in these patients.