Does the WHO 2010 classification of pancreatic neuroendocrine neoplasms accurately characterize pancreatic neuroendocrine carcinomas?

Relation between WHO Classification and Location- and Functionality-Based Classifications of Neuroendocrine Neoplasms of the Digestive Tract

Practice of neuroendocrine neoplasms (NENs) of the digestive tract, which comprise of a highly diverse group of tumors with a rising incidence, faces multiple biological, diagnostic, and therapeutic issues. Part of these issues is due to misuse and misinterpretation of the classification and terminology of NENs of the digestive tract, which make it increasingly challenging to evaluate and compare the literature. For instance, grade 3 neuroendocrine tumors (NETs) are frequently referred to as neuroendocrine carcinomas (NECs) and vice versa, while NECs are, by definition, high grade and therefore constitute a separate entity from NETs. Moreover, the term NET is regularly misused to describe NENs in general, and NETs are frequently referred to as benign, while they should always be considered malignancies as they do have metastatic potential. To prevent misconceptions in future NEN-related research, we reviewed the most recent terminology used to classify NENs of the digestive tract and created an overview that combines the classification of these NENs according to the World Health Organization (WHO) with location- and functionality-based classifications. This overview may help clinicians and researchers in understanding the current literature and could serve as a guide in the clinic as well as for writing future studies on NENs of the digestive tract. In this way, we aim for the universal use of terminology, thereby providing an efficient foundation for future NEN-related research.

Models in Pancreatic Neuroendocrine Neoplasms: Current Perspectives and Future Directions

Pancreatic neuroendocrine neoplasms (pNENs) are a heterogeneous group of tumors derived from multiple neuroendocrine origin cell subtypes. Incidence rates for pNENs have steadily risen over the last decade, and outcomes continue to vary widely due to inability to properly screen. These tumors encompass a wide range of functional and non-functional subtypes, with their rarity and slow growth making therapeutic development difficult as most clinically used therapeutics are derived from retrospective analyses. Improved molecular understanding of these cancers has increased our knowledge of the tumor biology for pNENs. Despite these advances in our understanding of pNENs, there remains a dearth of models for further investigation. In this review, we will cover the current field of pNEN models, which include established cell lines, animal models such as mice and zebrafish, and three-dimensional (3D) cell models, and compare their uses in modeling various disease aspects. While no study model is a complete representation of pNEN biology, each has advantages which allow for new scientific understanding of these rare tumors. Future efforts and advancements in technology will continue to create new options in modeling these cancers.

Pancreatic Neuroendocrine Neoplasms: Updates on Genomic Changes in Inherited Tumour Syndromes and Sporadic Tumours Based on WHO Classification

Pancreatic neuroendocrine neoplasms (PanNENs) are the neuroendocrine neoplasms with greatest rate of increase in incidence. Approximately 10% of PanNENs arise as inherited tumour syndromes which include multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 4, von Hippel-Lindau syndrome, neurofibromatosis type1, tuberous sclerosis complex 1/2, Cowden syndrome, and Glucagon cell hyperplasia and neoplasia as well as familial insulinomatosis. In sporadic PanNENs, driver mutations in MEN1, DAXX/ATRX and mTOR pathway genes are associated with development and progression in pancreatic neuroendocrine tumours. The other changes are in VEGF pathway, Notch pathway, germline mutations in MUTYH, CHEK2, BRCA2, PHLDA3 as well as other genetic alterations. On the other hand, pancreatic neuroendocrine carcinomas share similar genetic alterations with ductal adenocarcinomas, e.g., TP53, RB1 or KRAS. In addition, microRNA and changes in immune microenvironment were noted in PanNENs. Updates on these genetic knowledges contribute to the development of management strategies for patients with PanNENs.

A case of pancreatic endocrine carcinoma with a different clinical diagnosis before chemotherapy and pathological autopsy

We encountered a case of pancreatic neuroendocrine carcinoma (pNEC) diagnosed via pathological autopsy that was initially diagnosed clinically as G3 pancreatic neuroendocrine tumor (G3 pNET) and discussed the differences between these entities in the literature. A 76-year-old man was admitted to our department because of jaundice. Computed tomography revealed multiple round nodules in both lung fields, suggesting metastasis, and a mass lesion was detected in the head of the pancreas with poor contrast in the arterial phase and slight contrast enhancement in the equilibrium phase. Biopsy of the lungs and pancreas led to a diagnosis of multiple pulmonary metastases of G3 pNET. Because the lesions were unresectable, chemotherapy was administered. Treatment was started with everolimus for 5 weeks. However, the patient experienced severe loss of appetite and malaise, and the lung lesions progressed, prompting treatment discontinuation. Subsequently, the patient's disease progressed rapidly, and he died 99 days after the start of chemotherapy. We performed a pathological autopsy with the consent of the family because of the rapid tumor growth. A pathological autopsy revealed a final diagnosis of pNEC, which differed from the clinical diagnosis.

Frequency of Neuroendocrine Tumor Studies: Using Latent Dirichlet Allocation and HJ-Biplot Statistical Methods

Background: Neuroendocrine tumors (NETs) are severe and relatively rare and may affect any organ of the human body. The prevalence of NETs has increased in recent years; however, there seem to be more data on particular types, even though, despite the efforts of different guidelines, there is no consensus on how to identify different types of NETs. In this review, we investigated the countries that published the most articles about NETs, the most frequent organs affected, and the most common related topics. Methods: This work used the Latent Dirichlet Allocation (LDA) method to identify and interpret scientific information in relation to the categories in a set of documents. The HJ-Biplot method was also used to determine the relationship between the analyzed topics, by taking into consideration the years under study. Results: In this study, a literature review was conducted, from which a total of 7658 abstracts of scientific articles published between 1981 and 2020 were extracted. The United States, Germany, United Kingdom, France, and Italy published the majority of studies on NETs, of which pancreatic tumors were the most studied. The five most frequent topics were t_21 (clinical benefit), t_11 (pancreatic neuroendocrine tumors), t_13 (patients one year after treatment), t_17 (prognosis of survival before and after resection), and t_3 (markers for carcinomas). Finally, the results were put through a two-way multivariate analysis (HJ-Biplot), which generated a new interpretation: we grouped topics by year and discovered which NETs were the most relevant for which years. Conclusions: The most frequent topics found in our review highlighted the severity of NETs: patients have a poor prognosis of survival and a high probability of tumor recurrence.

A case of pancreatic neuroendocrine carcinoma with a favorable clinical response to pembrolizumab

A 76-year-old man with epigastric pain developed 1 month earlier was referred to our department for additional screening and treatment after abdominal ultrasound revealed a mass shadow in the pancreatic head and liver. Blood biochemistry revealed signs of mild jaundice and hepatic dysfunction. Abdominal contrast-computed tomography revealed an irregular hypodense mass with poor enhancement in the pancreatic head and several hypodense nodules in the liver. Endoscopic examination revealed duodenal infiltration signs. The biopsied duodenal mucosa contained atypical cells with high nuclear-to-cytoplasmic ratios; the cells stained positive for CD56, chromogranin, and synaptophysin, and the Ki-67 index was 90%. Accordingly, pancreatic neuroendocrine carcinoma (PanNEC) was diagnosed. Platinum-based chemotherapy (6 courses) and streptozotocin (10 courses) were adopted as the first- and second-line regimens, respectively. However, the patient showed progressive disease (PD). Pembrolizumab was added as a third-line regimen (13 courses) after confirming PanNEC with high microsatellite instability (MSI-high). Despite a temporary partial response (PR), the patient showed PD by the end of the 13 courses and died 1 year and 7 months after diagnosis. Although there is no established PanNEC therapy, those with MSI-high may respond favorably to pembrolizumab. Therefore, we should ascertain the MSI status of any PanNEC in routine practice.

New staging classification for pancreatic neuroendocrine neoplasms combining TNM stage and WHO grade classification []

AJCC TNM stage and WHO grade (G) are two widely used staging systems to guide clinical management for pancreatic neuroendocrine neoplasms (panNENs), based on clinical staging and pathological grading information, respectively. We proposed to integrate TNM stage and G grade into one staging system (TNMG) and to evaluate its clinical application as a prognostic indicator for panNENs. Accordingly, 5254 patients diagnosed with panNENs were used to evaluate and to validate the applicability of TNMG to panNENs. The predictive accuracy of TNMG system was compared with that of each separate staging/grading system. We found that TNM stage and G grade were independent risk factors for survival in both the Surveillance, Epidemiology, and End Result (SEER) and multicenter series. The interaction effect between TNM stage and G grade was significant. Twelve subgroups combining the TNM stage and G grade were proposed in the TNMG stage, which were classified into five stages TNMG. According to the TNMG staging classification in the SEER series, the estimated median survival for stages I, II, III, IV, and V were 203, 174, 112, 61, and 8 months, respectively. The predictive accuracy of TNMG stage was higher than that of TNM stage and G grade used independently. The TNMG stage classification was more accurate in predicting panNEN patient's prognosis than either the TNM stage or G grade.

A comparison of outcomes in patients with intracholecystic papillary neoplasms or conventional adenocarcinomas of the gallbladder

BACKGROUND

Intracholecystic papillary neoplasm (ICPN) of the gallbladder (GB) is an exophytic intraepithelial neoplasm. This study aimed to investigate clinicopathologic findings, prognosis and recurrence patterns of patients with ICPN as compared to those patients with conventional adenocarcinoma of the gallbladder (GBC).

METHODS

Patients who underwent surgical resection for suspected GB cancer between 2000 and 2018 were included. ICPN was defined as an exophytic papillary mass within the GB lumen with a size ≥1.0 cm.

RESULTS

Of 607 patients, 241 patients (40%) were pathologically diagnosed with ICPN. Of the 241 patients with ICPNs, 110 (46%) were T1 or less. Following T stage-matched analysis, the rate of lymph node metastases were comparable (50 [52%] vs. 37 [49%], P = 0.581). The five-year survival rate was higher in ICPN, but after T stage-matching, they were comparable (69.1 vs. 63.2%, P = 0.171). Overall recurrence rates were also comparable, with the exception of lower peritoneal seeding in patients with ICPN.

CONCLUSION

Patients with ICPN who underwent resection were more likely to have an earlier T stage. There was no significant difference in prognosis and recurrence between ICPN and conventional GBC after stage matching. Therefore, the treatment strategy for ICPN should follow the same protocols used for conventional GBC.

Ki-67 Index of 55% Distinguishes Two Groups of Bronchopulmonary Pure and Composite Large Cell Neuroendocrine Carcinomas with Distinct Prognosis

BACKGROUND

Little information is available concerning prognostic factors for bronchopulmonary large cell neuroendocrine carcinomas (BP-LCNECs) and even less is known about combined LCNECs (Co-LCNECs). We investigated whether an integrated morphological, immunohistochemical, and molecular approach could be used for their prognostic evaluation.

METHODS

Morphological (including combined features), proliferative (mitotic count/Ki-67 index), immunohistochemical (napsin A, p40, TTF-1, CD44, OTP, SSTR2A, SSTR5, mASH1, p53, RB1, and MDM2), and genomic (TP53, RB1, ATM, JAK2, KRAS, and STK11) findings were analyzed in BP-LCNECs from 5 Italian centers, and correlated with overall survival (OS). The Ki-67 index was expressed as the percentage of positive cells in hot spots as indicated in the WHO 2019 Digestive System Tumors and, for Co-LCNECs, the Ki-67 index was evaluated only in the LCNEC component.

RESULTS

A total of 111 LCNECs were distinguished into 70 pure LCNECs, 35 Co-LCNECs (27 with adenocarcinoma [ADC] and 8 with squamous cell carcinoma [SqCC]), and 6 LCNECs with only napsin A immunoreactivity. The Ki-67 index cutoff at 55% evaluated in the neuroendocrine component was the most powerful predictor of OS (log-rank p = 0.0001) in all LCNECs; 34 cases had a Ki-67 index <55% (LCNEC-A) and 77 had a Ki-67 index ≥55% (LCNEC-B). Statistically significant differences in OS (log-rank p = 0.0001) were also observed between pure and Co-LCNECs. A significant difference in OS was found between pure LCNECs-A and Co-LCNECs-A (p < 0.05) but not between pure LCNECs-B and Co-LCNECs-B. Co-LCNEC-ADC and LCNEC napsin A+ cases had longer OS than pure LCNEC and Co-LCNEC-SqCC cases (log-rank p = 0.0001). On multivariable analysis, tumor location, pure versus combined features, and napsin A, but no single gene mutation, were significantly associated with OS after adjustment for Ki-67 index and study center (p < 0.05).

CONCLUSIONS

The Ki-67 proliferation index and the morphological characterization of combined features in LCNECs seem to be important tools for predicting clinical outcome in BP-LCNECs.

A pancreatic mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) (NET and undifferentiated carcinoma of the pancreas with osteoclast-like giant cells) with metastatic neuroendocrine component to the liver

Undifferentiated carcinoma of the pancreas with osteoclast-like giant cells (UCOGCs) is an extremely rare morphologically and clinically distinct variant of pancreatic ductal adenocarcinoma (PDAC), exhibiting a characteristic component of reactive osteoclast-like giant cells admixed with neoplastic mononuclear cells. Sommers and Meissner first described it in 1954 as an “unusual carcinoma of the pancreas”. Later it acquired many different names. In 2010, the WHO classified these tumors as a variant of PDAC under the heading of “undifferentiated carcinoma with osteoclast-like giant cells”. Here we describe the first case of pancreatic mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) composed of UCOGC and pancreatic neuroendocrine tumor (NET), which occurred in a 78-year-old man with biliary colic and pancreatitis. The mass did not respond to the chemotherapy, and he soon developed liver metastasis from the NET component, and unfortunately, the patient passed away 10 months later. Since UCOGC is extremely rare, and its association with NET has not been reported yet, our case expands the knowledge regarding its unusual presentation and poor prognosis.

Pancreatic neuroendocrine carcinoma G3 may be heterogeneous and could be classified into two distinct groups

BACKGROUND/OBJECTIVES

Pancreatic neuroendocrine carcinoma (PanNEC)-G3 often presents along with genetic abnormalities such as KRAS, RB1, and TP53 mutations. However, the association between these genetic findings and response to chemotherapy and prognosis has not been clarified. This study aimed to clarify the clinicopathological features of PanNEC-G3.

METHODS

We performed a subgroup analysis of the Japanese PanNEN-G3 study (multicenter, retrospective study), which revealed that Rb loss and KRAS mutation were predictors of the response to platinum-based regimen in PanNEN-G3. We re-classified WHO grades of PanNENs using the 2017 WHO classification and then analyzed the clinicopathological features and prognostic factors in 49 patients with PanNEC-G3.

RESULTS

The rates of Rb loss and KRAS mutation in PanNEC-G3 were 54.5% and 48.7%, respectively. Patients with Rb loss and/or KRAS mutation showed a higher response rate to first-line platinum-based regimen than those without Rb loss or KRAS mutation (object response rate 70.0% vs 33.3%, odds ratio 9.22; 95% CI 1.26-67.3, P = 0.029), but tended to have shorter overall survival rates than those without Rb loss or KRAS mutation (median 239 vs 473 days, hazard ratio 2.11; 95% CI 0.92-4.86, P = 0.077).

CONCLUSIONS

Patients with PanNEC-G3 have varied clinical outcomes for platinum-based regimen. When grouped based on Rb loss and KRAS mutation, there seemed to be two groups with distinct prognoses and responses to the platinum-based regimen. PanNEC-G3 could, therefore, be classified into two distinct groups based on immunohistochemical and genetic findings.

Neuroendocrine neoplasia of the gastrointestinal tract revisited: towards precision medicine

Over the past 5 years, a number of notable research advances have been made in the field of neuroendocrine cancer, specifically with regard to neuroendocrine cancer of the gastrointestinal tract. The aim of this Review is to provide an update on current knowledge that has proven effective for the clinical management of patients with these tumours. For example, for the first time in the tubular gastrointestinal tract, well-differentiated high-grade (grade 3) tumours and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are defined in the WHO classification. This novel classification enables efficient identification of the most aggressive well-differentiated neuroendocrine tumours and helps in defining the degree of aggressiveness of MiNENs. The Review also discusses updates to epidemiology, cell biology (including vesicle-specific components) and the as-yet-unresolved complex genetic background that varies according to site and differentiation status. The Review summarizes novel diagnostic instruments, including molecules associated with the secretory machinery, novel radiological approaches (including pattern recognition techniques), novel PET tracers and liquid biopsy combined with DNA or RNA assays. Surgery remains the treatment mainstay; however, peptide receptor radionuclide therapy with novel radioligands and new emerging medical therapies (including vaccination and immunotherapy) are evolving and being tested in clinical trials, which are summarized and critically reviewed here.

Curative Surgery and Ki-67 Value Rather than Tumor Differentiation Predict the Survival of Patients with High-grade Neuroendocrine Neoplasms

OBJECTIVE

To elucidate the role of surgery in patients with high-grade neuroendocrine neoplasms (hg-NENs) and Ki-67 > 20%.

BACKGROUND

Although surgery is the first treatment choice in patients with low-grade NENs, whether it increases the survival of patients with hg-NENs is debatable.

METHODS

Between 2005 and 2018, 63 patients pathologically diagnosed with hg-NENs treated at our institution were retrospectively analyzed. The risk factors for overall survival (OS) and recurrence-free survival (RFS) were analyzed, and OS was compared between each treatment group.

RESULTS

The median observation time was 21.2 months, and the median Ki-67 value was 52%. Patients with hg-NENs were classified into low Ki-67 (Ki-67 < 52%) and high Ki-67 (Ki-67 ≥ 52%) groups. Multivariate analysis for OS identified surgery (P = 0.013) and low Ki-67 value (P = 0.007) as independent risk factors, while morphological differentiation defined by the WHO 2017 criteria showed no association with OS. Patients with low Ki-67 value subjected to R0/1, R2, and chemotherapy had a median survival time (MST) of 83.8, 16.6, and 28.1 months, respectively. The MST for R0/1 group was significantly longer than that for chemotherapy group (P = 0.001). However, no difference in survival was reported between patients from R0/1 and chemotherapy groups with high Ki-67. Ki-67 value could determine RFS (P = 0.006) in patients that underwent R0/1 surgery for pancreatic hg-NENs.

CONCLUSION

R0/1 surgery predicted prognoses in the low Ki-67 group. The indication of surgery for patients with hg-NENs did not depend on tumor differentiation.

Pancreatic neuroendocrine tumors G3 and pancreatic neuroendocrine carcinomas: Differences in basic biology and treatment

In 2017 the World Health Organization revised the criteria for classification of pancreatic neuroendocrine neoplasms (pNENs) after a consensus conference at the International Agency for Research on Cancer. The major change in the new classification was to subclassify the original G3 group into well-differentiated pancreatic neuroendocrine tumors G3 (pNETs G3) and poorly differentiated pancreatic neuroendocrine carcinomas (pNECs), which have been gradually proven to be completely different in biological behavior and clinical manifestations in recent years. In 2019 this major change subsequently extended to NENs involving the entire digestive tract. The updated version of the pNENs grading system marks a growing awareness of these heterogeneous tumors. This review discusses the clinicopathological, genetic and therapeutic features of poorly differentiated pNECs and compare them to those of well-differentiated pNETs G3. For pNETs G3 and pNECs (due to their lower incidence), there are still many problems to be investigated. Previous studies under the new grading classification also need to be reinterpreted. This review summarizes the relevant literature from the perspective of the differences between pNETs G3 and pNECs in order to deepen understanding of these diseases and discuss future research directions.

Prognostic value of the 2017 World Health Organization Classification System for gastric neuroendocrine tumors: A single-center experience

BACKGROUND/AIMS

Gastric neuroendocrine tumors (G-NETs) are rare tumors, but their incidence is gradually increasing. Despite the existence of many classification systems, determining prognosis and planning treatment in patients with G-NETs remains a clinical challenge. In this study, the prognostic value of the World Health Organization (WHO) 2017 grading system and the effect of surgery on survival in low grade neuroendocrine tumors were investigated.

MATERIALS AND METHODS

G-NETs who were diagnosed between January 2000 and May 2017 were included in the study. Patients' demographic characteristics, treatment details, and survival data were obtained from medical charts. Pathological samples were re-classified according to the WHO 2017 grading system.

RESULTS

Of the total 94 evaluated patients, 50 (53.2%) were classified with G1 NETs, 37(39.4%) with G2 NETs, 4(4.2%) with well-differentiated G3 NETs, and the remaining 3 patients with poorly differentiated G3 neuroendocrine carcinoma (NEC). The median follow-up time was 83.2 months. There was a statistically significant difference in 5-year progression free survival (PFS) between G1 tumors (100%) and G2 tumors (76%) (p<0.001). However, there was no statistically significant deference in 5-year overall survival rate (OS) for G1 (97%) and G2 (82%) tumors (p=0.141). When G2 and G1 NETs were compared according to their surgical approach, radical surgery was more frequently performed in patients with G2 tumors (p<0.001). However, radical surgery did not improve PFS in G1 and G2 NETs.

CONCLUSION

The WHO 2017 NET classification system may have low prognostic value for determining the prognosis of patients with G1 and G2 tumors. Radical surgery for G1 and G2 NETs did not improve PFS in our study.

Classifications des tumeurs neuroendocrines gastroentéropancréatiques : ce qui change

La classification OMS des tumeurs des organes endocrines, parue en juillet 2017 et celle des tumeurs digestives, parue en juillet 2019, ont introduit plusieurs modifications dans la classification des tumeurs neuroendocrines (TNE) gastroentéropancréatiques, dont la précédente version remontait à 2010. La principale modification est l’introduction d’une catégorie supplémentaire de tumeurs bien différenciées, les TNE G3, qui vient s’ajouter aux deux catégories déjà existantes. Les autres modifications concernent : 1) le seuil de l’index Ki-67 entre TNE G1 et G2, désormais fixé à 3 % et 2) la terminologie proposée pour désigner les tumeurs mixtes : MiNEN (mixed neuroendocrine-non neuroendocrine neoplasm) remplace MANEC (mixed adenoneuroendocrine carcinoma, carcinome mixte adénoneuroendocrine). L’année 2017 a également vu la révision de la classification TNM, qui affine les critères pour la plupart des TNE digestives. Ces différentes modifications doivent être prises en compte dans nos pratiques.

Gastroenteropancreatic High-Grade Neuroendocrine Neoplasms: Histology and Molecular Analysis, Two Sides of the Same Coin

BACKGROUND

In gastroenteropancreatic (GEP) high-grade neuroendocrine neoplasms (H-NENs), Ki-67 threshold of 55% defines three prognosis subclasses: neuroendocrine tumor (NET) G3, neuroendocrine carcinoma (NEC) <55%, and NEC ≥55%. We investigated whether the molecular profiling of H-NENs differs among these subcategories and evaluated potential therapeutic targets, including PD-L1.

METHODS

In GEP-NEN patients, we evaluated: (i) 55% threshold for Ki-67 labeling index for further stratifying NEC and (ii) immunoreactivity and gene mutations by immunohistochemistry and targeted next-generation sequencing (T-NGS).

RESULTS

Fifteen NETs G3 and 39 NECs were identified. Ki-67 labeling index was <55% in 9 NECs and ≥55% in 30 NECs. Gene mutations by NGS (TP53, 32.9%; KRAS, 5.5%; BRAF, 4.1%) were detected in 46.6% NENs, significantly enriched in NEC ≥55% (76.7%) compared to NEC <55% (55.6%) or NET (20.0%). PD-L1 staining in tumor-infiltrating lymphocytes was observed in NEC ≥55% (36.7%; p = 0.03). Median OS was 4.3 years in NET G3, 1.8 years in NEC <55%, and 0.7 years in NEC ≥55% (p <0.0001); it was 2.3 years with NGS wild-type, 0.7 years with ≥1 mutation (p <0.0001), 0.8 years in PD-L1-positive patients, and 1.7 years in PD-L1-negative subjects (p = 0.0004). In multivariate analysis, only the proposed subclassification approach yielded statistically significant differences between groups (NEC <55% vs. NET G3, HR 14.1, 95% CI 2.2-89.8, p = 0.005; NEC ≥55% vs. NET G3, HR 25.8, 95% CI 3.9-169, p = 0.0007).

CONCLUSIONS

These findings identify NEC ≥55% as a biologically and prognostically distinct subtype and pave the way for more personalized treatment.

Updates on the Role of Molecular Alterations and NOTCH Signalling in the Development of Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) comprise a heterogeneous group of rare malignancies, mainly originating from hormone-secreting cells, which are widespread in human tissues. The identification of mutations in ATRX/DAXX genes in sporadic NENs, as well as the high burden of mutations scattered throughout the multiple endocrine neoplasia type 1 (MEN-1) gene in both sporadic and inherited syndromes, provided new insights into the molecular biology of tumour development. Other molecular mechanisms, such as the NOTCH signalling pathway, have shown to play an important role in the pathogenesis of NENs. NOTCH receptors are expressed on neuroendocrine cells and generally act as tumour suppressor proteins, but in some contexts can function as oncogenes. The biological heterogeneity of NENs suggests that to fully understand the role and the potential therapeutic implications of gene mutations and NOTCH signalling in NENs, a comprehensive analysis of genetic alterations, NOTCH expression patterns and their potential role across all NEN subtypes is required.

Imaging of Pancreatic-Neuroendocrine Tumours: An Outline of Conventional Radiological Techniques

IIntroduction:

Pancreatic Neuroendocrine Tumours (p-NETs) are an important disease entity and comprise of peptide-secreting tumours often with a functional syndrome.

:

Accounting for a small percentage of all pancreatic tumours, they have a good overall survival rate when diagnosed early, with surgery being curative. The role of nuclear medicine in the diagnosis and treatment of these tumours is evident. However, the vast majority of patients will require extensive imaging in the form of conventional radiological techniques. It is important for clinicians to have a fundamental understanding of the p-NET appearances to aid prompt identification and to help direct management through neoplastic staging.

Methods:

This article will review the advantages and disadvantages of conventional radiological techniques in the context of p-NETs and highlight features that these tumours exhibit.

Conclusion:

Pancreatic neuroendocrine tumours are a unique collection of neoplasms that have markedly disparate clinical features but similar imaging characteristics. Most p-NETs are small and welldefined with homogenous enhancement following contrast administration, although larger and less welldifferentiated tumours can demonstrate areas of necrosis and cystic architecture with heterogeneous enhancement characteristics.

:

Prognosis is generally favourable for these tumours with various treatment options available. However, conventional radiological techniques will remain the foundation for the initial diagnosis and staging of these tumours, and a grasp of these modalities is extremely important for physicians.

Analysis of B-ultrasound and contrast-enhanced ultrasound characteristics of different hepatic neuroendocrine neoplasm

BACKGROUND

Hepatic neuroendocrine neoplasm (hNEN) is a highly heterogeneous tumor. The exact identification of the source and malignant degree of hNEN is important. However, there is a lack of information regarding diagnosis of hNEN with imaging. In addition, no studies have compared the imaging between hNEN and hepatocellular carcinoma (HCC) and among different sources and malignant degrees of hNEN.

AIM

To compare the ultrasound characteristics between hNEN and HCC and among different sources and malignant degrees of hNEN.

METHODS

A total of 55 patients with hNEN were recruited and defined as the hNEN group. Among them, 35 cases of hNET were defined as the hNET group. Twenty cases of hepatic neuroendocrine carcinoma (hNEC) were defined as the hNEC group. Among the 55 lesions, 29 were transferred from the pancreas, 20 were from the gastrointestinal tract, and six were from other sites. In total, 55 patients with HCC were recruited and defined as the HCC group. The characteristic differences of B-mode ultrasound and contrast-enhanced ultrasound (CEUS) between hNEN and HCC and among different sources and malignant degrees of hNEN were compared.

RESULTS

In the hNEN group, the proportions of multiple liver lesions, unclear borders, and high echo lesions were higher than those in the HCC group. The proportions of non-uniform echo and peripheral acoustic halo were lower than those in the HCC group (P < 0.05). The washout to iso-enhancement time and washout to hypo-enhancement time were lower than those in the HCC group (P < 0.05). The characteristics of B-ultrasound and CEUS among different sources of hNEN were similar, and the differences were not statistically significant (P > 0.05). B-mode ultrasound characteristics of hNET and hNEC were similar. The proportions of low enhancement at portal venous phase, non-uniform enhancement forms, and combined tumor vasculature in the hNEC group were larger than those in the hNEN group (P < 0.05).

CONCLUSION

Compared with HCC, hNEN showed multiple intrahepatic lesions, uniform high echo, uniform high enhancement at arterial phase, and rapid washout. Low enhancement at portal venous phase, overall non-uniform enhancement form, and the proportion of combined tumor vasculature in hNEC were larger than those in hNET.

A Neuroendocrine Tumor of Unknown Primary Origin that Responded to Treatment Based on Tumor Grade Progression

The standard chemotherapies for neuroendocrine tumors (NETs) are somatostatin analog (SSA) and targeted-agents for NET G1/G2 and platinum-based chemotherapy for neuroendocrine carcinoma (NEC), classified according to the WHO criteria of 2010. We report a case of NET, in which tumors were successfully treated with platinum-containing chemotherapy after remarkable progression with SSA. A 46-year-old man with multiple lymph nodes and liver metastases of unknown primary origin was diagnosed with NET G2 based on the examination of a biopsy specimen. His tumors were stable with SSA for a year, but rapidly became enlarged. A second biopsy revealed NEC. He received cisplatin plus etoposide, and his tumors showed a marked reduction in size.

Clinical significance of programmed death 1/programmed death ligand 1 pathway in gastric neuroendocrine carcinomas

BACKGROUND

Recently, more and more studies have demonstrated the pivotal role of programmed death 1/programmed death ligand 1 (PD-1/PD-L1) pathway in the immune evasion of tumors from the host immune system. However, the role of PD-1/PD-L1 pathway in gastric neuroendocrine carcinomas (G-NECs) remains unknown.

AIM

To investigate the expression of PD-1/PD-L1 and role of PD-1/PD-L1 pathway in G-NECs, which occur rarely but are highly malignant and clinically defiant.

METHODS

We investigated the expression of PD-L1 on tumor cells and PD-1⁺, CD8⁺, and FOXP3⁺ T cell infiltration by immunohistochemistry in 43 resected G-NEC tissue specimens. The copy number alterations of PD-L1 were assessed by qRT-PCR.

RESULTS

Most of the G-NECs tumor cells exhibited a near-uniform expression pattern of PD-L1, while some showed a tumor-stromal interface enhanced pattern. Of the 43 G-NECs, 21 (48.8%) were classified as a high PD-L1 expression group, and the high expression of PD-L1 was associated with poor overall survival (OS). The high expression of PD-L1 was correlated with abundant PD-1⁺ tumor infiltrating lymphocytes (TILs) instead of CD8⁺ TILs and FOXP3⁺ regulatory T cells (Tregs). Our analysis also suggested that the infiltration of CD8⁺ TILs tended to be a favorable factor for OS, although the difference did not reach the statistical significance (P = 0.065). Meanwhile, PD-L1 was significantly overexpressed in cases with copy number gain as compared with those without.

CONCLUSION

Our data demonstrated for the first time that high expression of PD-L1 in G-NECs is associated with a poor prognosis, while the high expression may be due to the copy number variation of PD-L1 gene or stimulation of TILs. These results provide a basis for the immunotherapy targeting PD-1/PD-L1 pathway in G-NECs.

Genetics and Epigenetics of Gastroenteropancreatic Neuroendocrine Neoplasms

Gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs) are heterogeneous regarding site of origin, biological behavior, and malignant potential. There has been a rapid increase in data publication during the last 10 years, mainly driven by high-throughput studies on pancreatic and small intestinal neuroendocrine tumors (NETs). This review summarizes the present knowledge on genetic and epigenetic alterations. We integrated the available information from each compartment to give a pathway-based overview. This provided a summary of the critical alterations sustaining neoplastic cells. It also highlighted similarities and differences across anatomical locations and points that need further investigation. GEP-NENs include well-differentiated NETs and poorly differentiated neuroendocrine carcinomas (NECs). NENs are graded as G1, G2, or G3 based on mitotic count and/or Ki-67 labeling index, NECs are G3 by definition. The distinction between NETs and NECs is also linked to their genetic background, as TP53 and RB1 inactivation in NECs set them apart from NETs. A large number of genetic and epigenetic alterations have been reported. Recurrent changes have been traced back to a reduced number of core pathways, including DNA damage repair, cell cycle regulation, and phosphatidylinositol 3-kinase/mammalian target of rapamycin signaling. In pancreatic tumors, chromatin remodeling/histone methylation and telomere alteration are also affected. However, also owing to the paucity of disease models, further research is necessary to fully integrate and functionalize data on deregulated pathways to recapitulate the large heterogeneity of behaviors displayed by these tumors. This is expected to impact diagnostics, prognostic stratification, and planning of personalized therapy.

Surgery for Pancreatic Neuroendocrine Tumor G3 and Carcinoma G3 Should be Considered Separately

BACKGROUND

The role of surgery in pancreatic neuroendocrine neoplasm grade 3 (pNEN-G3) treatment remains unclear. We aimed to clarify the role of surgery for pNEN-G3, which has recently been reclassified as pancreatic neuroendocrine tumor-G3 (pNET-G3) and pancreatic neuroendocrine carcinoma-G3 (pNEC-G3), with and without metastases, respectively.

METHODS

We analyzed a subgroup of patients from the Japanese pancreatic NEC study, a Japanese multicenter case-series study of pNEN-G3. Pathologists subclassified 67 patients as having pNET-G3 or pNEC-G3 based on morphological features. We compared the overall survival (OS) rates among patients who were grouped according to whether they had undergone tumor-targeted surgery for tumors without (SwoM) or with (SwM) metastases, or non-surgical procedures (NS).

RESULTS

Data from 21 patients with pNET-G3 (SwoM, n = 6; SwM, n = 5; NS, n = 10) and 46 patients with pNEC-G3 (SwoM, n = 8; SwM, n = 5; NS, n = 33) were analyzed. OS of patients with pNET-G3 was significantly longer after SwoM and SwM than with NS (p = 0.018 and p = 0.022). In contrast, OS did not significantly differ between either SwoM or SwM and NS (p = 0.093 and p = 0.489) among patients with pNEC-G3.

CONCLUSION

The role of surgery should be considered separately for pNET-G3 and pNEC-G3. Although SwoM and SwM can be considered for pNET-G3, caution is advised before considering SwM and SwoM for pNEC-G3.

Neoplasms of the Neuroendocrine Pancreas: An Update in the Classification, Definition, and Molecular Genetic Advances

This review focuses on discussing the main modifications of the recently published 2017 WHO Classification of Neoplasms of the Neuroendocrine Pancreas (panNEN). Recent updates separate pancreatic neuroendocrine tumors into 2 broad categories: well-differentiated pancreatic neuroendocrine tumors (panNET) and poorly differentiated pancreatic neuroendocrine carcinoma (panNEC), and incorporates a new subcategory of "well-differentiated high-grade NET (G3)" to the well-differentiated NET category. This new classification algorithm aims to improve the prediction of clinical outcomes and survival and help clinicians select better therapeutic strategies for patient care and management. In addition, these neuroendocrine neoplasms are capable of producing large quantity of hormones leading to clinical hormone hypersecretion syndromes. These functioning tumors include, insulinomas, glucagonomas, somatostatinomas, gastrinomas, VIPomas, serotonin-producing tumors, and ACTH-producing tumors. Although most panNENs arise as sporadic diseases, a subset of these heterogeneous tumors present as parts on inherited genetic syndromes, such as multiple endocrine neoplasia type 1, von Hippel-Lindau, neurofibromatosis type 1, tuberous sclerosis, and glucagon cell hyperplasia and neoplasia syndromes. Characteristic clinical and morphologic findings for certain functioning and syndromic panNENs should alert both pathologists and clinicians as appropriate patient management and possible genetic counseling may be necessary.

Systematic review of current prognostication systems for pancreatic neuroendocrine neoplasms

BACKGROUND

Pancreatic neuroendocrine neoplasms are a heterogenous group of rare tumors whose natural history remains poorly defined. Accurate prognostication of pancreatic neuroendocrine neoplasms is essential for guiding clinical decisions. This paper aims to summarize all the commonly utilized and recently proposed prognostication systems for pancreatic neuroendocrine neoplasms published in the literature to date.

METHODS

A systematic review of Pubmed, Scopus, and Embase databases, of the period from January 1, 2000-November 29, 2016, was conducted to identify all published articles reporting on prognostication systems of pancreatic neuroendocrine neoplasms.

RESULTS

A total of 23 articles were included in our review, and a total of 25 classification systems were identified. There were 2 modifications of the World Health Organization 2004 criteria, 4 modifications of the World Health Organization 2010 criteria, 2 modifications of the American Joint Committee on Cancer 2010 staging system, 3 modifications of the European Neuroendocrine Tumor Society 2006 tumor, node, metastasis staging system, 7 novel categorial classification systems, and 2 novel proposed continuous classifications. The most commonly included variables included age, size of tumor, presence of distant and lymph node metastases, Ki-67 index, and mitotic count.

CONCLUSION

Numerous prognostication systems have been proposed for pancreatic neuroendocrine neoplasms, of which the most commonly used systems presently include the World Health Organization 2010 criteria and the two tumor, node, metastasis staging systems by the European Neuroendocrine Tumor Society and the American Joint Commission on Cancer. However, prognostication systems for pancreatic neuroendocrine neoplasms continue to evolve with time as more prognostication factors are identified. More validation and comparative studies are needed to identify the most effective prognostication system.

Establishment of a novel cell line from a rare human duodenal poorly differentiated neuroendocrine carcinoma

Poorly differentiated neuroendocrine carcinoma of the duodenum (D-NEC) is a rare cancer with poor prognosis. However, a D-NEC cell line has not yet been established to study the disease. We established a cell line, TCC-NECT-2, from the ascites tumor of a 59-year-old male Japanese patient with D-NEC. TCC-NECT-2 was positive for neuroendocrine markers, chromogranin A (CGA), cluster of differentiation 56 (CD56/NCAM), synaptophysin (SYN/p38), and neuron specific enolase (NSE). Cells exhibited retinoblastoma (RB) protein loss. Orthotopic implantation of TCC-NECT-2 cells into nu/nu mice resulted in tumor formation (incidence = 83.3%) with neuroendocrine characteristics, metastasis, and weight loss. BRAF^V600E and TP53 mutations and C-MYC gene amplification were also observed in TCC-NECT-2. BRAF^V600E-expressing TCC-NECT-2 cells were sensitive to BRAF inhibitor vemurafenib, and especially dabrafenib, in vitro, and were strongly inhibited in a dose-dependent manner. Dabrafenib treatment (30 mg/kg) in a xenograft model for 14 days significantly suppressed tumor growth (percent tumor growth inhibition, TGI% = 48.04). An enhanced therapeutic effect (TGI% = 95.81) was observed on combined treatment of dabrafenib and irinotecan (40 mg/kg). Therefore, TCC-NECT-2, the first reported cell line derived from D-NEC, might serve as a useful model to study the basic biology of D-NEC and translational applications for treatment.

The New World Health Organization Classification for Pancreatic Neuroendocrine Neoplasia

Based on the 2010 version, the 2017 World Health Organization (WHO 2017) classification is for pancreatic neuroendocrine neoplasms (PanNEN). The WHO 2017 classification introduces the novel well-differentiated neuroendocrine tumor of high grade (NET G3). A sharp distinction between NET and poorly differentiated neuroendocrine carcinoma (NEC) is emphasized to highlight substantial biological differences. Further changes comprise the definition of mixed neuroendocrine non-neuroendocrine neoplasm (MiNEN), to accommodate all grades of both neoplasm components, and the abolition of preneoplastic lesions given their rarity in the pancreas. The 2017 American Joint Cancer Committee classification (AJCC 2017) adopts such a classification for all digestive sites.

The Treatment Landscape and New Opportunities of Molecular Targeted Therapies in Gastroenteropancreatic Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms that originate from neuroendocrine stem cells and express both neural and endocrine markers. They are found in almost every organ, and while NENs are mostly associated with slow growth, complications due to the uncontrolled secretion of active peptides, and metastatic disease, may significantly impair the quality of life and can ultimately lead to the death of affected individuals. Expanding knowledge of the genetic, epigenetic, and proteomic landscapes of NENs has led to a better understanding of their molecular pathology and consequently increased treatment options for patients. Here, we review the principal breakthroughs in NEN treatment management, owing largely to omics technologies over the last few years, current recommendations of systemic treatment, and ongoing research into the identification of predictive and response biomarkers based on molecular targeted therapies.

An Advanced Well-differentiated Pancreatic Neuroendocrine Carcinoma (NET-G3) Associated with Von Hippel-Lindau Disease

A 45-year old woman who underwent several surgeries for tumors associated with von Hippel-Lindau disease (VHL) was referred to our hospital due to a pancreatic tumor and liver tumors. She was diagnosed with pancreatic neuroendocrine tumor (NET) with a Ki67 index of 40% based on the examination of a biopsy specimen of the liver tumors. She was treated with everolimus for 6 months and sunitinib for 6 weeks as first- and second-line therapies. She survived for 13 months. At autopsy the diagnosis of pancreatic neuroendocrine tumor (NET)-G3 was confirmed. We herein report an aggressive clinical course of VHL-related NET G3. The further accumulation of cases is required to reach a consensus on treatment for this disease.

Open issues on G3 neuroendocrine neoplasms: back to the future

The recent recognition that grade 3 (G3) neuroendocrine neoplasms (NENs) can be divided into two different categories according to the histopathological differentiation, that is G3 neuroendocrine tumors (NETs) and G3 neuroendocrine carcinomas (NECs) has generated a lot of interest concerning not only the diagnosis, but also the differential management of such new group of NENs. However, several issues need to be fully clarified in order to put G3 NETs and G3 NECs in the right place. The aim of this review is to focus on those issues that are still undetermined starting from the current knowledge, evaluating the available evidence and the possible clinical implications.

Everolimus in the treatment of neuroendocrine tumors: efficacy, side-effects, resistance, and factors affecting its place in the treatment sequence

INTRODUCTION

Since the initial approval of everolimus in 2011, there have been a number of important changes in therapeutic/diagnostic modalities as well as classification/staging systems of neuroendocrine tumors (NETs), which can significantly impact the use of everolimus in patients with advanced NETs. Areas covered: The efficacy of everolimus monotherapy and combination therapy demonstrated in clinical studies involving patients with advanced NETs are reviewed. Several factors affecting everolimus use are described including: the development and routine use of NET classification/staging systems; widespread use of molecular imaging modalities; side effects; drug resistance; and the availability of other treatment options. Furthermore, the current position of everolimus in the treatment approach is discussed, taking into account the recommendations from the recent guidelines. Expert opinion: Although everolimus demonstrated its high efficacy and tolerability in the RADIANT trials and other clinical studies, there still remain a number of controversies related to everolimus treatment in the management of NETs. The synergistic anti-growth effect of other agents in combination with everolimus or its effect on overall survival have not been established. The appropriate order of the use of everolimus in the treatment of advanced NETs still remains unclear, which needs to be defined in further studies and will be addressed in the new guidelines.

Sunitinib shrinks NET-G3 pancreatic neuroendocrine neoplasms

PURPOSE

The 2017 revised World Health Organization classification of pancreatic neuroendocrine neoplasms classified conventional G3 tumors into well-differentiated (NET-G3) and poorly differentiated (NEC-G3) tumors. However, guidelines for selection of drug therapy were not established in the 2017 revision. This study aimed to elucidate the rates of maximum tumor reduction of sunitinib, progression-free survival, and overall survival in the new classification.

METHODS

We investigated the reduction rate over time using computed tomography for 60 patients with unresectable or distant metastatic pancreatic neuroendocrine neoplasms who received 37.5 mg of sunitinib in our department from April 2013 to November 2017.

RESULTS

Of the 60 cases, 42, 10, and 5 were NET-G1/G2, NET-G3, and NEC-G3, respectively. The prognostic factors were analyzed according to clinicopathological factors using the Cox hazard model. The median observation period was 19 months, and the median duration of sunitinib administration was 7 months. The median maximum reduction rate of sunitinib was 18.3%. Tumor response was classified according to the Response Evaluation Criteria in Solid Tumors: 20 cases (33.3%) showed partial response, 29 cases (48.3%) showed stable disease, and 11 cases (18.3%) showed progressive disease. In a multivariate analysis of factors contributing to progression-free survival from the start of sunitinib administration, only histologically poor differentiation was a significant factor (p = 0.010). Progression-free survival and overall survival were significantly better in patients with NET-G3 than that in patients with NEC-G3 (p = 0.005, p = 0.012), while it was not different between those with NET-G3 and those with NET-G1/2.

CONCLUSION

Our results indicate that sunitinib is as effective for NET-G3 as for NET-G1/2.

Competitive Testing of the WHO 2010 versus the WHO 2017 Grading of Pancreatic Neuroendocrine Neoplasms: Data from a Large International Cohort Study

BACKGROUND

The World Health Organization (WHO) and the American Joint Cancer Committee (AJCC) modified the grading of pancreatic neuroendocrine neoplasms from a three-tier (WHO-AJCC 2010) to a four-tier system by introducing the novel category of NET G3 (WHO-AJCC 2017).

OBJECTIVES

This study aims at validating the WHO-AJCC 2017 and identifying the most effective grading system.

METHOD

A total of 2,102 patients were enrolled; entry criteria were: (i) patient underwent surgery; (ii) at least 2 years of follow-up; (iii) observation time up to 2015. Data from 34 variables were collected; grading was assessed and compared for efficacy by statistical means including Kaplan-Meier method, Cox regression analysis, Harrell's C statistics, and Royston's explained variation in univariable and multivariable analyses.

RESULTS

In descriptive analysis, the two grading systems demonstrated statistically significant differences for the major category sex but not for age groups. In Cox regression analysis, both grading systems showed statistically significant differences between grades for OS and EFS; however, no statistically significant difference was observed between the two G3 classes of WHO-AJCC 2017. In multivariable analysis for the two models fitted to compare efficacy, the two grading systems performed equally well with substantially similar optimal discrimination and well-explained variation for both OS and EFS. The WHO-AJCC 2017 grading system retained statistically significant difference between the two G3 classes for OS but not for EFS.

CONCLUSIONS

The WHO-AJCC 2017 grading system is at least equally performing as the WHO-AJCC 2010 but allows the successful identification of the most aggressive PanNET subgroup. Grading is confirmed as probably the most powerful tool for predicting patient survival.

[Classification of pancreatic neuroendocrine tumours: Changes made in the 2017 WHO classification of tumours of endocrine organs and perspectives for the future]

The WHO classification of the tumors of endocrine organs, published in July 2017, has introduced significant changes in the classification of pancreatic neuroendocrine tumors, the previous version of which has appeared in 2010, within the WHO classification of the tumors of the digestive system. The main change is the introduction of a new category of well-differentiated neoplasms, neuroendocrine tumors G3, in addition to the previous categories of neuroendocrine tumors G1 and G2. The differential diagnosis between neuroendocrine tumors G3 (well-differentiated) and neuroendocrine carcinomas (poorly-differentiated) might be difficult; the authors of the WHO classification therefore suggest the use of a number of immunohistochemical markers to facilitate the distinction between the two entities. The other changes are: (a) the modification of the threshold between neuroendocrine tumors G1 and G2, now set at 3%; (b) the terminology used for mixed tumors: the previous term mixed adeno-neuroendocrine carcinoma (MANEC) is substituted by the term mixed neuroendocrine-non neuroendocrine neoplasm (MiNEN). Finally, the recommendations for Ki-67 index evaluation are actualized. Even if these changes only concern, stricto sensu, the neuroendocrine tumors of pancreatic location, they will probably be applied, de facto, for all digestive neuroendocrine tumors. The revision of the histological classification of pancreatic neuroendocrine tumors coincides with the revision of their UICC TNM staging; significant changes have been made in the criteria for T3 and T4 stages. Our professional practices have to take into account all these modifications.

Rb Loss and KRAS Mutation Are Predictors of the Response to Platinum-Based Chemotherapy in Pancreatic Neuroendocrine Neoplasm with Grade 3: A Japanese Multicenter Pancreatic NEN-G3 Study

Purpose: Patients with pancreatic neuroendocrine neoplasm grade-3 (PanNEN-G3) show variable responses to platinum-based chemotherapy. Recent studies indicated that PanNEN-G3 includes well-differentiated neuroendocrine tumor with G3 (NET-G3). Here, we examined the clinicopathologic and molecular features of PanNEN-G3 and assessed the responsiveness to chemotherapy and survival.Experimental Design: A total of 100 patients with PanNEN-G3 were collected from 31 institutions, and after central review characteristics of each histologic subtype [NET-G3 vs. pancreatic neuroendocrine carcinoma (NEC-G3)] were analyzed, including clinical, radiological, and molecular features. Factors that correlate with response to chemotherapy and survival were assessed.Results: Seventy patients analyzed included 21 NETs-G3 (30%) and 49 NECs-G3 (70%). NET-G3 showed lower Ki67-labeling index (LI; median 28.5%), no abnormal Rb expression (0%), and no mutated KRAS (0%), whereas NEC-G3 showed higher Ki67-LI (median 80.0%), Rb loss (54.5%), and KRAS mutations (48.7%). Chemotherapy response rate (RR), platinum-based chemotherapy RR, and prognosis differed significantly between NET-G3 and NEC-G3. Chemotherapeutic outcomes were worse in NET-G3 (P < 0.001). When we stratified PanNEN-G3 with Rb and KRAS, PanNENs-G3 with Rb loss and those with mutated KRAS showed significantly higher RRs to platinum-based chemotherapy than those without (Rb loss, 80% vs. normal Rb, 24%, P = 0.006; mutated KRAS, 77% versus wild type, 23%, P = 0.023). Rb was a predictive marker of response to platinum-based chemotherapy even in NEC-G3 (P = 0.035).Conclusions: NET-G3 and NEC-G3 showed distinct clinicopathologic characteristics. Notably, NET-G3 does not respond to platinum-based chemotherapy. Rb and KRAS are promising predictors of response to platinum-based chemotherapy for PanNEN-G3, and Rb for NEC-G3. Clin Cancer Res; 23(16); 4625-32. ©2017 AACR.

Unraveling molecular pathways of poorly differentiated neuroendocrine carcinomas of the gastroenteropancreatic system: A systematic review

BACKGROUND

Poorly differentiated neuroendocrine carcinomas (NECs) are rare and aggressive tumors. Their molecular pathogenesis is still largely unknown, and consequently, the best therapeutic management also remains to be determined. We conducted a systematic review on molecular alterations found in gastroenteropancreatic NECs (GEP-NECs) and discuss potential applications of targeted therapies in setting.

MATERIALS AND METHODS

Systematic review of studies about molecular features in tumor tissues of patients with GEP-NECs. The Medline, Lilacs, Embase, Cochrane, Scopus and Opengrey databases were sought, without time, study design or language restrictions.

RESULTS

Of the 1.564 studies retrieved, 41 were eligible: 33 were retrospective studies and eight were case reports. The studies spanned the years 1997-2017 and involved mostly colorectal, stomach and pancreas primary tumors. Molecular alterations in the TP53 gene and the p53 protein expression were the most commonly observed, regardless of the primary site. Other consistently found molecular alterations were microsatellite instability (MSI) in approximately 10% of gastric and colorectal NEC, and altered signaling cascades of p16/Rb/cyclin D1, Hedgehog and Notch pathways, and somatic mutations in KRAS, BRAF, RB1 and Bcl2. In studies of mixed adeno-neuroendocrine carcinomas (MANECs) the molecular features of GEP-NEC largely resemble their carcinoma/adenocarcinomas tumor counterparts.

CONCLUSIONS

Despite the paucity of data about the molecular drivers associated with GEP-NEC, some alterations may be potentially targeted with new cancer-directed therapies. Collaborative clinical trials for patients with advanced GEP-NEC are urgently needed.

Factors influencing Ki67 calculation in neuroendocrine neoplasia

Aim: We compared different methodologies to evaluate Ki67 in neuroendocrine neoplasia (NEN). Patients & methods: ki67 was evaluated using three methods in 70 NEN cases: manual-count, eyeballed estimate made by three pathologists and ImmunoRatio-software. Manual-count was the standard method and agreement with it was evaluated through intraclass correlation (ICC). Results: Agreement between manual-count and eyeballed estimate had ICC: 0.887–0.929. Eyeballed estimate by three pathologists produced upgradation in 5.7–32.9% and downgradation in 5.7% of NEN cases. Agreement for ImmunoRatio-count had ICC: 0.989. Immunoratio produced upgradation in 17.1% and downgradation in 8.5% cases. Agreement between all methods was higher at low-Ki67. Cellularity, immune-cell infiltration, staining and sample quality did not affect agreement. Conclusion: Eyeballed estimate and ImmunoRatio showed good accuracy, especially at low-Ki67.

Everolimus in Pancreatic Neuroendocrine Carcinomas G3

OBJECTIVE

The aim of this study was to investigate everolimus efficacy in well-moderately differentiated pancreatic NEC (pNEC) G3.

METHODS

This was a retrospective analysis of patients with pNEC G3 and Ki67 20% to 55% treated with everolimus.

RESULTS

Fifteen patients with median Ki67 30% and Eastern Cooperative Oncology Group performance status 0 to 1 were evaluated. Of these, 4 patients received everolimus as first-line treatment, whereas 11 had been pretreated with chemotherapy or peptide receptor radionuclide therapy. Median progression-free survival was 6 months, and median overall survival was 28 months. Eleven patients achieved disease stabilization (DS) at 3 month follow-up. Six patients (40%) maintained DS for at least 12 months. Three of 4 patients who received everolimus as first-line therapy had sustained DS (progression-free survival, 12, 17, and 22 months). The safety profile was consistent with that previously reported, with adverse events occurring in 9 patients (66.7%).

CONCLUSIONS

This study suggests that everolimus is active in pNEC G3 with well-moderately differentiated morphology and Ki67 less than 55%, in which more toxic systemic chemotherapy is, to date, the only available treatment.

Clinicopathological, treatment, and prognosis study of 43 gastric neuroendocrine carcinomas

AIM

To provide more information and therapeutic methods about gastric neuroendocrine carcinomas (G-NECs) which occur rarely but are highly malignant and clinically challenging.

METHODS

We retrospectively analyzed the clinicopathological characteristics, treatments, and prognosis of 43 G-NEC patients at our hospital between January 2007 and December 2014. The diagnosis was based on the 2010 World Health Organization criteria.

RESULTS

Forty-three G-NECs containing 39 small cell carcinomas and 4 large cell NECs with Ki67 > 60% were included in this study, accounting for only 0.95% of all gastric carcinomas. The median patient age was 62 years (range, 33-82) and the male-to-female ratio was 4.4:1. All patients underwent surgery, including 38 curative resections and 5 palliative resections. Among these 43 patients, nearly half (48.84%) of these tumors were located in the cardiac region of the stomach, regional lymph node metastasis was found in 31 cases (72.09%), and liver metastasis was found in 6 cases (13.95%). Follow-up information was got for 40 patients. Twenty-three die of this disease with a median survival of 31 mo (range 1-90). The 1-year, 2-year, 3-year, and 5-year survival rate was 77.50%, 57.04%, 44.51%, and 35.05%, respectively. Survival was better in patients with tumor located in the cardiac region of the stomach, less than 7 lymph nodes metastasis and no liver metastasis. Five patients did not undergo postoperative chemotherapy, and the median survival time for these patients was 15 mo. For the remaining 34 patients who received postoperative chemotherapy, the median survival time was 44 mo and those received etoposide, cisplatin, and Paclitaxel survived the best. One patient with resected liver metastasis who received postoperative Capecitabine plus Oxaliplatin and Paclitaxel systemic chemotherapy plus octreotide LAR (30 mg intramuscularly, every 4 wk, for 2 years) has survived for 74 mo with no recurrence.

CONCLUSION

G-NECs are mostly nonfunctioning, which lead to a delay in detection. Local and/or distant metastases were noticed in most patients when diagnosed, and they required postoperative medical treatment. Adjuvant etoposide, cisplatin plus Paclitaxel systemic chemotherapy is recommended for these patients.

Pancreatic Neuroendocrine Neoplasms: Basic Biology, Current Treatment Strategies and Prospects for the Future

Pancreatic neuroendocrine neoplasms (pNENs) are rare tumors accounting for only 1%–2% of all pancreatic tumors. pNENs are pathologically heterogeneous and are categorized into three groups (neuroendocrine tumor: NET G1, NET G2; and neuroendocrine carcinoma: NEC) on the basis of the Ki-67 proliferation index and the mitotic count according to the 2010 World Health Organization (WHO) classification of gastroenteropancreatic NENs. NEC in this classification includes both histologically well-differentiated and poorly differentiated subtypes, and modification of the WHO 2010 classification is under discussion based on genetic and clinical data. Genomic analysis has revealed NETs G1/G2 have genetic alterations in chromatin remodeling genes such as MEN1, DAXX and ATRX, whereas NECs have an inactivation of TP53 and RB1, and these data suggest that different treatment approaches would be required for NET G1/G2 and NEC. While there are promising molecular targeted drugs, such as everolimus or sunitinib, for advanced NET G1/G2, treatment stratification based on appropriate predictive and prognostic biomarkers is becoming an important issue. The clinical outcome of NEC is still dismal, and a more detailed understanding of the genetic background together with preclinical studies to develop new agents, including those already under investigation for small cell lung cancer (SCLC), will be needed to improve the prognosis.

Ki-67 labeling index of neuroendocrine tumors of the lung has a high level of correspondence between biopsy samples and surgical specimens when strict counting guidelines are applied

Optimal histopathological analysis of biopsies from metastases of neuroendocrine tumor (NET) of the lung requires more than morphology only. Additional parameters such as Ki-67 labeling index are required for adequate diagnosis, but few studies have compared reproducibility of different counting protocols and modalities of reporting on biopsies of lung NET. We compared the results of four different manual counting techniques to establish Ki-67 LI. On 47 paired biopsies and surgical specimens from 22 typical carcinoids (TCs), 14 atypical carcinoids (ACs), six large cell neuroendocrine carcinomas (LCNECs), and five small cell carcinomas (SCCs) immunohistochemical staining of Ki-67 antigen was performed. We counted, in regions of highest nuclear staining (HSR), a full ×40-high-power field (diameter = 0.55 mm), 500 or 2000 cells, or 2 mm² surface area, including the HSR or the entire biopsy fragment(s). Mitoses and necrosis were evaluated in an area of 2 mm² or the entire biopsy fragment(s). Between the four counting methods, no differences in Ki-67 LI were observed. However, a Ki-67 LI higher than 5% was found in only four cases when in an HSR, 500 cells were counted (18%), five (23%) when in an HSR 2000 cells were counted, four (18%) when 2 mm² were counted, and one (5%) TC case when the entire biopsy was counted. A 20% cutoff distinguished TC and AC from LCNEC and SCC with 100% specificity and sensitivity, while mitoses and necrosis failed to a large extent. Ki-67 LI in biopsy samples was concordant with that in resection specimens when 2000 cells, 2 mm², or the entire biopsy fragment(s) were counted. Our results are important for clinical management of patients with metastases of a lung NET.

The Clinicopathologic Heterogeneity of Grade 3 Gastroenteropancreatic Neuroendocrine Neoplasms: Morphological Differentiation and Proliferation Identify Different Prognostic Categories

BACKGROUND/AIMS

Gastroenteropancreatic (GEP) neuroendocrine carcinomas (NECs) are defined as neuroendocrine neoplasms (NENs) with a Ki-67 index >20% according to the 2010 WHO classification. Some reports suggest that this category is heterogeneous. We retrospectively studied a series of 136 patients affected by grade 3 GEP-NECs with the aim to clarify the prognostic role of tumor morphological differentiation, proliferation, defect in mismatch repair proteins (MMRd), CD117 expression, and site of origin. The primary endpoint was the correlation between these parameters and the overall survival (OS).

METHODS

Univariate and multivariable Cox proportional hazards regression analyses were used to assess the prognostic significance of various clinical and histopathologic features.

RESULTS

With a median follow-up of 81 months, the median OS was 12.9 months. At multivariate analysis, morphological differentiation, Ki-67 index, MMRd, stage, and CD117 expression were independent prognostic markers in NECs. Three different prognostic categories of NECs were identified according to the degree of morphologic differentiation (well vs. poorly differentiated) and Ki-67 index (<55% vs. ≥55%). On this basis, median OS was 43.6 months in well-differentiated neoplasms with a Ki-67 index 20-55% (named type A), 24.5 months in poorly differentiated neoplasms with a Ki-67 index 20-55% (type B), and 5.3 months (p < 0.0001) in poorly differentiated neoplasms with a Ki-67 index ≥55% (type C).

CONCLUSIONS

The present study suggests that GEP-NECs represent a heterogeneous group of neoplasms which can be better classified in different prognostic categories using both tumor morphology and Ki-67 index.

Advances in the diagnosis and treatment of pancreatic neuroendocrine neoplasms in Japan

Several new developments have occurred in the field of pancreatic neuroendocrine neoplasm (PNEN) recently in Japan. First, the utility of chromogranin A (CgA), useful for the diagnosis and monitoring of the treatment response of neuroendocrine neoplasm (NEN), has been demonstrated in Japan. For PNEN diagnosis and treatment, grading and correct histological diagnosis according to the WHO 2010 classification is important. Regarding the histological diagnosis, the advent of endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has enabled correct pathological diagnosis and suitable treatment for the affected tissue. Furthermore, EUS-FNA has also facilitates the assessment of the presence or absence of gene mutations. In addition, patients who have a well-differentiated neuroendocrine tumor (NET) showing a Ki-67 index of higher than 20 % according to the WHO 2010 classification, have also been identified, and their responses to treatment were found to be different from those of patients with poorly differentiated neuroendocrine carcinoma (NEC). Therefore, the concept of NET G3 was proposed. Additionally, somatostatin receptor type 2 is expressed in several cases of NET, and somatostatin receptor scintigraphy (¹¹¹In-octreoscan) has also been approved in Japan. This advancement will undoubtedly contribute to the localization diagnosis, the identification of remote metastasis, and assessments of the treatment responses of PNEN. Finally, regarding the treatment strategy for PNEN, the management of liver metastasis is important. The advent of novel molecular-targeted agents has dramatically improved the prognosis of advanced PNEN. Multimodality therapy that accounts for the tumor stage, degree of tumor differentiation, tumor volume, and speed of tumor growth is required.

Neuroendocrine carcinoma of the pancreas with similar genetic alterations to invasive ductal adenocarcinoma

Neuroendocrine carcinoma (NEC) of the pancreas is very rare, and its origin is not fully elucidated. Here, we present a case of a small-size NEC of the pancreas that is genetically similar to invasive ductal adenocarcinoma (IDA). A 65-year-old man was referred to our hospital due to obstructive jaundice and found to have a 12-mm solid tumor in the pancreas head. The tumor exhibited low vascularity on enhanced computed tomography, and endoscopic retrograde pancreatographic imaging revealed an irregular obstruction in a branch duct of the pancreas. The patient was thereby diagnosed with a pancreatic ductal cancer, and stomach-preserving pancreaticoduodenectomy with regional lymph node resection was performed. Histochemical analysis of the resected tumor showed that the neoplastic cells with scanty cytoplasm and hyperchromatic nuclei strongly expressed chromogranin A and synaptophysin. The Ki-67 index was 40 % in the most proliferative tumor regions, and the tumor was diagnosed as a NEC of the pancreas. However, in the analysis of genetic alterations of the tumor tissue, the neoplastic cells showed altered KRAS, TP53, and SMAD4/DPC4, suggesting that the NEC in our case is genetically related to IDA. Our data suggest that poorly differentiated IDAs may transform into NECs.

Neuroendocrine tumor G3: a pancreatic well-differentiated neuroendocrine tumor with a high proliferative rate

A 68-year-old man was referred to our hospital because of left upper quadrant pain. Contrast enhanced computed tomography showed a low density mass with delayed contrast effects as well as para-aortic node swelling with homogenous contrast effects. Histological examination of specimens obtained by endoscopic ultrasound fine needle aspiration revealed a pancreatic neuroendocrine tumor (NET) G2, according to the World Health Organization 2010 classification, and lymph node metastasis. Distal pancreatectomy and lymph node dissection were performed. On histological examination, the tumor showed well-differentiated morphology with an organoid pattern. The Ki67 labeling index was 21.6 %, and the mitotic count was 25/10 high power fields. As mentioned above, we made a final diagnosis of the lesion as "NET G3," because the tumor presented with well-differentiated morphology. Chemotherapy with Everolimus was administered. Liver metastasis occurred 11 months after the first operation, and a partial hepatectomy was performed. Histological findings were similar to those of the first operation. Herein we present a case of pancreatic well-differentiated neuroendocrine tumor with a high proliferative rate referred to as "NET G3," and review the relevant literature.