Molecular typing and mutational characterization of rectal neuroendocrine neoplasms

BACKGROUND

Rectal neuroendocrine neoplasms (NENs) are rare neoplasms with limited understanding of its genomic alterations and molecular typing.

METHODS

The paraffin-embedded tissue specimens of 38 patients with rectal NENs after surgery were subjected to whole gene sequencing (WGS), and mutation profilings were drawn to identify high-frequency mutation genes, copy-number variations (CNVs), tumor mutation burden (TMB), signal pathways, mutation signatures, DNA damage repair (DDR) genes, and molecular types. The differences of mutated genes and signaling pathways in different pathological grades and metastatic/non-metastatic groups were compared. It helped to search for potential targets.

RESULTS

C > T and T > C transitions are the most common base substitutions in rectal NENs. DNA mismatch repair deficiency, DNA base modifications, smoking and exposure to ultraviolet light might play a role in the occurrence of rectal NENs. DAXX, KMT2C, BCL2L1, LTK, MERTK, SPEN, PKN1, FAT3, and LRP2 mutations were found in only low-grade rectal NETs, whereas APC, TP53, NF1, SOX9, and BRCA1 mutations were common in high-grade rectal NECs/MiNENs. These genes helped in distinguishing poorly-differentiated or well-differentiated rectal NENs. Alterations in P53, Wnt and TGFβ signaling pathways were more pronounced in rectal NECs and MiNENs. Alterations in Wnt, MAPK and PI3K/AKT signaling pathways promoted metastases. Rectal NENs were classified into two molecular subtypes by cluster analysis based on the mutant genes and signaling pathways combined with clinicopathological features. Patients with mutations in the LRP2, DAXX, and PKN1 gene showed a trend of well-differentiated and early-stage tumors with less metastasis (p = 0.000).

CONCLUSIONS

This study evaluated risk factors for regional lymphatic and/or distant metastases, identified high-frequency mutated genes, mutation signatures, altered signaling pathways through NGS. Rectal NENs were divided into two molecular types. This helps to evaluate the likelihood of metastasis, formulate follow-up strategies for patients and provide a target for future research on precision treatment of rectal NENs. PARP inhibitors, MEK inhibitors, mTOR/AKT/PI3K and Wnt signaling pathway inhibitors may be effective drugs for the treatment of metastatic rectal NENs.

Risk factors for gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs): a three-centric case-control study

PURPOSE

Risk factors for sporadic GEP-NENs are still not well defined. To identify the main clinical risk factors represents the aim of this study performed by three Italian referral centers for NENs.

METHODS

We performed a retrospective case-control study including 148 consecutive sporadic GEP-NENs and 210 age- and sex-matched controls. We collected data on clinical features, cancer family history and other potential risk factors.

RESULTS

Mean age was 58.3 ± 15.8 years; 50% males, primary site was pancreas (50.7%), followed by ileum (22.3%). The 62.8% and 29.1% of cases were G1 and G2, respectively; the 40% had locally advanced or metastatic disease at diagnosis. Independent risk factors for GEP-NENs were: family history of non-neuroendocrine GEP cancer (OR 2.16, 95% CI 1.31-3.55, p = 0.003), type 2 diabetes mellitus (T2DM) (OR 2.5, 95% CI 1.39-4.51, p = 0.002) and obesity (OR 1.88, 95% CI 1.18-2.99, p = 0.007). In the T2DM subjects, metformin use was a protective factor (OR 0.28, 95% CI 0.08-0.93, p = 0.049). T2DM was also associated with a more advanced (OR 2.39, 95% CI 1.05-5.46, p = 0.035) and progressive disease (OR 2.47, 95% CI 1.08-5.34, p = 0.03). Stratifying cases by primary site, independent risk factors for pancreatic NENs were T2DM (OR 2.57, 95% CI 1.28-5.15, p = 0.008) and obesity (OR 1.98, 95% CI 1.11-3.52, p = 0.020), while for intestinal NENs family history of non-neuroendocrine GEP cancer (OR 2.46, 95% CI 1.38-4.38, p = 0.003) and obesity (OR 1.90, 95% CI 1.08-3.33, p = 0.026).

CONCLUSION

This study reinforces a role for family history of non-neuroendocrine GEP cancer, T2DM and obesity as independent risk factors for GEP-NENs and suggests a role of metformin as a protective factor in T2DM subjects. If confirmed, these findings could have a significant impact on prevention strategies for GEP-NENs.

Middle Ear "Adenoma": a Neuroendocrine Tumor with Predominant L Cell Differentiation

This morphological and immunohistochemical study demonstrates that tumors currently known as "middle ear adenomas" are truly well-differentiated epithelial neuroendocrine tumors (NETs) composed of cells comparable to normal intestinal L cells, and therefore, these tumors resemble hindgut NETs. These tumors show consistent expression of glucagon, pancreatic polypeptide, PYY, and the transcription factor SATB2, as well as generic neuroendocrine markers and keratins. The same L cell markers are expressed by cells within the normal middle ear epithelium. These markers define a valuable immunohistochemical profile that can be used for differential diagnosis of middle ear neoplasms, particularly in distinguishing epithelial NETs from paragangliomas. The discovery of neuroendocrine cells expressing the same markers in non-neoplastic middle ear mucosa opens new areas of investigation into the physiology of the normal middle ear and the pathophysiology of middle ear disorders.

The genomic landscape of 85 advanced neuroendocrine neoplasms reveals subtype-heterogeneity and potential therapeutic targets

Metastatic and locally-advanced neuroendocrine neoplasms (aNEN) form clinically and genetically heterogeneous malignancies, characterized by distinct prognoses based upon primary tumor localization, functionality, grade, proliferation index and diverse outcomes to treatment. Here, we report the mutational landscape of 85 whole-genome sequenced aNEN. This landscape reveals distinct genomic subpopulations of aNEN based on primary localization and differentiation grade; we observe relatively high tumor mutational burdens (TMB) in neuroendocrine carcinoma (average 5.45 somatic mutations per megabase) with TP53, KRAS, RB1, CSMD3, APC, CSMD1, LRATD2, TRRAP and MYC as major drivers versus an overall low TMB in neuroendocrine tumors (1.09). Furthermore, we observe distinct drivers which are enriched in somatic aberrations in pancreatic (MEN1, ATRX, DAXX, DMD and CREBBP) and midgut-derived neuroendocrine tumors (CDKN1B). Finally, 49% of aNEN patients reveal potential therapeutic targets based upon actionable (and responsive) somatic aberrations within their genome; potentially directing improvements in aNEN treatment strategies.

Pancreatic Neuroendocrine Neoplasms in Multiple Endocrine Neoplasia Type 1

Pancreatic neuroendocrine tumors (pNETs) are a rare group of cancers accounting for about 1-2% of all pancreatic neoplasms. About 10% of pNETs arise within endocrine tumor syndromes, such as Multiple Endocrine Neoplasia type 1 (MEN1). pNETs affect 30-80% of MEN1 patients, manifesting prevalently as multiple microadenomas. pNETs in patients with MEN1 are particularly difficult to treat due to differences in their growth potential, their multiplicity, the frequent requirement of extensive surgery, the high rate of post-operative recurrences, and the concomitant development of other tumors. MEN1 syndrome is caused by germinal heterozygote inactivating mutation of the MEN1 gene, encoding the menin tumor suppressor protein. MEN1-related pNETs develop following the complete loss of function of wild-type menin. Menin is a key regulator of endocrine cell plasticity and its loss in these cells is sufficient for tumor initiation. Somatic biallelic loss of wild-type menin in the neuroendocrine pancreas presumably alters the epigenetic control of gene expression, mediated by histone modifications and DNA hypermethylation, as a driver of MEN1-associated pNET tumorigenesis. In this light, epigenetic-based therapies aimed to correct the altered DNA methylation, and/or histone modifications might be a possible therapeutic strategy for MEN1 pNETs, for whom standard treatments fail.

High-Grade Gastroenteropancreatic Neuroendocrine Neoplasms and Improved Prognostic Stratification With the New World Health Organization 2019 Classification: A Validation Study From a Single-Institution Retrospective Analysis

OBJECTIVES

There is a pressing need to develop clinical management pathways for grade 3 (G3) gastroenteropancreatic neuroendocrine neoplasms (GEP NEN).

METHODS

We performed a retrospective study on patients with metastatic G3 GEP NEN. The relationship between baseline characteristics and progression-free survival and overall survival was analyzed using the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Cox proportional hazards model.

RESULTS

We included 142 patients (74 well-differentiated neuroendocrine tumors [WDNETs], 68 poorly differentiated neuroendocrine carcinomas [PDNECs]). Patients with WDNET had prolonged survival compared with PDNEC (median, 24 vs 15 months, P = 0.0001), which persisted in both pancreatic and nonpancreatic cohorts. Well-differentiated morphology, Ki-67 <50% and positive somatostatin receptor imaging were independently associated with prolonged survival. Of the subgroup treated with first-line platinum-based chemotherapy, response rates were favorable (partial response, 47%; stable disease, 30%); there was no significant difference in response rates nor progression-free survival between WDNET and PDNEC despite significantly prolonged overall survival in the WDNET cohort.

CONCLUSIONS

Our study corroborates the knowledge of 2 prognostically distinct subgroups within the World Health Organization 2019 G3 GEP NEN population, observed in both pancreatic and nonpancreatic gastrointestinal cohorts. Definitive management pathways are needed to reflect the differences between G3 WDNET and PDNEC.

Pancreatic neuroendocrine neoplasms: Clinicopathological features and pathological staging

The nomenclature and classification of pancreatic neuroendocrine neoplasms has evolved in the last 15 years based on the advances in knowledge of the genomics, clinical behaviour and response to therapies. The current 2019 World Health Organization classification of pancreatic neuroendocrine neoplasms categorises them into three groups; pancreatic neuroendocrine tumours (PanNETs)(grade 1 grade 2, grade 3), pancreatic neuroendocrine carcinomas and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) based on the mitotic rate, Ki-67 index, morphological differentiation and/or co-existing tissue subtype. PanNETs are also classified into non-functional NET, insulinoma, gastrinoma, VIPoma, glucagonoma, somatostatinoma, ACTH-producing NET and serotonin producing NET based on hormone production and clinical manifestations. A portion of the cases were associated with genetic syndromes such as multiple neuroendocrine neoplasia 1 (MEN 1), neurofibromatosis and Von Hippel-Lindau syndrome. In view of the distinctive pathology and clinical behaviour of PanNENs, the current 8th AJCC/UICC staging system has separated prognostic staging grouping for PanNETs from the pancreatic neuroendocrine carcinomas or MiNENs. Pancreatic neuroendocrine carcinomas and MiNENs are staged according to the prognostic stage grouping for exocrine pancreatic carcinoma. The new stage grouping of PanNETs was validated to have survival curves separated between different prognostic groups. This refined histological and staging would lead to appropriate selections of treatment strategies for the patients with pancreatic neuroendocrine neoplasms.

Correlation of World Health Organization 2010 Classification for Gastroenteropancreatic Neuroendocrine Neoplasms with the Prognosis of Ovarian Neuroendocrine Neoplasms: Kansai Clinical Oncology Group-Protocol Review Committee/Intergroup Study

BACKGROUND

In 2014, the World Health Organization (WHO) released a classification system introducing neuroendocrine neoplasms (NENs) of the female reproductive tract, excluding the ovaries. This study aimed to evaluate whether retrospective adaption of the gastroenteropancreatic (GEP)-NEN classification is feasible for ovarian NENs (O-NENs) and correlates with prognosis.

METHODS

Sixty-eight patients diagnosed with carcinoid, small cell carcinoma (pulmonary type), paraganglioma, non-small/large cell neuroendocrine carcinoma (NEC), mixed NEC, or undifferentiated carcinomas at 20 institutions in Japan were included in this retrospective cross-sectional study. We identified O-NENs through central pathological review using a common slide set, followed by reclassification according to WHO 2010 guidelines for GEP-NENs. A proportional hazards model was used to assess the association of prognostic factors (age, stage, performance status, histology, and residual disease) with overall survival (OS) and progression-free survival (PFS).

RESULTS

Of the 68 enrolled patients, 48 were eligible for analysis. All carcinoids (n = 32) were reclassified as NET G1/G2, whereas 14 of 16 carcinomas were reclassified as NEC/mixed adeno-NEC (MANEC) (Fisher's exact test; p < 0.01). The OS/PFS was 49.0/42.5 months and 6.5/3.9 months for NET G1/G2 and NEC/MANEC, respectively. Histology revealed that NEC/MANEC was associated with increased risk of death (HR = 48.0; 95% CI, 3.93-586; p < 0.01) and disease progression (HR = 51.6; 95% CI, 5.54-480; p < 0.01).

CONCLUSION

Retrospective adaption of GEP-NEN classification to O-NENs is feasible and correlates well with the prognosis of O-NENs. This classification could be introduced for ovarian tumors.

How to Classify and Define Pituitary Tumors: Recent Advances and Current Controversies

Pituitary tumors are very complex and heterogeneous and have a very wide range of proliferative and aggressive behaviors, and how to define and classify these tumors remains controversial. This review summarizes the epidemiology and progress in the classification and definition of pituitary tumors, as well as controversial issues. Based on the results of radiologic and autopsy studies, the prevalence of pituitary tumors has recently increased significantly. However, the majority of pituitary tumors are incidentally discovered and asymptomatic, and such tumors are called pituitary incidentalomas. Most of these incidentalomas do not induce symptoms, remain stable in size, and do not need treatment. The recent revised classification strategies mainly depend on immunohistochemistry (IHC) to detect pituitary hormones and pituitary transcription factors; therefore, the accuracy of diagnosing pituitary tumors has improved. Although new classification strategies and definitions for pituitary tumors have been presented, there are still some controversies. The term pituitary neuroendocrine tumor (PitNET) was proposed by the International Pituitary Pathology Club, and this terminology can encompass the unpredictable malignant behavior seen in the subset of aggressive pituitary adenomas (PAs). However, some endocrinologists who oppose this change in terminology have argued that the use of tumor in the terminology is misleading, as it gives PAs a harmful connotation when the majority are not aggressive. Such terminology may add new ambiguity to the origin of PAs and unnecessary anxiety and frustration for the majority of patients with benign PAs. The classification of aggressive PAs mainly relies on subjective judgment of clinical behavior and lacks objective biomarkers and unified diagnostic criteria. However, the term "refractory" could more accurately represent the characteristics of these tumors, including their clinical behaviors, radiological features, and pathologic characteristics. Moreover, the diagnostic criteria for refractory PAs are stricter, more objective, and more accurate than those for aggressive PAs. Early identification of patients with these tumors through recognition and increased awareness of the definition of refractory PAs will encourage the early use of aggressive therapeutic strategies.

Structure, Function, and Morphology in the Classification of Pituitary Neuroendocrine Tumors: the Importance of Routine Analysis of Pituitary Transcription Factors

The traditional approach to the diagnosis of primary adenohypophyseal cell proliferations uses hormone immunohistochemistry to classify pituitary neuroendocrine tumors (PitNETs). The routine application of immunolocalization of pituitary transcription factors (SF1, PIT1, TPIT, ERα, and recently GATA3) along with adenohypophyseal hormones has taught us critical lessons that are discussed in this communication. We point out that appropriate patient care requires accurate diagnosis and is critical in the era of precision medicine. A misdiagnosis can result in far greater health care costs than the cost of accurate tumor classification and may have other unintended consequences. We provide additional insights about confusing findings in genomic studies, emphasizing that high-quality pathology is essential for strong science and translational research.

Northstar enables automatic classification of known and novel cell types from tumor samples

Single cell transcriptomics is revolutionising our understanding of tissue and disease heterogeneity, yet cell type identification remains a partially manual task. Published algorithms for automatic cell annotation are limited to known cell types and fail to capture novel populations, especially cancer cells. We developed northstar, a computational approach to classify thousands of cells based on published data within seconds while simultaneously identifying and highlighting new cell states such as malignancies. We tested northstar on data from glioblastoma, melanoma, and seven different healthy tissues and obtained high accuracy and robustness. We collected eleven pancreatic tumors and identified three shared and five private neoplastic cell populations, offering insight into the origins of neuroendocrine and exocrine tumors. Northstar is a useful tool to assign known and novel cell type and states in the age of cell atlases.

Neuroendocrine neoplasm update: toward universal nomenclature

Neuroendocrine neoplasia is described in almost every tissue, either in the pure endocrine organs, the nerve structures or in the so-called diffuse neuroendocrine system. The current nomenclature contains time-honored, widely accepted definitions; however, it is different according to anatomical sites. Diverse definitions may generate confusion and non-standard patient management. The International Agency for Research on Cancer - World Health Organization (IARC-WHO) proposed a framework for universal classification of neuroendocrine neoplasia. Evidence indicates that neuroendocrine cancer is composed by cells with a distinctive phenotype characterized by the expression of general and specific neuroendocrine markers. The neuroendocrine phenotype is indicated as descriptor of a unique cancer category, now recommended for all organs as neuroendocrine neoplasm. Evidence indicates that neuroendocrine neoplasia may be well or poorly differentiated, with diverse incidence and prevalence in different organs. It is proposed that the well-differentiated neoplasm is universally defined as neuroendocrine tumor (NET) and the poorly differentiated as neoplasm neuroendocrine carcinoma (NEC). Evidence indicates that a cancer grading tool based on a proliferation measure by mitotic count, Ki67 % and/or necrosis assessment is useful to predict NET patient behavior. It is proposed to utilize this tool for grading NET universally, with site-specific cut-offs to be defined. It is also acknowledged that significant biological site-specific differences exist. It is recommended that current pathology reports contain this classification together with the current traditional classifiers. This IARC-WHO common classification framework for neuroendocrine neoplasm aims at uniformizing nomenclature toward different organs and at fostering the definition of a similar site-specific gene signature.

Utility of GATA-3 Expression in the Analysis of Pituitary Neuroendocrine Tumour (PitNET) Transcription Factors

With the introduction of the WHO 2017 classification of endocrine neoplasms, the use of the pituitary transcription factors PIT-1, Tpit and SF-1 has become the standard of care. However, immunohistochemistry for these transcription factors is not available in all institutions, and their reliability has been questioned. We read with interest the findings of Mete et al. that GATA-3 expression was detected in some pituitary neuroendocrine tumours (PitNET). We therefore sort to validate this in our large cohort of PitNETs. We searched the database of Royal North Shore Hospital for PitNETs between 1998 and 2012, constructed a tissue microarray and reclassified these entities based on their expression for PIT-1, Tpit and SF-1. We then scored the expression of GATA-3 immunohistochemistry on a scale of 0-2, where 0 was no staining, 1 was patchy or weak staining and 2 was strong and diffuse staining. 265 of 346 tumours were able to be classified into a specific tumour subtype, and 263 tumours had tissue available for GATA-3 immunohistochemistry. 89% of gonadotrophs and 93% of triple-negative tumours with expression for luteinising hormone and follicle-stimulating hormone were positive for GATA-3. In the triple-negative group, GATA-3 was positive in 1 mammosomatotroph and 80% of tumours with thyroid-stimulating hormone expression. In the triple-negative hormone-negative group, 21 of 33 tumours were positive (64%). The results demonstrate that GATA-3 is a useful marker to supplement the existing pituitary transcription factors, albeit slightly less sensitive and specific than previously reported. GATA-3 may be employed in addition to the current array of immunohistochemical transcription factors, especially in the resource poor setting. However, given its potential cross-reactivity with other entities of the Sella, positive staining should be interpreted with caution and in the morphological and clinical context.

The Eighth Edition of the American Joint Committee on Cancer Distant Metastases Stage Classification for Metastatic Pancreatic Neuroendocrine Tumors Might Be Feasible for Metastatic Pancreatic Ductal Adenocarcinomas

BACKGROUND

Significant modifications have been made to the 8th edition of the American Joint Committee on Cancer (AJCC) distant metastases (M) stage classification for metastatic pancreatic neuroendocrine tumors (PanNETs). We aimed to validate this revised classification among metastatic PanNET patients using the Surveillance, Epidemiology, and End Results database. We further sought to evaluate the feasibility of applying this classification to metastatic pancreatic neuroendocrine carcinoma (PanNEC) and pancreatic ductal adenocarcinoma (PDAC) patients.

METHODS

Stage IV pancreatic neuroendocrine neoplasm (PanNEN, including G1/G2 PanNET and G3 PanNEC classified according to the World Health Organization [WHO] 2010 grading scheme) and PDAC patients with metastatic disease diagnosed between 2010 and 2015 were identified and restaged according to the revised M stage classification for PanNET. Overall survival (OS) was compared using Kaplan-Meier analysis and log-rank test. Uni- and multivariate Cox regression models were utilized to identify prognostic factors.

RESULTS

A total of 1,371 stage IV PanNEN and 634 PDAC patients were included. Among PanNEN patients, liver (75.0%) was the most common metastatic site, followed by distant lymph nodes (8.5%), lung (8.4%), bone (7.3%), and brain (1.0%). The 5-year OS for PanNET patients with M1a, M1b, and M1c stage was 44.15, 53.32, and 19.70%, respectively. However, survival comparison showed no significant difference between M1a and M1b stages among PanNET patients. Similar findings were noted after applying this classification to PanNEC patients. Multivariate analysis showed that the age at diagnosis and the number of distant metastatic sites were independent prognostic factors for metastatic PanNEN patients. Interestingly, excellent survival discrimination by M stage among stage IV PDAC patients was noted (M1a vs. M1b vs. M1c, 5-year OS: 5.42, 2.46, and 0%, respectively).

CONCLUSION

Our study is the first large sample-based validation of the AJCC 8th M stage classification for PanNET. The revised classification did not effectively stratify metastatic PanNEN patients. However, further study is warranted to validate this classification for PanNET patients according to the WHO 2017 classification. Interestingly, the revised M stage classification might be feasible for PDAC patients with metastatic disease.

Classification and Prognostic Stratification of Bronchopulmonary Neuroendocrine Neoplasms

The accuracy and reproducibility of the World Health Organization (WHO) 2015 classification of bronchopulmonary neuroendocrine neoplasms (BP-NENs) is disputed. The aim of this study is to classify and grade BP-NENs using the WHO 2019 classification of digestive system NENs (DiS-NEN-WHO 2019), and to analyze its accuracy and prognostic impact. Two BP-NEN cohorts from Japan and Germany, 393 tumors (88% surgically resected), were reviewed and the clinicopathological data of the resected tumors (n = 301) correlated to patients' disease-free survival (DFS). The DiS-NEN-WHO 2019 stratified the 350 tumors into 91 (26%) neuroendocrine tumors (NET) G1, 52 (15%) NET G2, 15 (4%) NET G3, and 192 (55%) neuroendocrine carcinomas (NEC). NECs, but not NETs, were immunohistochemically characterized by abnormal p53 (100%) and retinoblastoma 1 (83%) expression. The Ki67 index, which was on average 4 times higher than mitotic count (p < 0.0001), was prognostically more accurate than the mitotic count. NET G3 patients had a worse outcome than NET G1 (p < 0.01) and NET G2 patients (p = 0.02), respectively. No prognostic difference was detected between NET G3 and NEC patients after 5 year DFS. It is concluded that stratifying BP-NEN patients according to the DiS-NEN-WHO 2019 classification results in 3 prognostically well-defined NET groups, if grading is solely based on Ki67 index. Mitotic count alone may underestimate malignant potential of NETs.

Natural History of Renal Neuroendocrine Neoplasms: A NET by Any Other Name?

Renal neuroendocrine neoplasms are rare, with descriptions of cases limited to individual reports and small series. The natural history of this group of neuroendocrine neoplasms is poorly understood. In this study, we queried the Surveillance, Epidemiology and End Results (SEER) database over a four-decade period where we identified 166 cases of primary renal neuroendocrine neoplasms. We observed a 5-year overall survival of 50%. On multivariate analysis, survival was influenced by stage, histology, and if surgery was performed. We observed that patients managed by operative management had a greater frequency of localized or regional stage disease as well as a greater frequency of neuroendocrine tumor, grade 1 histology; whereas those managed non-operatively tended to have distant disease and histologies of neuroendocrine carcinoma, NOS and small cell neuroendocrine carcinoma. This is the largest description of patients with renal neuroendocrine neoplasms. Increased survival was observed in patients with earlier stage and favorable histologies.

Recent classifications systems for gastroenteropancreatic neuroendocrine tumors A single-center experience

AIM

In this study, we aimed to review the demographic histopathological and clinical findings and long-term results of our GEP-NET cases, as well as to re-evaluate our cases according to the new classification systems.

MATERIAL AND METHOD

46 patients diagnosed as GEPNETs were presented. Immunohistochemical studies were performed in all cases. The cases were divided into 3 groups according to their embryogenic origin (Foregut, Midgut and Hindgut). All cases re-evaluated according to recent WHO (2019) and AJCC (2017) TNM calcification. Investigation was made to find differences between the embryonic origins and to find correlation between stage and grading systems with each other.

RESULTS

The most common localization was appendix (52.3%) The distribution of cases according to embryologic origin were as follows: foregut tumors 13 cases (27.7%), midgut tumors 27 cases (57.4%) and hindgut tumors in 6 cases (12.8%). The Ki-67 ratio was evaluated in all patients, with a mean of 6.34%±2.51 (range: 1-80). The Ki-67 ratio was less than 3% in 82.6% of patients. Mitotic count was less than 2 per/10 HPF in 76% of patients. According to WHO 2019 most of patients were Grade 1 Neuroendocrine Tumor (65.2%) and there were only 2 Neuroendocrine Carcinoma (NEC) cases. According to AJCC 2017 most cases were Stage 1 (52.1%) and only 4 cases were Stage 4. The grades and stages of our cases were statistically significantly correlated. Overall survival did not differ significantly with regard to embryologic origin (log-rank test, p=0.062). The median overall survival was 106±7.4 months. The 5-year cumulative survival rate was 84.1±5.6 years. Seven patients died during this time with a median time of 5 months (range: 1-31 months). In the Cox regression analysis, the percentage of Ki- 67 was found to have a statistically significant effect on overall survival (p=0.000) CONCLUSION: Correlation was noticed between WHO 2019 and AJCC 2017 classification for grade and stage and controlled trials must be undertaken to develop a single diagnostic algorithm and to change the future management of such patients.

KEY WORDS

Neuroendocrine Tumors, Gastroenteropancreatic neuroendocrine tumor.

[Neuroendocrine tumors : Classification, clinical presentation and imaging]

CONTEXT

Neuroendocrine tumors (NET) are a heterogeneous group of neoplasms found in all organs. They often present with characteristic clinical syndromes due to hormone hypersecretion.

DIAGNOSTICS

In addition to hormone diagnostics molecular-genetic work-up can play an important role.

IMAGING

Morphological imaging comprises ultrasound, endoscopy, computed tomography (CT) and magnetic resonance imaging (MRI) scans. Functional imaging of NET relies on radioligands that bind to specific receptors or transporters (Ga-68-DOTATATE-PET-CT, Tc-99-tektrotyd-SPECT/CT, F‑18-DOPA-PET/CT).

THERAPY

Somatostatin analogs either native or coupled to radionuclides are potent drugs for treating various neuroendocrine tumors.

CONCLUSION

The requirements of imaging are determined by clinical presentation, laboratory findings, tumor stage, the presence of a tumor syndrome and the need of a personalized systemic treatment modality.

Tumour type and size are prognostic factors in gastric neuroendocrine neoplasia: A multicentre retrospective study

BACKGROUND

Gastric neuroendocrine neoplasias (gNEN) are defined as type I if associated with atrophic body gastritis and type III when tumour is sporadic. This classification, together with grading and size, plays a crucial prognostic role. Nevertheless, the impact of these features on clinical outcome is not clear.

AIM

To identify factors predicting poor outcome.

PATIENTS AND METHODS

Analysis of type I and type III gNEN. A composite endpoint was defined if tumour-related death or metastases or angioinvasion were observed.

RESULTS

156 gNENs were evaluated: 137 (87.8%) type I and 19 (12.2%) type III. Among type I, 103 were G1 (75.2%) and 34 (24.8%) were G2. In type III group, 8 were G1 (42.1%), 10 were G2 (52.6%), and 1 was G3 (5.3%). Negative endpoint occurred in 18 patients including 10 type III and 8 type I. Male gender (p = 0.032), tumour type (p = 0.003) and size >10 mm (p = 0.024) were predictors for poor outcome, whereas Ki67 was not confirmed on multivariate analysis (p = 0.192). 5-yr survival rates in type I and type III were 100% and 76.2%, respectively (p = 0.0002).

CONCLUSIONS

Tumour size, tumour type and gender affect clinical outcome in gNENs. In contrast to NENs rising from other sites, Ki67 plays a less important role.

Gastric neuroendocrine neoplasias: manifestations and comparative outcomes

Although gastric neuroendocrine neoplasias (gNEN) are an orphan disease, their incidence is rising. The heterogeneous clinical course powers the ongoing discussion of the most appropriate classification system and management. Prognostic relevance of proposed classifications was retrospectively analysed in 142 patients from a single tertiary referral centre. Baseline, management and survival data were acquired for statistical analyses. The distribution according to the clinicopathological typification was gNEN-1 (n = 86/60.6%), gNEN-2 (n = 7/4.9%), gNEN-3 (n = 24/16.9%) and gNEN-4 (n = 25/17.6%), while hypergastrinemia-associated gNEN-1 and -2 were all low-grade tumours (NET-G1/2), formerly termed sporadic gNEN-3 could be subdivided into gNEN-3 with grade 1 or 2 and gNEN-4 with grade 3 (NEC-G3). During follow-up 36 patients died (25%). The mean overall survival (OS) of all gNEN was 14.2 years. The OS differed statistically significant across all subgroups with either classification system. According to UICC 2017 TNM classification, OS differed for early and advanced stages, while WHO grading indicated poorer prognosis for NEC-G3. Cox regression analysis confirmed the independent prognostic validity of either classification system for survival. Particularly careful analysis of the clinical course of gNEN-1 (ECLomas, gastric carcinoids) confirmed their mostly benign, but recurrent and extremely slowly progressive behaviour with low risk of metastasis (7%) and an efficient long-term control by repetitive endoscopic procedures. Our study provides evidence for the validity of current classifications focusing on typing, grading and staging. These are crucial tools for risk stratification, especially to differentiate gNEN-1 as well as sporadic gNET and gNEC (gNEN-3 vs -4).

Colorectal Neuroendocrine Neoplasms: Areas of Unmet Need

The subject of colorectal neuroendocrine neoplasms (NENs), subdivided into well-differentiated NENs, termed neuroendocrine tumours (NETs; grade (G) 1 and 2), and poorly differentiated NENs, termed neuroendocrine carcinomas (NECs; G3) according to the 2010 World Health Organisation (WHO) classification, has arguably not had as much attention or study as NENs occurring in other sites. Colorectal NETs and NECs are however easier to study than many others since they are usually not difficult to remove and are increasingly detected because of intensified colorectal cancer screening and surveillance programmes. Colorectal NETs and NECs show site-specific heterogeneity with variable behaviour and different therapeutic options; these various aspects provide unique challenges. Because of bowel cancer screening programmes, colorectal NENs, like conventional adenocarcinomas, may be diagnosed at a stage that is associated with improved survival. In this article we intend to describe and define areas of unmet needs relating to the epidemiology, classification, pathology, diagnosis and therapy of colorectal NETs (including NETs G3), colorectal NECs, and finally, mixed adeno-neuroendocrine carcinomas (MANECs) by reviewing and discussing the relevant literature.

Unmet Medical Needs in Pulmonary Neuroendocrine (Carcinoid) Neoplasms

Pulmonary carcinoids (PCs) display the common features of all well-differentiated neuroendocrine neoplasms (NEN) and are classified as low- and intermediate-grade malignant tumours (i.e., typical and atypical carcinoid, respectively). There is a paucity of randomised studies dedicated to advanced PCs and management principles are drawn from the larger gastroenteropancreatic NEN experience. There is growing evidence that NEN anatomic subgroups have different biology and different responses to treatment and, therefore, should be investigated as separate entities in clinical trials. In this review, we discuss the existing evidence and limitations of tumour classification, diagnostics and staging, prognostication, and treatment in the setting of PC, with focus on unmet medical needs and directions for the future.

A common classification framework for neuroendocrine neoplasms: an International Agency for Research on Cancer (IARC) and World Health Organization (WHO) expert consensus proposal

The classification of neuroendocrine neoplasms (NENs) differs between organ systems and currently causes considerable confusion. A uniform classification framework for NENs at any anatomical location may reduce inconsistencies and contradictions among the various systems currently in use. The classification suggested here is intended to allow pathologists and clinicians to manage their patients with NENs consistently, while acknowledging organ-specific differences in classification criteria, tumor biology, and prognostic factors. The classification suggested is based on a consensus conference held at the International Agency for Research on Cancer (IARC) in November 2017 and subsequent discussion with additional experts. The key feature of the new classification is a distinction between differentiated neuroendocrine tumors (NETs), also designated carcinoid tumors in some systems, and poorly differentiated NECs, as they both share common expression of neuroendocrine markers. This dichotomous morphological subdivision into NETs and NECs is supported by genetic evidence at specific anatomic sites as well as clinical, epidemiologic, histologic, and prognostic differences. In many organ systems, NETs are graded as G1, G2, or G3 based on mitotic count and/or Ki-67 labeling index, and/or the presence of necrosis; NECs are considered high grade by definition. We believe this conceptual approach can form the basis for the next generation of NEN classifications and will allow more consistent taxonomy to understand how neoplasms from different organ systems inter-relate clinically and genetically.

Histopathology of Neuroendocrine Neoplasms of the Gastrointestinal System

BACKGROUND

Tumors arising from neuroendocrine cells are defined as epithelial neoplasms with predominantly neuroendocrine differentiation. They comprise a distinct group of tumors with a characteristic histological structure and functional properties that develop at various sites, particularly the gastrointestinal system (67%) and lungs (25%). Although such tumors are usually slow-growing and indolent, almost all have malignant potential and most can produce active hormones. Clinical signs vary, and many are dependent on the site at which the tumor develops. Although these tumors were identified more than 130 years, their classification remains unclear.

PURPOSE

This review provides a comprehensive overview of the human neuroendocrine system and its neoplasms, from their discovery to current terminology and classifications. In addition, the clinical symptomatology and macroscopic/microscopic features of tumors arising from endocrine cells of the gastrointestinal tract are described, with an emphasis on their classification, diagnostic criteria for their grading and TNM (tumor, node, metastasis) staging, and how these tumors differ according to their localization in the gastrointestinal tract.

CONCLUSION

Tumors arising from neuroendocrine cells are rare and can cause typical symptoms of carcinoid syndrome. However, most of these tumors are asymptomatic, which, together with their typical small size and localization in the gut, makes them difficult to access endoscopically and often leads to diagnosis at an advanced stage. To successfully diagnose and treat tumors arising from neuroendocrine cells, they should be assessed using a differential diagnostic procedure and be histopathologically classified, graded, and staged according to specified criteria and the latest classifications and guidelines. Although the terms "carcinoid", "neuroendocrine tumor", and "neuroendocrine carcinoma" are often used synonymously in the literature and by professionals, more precise terminology is required for nomenclature and classification. Key words: gastrointestinal neuroendocrine neoplasms - neuroendocrine tumors - neuroendocrine carcinomas - classification - NET - NEC The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 21. 3. 2018 Accepted: 16. 4. 2018.

A modified M-stage classification based on the metastatic patterns of pancreatic neuroendocrine neoplasms: a population-based study

BACKGROUND

The present study aims to improve the M-stage classification of pancreatic neuroendocrine neoplasms (pNENs).

METHODS

Two thousand six hundred sixty six pNENs were extracted from the Surveillance, Epidemiology, and End Results database to explore the metastatic patterns of pNENs. Metastatic patterns were categorized as single, two, or multiple (three or more) distant organ metastasis. The mean overall survival and hazard rate of different metastatic patterns were calculated by Kaplan-Meier and Cox proportional hazards models, respectively. The discriminatory capability of the modified M-stage classification was evaluated by Harrell's concordance index.

RESULTS

The overall survival time significantly decreased with an increasing number of metastatic organs. In addition, pNENs with only liver metastasis had better prognosis when compared to other metastatic patterns. Thus, we modified the M-stage classification (mM-stage) as follows: mM₀-stage, tumor without metastasis; mM₁-stage, tumor only metastasized to liver; mM₂-stage, tumor metastasized to other single distant organ (lung, bone, or brain) or two distant organs; mM₃-stage, tumor metastasized to three or more distant organs. Harrell's concordance index showed that the modified M-stage classification had superior discriminatory capability than both the American Joint Committee on Cancer (AJCC) and the European Neuroendocrine Tumor Society (ENETS) M-stage classifications.

CONCLUSIONS

The modified M-stage classification is superior to both AJCC and ENETS M-stage classifications in the prognosis of pNENs. In the future, individualized treatment and follow-up programs should be explored for patients with distinct metastatic patterns.

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.

Clinical outcome and long-term survival of 150 consecutive patients with pancreatic neuroendocrine tumors: A comprehensive analysis by the World Health Organization 2010 grading classification

BACKGROUND AND OBJECTIVE

The World Health Organization (WHO) has revised its grading system for pancreatic neuroendocrine tumors (PNETs) in 2010 into three main group, which has not been widely and comprehensively evaluated. We aimed to validate the clinical valve of this system associated with the clinical outcome and long-term survival when applied to PNETs, which were rare and heterogeneous.

METHODS

We retrospectively collected and analyzed the data of 150 consecutive patients with PNETs who underwent a resection.

RESULTS

Sixty-four males and 86 females with PNETs were enrolled in our study. The clinical stage from I to IV by European Neuroendocrine Tumor Society were respectively defined in 53, 60, 19 and 18 patients. Seventy-two patients were pathologically diagnosed as neuroendocrine tumor G1 (NET G1), 48 as neuroendocrine tumor G2 (NET G2) and 30 as neuroendocrine carcinoma G3 (NEC G3). Patients with a radical resection obtained a notably higher overall survival (OS) than that of patients who underwent a palliative surgery (P=0.001). The 5-year OS of patients with NET G1 was significantly higher than that of patients with NET G2 (P=0.015) and NEC G3 (P<0.001); the comparison of OS for patients with NET G2 and NEC G3 was also statistically significant (P=0.005). In both univariate and multivariate analysis, clinical staging by ENETS (stage I and II vs. stage III and IV), resection (radical vs. palliative) and WHO 2010 grading classification (NET G1 and G2 vs. NEC G3) were validated to be independent predictors for the survivals of PNETs.

CONCLUSION

The newly-updated WHO 2010 grading classification was prognostic for the OS of PNETs and could be widely adopted in clinical practice.

A classification prognostic score to predict OS in stage IV well-differentiated neuroendocrine tumors

No validated prognostic tool is available for predicting overall survival (OS) of patients with well-differentiated neuroendocrine tumors (WDNETs). This study, conducted in three independent cohorts of patients from five different European countries, aimed to develop and validate a classification prognostic score for OS in patients with stage IV WDNETs. We retrospectively collected data on 1387 patients: (i) patients treated at the Istituto Nazionale Tumori (Milan, Italy; n = 515); (ii) European cohort of rare NET patients included in the European RARECAREnet database (n = 457); (iii) Italian multicentric cohort of pancreatic NET (pNETs) patients treated at 24 Italian institutions (n = 415). The score was developed using data from patients included in cohort (i) (training set); external validation was performed by applying the score to the data of the two independent cohorts (ii) and (iii) evaluating both calibration and discriminative ability (Harrell C statistic). We used data on age, primary tumor site, metastasis (synchronous vs metachronous), Ki-67, functional status and primary surgery to build the score, which was developed for classifying patients into three groups with differential 10-year OS: (I) favorable risk group: 10-year OS ≥70%; (II) intermediate risk group: 30% ≤ 10-year OS < 70%; (III) poor risk group: 10-year OS <30%. The Harrell C statistic was 0.661 in the training set, and 0.626 and 0.601 in the RARECAREnet and Italian multicentric validation sets, respectively. In conclusion, based on the analysis of three 'field-practice' cohorts collected in different settings, we defined and validated a prognostic score to classify patients into three groups with different long-term prognoses.

Well differentiated grade 3 pancreatic neuroendocrine tumors compared with related neoplasms: A morphologic study

BACKGROUND

Pancreatic neuroendocrine neoplasms with a Ki-67 labeling index greater than 20% were reclassified in 2017 by the World Health Organization into well differentiated (WD) and poorly differentiated grade 3 neuroendocrine carcinoma (NEC). The authors describe the cytologic features of grade 3 WD pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NEC.

METHODS

Fine-needle aspirates from 65 pancreatic neuroendocrine neoplasms were reviewed, and their cytomorphologic features were compared across grade 2, WD grade 3, and PD small cell type (PD-S), large cell type (PD-L), and type not otherwise specified (PD-NOS) neoplasms.

RESULTS

The 65 aspirates consisted of 19 grade 2 neoplasms, 32 WD grade 3 neoplasms, and 14 NECs (6 PD-S, 5 PD-L, and 3 PD-NOS). The medians Ki-67 proliferation index was 11% (range, 3.2%-17%) in grade 2 neoplasms, 40% (range, 21%-89%) in WD grade 3 neoplasms, 80% (range, 63%-95%) in PD-S neoplasms, 39% (range, 25%-61%) in PD-L neoplasms, and 70% (range, 30%-80%) in PD-NOS neoplasms. Both grade 2 and WD grade 3 neoplasms were associated with plasmacytoid morphology and smooth nuclear contours, but WD grade 3 neoplasms had significant increases in abundant cytoplasm (72% vs 17%; P = .007), nuclear tangles (75% vs 42%; P = .006), and apoptosis (86% vs 58%; P = .005). Compared with NECs, WD grade 3 neoplasms had increased plasmacytoid morphology (75% vs 7%; P < .001), smooth nuclear contours (94% vs 64%; P = .02), round nuclei (59% vs 21%; P = .01), and less pleomorphism (13% vs 50%; P = .004), molding (9% vs 79%; P < .001), and necrosis (13% vs 43%; P = .003). WD grade 3 neoplasms had less pleomorphism (13% vs 50%; P = .04), less necrosis (13% vs 60%; P = .04), and more plasmacytoid morphology (75% vs 20%; P = .03) than PD-L.

CONCLUSIONS

The prevalence of cytologic features differs in WD grade 3 pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NECs, and these differences assist in the recognition of this newly classified entity. Cancer Cytopathol 2018;126:326-35. © 2018 American Cancer Society.

Recommended parameters for pathology reporting of gastroenteropancreatic neuroendocrine tumours (GEP-NETs)

No abstract available.

Neuroendocrine Tumor Heterogeneity Adds Uncertainty to the World Health Organization 2010 Classification: Real-World Data from the Spanish Tumor Registry (R-GETNE)

BACKGROUND

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are a complex family of tumors of widely variable clinical behavior. The World Health Organization (WHO) 2010 classification provided a valuable tool to stratify neuroendocrine neoplasms (NENs) in three prognostic subgroups based on the proliferation index. However, substantial heterogeneity remains within these subgroups, and simplicity sometimes entails an ambiguous and imprecise prognostic stratification. The purpose of our study was to evaluate the prognostic impact of histological differentiation within the WHO 2010 grade (G) 1/G2/G3 categories, and explore additional Ki-67 cutoff values in GEP-NENs.

SUBJECTS, MATERIALS, AND METHODS

A total of 2,813 patients from the Spanish National Tumor Registry (RGETNE) were analyzed. Cases were classified by histological differentiation as NETs (neuroendocrine tumors [well differentiated]) or NECs (neuroendocrine carcinomas [poorly differentiated]), and by Ki-67 index as G1 (Ki-67 <2%), G2 (Ki-67 3%-20%), or G3 (Ki-67 >20%). Patients were stratified into five cohorts: NET-G1, NET-G2, NET-G3, NEC-G2, and NEC-G3.

RESULTS

Five-year survival was 72%. Age, gender, tumor site, grade, differentiation, and stage were all independent prognostic factors for survival. Further subdivision of the WHO 2010 grading improved prognostic stratification, both within G2 (5-year survival: 81% [Ki-67 3%-5%], 72% [Ki-67 6%-10%], 52% [Ki-67 11%-20%]) and G3 NENs (5-year survival: 35% [Ki-67 21%-50%], 22% [Ki-67 51%-100%]). Five-year survival was significantly greater for NET-G2 versus NEC-G2 (75.5% vs. 58.2%) and NET-G3 versus NEC-G3 (43.7% vs. 25.4%).

CONCLUSION

Substantial clinical heterogeneity is observed within G2 and G3 GEP-NENs. The WHO 2010 classification can be improved by including the additive effect of histological differentiation and the proliferation index.

IMPLICATIONS FOR PRACTICE

Gastroenteropancreatic neuroendocrine neoplasms are tumors of widely variable clinical behavior, roughly stratified by the World Health Organization (WHO) 2010 classification into three subgroups based on proliferation index. Real-world data from 2,813 patients of the Spanish Registry RGETNE demonstrated substantial clinical heterogeneity within grade (G) 2 and G3 neuroendocrine neoplasms. Tumor morphology and further subdivision of grading substantially improves prognostic stratification of these patients and may help individualize therapy. This combined, additive effect shall be considered in future classifications of neuroendocrine tumors and incorporated for stratification purposes in clinical trials.

Aspects regarding nomenclature, classification and pathology of neuroendocrine neoplasms of the digestive system - a review

Neuroendocrine neoplasms (NENs) of the digestive system are composed of cells with a neuroendocrine phenotype. These tumors produce and secrete peptide hormones and biogenic amines and they are called neuroendocrine neoplasms because of the marker proteins that they share with the neural cell system. The classification and nomenclature used to designate NENs have undergone changes over the past decades due to the accumulation of evidence related to the biological characteristics and their evolution. The European Neuroendocrine Tumor Society (ENETS) proposed a classification system based on the tumor grading and staging according to their localization. The latest internationally recognized NEN classification was published by the World Health Organization (WHO) in 2010. In accordance with the 2010 WHO criteria, the determination of the NEN malignancy potential is based on grading, depending on the mitotic activity and the Ki67 proliferation index, as well as on the tumor TNM stage. It is worth emphasizing that the terms neuroendocrine tumor (NET) and neuroendocrine carcinoma (NEC), without reference to grading or differentiation, are inadequate for prognostic assessment or the therapy determination, being inappropriate in pathology reports. The functional status of the tumor is based on the clinical findings but not on the pathological data or immunohistochemically profile. Despite the inability to establish a single system of sites, these are common features to establish the basis of most systems, documentation of these features allowing for greater reliability in the pathology reporting of these neoplasms.

Prognostic Evaluations Tailored to Specific Gastric Neuroendocrine Neoplasms: Analysis Of 200 Cases with Extended Follow-Up

BACKGROUND

Gastric neuroendocrine neoplasms (NENs) are very heterogeneous, ranging from mostly indolent, atrophic gastritis-associated, type I neuroendocrine tumors (NETs), through highly malignant, poorly differentiated neuroendocrine carcinomas (pdNECs), to sporadic type III NETs with intermediate prognosis, and various rare tumor types. Histologic differentiation, proliferative grade, size, level of gastric wall invasion, and local or distant metastases are used as prognostic markers. However, their value remains to be tailored to specific gastric NENs.

METHODS

Series of type I NETs (n = 123 cases), type III NETs (n = 34 cases), and pdNECs (n = 43 cases) were retrospectively collected from four pathology centers specializing in endocrine pathology. All cases were characterized clinically and histopathologically. During follow-up (median 93 months) data were recorded to assess disease-specific patient survival.

RESULTS

Type I NETs, type III NETs, and pdNECs differed markedly in terms of tumor size, grade, invasive and metastatic power, as well as patient outcome. Size was used to stratify type I NETs into subgroups with significantly different invasive and metastatic behavior. All 70 type I NETs < 0.5 cm (micro-NETs) were uneventful. Ki67-based grading proved efficient for the prognostic stratification of type III NETs; however, grade 2 (G2) was not associated with tumor behavior in type I NETs. Although G3 NETs (2 type I and 9 type III) had a very poor prognosis, it was found that patient survival was longer with type III G3 NETs compared to pdNECs.

CONCLUSIONS

Given the marked, tumor type-related behavior differences, evaluation of gastric NEN prognostic parameters should be tailored to the type of neoplastic disease.

[Consensus and controversy on subtype classification of gastric neuroendocrine neoplasms]

Gastric neuroendocrine neoplasms (g-NENs) are a heterogeneous group of tumors. Often silent, g-NENs may however be aggressive and sometimes mimic the course of gastric adenocarcinoma. Well-differentiated gastric neuroendocrine tumors (NET) can be subclassified into 3 distinct groups (type1, type 2 and type 3) according to Neuroendocrine Neoplasm Society (ENETS) guideline version 2006 as well as North America Neuroendocrine Tumor Society (NANETS) and National Comprehensive Cancer Network (NCCN) guidelines. However, since the publication of ENETS guideline version 2012, the subtype classification of g-NENs has been confusing due to the revised definition of type 3 g-NEN in versions 2012 and 2016. ENETS version 2012 indicated that type 3 g-NEN was usually solitary and its pathology was mostly WHO grade 3 (neuroendocrine carcinoma, NEC G3) with higher Ki-67 index, greater tumor diameter and infiltrative growth. While ENETS version 2006 showed that type 3 g-NEN was well-differentiated or moderate-differentiated, neither type 1 nor type 2, and other g-NENs without basic diseases. Besides, in renewal consensus guidance of ENETS version 2016, description about clinical and histological features altered as "well-differentiated g-NEN can be classified as type 3", but its pathology is still NEC G3. According to such classification, those gastric NET patients with well-differentiated, neither type 1 nor type 2 tumors, seem to be unable to classify. In this article, description about the subtype classification of g-NENs in several guidelines, including ENETS versions 2006, 2012 and 2016, NANETS version 2010 and NCCN version 2016, is introduced and the controversy focuses on type 3 g-NEN definition by ENETS versions 2012 and 2016. Hence, the four-type classification of g-NENs is recommended, which has been written in Chinese Consensus for the Diagnosis and Management of GEP-NEN (version 2016). Well-differentiated gastric NET is classified as type 3, and poor-differentiated gastric NEC as type 4. This four-type classification of g-NENs covers all the patients with g-NENs. Advances on clinical research of g-NENs in China are reviewed and the existing problems are analyzed. We also put forward the research direction in the future.

[Clinicopathological classification and prognostic factors of gastrointestinal neuroendocrine neoplasms: an analysis of 119 cases]

OBJECTIVE

To investigate the clinical characteristics, pathological classification and prognostic factors of gastrointestinal neuroendocrine neoplasms (GI-NENs).

METHODS

Clinicopathological data of 119 GI-NENs patients at Shanghai Renji Hospital from November 2007 to December 2016 were analyzed retrospectively. According to the classification and grading criteria of the WHO Neuroendocrine Tumor 2010 edition, patients were classified pathologically to realize the malignant degree of tumors. The overall survival rate was calculated by Kaplan-Meier curve, the prognostic risk factors were analyzed by Cox regression model, and the factors including the platelet/lymphocyte ratio (PLR) and neutrophil/lymphocyte ratio (NLR) were included in the analysis in addition to the routine clinicopathological factors.

RESULTS

Of 119 patients with GI-NENs, there were 83 cases (69.7%) of male and 36 cases (30.3%) of female. The age of patients ranged from 24 to 86 (median 61) years. Tumor locations included the stomach(n=70, 58.8%), duodenum(n=10, 8.4%), small intestine(n=2, 1.7%), appendix(n=3, 2.5%), colon(n=12, 10.1%), and rectum(n=22, 18.5%). The tumor diameter was 0.6 to 20 cm, the mean diameter was 5.4 cm, and the median diameter was 4 cm. There were 25 cases of G1 neuroendocrine tumor (NET), 7 cases of G2 NET and 87 cases of G3 neuroendocrine carcinoma (NEC). Among the 119 patients, 113 cases (95%) had complete follow-up, and the median follow-up was 75 (1 to 112) months. The 5-years overall survival rate was 58.4%. The survival rate of G1 NET, G2 NET and G3 NEC were 100%, 71.4%, 44.4%, and the difference was statistically significant (P=0.000). Univariate analysis showed that age ≥61 years (P=0.000), tumor located in the stomach, duodenum and colon (P=0.041), tumor size ≥4 cm (P=0.002), pathology classification of G3 NEC (P=0.000), late TNM staging (P=0.000) and blood PLR ≥133 (P=0.017) were associated with lower 5-year survival rate, but blood NLR level was not(P=0.263). Multivariate analysis showed that the patient age (HR=3.036, 95%CI: 1.548 to 5.956, P=0.001), the pathology classification(HR = 1.852, 95%CI:1.099 to 3.122, P=0.021), lymph node metastasis (HR=2.635, 95%CI:1.198 to 5.797, P=0.016) and distant metastasis (HR=2.685, 95%CI:1.383 to 5.214, P=0.004) were independent risk factors affecting the prognosis of patients, but the blood PLR level was not (HR=1.735, 95%CI: 0.947 to 3.176, P=0.074).

CONCLUSIONS

The malignant degree of GI-NEN is quite high, and the prognosis of patients is relatively poor. The age, pathological type and TNM staging are closely related to the prognosis of patients. Preoperative blood PLR may play a role in the prediction of prognosis, but preoperative blood NLR is not related with the prognosis of patients.

Risk of Recurrence in Pituitary Neuroendocrine Tumors: A Prospective Study Using a Five-Tiered Classification

BACKGROUND

Most pituitary neuroendocrine tumors (PitNETs) show benign behavior, but a substantial number are invasive, recur, or resist medical treatment. Based on a retrospective case-control study, we recently proposed a classification of PitNETs of prognostic relevance. This prospective study aims to test the value of this classification in an independent patient cohort.

METHODS

All patients who underwent PitNET surgery from 2007 to 2012 in one single center were included. Using a grading system based on invasion on magnetic resonance imaging, immunocytochemical profile, Ki-67, mitotic index, and p53 positivity, tumors were classified. Progression-free survival of the graded tumors was calculated by the Kaplan-Meier method and compared using the log-rank test. A multivariate analysis, using a Cox regression model, was also performed.

RESULTS

In total, 365 patients had grade 1a PitNETs (51.2%), followed by grade 2a (32.3%), 2b (8.8%), and 1b tumors (7.7%). Of 213 patients with a follow-up, 42% had recurrent (n = 52) or progressive disease (n = 37) at 3.5 years. Grade was a significant predictor of progression-free survival (P < 0.001). Multivariate analysis indicated grade (P < 0.001), age (P = 0.035), and tumor type (P = 0.028) as independent predictors of recurrence and/progression. This risk was 3.72-fold higher for a grade 2b tumor compared with grade 1a tumor.

CONCLUSIONS

Our data suggest that classification of PitNETs into five grades is of prognostic value to predict postoperative tumor behavior and identifies patients who have a high risk of early recurrence or progression. It therefore will allow clinicians to adapt their therapeutic strategies and stratify patients in future clinical trials.

Gastrointestinal neuro-endocrine tumors: retrospective study of 36 cases

BACKGROUND

Neuroendocrine tumors (NETs) of the gastrointestinal tract are a heterogeneous group of tumors which have different malignant potential and evolution. The World Health Organization (WHO) has set up a new classification of gastrointestinal NETs in 2010. However, it does not evaluate the risk of malignancy for each tumor.

AIM

To evaluate the prognostic impact of the WHO classification in 2010 by reclassifying the tumor according to new recommendations and to identify histoprognostic factors to better predict changes.

METHODS

This is a descriptive retrospective study of 36 cases of gastrointestinal NETs, collected at the pathological anatomy department in Rabta hospital, over a period of 11 years from 2003 to 2013.

RESULTS

Our series included 11 NETs of Appendix, nine of the pancreas, seven of the small bowel, four of the stomach, three of the rectum, one of the colon and one of the esophagus. The mean age of patients across all sites, was 50.3 years old and the sex ratio was 0,44. The tumors were classified according to the 2010 WHO classification. They were divided into: G1 in 27 cases (75%); G2 in three cases (8.3%); G3 small cell carcinoma in two cases (5.6%); G3 large cell carcinoma in one case (2.8%) and mixed adeno-neuroendocrine carcinoma in three cases (8.3%).

CONCLUSION

Our study has shown limits of the latest 2010 WHO classification of NETs. The prognosis of these tumors could be better predicted by the evaluation of other histoprognostic factors and by the improvement of criteria defining histological degrees including tumor size.

GASTRIC NEUROENDOCRINE TUMOR: REVIEW AND UPDATE

INTRODUCTION

The frequency of gastric neuroendocrine tumors is increasing. Reasons are the popularization of endoscopy and its technical refinements. Despite this, they are still poorly understood and have complex management.

AIM

Update the knowledge on gastric neuroendocrine tumor and expose the future perspectives on the diagnosis and treatment of this disease.

METHOD

Literature review using the following databases: Medline/PubMed, Cochrane Library and SciELO. Search terms were: gastric carcinoid, gastric neuroendocrine tumor, treatment. From the selected articles, 38 were included in this review.

RESULTS

Gastric neuroendocrine tumors are classified in four clinical types. Correct identification of the clinical type and histological grade is fundamental, since treatment varies accordingly and defines survival.

CONCLUSION

Gastric neuroendocrine tumors comprise different subtypes with distinct management and prognosis. Correct identification allows for a tailored therapy. Further studies will clarify the diseases biology and improve its treatment.

From pituitary adenoma to pituitary neuroendocrine tumor (PitNET): an International Pituitary Pathology Club proposal

The classification of neoplasms of adenohypophysial cells is misleading because of the simplistic distinction between adenoma and carcinoma, based solely on metastatic spread and the poor reproducibility and predictive value of the definition of atypical adenomas based on the detection of mitoses or expression of Ki-67 or p53. In addition, the current classification of neoplasms of the anterior pituitary does not accurately reflect the clinical spectrum of behavior. Invasion and regrowth of proliferative lesions and persistence of hormone hypersecretion cause significant morbidity and mortality. We propose a new terminology, pituitary neuroendocrine tumor (PitNET), which is consistent with that used for other neuroendocrine neoplasms and which recognizes the highly variable impact of these tumors on patients.

A Step-by-Step Clinical Approach for the Management of Neuroendocrine Tumours

Neuroendocrine tumours (NET) are rare neoplasms, but the incidence is permanently increasing. Most of the NETs are slow proliferating and clinically silent, and for that reason, they are often diagnosed at a stage with advanced disease. The complexity and diversity of the NET-biology require the treatment of patients in specialised centres to guarantee a qualified, multidisciplinary treatment planning. At our institution, we developed an interdisciplinary model for the assessment and treatment of NET. The aim was to adapt the guidelines to the clinical practice, exchange of current knowledge, and a tailored approach to the individual patient. In our team are included medical professionals from pathology, radiology, oncology, gastroenterology, oncological surgery, and nuclear medicine. In this paper, we describe step-by-step a procedural algorithm for the management of patients with neuroendocrine tumours, focusing on midgut-NETs in terms of therapy.

Trends in Incidence of Neuroendocrine Neoplasms in Norway: A Report of 16,075 Cases from 1993 through 2010

BACKGROUND

Epidemiological studies show an increasing trend in the incidence of neuroendocrine neoplasms (NENs). A significant number of NENs occur in less common primary sites, but they are often excluded from the population-based studies. We studied the incidence trends of all NENs in Norway according to different primary sites.

MATERIALS AND METHODS

Our analyses were based on cancer cases diagnosed between 1993 and 2010 and reported to the national population-based Cancer Registry of Norway. A total of 65 morphological codes were identified as neuroendocrine and stratified into 3 different groups of aggressiveness: low, intermediate and high.

RESULTS

We identified 16,075 NENs of which 49.5% were in women. The median age at diagnosis was 65 years. The most common primary sites were the lung (48.1%) and the gastroenteropancreatic system (18.0%). Stage at diagnosis was local in 40.4% of the cases, regional in 17.5% and distant in 42.1%. The stage distribution was stable throughout the study period. The age-standardized (European) incidence rate (per 100,000 person-years) increased from 13.3 in 1993 to 21.3 in 2010 with an estimated annual increase of 5.1% in women and 2.1% in men. The increase was most pronounced for tumors of intermediate aggressiveness from 3.3 in 1993 to 7.3 in 2010. The largest annual increases were estimated for the adrenal gland (8.8%), the pancreas (6.9%) and the lungs (6.1%).

CONCLUSION

The incidence of NENs increased. Most primary tumors were found in the lungs or in the gastroenteropancreatic system. The increase in the incidence differed according to the primary site, gender and tumor aggressiveness.

Thymic Neuroendocrine Neoplasms: Biological Behaviour and Therapy

Thymic neuroendocrine neoplasms are rare tumours, but their management can often be highly problematic. While previously assumed to be essentially variants of bronchopulmonary (lung) carcinoids, they are generally more aggressive and more difficult to treat. Some 25% are associated with multiple endocrine neoplasia-1, while a higher proportion are associated with the ectopic ACTH syndrome, and occasionally both. We discuss the classification of these tumours, their biology as far as is known, and their clinical, biochemical and imaging features. We also review possible management options and suggest stratagems to optimise their treatment, which even today is far from optimal.

Digestive System Mixed Neuroendocrine-Non-Neuroendocrine Neoplasms

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) are a heterogeneous subgroup of rare neoplasms that represent about a third of all poorly differentiated neuroendocrine carcinomas (PDNEC). MiNEN combine a neuroendocrine component, usually a PDNEC, and a non-neuroendocrine component, generally an adenocarcinoma, both accounting for at least 30% of the neoplasm. MiNEN are classified as high-, intermediate-, or low-grade malignancies depending on the metastatic potential of the tumour components. High-grade malignant component should be considered even if it represents <30% of the tumour. The prognosis of MiNEN is generally intermediate between those of the two "pure" components composing it. The aim of this comprehensive review of the literature is to suggest a standardized management of MiNEN. An increasing body of evidence suggests that PDNEC components share molecular abnormalities with their adenocarcinoma counterparts, but also display additional alterations. This advocates for a common origin, and that the presence of a PDNEC component in an adenocarcinoma could indicate a turning point in carcinogenesis.

Changes in the Epidemiology of Neuroendocrine Tumours

BACKGROUND

The reviewing and assessment of epidemiological characteristics of neuroendocrine tumours (NETs) remains a challenge. Despite the fact that it is an uncommon family of neoplasms, several worldwide series have revealed an increasing incidence of this rare condition. However, the data are difficult to compare over time due to changes in classification.

METHODS

We compared the data related to incidence, prevalence, stage of the disease at diagnosis and survival reported in several series, focusing on the differences and trying to examine some of the probable reasons that may explain the variations in the results between studies.

RESULTS AND CONCLUSIONS

The incidence of NETs is increasing over time, and their incidental discovery due to improved and more frequent imaging does not seem to be enough to explain this rise. Significant differences can be found between geographic regions and races, suggesting that environmental or genetic factors may contribute to the clinical and biological behaviour of these tumours; increasing our knowledge of oncogenesis will be necessary to explain them. As with other rare diseases, creating specific databases and multidisciplinary working groups would improve the accuracy of the information gained.

Mixed Neuroendocrine-Nonneuroendocrine Neoplasms (MiNENs): Unifying the Concept of a Heterogeneous Group of Neoplasms

The wide application of immunohistochemistry to the study of tumors has led to the recognition that epithelial neoplasms composed of both a neuroendocrine and nonneuroendocrine component are not as rare as traditionally believed. It has been recommended that mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are classified as only those in which either component represents at least 30 % of the lesion but this cutoff has not been universally accepted. Moreover, since their pathogenetic and clinical features are still unclear, mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are not included as a separate clinicopathological entity in most WHO classifications, although they have been observed in virtually all organs. In the WHO classification of digestive tumors, mixed neuroendocrine-nonneuroendocrine neoplasm is considered a specific type and is defined as mixed adenoneuroendocrine carcinoma, a definition that has not been accepted for other organs. In fact, this term does not adequately convey the morphological and biological heterogeneity of digestive mixed neoplasms and has created some misunderstanding among both pathologists and clinicians. In the present study, we have reviewed the literature on mixed neuroendocrine-nonneuroendocrine epithelial neoplasms reported in the pituitary, thyroid, nasal cavity, larynx, lung, digestive system, urinary system, male and female genital organs, and skin to give the reader an overview of the most important clinicopathological features and morphological criteria for diagnosing each entity. We also propose to use the term "mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN)" to define and to unify the concept of this heterogeneous group of neoplasms, which show different characteristics mainly depending on the type of neuroendocrine and nonneuroendocrine components.

Neuroendocrine neoplasms of liver - A 5-year retrospective clinico-pathological study applying World Health Organization 2010 classification

AIM

To study the clinicopathological characteristics of neuroendocrine neoplasms (NEN) on liver samples and apply World Health Organization (WHO) 2010 grading of gastroenteropancreatic (GEP) NEN.

METHODS

Clinicopathological features of 79 cases of NEN of the liver diagnosed between January 2011 to December 2015 were analyzed. WHO 2010 classification of GEP NEN was applied and the tumors were graded as G1, G2 or G3. Two more categories, D1/2 (discordant 1/2) and D2/3 (discordant 2/3) were also applied. The D1/2 grade tumors had a mitotic count of G1 and Ki-67 index of G2. The D2/3 tumors had a mitotic count of G2 and Ki-67 index of G3. The follow up details which were available till the end of the study period (December 2015) were collected.

RESULTS

Of the 79 tumors, 16 each were G1 and G2, and 18 were G3 tumors. Of the remaining 29 tumors, 13 were assigned to D1/2 and 16 were D2/3 grade. Male preponderance was noted in all tumors except for G2 neoplasms, which showed a slight female predilection. The median age at presentation was 47 years (range 10-82 years). The most common presentation was abdominal pain (81%). Pancreas (49%) was the most common site of primary followed by gastrointestinal tract (24.4%) and lungs (18%). Radiologically, 87% of the patients had multiple liver lesions. Histopathologically, necrosis was seen in only D2/3 and G3 tumors. Microvascular invasion was seen in all grades. Metastasis occurred in all grades of primary NEN and the grades of the metastatic tumors and their corresponding primary tumors were similar in 67% of the cases. Of the 79 patients, 36 had at least one follow up visit with a median duration of follow up of 8.5 mo (range: 1-50 mo). This study did not show any impact of the grade of tumor on the short term clinical outcome of these patients.

CONCLUSION

Liver biopsy is an important tool for clinicopathological characterization and grading of NEN, especially when the primary is not identified. Eighty-seven percent of the patients had multifocal liver lesions irrespective of the WHO grade, indicating a higher stage of disease at presentation. Follow up duration was inadequate to derive any meaningful conclusion on long term outcome in our study patients.

Digestive neuroendocrine tumors: reclassifying of 26 cases according to 2010 who classification

BACKGROUND

The classification of digestive neuroendocrine tumors is difficult due to their heterogeneity and rareness.

AIMS

Reclassify the digestive neuroendocrine tumors according  to  the  WHO-2010 classification .  Methods: A retrospective study included   26 patients having digestive neuroendocrine     tumors ,  is achieved  in our  Pathology  Laboratory  of the Military Hospital of  Tunis between 2000 and 2013.

RESULTS

The mean age of patients was 49.64 years. The Sex ratio was  1.36. It was 6 gastric tumors, 5 small intestine tumors , 5 pancreatic tumors, 5  appendix tumors , one hypatic tumor, one  gall bladder  tumor , one rectal tumor and one colon tumor. According to the WHO -2000 classification, tumors are categorised into 11 well differentiated  endocrine tumors, 13 well differentiated  endocrine carcinoma  and 2 poorly differentiated carcinoma . According to the WHO -2010 classification, tumors were re-evaluated as  16 neuroendocrine tumors grade 1, 6 neuroendocrine tumors grade 2 and 4 neuroendocrine carcinoma .

CONCLUSION

There was a concordance between the two classifications in 93% of cases. The WHO -2010 classification may allow a  better classification for the digestive neuroendocrine tumors, however there are some histological categories that remained difficult to classify.