Prognostic factors of non-functioning pancreatic neuroendocrine tumor revisited: The value of WHO 2010 classification

Advances in Management of Nonfunctional Pancreas Neuroendocrine Tumors

This article presents updates in the surgical management of non-functional sporadic pancreas neuroendocrine tumors NET, including considerations for assessment of biologic behavior to support decision-making, indications for surgery, and surgical approaches tailored to the unique nature of neuroendocrine tumors.

Endoscopic ultrasound-guided side-fenestrated needle biopsy sampling is sensitive for pancreatic neuroendocrine tumors but inadequate for tumor grading: a prospective study

Accurate pretreatment grading of pancreatic neuroendocrine tumors (PanNETs) is important to guide patient management. We aimed to evaluate endoscopic ultrasound-guided fine needle biopsy sampling (EUS-FNB) for the preoperative diagnosis and grading of PanNETs. In a tertiary-center setting, patients with suspected PanNETs were prospectively subjected to 22-gauge, reverse-bevel EUS-FNB. The EUS-FNB samples (Ki-67_EUS) and corresponding surgical specimens (Ki-67_SURG) were analyzed with Ki-67 indexing and thereafter tumor grading, (GRADE_EUS) and (GRADE_SURG) respectively. In total 52 PanNET-patients [median age: 66 years; females: 25/52; surgical resection 22/52 (42%)] were included. EUS-FNB was diagnostic in 44/52 (85%). In 42 available FNB-slides, the median neoplastic cell count was 1034 (IQR: 504-3667) with 32/42 (76%), 22/42 (52%), and 14/42 (33%) cases exceeding 500, 1000, and 2000 neoplastic cells respectively. Ki-67_SURG was significantly higher compared to Ki-67_EUS with a moderate correlation comparing Ki-67_EUS and Ki-67_SURG (Pearson r = 0.60, r² = 0.36, p = 0.011). The GRADE_EUS had a weak level of agreement (κ = 0.08) compared with GRADE_SURG. Only 2/12 (17%) G2-tumors were correctly graded in EUS-FNB-samples. EUS-guided fine needle biopsy sampling is sensitive for preoperative diagnosis of PanNET but biopsy quality is relatively poor. Therefore, the approach seems suboptimal for pretreatment grading of PanNET.

Predictors of disease recurrence after curative surgery for nonfunctioning pancreatic neuroendocrine neoplasms (NF-PanNENs): a systematic review and meta-analysis

PURPOSE

Patients submitted to curative surgery for non-functioning pancreatic neuroendocrine neoplasms (NF-PanNENs) exhibit a variable risk of disease relapse. Aims of this meta-analysis were to estimate the rate of disease recurrence and to investigate the risk factors for disease relapse in patients submitted to curative surgery for NF-PanNENs.

METHODS

Medline/Pubmed and Web of Science databases were searched for relevant studies. A meta-regression analysis was performed to investigate the source of recurrence rate heterogeneity. Pooled hazard ratios (HRs) and 95% confidence intervals (95% CI) were used to assess the effect of each possible prognostic factor on disease-free survival.

RESULTS

Fifteen studies, involving 2754 patients submitted to curative surgery for NF-PanNENs, were included. The pooled rate of disease recurrence was 21% (95% CI 15-26%). Study quality (Odds ratio, OR 0.94, P = 0.016) and G3-PanNENs rate (OR 2.18, P = 0.040) independently predicted the recurrence rate variability. Nodal metastases (HR 1.63, P < 0.001), tumor grade G2-G3 (G1 versus G2: HR 1.72, P < 0.001, G1 versus G3 HR 2.57, P < 0.001), microvascular (HR 1.25, P = 0.046) and perineural (HR 1.29, P = 0.019) invasion were identified as significant prognostic factors. T stage (T1-T2 versus T3-T4, P = 0.253) and status of resection margins (R0 versus R1, P = 0.173) did not show any significant relationship with NF-PanNENs recurrence.

CONCLUSION

Disease relapse occurs in approximately one out of five patients submitted to curative surgery for NF-PanNENs. Nodal involvement, tumor grade, microvascular and perineural invasion are relevant prognostic factors, that should be taken into account for follow-up and for possible trials investigating adjuvant or neoadjuvant treatments.

Childhood neuroendocrine tumors of the digestive system: A single center experience

The prevalence and incidence of neuroendocrine tumors (NETs) are increasing in the pediatric population. This increase can be associated with improved diagnostics and increased detection rates of the disease. We aimed to discuss the clinical and pathological characteristics of patients with this rare disease who were followed and treated at our center.The medical records of children (aged 0-18 years) with NETs of the digestive system, followed up and treated between 2007 and 2020 at Ondokuz Mayis University Faculty of Medicine, were reviewed.Overall, 16 patients (8 girls and 8 boys) were analyzed. Fifteen patients had NETs in the appendix; 14 of these had grade I NETs, and 1 had grade II NETs. No additional surgery was performed except for appendectomy. All patients were in complete remission at the last follow-up (median 38 months). The other patient, a 12-year-old girl, had a primary hepatic neuroendocrine carcinoma (grade III NET). Three cycles of neoadjuvant and adjuvant platinum-based chemotherapy were administered, and right hepatectomy was performed to remove the mass. The patient is being followed-up for approximately 3 years without disease recurrence.Most NETs are observed in adults, and most studies have focused on this population. Unlike adults, increasing awareness of the disease in the pediatric population (especially in cases of acute appendicitis), discovering therapeutic treatments, and sharing experiences are crucial for developing an optimal therapeutic approach for pediatric NETs.

A New Preoperative Scoring System for Predicting Aggressiveness of Non-Functioning Pancreatic Neuroendocrine Neoplasms

The management of non-functioning pancreatic neuroendocrine neoplasms (NF-PanNENs) is still controversial. This study aimed to develop a new scoring system for treatment decisions at initial diagnosis based on the identification of the predictive factors for aggressive NF-PanNENs. Seventy-seven patients who had been pathologically diagnosed with NF-PanNENs were enrolled. We retrospectively reviewed 13 variables that could be assessed preoperatively. Univariate and multivariate stepwise logistic regression analyses were performed to identify factors for the aggressiveness of NF-PanNENs, and a scoring system was developed by assigning weighted points proportional to their β regression coefficient. Tumor size > 20 mm on contrast-enhanced computed tomography, tumor non-vascularity, and Ki-67 labeling index ≥5% on endoscopic ultrasound-guided fine-needle aspiration specimens were identified as independent factors for predicting the aggressiveness of NF-PanNENs. The new scoring system, developed using the identified factors, had an excellent discrimination ability, with area under the curve of 0.92 (95% CI, 0.85–0.99), and good calibration (p = 0.72, Hosmer-Lemeshow test). Ten-year overall survival rates in low-risk (0 point), intermediate-risk (1 to 2 points), and high-risk (3 to 4 points) groups were 100%, 90.9%, and 24.3%, respectively. This new scoring system would be useful for treatment decisions and prognostic prediction at initial diagnosis.

Plasma Hemoglobin and Red Blood Cell Mass Levels as Dynamic Prognostic Markers for Progression and Survival in Pancreatic Neuroendocrine Tumors

There are scarce data on readily available markers enabling immediate risk stratification and personalized management in patients with advanced pancreatic neuroendocrine tumors. This study explores the association of red blood cells-related parameters as prognostic markers in patients harboring pancreatic neuroendocrine tumors. Retrospective analysis of a tertiary medical center database, acquiring data of patients with pancreatic neuroendocrine tumors including demographics, tumor-related parameters and consecutive imaging results, vital status at last follow-up, and red blood cells parameters at baseline, last follow-up, and dynamics (last/baseline ratio). Univariate and multivariable analyses were performed. Sixty-seven patients were identified (mean age at diagnosis of 63±11 years, 56.7% males). Patients with disease progression had lower hemoglobin, red blood cells mass values and hematocrit at the last evaluation (p<0.001 for all comparisons), with red blood cells mass level<3.9 m/μl and a 6% and 9% relative reduction in hemoglobin and hematocrit levels, respectively, associated with an increased risk for disease progression. Similarly, patients deceased during the study period had lower hemoglobin, red blood cells mass values and hematocrit (p<0.03 for all) than those alive, at last follow-up. Eleven percent reduction in hemoglobin level was noted indicating a higher mortality risk (p=0.04). Negative hemoglobin and hematocrit dynamics were independently associated with increased risk for disease progression (p=0.03 and 0.049, respectively). In conclusion, decrease in red blood cells mass, hemoglobin and/or hematocrit levels are all associated with poor prognosis in patients with pancreatic neuroendocrine tumors. We suggest utilizing these parameters as complementary follow-up prognostic markers to radiologic imaging in this patients population.

Canine insulinoma as a model for human malignant insulinoma research: Novel perspectives for translational clinical studies

Insulinomas are considered rare indolent neuroendocrine neoplasms in human medicine, however when metastases occur no curative treatment is available thus, novel therapies are needed. Recently advances have been made in unraveling the pathophysiology of malignant insulinoma still major challenges hinder the development of a functional model to study them. Canine malignant insulinoma have similar recurrence and a poor prognosis as human malignant insulinoma. Additionally, both human and canine patients share extensively the same environment, tend to develop insulinoma seemingly spontaneously with an etiological role for hormones, at a similar incidence and stage of lifespan, with metastasis commonly to liver and regional lymph nodes, which are unresponsive to current therapies. However, the occurrence of metastases in dogs is as high as 95% compared with only 5-16% in human studies. From a comparative oncology perspective, the shared features with human insulinoma but higher incidence of metastasis in canine insulinoma suggests the latter as a model for human malignant insulinomas. With the common purpose of increasing survival rates of human and veterinary patients, in this review we are going to compare and analyze clinical, pathological and molecular aspects of canine and human insulinomas to evaluate the suitability of the canine model for future translational clinical studies.

Cross-talk among MEN1, p53 and Notch regulates the proliferation of pancreatic neuroendocrine tumor cells by modulating INSM1 expression and subcellular localization

Genomic analysis of Pancreatic Neuroendocrine Tumors (PanNETs) has revealed that these tumors often lack mutations in typical cancer-related genes such as the tumor suppressor gene p53. Instead, PanNET tumorigenesis usually involves mutations in specific PanNET-related genes, such as tumor suppressor gene MEN1. Using a PanNET mouse model, human tissues and human cell lines, we studied the cross-talk among MEN1, p53 and Notch signaling pathways and their role in PanNETs. Here, we show that reactivation of the early developmental program of islet cells underlies PanNET tumorigenesis by restoring the proliferative capacity of PanNET cells. We investigated the role of INSM1, a transcriptional regulator of islet cells' development, and revealed that its expression and subcellular localization is regulated by MEN1 and p53. Both human and mouse data show that loss of MEN1 in a p53 wild-type genetic background results in increased nuclear INSM1 expression and cell proliferation. Additionally, inhibition of Notch signaling in a p53 wild-type background reduces the proliferation of PanNET cells, due to repression of INSM1 transcription and nuclear localization. Our study elucidates the molecular mechanisms governing the interactions of INSM1 with MEN1, p53 and Notch and their roles in PanNET tumorigenesis, suggesting INSM1 as a key transcriptional regulator of PanNET cell proliferation.

Diagnosis and Management of Gastrointestinal Neuroendocrine Tumors: A Comprehensive Literature Review

Neuroendocrine tumors (NETs) are epithelial neoplasms with predominant neuroendocrine differentiation and the ability to synthesize and secrete variable hormones and monoamines. They are relatively rare, accounting for 2% of all malignancy cases in the United States. The most common system affected by NETs is the gastrointestinal tract. Clinical presentation depends on the organ being involved and the hormone being secreted. It can be variable from asymptomatic incidental findings on imaging to intestinal obstruction, or carcinoid syndrome (CS). Several biochemical testings are developed to help with the diagnosis of NETs including 5-hydroxyindoleacetic acid (5-HIAA) and chromogranin A (CgA). Computerized tomography (CT) scans and magnetic resonance imaging (MRI) are the most commonly used modalities to localize the primary tumor and evaluate for metastasis. However, radionuclide imaging using somatostatin receptor-based imaging techniques has improved accuracy to detect smaller neoplasm. Surgical removal is the mainstay of treatment for locoregional tumors. Several medical managements are available for non-respectable NETs which include SSAs, peptide receptor radionuclide therapy (PRRT), and platinum-based chemotherapy agents.

Dual Tracer 68Ga-DOTATOC and 18F-FDG PET Improve Preoperative Evaluation of Aggressiveness in Resectable Pancreatic Neuroendocrine Neoplasms

PURPOSE

To define an imaging risk profile in a population of patients affected by Pancreatic neuroendocrine neoplasms (PanNENs) candidates to surgery, by assessing the predictive role of 68Ga-DOTATOC and 18F-FDG PET/CT and PET/MR derived parameters in risk stratification, particularly regarding histological features of aggressive behaviour.

PATIENTS AND METHODS

Retrospective study including 83 patients (53 males, 30 females; median age: 60 years, interquartile range 52-66.5), who underwent to 68Ga-DOTATOC (PET/CT: n = 77; PET/MR: n = 6) and, 68/83 patients, also to 18F-FDG PET (PET/CT: n = 65; PET/MR: n = 3) before surgery for PanNEN between 2011 and 2019, with available histological and follow-up data. The PET scans were interpreted with both qualitative (positive vs. negative) and semiquantitative measurements as follows: maximum and mean standardized uptake value (SUVmax and SUVmean) for both 18F-FDG and 68Ga-DOTATOC scans, metabolic tumour volume (MTV) and tumour lesion glycolysis (TLG) for 18F-FDG scans and somatostatin receptor density (SRD) and total lesion somatostatin receptor density (TLSRD) for 68Ga-DOTATOC PET. Receiver Operating Characteristics (ROC) curve analysis was used to investigate the performance of several PET parameters in predicting tumour stage or characteristic. For each PET parameter, the optimal cut-off was derived. Logistic regression analysis was used to assess if the PET parameters, categorized with the optimal cut-off values, were able to predict significantly the corresponding tumour stage or characteristic.

RESULTS

Overall, 29 (35%) patients had G1, 49 (59%) a G2 and five (6%) had a G3 PanNEN. The median Ki-67 index was 4% (interquartile range: 1-8%). SRD and TLSRD significantly discriminated between pT3 or pT4 PanNEN versus pT1 or pT2, as well as 18F-FDG MTV and TLG. 68Ga-DOTATOC SUVmax was able to significantly predict the presence of distant metastases with a threshold of 51.27 (sensitivity and specificity of 85.7 and 68.1%, respectively). 18F-FDG MTV and TLG were predictors of angioinvasion. The cut-off threshold for MTV was 7.98 (sensitivity and specificity of 69.7 and 82.4%, respectively) (p = 0.0004) whereas the cut-off for TLG was 32.4 (sensitivity and specificity of 69.7% and 82.4%, respectively) (p = 0.0004).

CONCLUSION

Dual tracer 68Ga-DOTATOC and 18F-FDG PET scans provide relevant information regarding tumour behaviour and aggressiveness, implementing the diagnostic preoperative work-up.

A review of pediatric neuroendocrine tumors, their detection, and treatment by radioisotopes

Neuroendocrine tumors (NETs) are rare in childhood. Neuroblastoma is the most common pediatric extracranial solid tumor, occurring >90% in children younger than 5 years of age. Pheochromocytoma and paraganglioma are rare NETs, causing hypertension in 0.5-2% of hypertensive children. Gastroenteropancreatic NETs can occur in children and are classified into carcinoids and pancreatic tumors. Nuclear medicine procedures have an essential role both in the diagnosis and treatment of NETs. Metaiodobenzylguanidine (MIBG) labeled with radioiodine has a well-established role in diagnosis as well as therapeutic management of the neuroblastoma group of diseases. During recent decades, establishing the abundant expression of somatostatin receptors by NETs first led to scintigraphy with somatostatin analogs (i.e. Tc/In-octreotide) and, later, with the emergence of positron-emitting labeled agents (i.e. Ga-DOTATATE/DOTATOC/DOTANOC) PET scans with significantly higher detection efficiency became available. Therapy with somatostatin analogs labeled with beta emitters such as Lu-177 and Y-90, known as peptide receptor radionuclide therapy, is a promising new option in the management of patients with inoperable or metastasized NETs. In this article, pediatric NETs are briefly reviewed and the role of radioactive agents in the detection and treatment of these tumors is discussed.

Risk of malignancy and prognosis of sporadic resected small (≤2 cm) nonfunctional pancreatic neuroendocrine tumors

Background

Small nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) ≤2 cm have variable biological features, and there is no gold standard treatment for their management. The present study aimed to evaluate the risk of malignancy of small NF-PNETs and their outcomes following curative resection.

Methods

Patients with NF-PNETs undergoing surgical resection at the First Affiliated Hospital, College of Medicine, Zhejiang University, between 2012 and 2017 were included. Clinicopathological characteristics, perioperative results, and prognosis were retrospectively analyzed.

Results

A total of 73 patients were identified, including 28 with small NF-PNETs and 45 large PNETs; 32.1% of NF-PNETs ≤2 cm underwent a parenchyma-sparing pancreas surgery, which was >6.7% in large NF-PNETs. No statistically significant differences in perioperative results, postoperative complications, and long-term outcomes were found between small tumors undergoing standard and parenchyma-sparing pancreatectomy. Eighteen small tumors (64.3%) developed a perioperative complication, with a clinically significant pancreatic fistula rate of 25%; however, only 2 patient needed reintervention. Small NF-PNETs in 3 patients were malignant. Multivariate logistic regression showed that grade ≥3 and lymphovascular invasion were independently related to malignancy in NF-PNETs.

Conclusions

Small NF-PNETs (≤2 cm) are not immune from potential malignancy. Surgical resection may be considered for small tumors and can provide favorable postoperative and long-term outcomes. Parenchyma-sparing pancreatectomy may be an alternative surgery for selected small local NF-PNETs.

Gastro-entero-pancreatic neuroendocrine neoplasia: The rules for non-operative management

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) with favorable pathological and clinical features may be considered as indolent lesions, and therefore be amenable to conservative management. According to the primary tumor site, different non-aggressive approaches, based on endoscopic resection or simple active surveillance, can be proposed to selected patients fulfilling specific criteria. Tumor size, Ki67 proliferative index and depth of invasion are markers that can be used in order to identify these subjects. Patients with type I gastric NENs <1 cm as well as those with non-ampullary duodenal NENs <1 cm with no associated syndrome can be safely managed by endoscopic resection. On the other hand, an active surveillance approach is preferred over surgery for patients with asymptomatic, non-functioning pancreatic NENs ≤2 cm without dilation of the main pancreatic duct or bile duct. As far as NENs of the appendix are concerned, appendectomy should be considered as curative when a R0 resection has been achieved in the presence of a tumor ≤1.5 cm, graded as G1 and without lymphovascular invasion. Finally, G1 rectal NENs ≤1 cm without invasion of the muscular layer can be safely treated by endoscopic resection. Therefore, surgeons should be aware of the existence of indolent GEP-NENs, in order to avoid unnecessary operations with associated postoperative complications.

Systematic Review and Metaanalysis of Lymph Node Metastases of Resected Pancreatic Neuroendocrine Tumors

BACKGROUND

The optimal surgical strategy for pancreatic neuroendocrine tumors (PNETs) is unknown. However, current guidelines recommend a watch-and-wait strategy for small nonfunctional PNETs (NF-PNETs). The aim of this study is to investigate the risk stratification and prognostic significance of lymph node metastasis (LNM) of PNETs to guide decision-making for lymphadenectomy.

PATIENTS AND METHODS

The MEDLINE and Web of Science databases were systematically searched for studies reporting either risk factors of LNM in resected PNETs or survival of patients with LNM. The weighted average incidence of LNM was calculated according to tumor characteristics. Random-effects metaanalyses were performed, and pooled hazard ratios (HR) and their 95% confidence intervals (CI) were calculated to determine the impact of LNM on overall survival (OS). In subgroup analyses, NF-PNETs were assessed.

RESULTS

From a total of 5883 articles, 98 retrospective studies with 13,374 patients undergoing resection for PNET were included. In all PNETs, the weighted median rates of LNM were 11.5% for small (≤ 2 cm) PNETs and 15.8% for G1 PNETs. In NF-PNETs, the rates were 11.2% for small PNETs and 10.3% for G1 PNETs. LNM of all PNETs (HR 3.87, 95% CI 3.00-4.99, P < 0.001) and NF-PNETs (HR 4.98, 95% CI 2.81-8.83, P < 0.001) was associated with worse OS.

CONCLUSIONS

LNM is potentially prevalent even in small and well-differentiated PNETs and is associated with worse prognosis. A watch-and-wait strategy for small NF-PNETs should be reappraised, and oncologic resection with lymphadenectomy can be considered. Prospective and controlled studies are needed in the future.

Prognostic and predictive factors on overall survival and surgical outcomes in pancreatic neuroendocrine tumors: recent advances and controversies

Introduction: Recent advances in diagnostic modalities and therapeutic agents have raised the importance of prognostic factors in predicting overall survival, as well as predictive factors for surgical outcomes, in tailoring therapeutic strategies of patients with pancreatic neuroendocrine neoplasms (panNENs).Areas covered: Numerous recent studies of panNEN patients report the prognostic values of a number of clinically related factors (clinical, laboratory, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors on long-term survival. In addition, an increasing number of studies showed the usefulness of various factors, specifically biomarkers and molecular makers, in predicting recurrence and mortality related to surgical treatment. Recent findings (from the last 3 years) in each of these areas, as well as recent controversies, are reviewed.Expert commentary: The clinical importance of prognostic and predictive factors for panNENs is markedly increased for both overall outcome and post resection, as a result of recent advances in all aspects of the diagnosis, management and treatment of panNENs. Despite the proven prognostic utility of routinely used tumor grading/classification and staging systems, further studies are required to establish these novel prognostic factors to support their routine clinical use.

Neuroendocrine Tumors in Pediatrics

Neuroendocrine cells are dispersed diffusely throughout many organ systems in the body and hence neuroendocrine tumors (NETs) can arise from almost anywhere in the body. NETs are considered rare tumors, and the current incidence is reported to be about 6 cases in 100 000 in adults and about 2.8 cases per million in the pediatric age group. Despite the indolent nature of these tumors, they have the potential for metastasis and significant morbidity. NETs can be asymptomatic at the time of diagnosis or can present with flushing, diarrhea, wheezing, weight loss, and fatigue among other symptoms. Due to the ambiguity of presenting symptoms, it is not uncommon for NETs to be diagnosed late in the disease course. Despite low incidence, the prevalence of the disease is high since patients live for many years and sometimes decades. Early detection of well-differentiated NETs has excellent outcomes with the majority of early-stage diseases being cured with surgical resection alone. There have been recent advancements in the management of metastatic progressive NETs with approval of peptide receptor radionuclide therapy, telotristat, and everolimus. Awareness of these rare tumors and its management is crucial for optimal management. This article will focus on pediatric NETs and current advances in its management.

Unmet Needs in Functional and Nonfunctional Pancreatic Neuroendocrine Neoplasms

Recently, the European Neuroendocrine Tumor Society (ENETS) held working sessions composed of members of the advisory board and other neuroendocrine neoplasm (NEN) experts to attempt to identify unmet needs in NENs in different locations or with advanced/poorly differentiated NENs. This report briefly summarizes the main proposed areas of unmet needs in patients with functional and nonfunctional pancreatic NENs.