Resection Versus Observation of Small Asymptomatic Nonfunctioning Pancreatic Neuroendocrine Tumors

Factors Affecting Nonfunctioning Small Pancreatic Neuroendocrine Neoplasms and Proposed New Treatment Strategies

BACKGROUND & AIMS

Despite previously reported treatment strategies for nonfunctioning small (≤20 mm) pancreatic neuroendocrine neoplasms (pNENs), uncertainties persist. We aimed to evaluate the surgically resected cases of nonfunctioning small pNENs (NF-spNENs) in a large Japanese cohort to elucidate an optimal treatment strategy for NF-spNENs.

METHODS

In this Japanese multicenter study, data were retrospectively collected from patients who underwent pancreatectomy between January 1996 and December 2019, were pathologically diagnosed with pNEN, and were treated according to the World Health Organization 2019 classification. Overall, 1490 patients met the eligibility criteria, and 1014 were included in the analysis cohort.

RESULTS

In the analysis cohort, 606 patients (59.8%) had NF-spNENs, with 82% classified as grade 1 (NET-G1) and 18% as grade 2 (NET-G2) or higher. The incidence of lymph node metastasis (N1) by grade was significantly higher in NET-G2 (G1: 3.1% vs G2: 15.0%). Independent factors contributing to N1 were NET-G2 or higher and tumor diameter ≥15 mm. The predictive ability of tumor size for N1 was high. Independent factors contributing to recurrence included multiple lesions, NET-G2 or higher, tumor diameter ≥15 mm, and N1. However, the independent factor contributing to survival was tumor grade (NET-G2 or higher). The appropriate timing for surgical resection of NET-G1 and NET-G2 or higher was when tumors were >20 and >10 mm, respectively. For neoplasms with unknown preoperative grades, tumor size >15 mm was considered appropriate.

CONCLUSIONS

NF-spNENs are heterogeneous with varying levels of malignancy. Therefore, treatment strategies based on tumor size alone can be unreliable; personalized treatment strategies that consider tumor grading are preferable.

Race and Odds of Surgery Offer in Small Bowel and Pancreas Neuroendocrine Neoplasms

BACKGROUND

Despite existing society guidelines, management of pancreatic (PanNEN) and small bowel (SBNEN) neuroendocrine neoplasms remains inconsistent. The purpose of this study was to identify patient- and/or disease-specific characteristics associated with increased odds of being offered surgery for PanNEN and SBNEN.

PATIENTS AND METHODS

The Surveillance, Epidemiology, and End Results (SEER) Program database and the National Cancer Database (NCDB) were queried for patients with PanNEN/SBNEN. Demographic and pathologic data were compared between patients who were offered surgery and those who were not. Multivariate logistic regression was performed to identify factors independently associated with being offered surgery.

RESULTS

In SEER, there were 3641 patients with PanNEN (54.7% were offered surgery) and 5720 with SBNEN (86.0% were offered surgery). On multivariate analysis of SEER, non-white race was associated with decreased odds of surgery offer for SBNEN [odds ratio (OR) 0.58, p < 0.001], but not PanNEN (p = 0.187). In NCDB, there were 28,483 patients with PanNEN (57.5% were offered surgery) and 42,675 with SBNEN (86.9% were offered surgery). On multivariate analysis of NCDB, non-white race was also associated with decreased odds of surgery offer for SBNEN (OR 0.61, p < 0.001) but not PanNEN (p = 0.414).

CONCLUSIONS

This study's findings suggest that, in addition to previously reported disparities in surgical resection and surgery refusal rates, racial/ethnic disparities also exist earlier in the course of treatment, with non-white patients being less likely to be offered surgery for SBNEN but not for PanNEN; this is potentially due to discrepancies in rates of referral to academic centers for pancreas and small bowel malignancies.

Resistant gastroenteropancreatic neuroendocrine tumors: a definition and guideline to medical and surgical management

Gastroenteropancreatic neuroendocrine tumors (NETs), also historically known as carcinoids, are tumors derived of hormone-secreting enteroendocrine cells. Carcinoids may be found in the esophagus, stomach, small intestine, appendix, colon, rectum, or pancreas. The biologic behavior of carcinoids differs based on their location, with gastric and appendiceal NETs among the least aggressive and small intestinal and pancreatic NETs among the most aggressive. Ultimately, however, biologic behavior is most heavily influenced by tumor grade. The incidence of NETs has increased by 6.4 times over the past 40 years. Surgery remains the mainstay for management of most carcinoids. Medical management, however, is a useful adjunct and/or definitive therapy in patients with symptomatic functional carcinoids, in patients with unresectable or incompletely resected carcinoids, in some cases of recurrent carcinoid, and in postoperative patients to prevent recurrence. Functional tumors with persistent symptoms or progressive metastatic carcinoids despite therapy are called "resistant" tumors. In patients with unresectable disease and/or carcinoid syndrome, an array of medical therapies is available, mainly including somatostatin analogues, molecular-targeted therapy, and peptide receptor radionuclide therapy. Active research is ongoing to identify additional targeted therapies for patients with resistant carcinoids.

Development and validation of CT-based radiomics deep learning signatures to predict lymph node metastasis in non-functional pancreatic neuroendocrine tumors: a multicohort study

Background

Lymph node status is an important factor for the patients with non-functional pancreatic neuroendocrine tumors (NF-PanNETs) with respect to the surgical methods, prognosis, recurrence. Our aim is to develop and validate a combination model based on contrast-enhanced CT images to predict the lymph node metastasis (LNM) in NF-PanNETs.

Methods

Retrospective data were gathered for 320 patients with NF-PanNETs who underwent curative pancreatic resection and CT imaging at two institutions (Center 1, n = 236 and Center 2, n = 84) between January 2010 and March 2022. RDPs (Radiomics deep learning signature) were developed based on ten machine-learning techniques. These signatures were integrated with the clinicopathological factors into a nomogram for clinical applications. The evaluation of the model's performance was conducted through the metrics of the area under the curve (AUC).

Findings

The RDPs showed excellent performance in both centers with a high AUC for predicting LNM and disease-free survival (DFS) in Center 1 (AUC, 0.88; 95% CI: 0.84-0.92; DFS, p < 0.05) and Center 2 (AUC, 0.91; 95% CI: 0.85-0.97; DFS, p < 0.05). The clinical factors of vascular invasion, perineural invasion, and tumor grade were associated with LNM (p < 0.05). The combination nomogram showed better prediction capability for LNM (AUC, 0.93; 95% CI: 0.89-0.96). Notably, our model maintained a satisfactory predictive ability for tumors at the 2-cm threshold, demonstrating its effectiveness across different tumor sizes in Center 1 (≤2 cm: AUC, 0.90 and >2 cm: AUC, 0.86) and Center 2 (≤2 cm: AUC, 0.93 and >2 cm: AUC, 0.91).

Interpretation

Our RDPs may have the potential to preoperatively predict LNM in NF-PanNETs, address the insufficiency of clinical guidelines concerning the 2-cm threshold for tumor lymph node dissection, and provide precise therapeutic strategies.

Funding

This work was supported by JSPS KAKENHI Grant Number JP22K20814; the Rare Tumor Research Special Project of the National Natural Science Foundation of China (82141104) and Clinical Research Special Project of Shanghai Municipal Health Commission (202340123).

Surgical Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are relatively uncommon malignancies, characterized as either functional or nonfunctional secondary to their secretion of biologically active hormones. A wide range of clinical behavior can be seen, with the primary prognostic indicator being tumor grade as defined by the Ki67 proliferation index and mitotic index. Surgery is the primary treatment modality for PNETs. While functional PNETs should undergo resection for symptom control as well as potential curative intent, nonfunctional PNETs are increasingly managed nonoperatively. There is increasing data to suggest small, nonfunctional PNETs (less than 2 cm) are appropriate follow with nonoperative active surveillance. Evidence supports surgical management of metastatic disease if possible, and occasionally even surgical management of the primary tumor in the setting of widespread metastases. In this review, we highlight the evolving surgical management of local and metastatic PNETs.

Small nonfunctional pancreatic neuroendocrine neoplasms: Time for a step-up treatment approach?

Surgery has been regarded as the only curative treatment for patients with small nonfunctional pancreatic neuroendocrine neoplasms (NF-PNENs) less than 2 cm. Due to the significant adverse event rates of surgery, the European Neuroendocrine Tumor Society issued guidelines favoring surveillance for those patients lacking criteria suggestive of an aggressive disease. Despite the above recommendations, a significant proportion of small NF-PNEN patients still undergo surgery. Recently, several studies have reported the safety and effectiveness of EUS-guided radiofrequency ablation (RFA) for the treatment of small NF-PNENs. The experience with EUS-RFA is, however, limited, but published results indicate a potential role as a minimally invasive alternative treatment for these patients, in particular in those in whom further progression is more probable, before they reach the absolute need for surgery. A step-up approach with EUS-RFA followed by surgery for the failure cases can become a valid option to be validated in clinical studies.

The Evolving Landscape of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) represent a heterogeneous group of tumors, with variable presentation based on the location of origin and degree of metastatic spread. There are no randomized control trials to guide surgical management; however, surgery remains the mainstay of treatment for most gastroenteropancreatic NETs based on retrospective studies. Metastatic disease is common at the time of presentation, particularly in the liver. There is a role for cytoreduction for improvement of both symptoms and survival. Robust prospective randomized data exists to support the use of medical therapies to improve progression-free and overall survival in patients with advanced, metastatic, and unresectable NETs.

Management of Small Nonfunctioning Pancreatic Neuroendocrine Neoplasms: Current Opinion and Controversies

The incidence of small and asymptomatic pancreatic neuroendocrine neoplasms (PNENs) has increased due to the widespread use of high-resolution diagnostic imaging in screening programs. Most PNENs are slow-growing indolent neoplasms. However, a local invasion or metastasis can sometimes occur with PNENs, leading to a poor prognosis. The management of small, nonfunctioning PNENs remains under debate. The National Comprehensive Cancer Network guidelines recommend observation in selected cases of small PNENs less than 2 cm. Pancreatic surgery remains a high-risk operation with a 28-30% morbidity and 1% mortality. Therefore, the decision on how to manage small PNENs is challenging. This review focuses on the management of small nonfunctioning PNENs. We also highlight the malignant potential of small PNENs according to tumor size, tumor grade, and tumor biomarker. Endoscopic-ultrasound-guided biopsy is recommended to evaluate the potential risk of malignancy. Furthermore, we discuss the current guidelines and future directions for the management of small PNENs.

A novel tool to predict nodal metastasis in small pancreatic neuroendocrine tumors: A multicenter study

BACKGROUND

Nonfunctional pancreatic neuroendocrine tumors display a wide range of biological behavior, and nodal disease is associated with metastatic disease and poorer survival. The aim of this study was to develop a tool to predict nodal disease in patients with small (≤2 cm) nonfunctional pancreatic neuroendocrine tumors.

METHODS

A multicenter retrospective study was performed on patients undergoing resection for small nonfunctional pancreatic neuroendocrine tumors. Patients with genetic syndromes, metastatic disease at diagnosis, neoadjuvant therapy, or positive resection margin were excluded. Factors associated with nodal disease were identified to develop a predictive model. Internal validation was performed using bootstrap with 1,000 resamples.

RESULTS

Nodal disease was observed in 39 (11.1%) of the 353 patients included. Presence of nodal disease was significantly associated with lower 5-year disease-free survival (71.6% vs 96.2%, P < .001). Two predictors were strongly associated with nodal disease: G2 grade (odds ratio: 3.51, 95% confidence interval: 1.71-7.22, P = .001) and tumor size (per mm increase, odds ratio: 1.14, 95% confidence interval: 1.03-1.25, P = .009). Adequate discrimination was observed with an area under the curve of 0.71 (95% confidence interval: 0.63-0.80). Based on risk distribution, 3 risk groups of nodal disease were identified; low (<5%), intermediate (≥5% to <20%), and high (≥20%) risk. The observed mean risk of nodal disease was 3.7% in the low-risk patients, 9.6% in the intermediate-risk patients, and 30.4% in the high-risk patients (P < .001). The 10-year disease-free survival in the low, intermediate, and high-risk groups was 100%, 88.8%, and 50.1%, respectively.

CONCLUSION

Our model using tumor grade and size can predict nodal disease in small nonfunctional pancreatic neuroendocrine tumors. Integration of this tool into clinical practice could help guide management of these patients.

[Controversy: asymptomatic small pancreatic neuroendocrine neoplasms : Current standards in diagnostics and treatment]

BACKGROUND

For the increasingly diagnosed entity of small asymptomatic, sporadic, nonfunctional, pancreatic neuroendocrine neoplasms (pNEN), a negligible or at least unclear prognostic relevance of the disease for patient survival has often been observed.

OBJECTIVE

Safety and acceptance of a watch-and-wait strategy versus surgical resection for small, asymptomatic nonfunctional (NF) pNEN.

METHODS

Presentation and evaluation of the relevant literature as well as the corresponding national and European guidelines.

RESULTS

Surgery of small NF-pNEN shows complication rates of 15-32% (Clavien-Dindo ≥ 3) and a mortality of 3.6%. Even for pNEN < 2 cm the presence of lymph node metastases has been observed in 11% of cases, while their prognostic relevance in G1-pNEN compared with active surveillance remains unclear. On average 14% of patients under active surveillance for small NF-pNEN, underwent a resection. Relevant tumor growth during surveillance was found in < 20% of cases. In all well-selected surveillance cohorts no metachronous lymphatic or distant metastases occurred during active surveillance and especially no cases of a metachronous no longer curable disease.

CONCLUSION

Even small asymptomatic NF-pNEN have a certain metastatic potential but the clinical relevance has prospectively not yet been clearly determined. Controlled surveillance of these tumors is at least an alternative to immediate tumor resection. Especially patients above 70 years old do not seem to benefit from resection. The pros and cons of a resection should therefore be individually evaluated with the patient.

Impact of Surgery on Non-Functional Pancreatic Neuroendocrine Tumors ≤2 cm: Analyses With Propensity Score–Based Inverse Probability of Treatment Weighting

Purpose

The impact of surgery on non-functional pancreatic neuroendocrine tumors (NF-PNETs) ≤2 cm is controversial. This study sought to demonstrate the impact of surgery on the prognosis of NF-PNETs ≤2 cm with different biological behaviors.

Methods

Patients with NF-PNETs ≤2 cm from 2004 to 2015 in the Surveillance, Epidemiology, and End Results database were included in this study. An inverse probability of treatment weighting (IPTW) method was used to reduce the selection bias. Kaplan–Meier survival analysis and Cox proportional hazards regression were used to evaluate the effect of surgery on the prognosis.

Results

In the IPTW-adjusted Cox proportional hazards regression analysis, surgery improved the cancer-specific survival (CSS) in the overall cohort (hazard ratio [HR], 0.187; 95% confidence interval [CI], 0.102–0.343; p < 0.001), patients with poorly differentiated or undifferentiated tumor grades (HR, 0.238; 95% CI, 0.105–0.64; p < 0.001), patients with distant metastasis (HR, 0.102; 95% CI, 0.021–0.496; p = 0.005), and patients with local invasion (HR, 0.059; 95% CI, 0.005–0.683; p = 0.002). Surgery did not improve the CSS in patients with lymph node metastasis only (HR, 0.26; 95% CI, 0.0462–1.461; p = 0.126) or patients with well or moderate differentiation while without distant and lymph node metastasis (HR, 0.387; 95% CI, 0.146–1.028; p = 0.057).

Conclusions

Among patients with NF-PNETs ≤2 cm, different biological behaviors correlate with different prognostic impacts of surgery. As long as distant metastasis does not occur and the grade is well–moderately differentiated, these patients will not benefit from surgery no matter whether lymph node metastasis occurs or not. However, when local invasion appears in this group of patients, surgery should be performed. Moreover, patients with a tumor grade of poorly differentiated or undifferentiated or those with distant metastases may benefit from surgery.

Evaluation of Risk Factors for Distant and Lymph Node Metastasis of Pancreatic Neuroendocrine Tumors

Purpose

Metastases of pancreatic neuroendocrine tumors (pNETs) can be found at the time of diagnosis in 20–50% of cases. Small asymptomatic tumors may be left for observation; however, they can metastasize. The aim of the study was to evaluate risk factors for distant and lymph node metastases of pNETs.

Patients and methods

One hundred and fourteen patients with postoperatively confirmed pNET were analyzed retrospectively in a single ENETS Center of Excellence. The relationship between location, size, differentiation of the tumor, and occurrence of lymph node and distant metastases was analyzed.

Results

pNETs’ location was pancreatic head – 38 (33.3%), body or tail – 68 (59.7%), and 8 (7.0%) involved the entire organ. Fifty-six (49.1%) tumors were graded G1, 50 (43.9%) G2, and 8 (7.0%) G3. Seventy-two (63.2%) tumors were ≥2 cm in diameter, and 42 (36.8%) <2 cm. Twenty-two (19.3%) patients had distant metastases and 47 (41.2%) had lymph node metastases. In ≥2 cm tumors distant and lymph node metastases were more frequent (p < 0.05). Distant metastases incidence was significantly higher in distally located tumors (p = 0.01) and in G2 and G3 tumors (p < 0.01). In 9.5% of <2cm tumors, distant metastases were present at diagnosis.

Conclusion

Distant metastases are more often found in larger, distally located pNETs grade G2 and G3, while a higher occurrence of lymph node metastases seems to be associated only with larger tumor size. A considerable number of tumors <2 cm in size have distant metastases already at the diagnosis, which might indicate the need for careful qualification of smaller lesions for observation.

Current updates and future directions in diagnosis and management of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms are a heterogenous group of rare neoplasms that are increasingly being discovered, often incidentally, throughout the gastrointestinal tract with varying degrees of activity and malignant potential. Confusing nomenclature has added to the complexity of managing these lesions. The term carcinoid tumor and embryonic classification have been replaced with gastroenteropancreatic neuroendocrine neoplasm, which includes gastrointestinal neuroendocrine and pancreatic neuroendocrine neoplasms. A comprehensive multidisciplinary approach is important for clinicians to diagnose, stage and manage these lesions. While histological diagnosis is the gold standard, recent advancements in endoscopy, conventional imaging, functional imaging, and serum biomarkers complement histology for tailoring specific treatment options. In light of developing technology, our review sets out to characterize diagnostic and therapeutic advancements for managing gastroenteropancreatic neuroendocrine tumors, including innovations in radiolabeled peptide imaging, circulating biomarkers, and endoscopic treatment approaches adapted to different locations throughout the gastrointestinal system.

Value of lymphadenectomy in patients with surgically resected pancreatic neuroendocrine tumors

BACKGROUND

Although some factors that predict the prognosis in pancreatic neuroendocrine tumor (pNET) have been confirmed, the predictive value of lymph node metastasis (LNM) in the prognosis of pNETs remains conflicting and it is not clear whether regional lymphadenectomy should be performed in all grades of tumors.

METHODS

We included pNET patients undergoing surgery in Shanghai pancreatic cancer institute (SHPCI). The risk factors for survival were investigated by the Kaplan-Meier method and Cox regression model. We evaluated the predictors of LNM using Logistic regression.

RESULTS

For 206 patients in the SHPCI series, LNM was an independent prognostic factor for entire cohort suggested by multivariate Cox regression analysis. LNM (P = 0.002) predicted poorer overall survival (OS) in grade 2/3 cohort, but there is no significant association between LNM and OS in grade 1 cohort. Grade (P < 0.001) and size (P = 0.049) predicted LNM in entire cohort. Grade (P = 0.002) predicted LNM while regardless of size in grade 2/3 cohort.

CONCLUSIONS

Based on our own retrospective data obtained from a single center series, LNM seems to be associated with poorer outcome for patients with grade 2/3 and/or grade 1 > 4 cm tumors. On the other way, LNM was seems to be not associated with prognosis in patients with grade 1 tumors less than 4 cm. Moreover, tumor grade and tumor size seem to act as independent predictors of LNM. Thus, regional lymphadenectomy should be performed in grade 2/3 patients but was not mandatory in grade 1 tumors < 4 cm. It is reasonable to perform functional sparing surgery for grade 1 patients or propose a clinical-radiological monitoring.

Therapeutic strategies for gastroenteropancreatic neuroendocrine neoplasms: State-of-the-art and future perspectives

Although gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have always been considered rare tumors, their incidence has risen over the past few decades. They represent a highly heterogeneous group of neoplasms with several prognostic factors, including disease stage, proliferative index (Ki67), and tumor differentiation. Most of these neoplasms express somatostatin receptors on the cell surface, a feature that has important implications in terms of prognosis, diagnosis, and therapy. Although International Guidelines propose algorithms aimed at guiding therapeutic strategies, GEP-NEN patients are still very different from one another, and the need for personalized treatment continues to increase. Radical surgery is always the best option when feasible; however, up to 80% of cases are metastatic upon diagnosis. Regarding medical treatments, as GEP-NENs are characterized by relatively long overall survival, multiple therapy lines are adopted during the lifetime of these patients, but the optimum sequence to be followed has never been clearly defined. Furthermore, although new molecular markers aimed at predicting the response to therapy, as well as prognostic scores, are currently being studied, their application is still far from being part of daily clinical practice. As they represent a complex disease, with therapeutic protocols that are not completely standardized, GEP-NENs require a multidisciplinary approach. This review will provide an overview of the available therapeutic options for GEP-NENs and attempts to clarify the possible approaches for the management of these patients and to discuss future perspectives in this field.

Reappraisal of a 2-cm Cutoff Size for the Management of Nonfunctional Pancreatic Neuroendocrine Tumors: A Population-Based Study

BACKGROUND

Expectant observation and aggressive surgery are both recommended for small nonfunctional pancreatic neuroendocrine tumors (NF-PanNETs). However, the optimal management of small NF-PanNETs remains disputable due to the heterogeneous clinical behavior.

METHODS

Patients who were diagnosed with pancreatic neuroendocrine neoplasms (PanNENs) between 2000 and 2018 were identified from the surveillance, epidemiology, and end results (SEER) database and reviewed retrospectively. Tumor aggressiveness was defined as poor differentiation, lymph node involvement, liver involvement, and advanced stage. The best cutoff of tumor size associated with tumor aggressiveness was determined through the receiver operating characteristic (ROC) curve analysis. Univariate and multivariate analyses were used to identify prognostic factors in patients with tumors of ≤2 cm.

RESULTS

A total of 5,172 patients with PanNENs were enrolled, including 1,760 (34.0%) tumors ≤2 cm and 3,412 (66.0%) tumors >2 cm. A 2.5-cm cutoff size was found to be associated with a satisfactory ability in predicting tumor aggressiveness. On multivariate analysis, age, gender, ethnicity, tumor grade, tumor number, and stage were independent prognostic factors for overall survival (OS) in patients with tumors less than or equal to 2 cm in size. A total of 1,621 patients were diagnosed with NF-PanNETs according to the WHO classification, of whom 1,350 underwent surgery, 271 performed active observation. The OS was significantly better in the surgery group compared to the observation group regardless of propensity score analysis. Additionally, a total of 407 patients were selected based on the multivariate Cox regression analysis, of whom 46 underwent observation, 361 underwent surgery, and the OS was comparable.

CONCLUSION

Expectant observation may be a reasonable alternative to aggressive surgical resection in highly selected small NF-PanNET patients. Also, the decision to observe versus surgery should not only be based on tumor size alone but also take into account other important clinicopathological factors.

Observation Versus Resection for Small, Localized, and Nonfunctional Pancreatic Neuroendocrine Tumors: A Propensity Score Matching Study

OBJECTIVES

The best treatment modalities for small (1-2 cm), localized, and nonfunctional pancreatic neuroendocrine tumors remain controversial. Therefore, we aimed to evaluate whether surgical resection provides survival benefit over observation in those patients.

METHODS

From 1973 to 2015, all eligible patients were retrieved from the Surveillance, Epidemiology, and End Results database. Propensity score matching (1:2) method was performed. The primary endpoints evaluated were overall survival (OS) and cancer-specific survival (CSS).

RESULTS

We identified 681 patients, of which 122 and 559 patients received observation and resection, respectively. Propensity score-matched patients who underwent surgery (n = 183) had significantly improved OS (P = 0.008) compared with matched patients who underwent observation (n = 106), but there was no difference in CSS (P = 0.310). On multivariate analysis, resection could improve OS but not CSS. Besides, poorly differentiated/undifferentiated tumor had a worse OS and CSS. Subgroup analysis showed that patients 60 years and older who underwent resection could achieve a longer OS and CSS.

CONCLUSIONS

This disease exhibits a very good prognosis. Patients undergoing resection were associated with comparable 5-year CSS but longer 5-year OS compared with those receiving observation. Elderly patients (≥60) may obtain benefit from surgery, whereas the treatment of younger patients should be individualized.

What Are the Place and Modalities of Surgical Management for Pancreatic Neuroendocrine Neoplasms? A Narrative Review

Pancreatic neuroendocrine neoplasms (panNENs) are a heterogeneous group of tumors derived from cells with neuroendocrine differentiation. They are considered malignant by default. However, their outcomes are variable depending on their presentation in the onset of hereditary syndromes, hormonal secretion, grading, and extension. Therefore, although surgical treatment has long been suggested as the only treatment of pancreatic neuroendocrine neoplasms, its modalities are an evolving landscape. For selected patients (small, localized, non-functional panNENs), a "wait and see" strategy is suggested, as it is in the setting of multiple neuroendocrine neoplasia type 1, but the accurate size cut-off remains to be established. Parenchyma-sparring pancreatectomy, aiming to limit pancreatic insufficiency, are also emerging procedures, which place beyond the treatment of insulinomas and small non-functional panNENs (in association with lymph node picking) remains to be clarified. Furthermore, giving the fact that the liver is generally the only metastatic site, surgery keeps a place of choice alongside medical therapies in the treatment of metastatic disease, but its modalities and extensions are still a matter of debate. This narrative review aims to describe the current recommended surgical management for pancreatic NENs and controversies in light of the actual recommendations and recent literature.

Management and outcomes of patients for non-functioning pancreatic neuroendocrine tumours: a multi-institutional analysis

BACKGROUND

To analysed the short- and long-term outcomes of patients who underwent surgical resection for non-functioning pancreatic neuroendocrine tumours (NF-PNETs) to gain insights into treatment approaches for this rare and heterogeneous entity.

METHODS

All patients who underwent surgical resection for NF-PNETs at The Second Affiliated Hospital of Guangzhou Medical University, and West China Hospital, Sichuan University, from 2009 to 2019 were retrospectively reviewed. The data of patients was including perioperative management, pathologic analysis and follow-up.

RESULTS

A total of 119 cases with histologically or cytologically confirmed NF-PNETs, The mean age of the patients was 52, and 56.3% were female. Twenty-three patients received post-operative adjuvant therapy, and five of nine (55.6%) patients with distant metastasis showed recurrence 14(60.9%) G2/G3 patients without distant metastasis received post-operative therapy with octreotide. Of these 14 patients, 3 (21.4%) revealed recurrence. Univariate analysis indicated that symptoms (P = 0.03), tumour size >4 cm (P = 0.029), ENETS stages III-IV (P < 0.001), positive lymph nodes (P < 0.001), vascular/perineural invasion (P < 0.001), and pathology grade G2 were associated with significantly higher risks of recurrence; age, gender, surgery type, and tumour location were not. Multivariate analysis revealed that positive lymph nodes (P < 0.001), vascular/peripheral invasion (P < 0.001), and pathology grade G3 (P = 0.03) are significant prognostic factors of tumour recurrence.

CONCLUSION

Positive lymph nodes, vascular/peripheral invasion and pathology grade G3 were related to recurrence of NF-PNETs. Lymph node resection is recommend when FNA biopsy indicates pathology grade G3 for patients with NF-PNETs.

The Landmark Series: Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) comprise a heterogeneous group of neoplasms arising from pancreatic islet cells that remain relatively rare but are increasing in incidence worldwide. While significant advances have been made in recent years with regard to systemic therapies for patients with advanced disease, surgical resection remains the standard of care for most patients with localized tumors. Although formal pancreatectomy with regional lymphadenectomy is the standard approach for most PNETs, pancreas-preserving approaches without formal lymphadenectomy are acceptable for smaller tumors at low risk for lymph node metastases. Furthermore, observation of small, asymptomatic, low-grade PNETs is a safe, initial strategy and is generally recommended for tumors < 1 cm in size. In this Landmark Series review, we highlight the critical studies that have defined the surgical management of PNETs.

Surgical Principles in the Management of Pancreatic Neuroendocrine Neoplasms

OPINION STATEMENT

Pancreatic neuroendocrine neoplasms (PanNENs) are increasingly recognized entities, whose incidence has dramatically grown during the last two decades. Surgery plays a pivotal role in their management as it represents the only chance of cure. Since PanNENs display a wide range of aggressiveness, their surgical management needs to be tailored on tumor's and patient's characteristics. Currently, there are several open questions and burning issues in the field of PanNEN, such as the management of asymptomatic nonfunctioning pancreatic neuroendocrine tumors (NF-PanNET) ≤ 2 cm. An active surveillance of these small lesions has been demonstrated to be safe although the available evidences are only based on retrospective studies. On the other hand, formal pancreatic resection associated with lymphadenectomy represents the gold standard for patients with localized NF-PanNEN > 2 cm or NF-PanNEN ≤ 2 cm in the presence of symptoms, dilation of the main pancreatic duct or suspicion of nodal metastases. Surgery plays also an important role in the setting of metastatic disease. In particular, surgery is generally recommended in the presence of low-grade, resectable, metastatic disease, but several series have reported also a survival benefit of palliative primary tumor resection in patients with unresectable liver metastases. The role of surgery in PanNEN G3 is still controversial. Indeed, surgery is associated with an improved survival in patients with well-differentiated PanNET G3, whereas there is almost no survival benefit in case of poorly differentiated lesions.

Update on the Surgical Treatment of Pancreatic Neuroendocrine Tumors

BACKGROUND AND AIMS

Pancreatic neuroendocrine tumors (PNET) arise from uncontrolled proliferation of neuroendocrine cell and further genetic alterations that may induce hormone secretion such as glucagon/insulin/gastrin/VIP. Their incidence is rapidelly growing, especially because of the frequent incidental diagnosis of small asymptomatic non-functionnal neuroendocrine tumors with the widespread use of cross-sectional imaging. The vast majority of pancreatic neuroendocrine tumors are sporadic but up to 5%-10% of them arise from genetic syndromes, the main one being Multiple Endocrine Neopalsm type 1 (MEN1). Appropriate management of patients with PNET is a complex challenge for surgeons, and require extensive medical collaboration. This review aims to summarize major and recent updates regarding the medico-surgical management of PNETs.

MATERIAL AND METHODS

Review of pertinent English language literature.

RESULTS

This article provides a concise summary of the clinical presentation, diagnosis, surgical management, alternative treatments and follow up of PNETs.

CONCLUSION

PNET are a rare, heterogeneous group of neoplasms with a generally favorable prognosis at least compared to pancreatic adenocarcinoma. Surgical resection is the cornerstone of their management, particularly for localized disease, and should always be discussed in multidisciplinary tumor board.