Prognosis of sporadic resected small (≤2 cm) nonfunctional pancreatic neuroendocrine tumors - a multi-institutional study

Management of Pancreatic Neuroendocrine Tumors: Surgical Strategies and Controversies

OBJECTIVE

Pancreatic neuroendocrine tumors (PNETs) are uncommon tumors which are increasing in incidence. The management of these tumors continues to evolve. This review examines the current role of surgery in the treatment of these tumors.

METHODS

Studies published over the past 10 years were identified using several databases including PubMed, MEDLINE, and Science Direct. Search terms included PNETs, treatment, and surgery. Clinical practice guidelines and updates from several major groups were reviewed.

RESULTS

Surgery continues to have a major role in the treatment of sporadic functional and nonfunctional PNETs. Pancreas-sparing approaches are increasingly accepted as alternatives to formal pancreatic resection in selected patients. Options such as watch and wait or endoscopic ablation may be reasonable alternatives to surgery for non-functional PNETs < 2 cm in size. Surgical decision-making in multiple endocrine neoplasia type 1 patients remains complex and in some situations such as gastrinoma quite controversial. The role of surgery has significantly diminished in patients with advanced disease due to the advent of more effective systemic and liver-directed therapies. However, the optimal treatments and sequencing in advanced disease remain poorly defined, and it has been suggested that surgery is underutilized in these patients.

CONCLUSIONS

Surgery remains a major treatment modality for PNETs. Given the plethora of available treatments, ongoing controversies and the changing landscape, management has become increasingly complex. An experienced multidisciplinary team which includes surgery is essential to manage these patients.

[Gastroenteropancreatic neuroendocrine neoplasms-Surgery in a multimodal concept]

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) are mainly found in the small intestine and pancreas. The course of the disease in patients is highly variable and depends on the degree of differentiation (G1-G3) of the neoplasm. The potential for metastasis formation of GEP-NEN is high even with good differentiation (G1). Lymph node metastases and, in many cases, liver metastases are also often found. Less common are bone metastases or peritoneal carcinomas. The treatment of these GEP-NENs is surgical, whenever possible. If an R0 resection with removal of all lymph node and liver metastases is successful, the prognosis of the patients is excellent. Patients with diffuse liver or bone metastases can no longer be cured by surgery alone. The long-term survival of these patients is nowadays possible due to the availability of drugs (e.g., somatostatin analogues, tyrosine kinase inhibitors), peptide receptor radionuclide therapy (PRRT) and liver-directed procedures, with a good quality of life.

Enucleation for Sporadic Nonfunctioning Pancreatic Neuroendocrine Tumors Larger than 2 Centimeters Is Associated with Equivalent Morbidity and Survival Compared to Smaller Tumors: A Multi-Institutional Study

INTRODUCTION

Nonfunctioning pancreatic neuroendocrine tumor (NF-PanNET) ≤2 cm can be observed or resected. Surgery remains recommended for NF-PanNET >2 cm but its extent, enucleation (EN) versus formal resection, remains controversial.

METHODS

Multicentric retrospective cohort of sporadic NF-PanNET patients treated with EN. Short- and long-term outcomes were compared according to tumor size on imaging ≤2 cm versus >2 cm.

RESULTS

131 patients underwent EN for NF-PanNET, including 103 (79.0%) ≤2 cm and 28 (21.0%) >2 cm (extremes, 4-55 mm). Patients' characteristics were comparable, and tumor characteristics only differed in their diameter. Clavien III-IV complications were similar (18.4% vs. 17.9%, p = 1.00) with one death in NF-PanNET ≤2 cm. Grade B/C pancreatic fistula were comparable (16.5% vs. 10.7%, p = 0.850). In NF-PanNET >2 cm there were more pT2/3 stage tumors (85.7% vs. 21.4%, p < 0.001), similar rates of grade G2/3 tumors (25% vs. 16.5%, p = 0.408) with a median Ki67 of 2 (interquartile range: 1-3), and of lymphovascular and perineural invasions. Lymph node picking was done in 46 (35.1%) patients, with a higher median number of harvested lymph nodes in NF-PanNET >2 cm (4 vs. 3, p = 0.01). All were pN0. R0 resection rate (78.6% vs. 82.5%, respectively; p = 0.670) was equivalent. Five-year overall (100% vs. 99%, p = 0.602) and 10-year disease-free (96% vs. 92%, respectively; p = 0.532) survivals were comparable.

CONCLUSIONS

EN for selected NF-PanNET >2 cm carries equivalent morbidity, overall and disease-free survivals compared to those observed with NF-PanNET ≤2 cm.

Loss of ATRX and DAXX in pancreatic neuroendocrine tumors: Association with recurrence risk, cellular phenotype, and heterogeneity

Pancreatic neuroendocrine tumors (PanNETs) comprise a heterogeneous group of neoplasms in terms of biological behavior. This study aims to develop a practical algorithm based on emerging biomarkers, including chromatin-remodeling molecules DAXX/ATRX/H3K36me3, in conjunction with established prognostic factors, such as WHO grade and size. In immunohistochemical analyses, 18 of the 111 (16.2%) primary PanNETs showed DAXX or ATRX loss in a mutually exclusive manner. DAXX/ATRX loss was significantly correlated with higher recurrence risk and better predicted postoperative recurrence than WHO grade. We proposed a novel algorithm for stratifying patients with resectable PanNET into three groups according to recurrence risk: (A) WHO Grade 1 and ≤2 cm (very low-risk); for the others, (B) retained DAXX/ATRX (low-risk) and (C) DAXX/ATRX complete/heterogeneous loss (high-risk). Furthermore, we elucidated the intratumoral heterogeneities of PanNETs. Among cases with DAXX or ATRX loss, nine cases demonstrated heterogeneous loss of expression of DAXX/ATRX/H3K36me3. The majority of cases with DAXX/ATRX loss, either homogeneous or heterogeneous loss, showed uniform α-cell-like phenotype (ARX1+/PDX1-). In cases of metastatic or recurrent tumors, the expression pattern was identical to that observed in at least part of the primary tumor. In some instances, the expression pattern differed among different metastatic or recurrent tumors of the same patient. In summary, we propose a clinically useful and practical algorithm for postoperative recurrence risk stratification in PanNETs, by combining DAXX/ATRX status with WHO grade and size. Moreover, our findings highlighted the frequent spatiotemporal heterogeneity of chromatin-remodeling molecule expression in PanNETs with an α-cell phenotype, offering insights into tumorigenesis.

Portuguese Pancreatic Club Perspectives on Endoscopic Ultrasound-Guided and Surgical Treatment of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (panNETs) are a group of neoplasms with heterogenous biological and clinical phenotypes. Although historically regarded as rare, the incidence of these tumors has been increasing, mostly owing to improvements in the detection of small, asymptomatic tumors with imaging. The heterogeneity of these lesions creates significant challenges regarding diagnosis, staging, and treatment. Endoscopic ultrasound (EUS) has improved the characterization of pancreatic lesions. Furthermore, EUS nowadays has evolved from a purely diagnostic modality to allow the performance of minimally invasive locoregional therapy for pancreatic focal lesions. The choice of treatment as well as the treatment goals depend on several factors, including tumor secretory status, grading, staging, and patient performance status. Surgery has been the mainstay for the management of these patients, particularly for localized, low-grade, large panNETs >2 cm. Over the last decade, a significant body of evidence has been accumulated evaluating the role of EUS for the ablative therapy of panNETs, namely by the use of chemoablative agents and radiofrequency. Although endoscopic techniques are not routinely recommended by international guidelines, they may be considered for the treatment of smaller lesions in patients who are unwilling or unfit for pancreatic surgery. In this review, we summarize the existing evidence on the interventional techniques for the treatment of patients with panNETs, focusing on the EUS-guided and surgical approaches.

Surgical Management and Long-Term Evaluation of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) arise from neuroendocrine cells and are a rare class of heterogenous tumors with increasing incidence. The diagnosis, staging, treatment, and prognosis of PNETs depend heavily on identifying the histologic features and biological mechanisms. Here, the authors provide an overview of the diagnostic workup (biomarkers and imaging), grade, and staging of PNETs. The authors also explore associated genetic mutations and molecular pathways and describe updated guidelines on surgical and systemic treatment modalities.

Impact of Regional Metastasis on Survival for Patients with Nonfunctional Pancreatic Neuroendocrine Tumors: A Systematic Review

BACKGROUND

Controversy exists regarding the benefit of lymphadenectomy for nonfunctional pancreatic neuroendocrine tumors (NF-PNET).

PATIENTS AND METHODS

MEDLINE/PubMed, EMBASE, and the Cochrane Library were searched for studies of pancreatic neuroendocrine tumors (PNET) published between 1990 and 2021. Studies of functional PNET were excluded. Reported incidence of lymph node metastasis (LNM) and survival analysis of either disease-free survival (DFS) or overall survival (OS) were required for inclusion.

RESULTS

Overall, 52 studies analyzing 24,608 PNET met the inclusion criteria. The reported LNM rate for NF-PNET ranged from 7 to 64 % (median 24.5%). Reported LNM rates ranged from 7 to 51% (median 11%) for NF-PNET< 2 cm in 14 studies and 29-47% (median 38%) in NF-PNET > 2 cm. In total, 19 studies (66%) reported LNM to have a negative impact on DFS. Additionally, 21 studies (60%) reported LNM to have a negative impact on OS. Two studies investigating the impact of lymphadenectomy (LND) found LND had the greatest impact for large, high-grade tumors. The overall quality of available evidence was low as assessed by the Grading of Recommendations, Assessment, Development, and Evaluation System.

CONCLUSIONS

Published literature evaluating the impact of regional LNM and LND in PNET is confounded by heterogeneity in practice patterns and the retrospective nature of these cohort studies. Most studies suggest high rates of LNM in NF-PNET that negatively impact DFS and OS. Given the high rate of LNM in NF-PNET and its potential detrimental effect on DFS and OS, we recommend lymphadenectomy be completed for NF-PNET > 2 cm and strongly considered for NF-PNET < 2 cm.

Long-Term Oncologic Outcome following Duodenum-Preserving Pancreatic Head Resection for Benign Tumors, Cystic Neoplasms, and Neuroendocrine Tumors: Systematic Review and Meta-analysis

BACKGROUND

Pancreatoduodenectomy (PD) has a considerable surgical risk for complications and late metabolic morbidity. Parenchyma-sparing resection of benign tumors has the potential to cure patients associated with reduced procedure-related short- and long-term complications.

MATERIALS AND METHODS

Pubmed, Embase, and Cochrane libraries were searched for studies reporting surgery-related complications following PD and duodenum-preserving total (DPPHRt) or partial (DPPHRp) pancreatic head resection for benign tumors. A total of 38 cohort studies that included data from 1262 patients were analyzed. In total, 729 patients underwent DPPHR and 533 PD.

RESULTS

Concordance between preoperative diagnosis of benign tumors and final histopathology was 90.57% for DPPHR. Cystic and neuroendocrine neoplasms (PNETs) and periampullary tumors (PATs) were observed in 497, 89, and 31 patients, respectively. In total, 34 of 161 (21.1%) patients with intraepithelial papillar mucinous neoplasm exhibited severe dysplasia in the final histopathology. The meta-analysis, when comparing DPPHRt and PD, revealed in-hospital mortality of 1/362 (0.26%) and 8/547 (1.46%) patients, respectively [OR 0.48 (95% CI 0.15-1.58); p = 0.21], and frequency of reoperation of 3.26 % and 6.75%, respectively [OR 0.52 (95% CI 0.28-0.96); p = 0.04]. After a follow-up of 45.8 ± 26.6 months, 14/340 patients with intraductal papillary mucinous neoplasms/mucinous cystic neoplasms (IPMN/MCN, 4.11%) and 2/89 patients with PNET (2.24%) exhibited tumor recurrence. Local recurrence at the resection margin and reoccurrence of tumor growth in the remnant pancreas was comparable after DPPHR or PD [OR 0.94 (95% CI 0.178-5.34); p = 0.96].

CONCLUSIONS

DPPHR for benign, premalignant neoplasms provides a cure for patients with low risk of tumor recurrence and significantly fewer early surgery-related complications compared with PD. DPPHR has the potential to replace PD for benign, premalignant cystic and neuroendocrine neoplasms.

Optimal surgical management of unifocal vs. multifocal NF-PNETs: a respective cohort study

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) represent 1-2% of pancreatic tumors, with recent guidelines recommending active surveillance for non-functioning PNETs (NF-PNETs) smaller than 2 cm. However, the management of multiple NF-PNETs, as well as the influence of tumor number on prognosis, remains under-researched.

METHODS

This retrospective study analyzed NF-PNET patients who underwent pancreatic resection at Severance Hospital between February 1993 and August 2023, comparing the characteristics of patients diagnosed with multifocal tumors and those with unifocal tumors. A subgroup analysis of overall survival (OS) and recurrence-free survival (RFS) was performed based on multifocality employing the Kaplan-Meier method and the log-rank test.

RESULTS

Of 187 patients, 169 (90.4%) had unifocal and 18 (9.6%) had multifocal tumors. Multifocal tumors were more likely to be diffusely spread, necessitating more total pancreatectomies (diffuse tumor location: 4.7% in unifocal vs. 38.9% in multifocal cases, p < 0.001; total pancreatectomy: 4.1% in unifocal vs. 33.3% in multifocal cases, p < 0.001). In patients with NF-PNET who underwent the same extent of pancreatic resection, no significant difference in the incidence of complication was observed regardless of multifocality. Moreover, no significant difference in OS was seen between the unifocal and multifocal groups (log-rank test: p = 0.93). However, the multifocal group exhibited a poorer prognosis in terms of RFS compared to the unifocal group (log-rank test: p = 0.004) Hereditary syndrome, tumor grade, size, lymphovascular invasion, and lymph node metastasis were key factors in the recurrence.

CONCLUSION

This study's findings suggest that the presence of multiple tumors was associated with poorer recurrence-free survival but did not affect long-term survival following surgery. Given the long-term oncologic outcome and quality of life following surgery, resection of tumors over 2 cm is advisable in patients with multifocal PNETs, while a cautious "wait-and-see" approach for smaller tumors (under 2 cm) can minimize the extent of resection and improve the quality of life. In cases with only small multifocal NF-PNETs (< 2 cm), immediate resection may not be crucial, but the higher recurrence rate than that in solitary NF-PNET necessitates intensified surveillance.

Predicting histologic grades for pancreatic neuroendocrine tumors by radiologic image-based artificial intelligence: a systematic review and meta-analysis

Background

Accurate detection of the histological grade of pancreatic neuroendocrine tumors (PNETs) is important for patients' prognoses and treatment. Here, we investigated the performance of radiological image-based artificial intelligence (AI) models in predicting histological grades using meta-analysis.

Method

A systematic literature search was performed for studies published before September 2023. Study characteristics and diagnostic measures were extracted. Estimates were pooled using random-effects meta-analysis. Evaluation of risk of bias was performed by the QUADAS-2 tool.

Results

A total of 26 studies were included, 20 of which met the meta-analysis criteria. We found that the AI-based models had high area under the curve (AUC) values and showed moderate predictive value. The pooled distinguishing abilities between different grades of PNETs were 0.89 [0.84-0.90]. By performing subgroup analysis, we found that the radiomics feature-only models had a predictive value of 0.90 [0.87-0.92] with I2 = 89.91%, while the pooled AUC value of the combined group was 0.81 [0.77-0.84] with I2 = 41.54%. The validation group had a pooled AUC of 0.84 [0.81-0.87] without heterogenicity, whereas the validation-free group had high heterogenicity (I2 = 91.65%, P=0.000). The machine learning group had a pooled AUC of 0.83 [0.80-0.86] with I2 = 82.28%.

Conclusion

AI can be considered as a potential tool to detect histological PNETs grades. Sample diversity, lack of external validation, imaging modalities, inconsistent radiomics feature extraction across platforms, different modeling algorithms and software choices were sources of heterogeneity. Standardized imaging, transparent statistical methodologies for feature selection and model development are still needed in the future to achieve the transformation of radiomics results into clinical applications.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42022341852.

Contemporary Approaches to the Surgical Management of Pancreatic Neuroendocrine Tumors

The incidence of pancreatic neuroendocrine tumors (PNETs) is on the rise primarily due to the increasing use of cross-sectional imaging. Most of these incidentally detected lesions are non-functional PNETs with a small proportion of lesions being hormone-secreting, functional neoplasms. With recent advances in surgical approaches and systemic therapies, the management of PNETs have undergone a paradigm shift towards a more individualized approach. In this manuscript, we review the histologic classification and diagnostic approaches to both functional and non-functional PNETs. Additionally, we detail multidisciplinary approaches and surgical considerations tailored to the tumor's biology, location, and functionality based on recent evidence. We also discuss the complexities of metastatic disease, exploring liver-directed therapies and the evolving landscape of minimally invasive surgical techniques.

Approach to the Patient: Insulinoma

Insulinomas are hormone-producing pancreatic neuroendocrine neoplasms with an estimated incidence of 1 to 4 cases per million per year. Extrapancreatic insulinomas are extremely rare. Most insulinomas present with the Whipple triad: (1) symptoms, signs, or both consistent with hypoglycemia; (2) a low plasma glucose measured at the time of the symptoms and signs; and (3) relief of symptoms and signs when the glucose is raised to normal. Nonmetastatic insulinomas are nowadays referred to as "indolent" and metastatic insulinomas as "aggressive." The 5-year survival of patients with an indolent insulinoma has been reported to be 94% to 100%; for patients with an aggressive insulinoma, this amounts to 24% to 67%. Five percent to 10% of insulinomas are associated with the multiple endocrine neoplasia type 1 syndrome. Localization of the insulinoma and exclusion or confirmation of metastatic disease by computed tomography is followed by endoscopic ultrasound or magnetic resonance imaging for indolent, localized insulinomas. Glucagon-like peptide 1 receptor positron emission tomography/computed tomography or positron emission tomography/magnetic resonance imaging is a highly sensitive localization technique for seemingly occult, indolent, localized insulinomas. Supportive measures and somatostatin receptor ligands can be used for to control hypoglycemia. For single solitary insulinomas, curative surgical excision remains the treatment of choice. In aggressive malignant cases, debulking procedures, somatostatin receptor ligands, peptide receptor radionuclide therapy, everolimus, sunitinib, and cytotoxic chemotherapy can be valuable options.

Premalignant Lesions in the Kidney Transplant Candidate

End-stage kidney disease patients who are referred for transplant undergo an extensive evaluation process to ensure their health prior to transplant due in part to the shortage of available organs. Although management and surveillance guidelines exist for malignancies identified in the transplant and waitlist populations, less is written about the management of premalignant lesions in this population. This review covers the less common premalignant lesions (intraductal papillary mucinous neoplasm, gastrointestinal stromal tumor, thymoma, and pancreatic neuroendocrine tumor) that can be found in the transplant candidate population. High-level evidence for the management of these rarer premalignant lesions in the transplant population is lacking, and this review extrapolates evidence from the general population and should not be a substitute for a multidisciplinary discussion with medical and surgical oncologists.

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.

Resection Versus Observation for Small (≤2 cm) Pancreatic Neuroendocrine Tumors

BACKGROUND

We hypothesized that those patients with pancreatic neuroendocrine tumors (pNETs) ≤2 cm managed nonoperatively would have comparable disease progression to individuals undergoing an operation.

METHODS

Patients diagnosed with nonfunctional pNETs ≤ 2 cm who were evaluated at a single comprehensive cancer center from 2010 to 2017 were selected from a cancer registry database. Clinicopathologic variables were obtained via retrospective chart review. Primary outcomes were overall and disease specific survival. Variables were compared between the 2 groups using chi-square and independent t-test.

RESULTS

Fifty-two individuals had tumors ≤2 cm, of whom 75% had an operation, while 25% were observed. Each treatment arm had similar distributions of gender, race, and tumor location. The most common operation was distal pancreatectomy (n = 29) followed by pancreatoduodenectomy (n = 6). Nine patients had grade III postoperative complications and 4 had grade IV under Clavien-Dindo classification. The observation group was noted to have a mean disease progression interval of 80.9 months, while those who underwent an operation had a mean disease progression interval of 94.6 months (P = .246).

CONCLUSIONS

Overall disease progression in patients with pNETs ≤ 2 cm without evidence of metastasis at the time of presentation is not different between those who underwent operation compared to those observed.

Optimal Lymphadenectomy in Patients with Well-Differentiated Nonfunctioning Pancreatic Neuroendocrine Neoplasms

This study aimed to evaluate the optimal extent of lymphadenectomy in patients with nonfunctioning pancreatic neuroendocrine neoplasms. We retrospectively analyzed the clinicopathological data of patients with nonfunctioning pancreatic neuroendocrine neoplasms who underwent surgical resection. We investigated the frequency of metastases at each lymph node station according to tumor location and analyzed the factors contributing to poor overall survival (OS) and disease-free survival (DFS). Overall, data of 84 patients were analyzed. Among patients with pancreatic head tumors, metastases at stations 8, 13, and 17 were found in one (3.1%), four (12.5%), and three (9.3%) patients, respectively. However, none of the other stations showed metastases. For pancreatic body and tail tumors, metastases only at station 11 were found in two (5.1%) patients. Additionally, multivariate DFS and OS analyses showed that lymph node metastasis was the only independent prognostic factor. In conclusion, lymph node metastasis near the primary tumor was the only independent factor of poor prognosis in patients with nonfunctioning pancreatic neuroendocrine neoplasms after undergoing curative surgery. Peri-pancreatic lymphadenectomy might be recommended for nonfunctioning pancreatic neuroendocrine neoplasms.

Role of Advanced Gastrointestinal Endoscopy in the Comprehensive Management of Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs), also called neuroendocrine tumors (NETs), are relatively uncommon, heterogenous tumors primarily originating in the gastrointestinal tract. With the improvement in technology and increasing use of cross-sectional imaging and endoscopy, they are being discovered with increasing frequency. Although traditionally considered indolent tumors with good prognoses, some NENs exhibit aggressive behavior. Timely diagnosis, risk stratification, and management can often be a challenge. In general, small NENs without local invasion or lymphovascular involvement can often be managed using minimally invasive advanced endoscopic techniques, while larger lesions and those with evidence of lymphovascular invasion require surgery, systemic therapy, or a combination thereof. Ideal management requires a comprehensive and accurate understanding of the stage and grade of the tumor. With the recent advancements, a therapeutic advanced endoscopist can play a pivotal role in diagnosing, staging, and managing this rare condition. High-definition white light imaging and digital image enhancing technologies like narrow band imaging (NBI) in the newer endoscopes have improved the diagnostic accuracy of traditional endoscopy. The refinement of endoscopic ultrasound (EUS) over the past decade has revolutionized the role of endoscopy in diagnosing and managing various pathologies, including NENs. In addition to EUS-directed diagnostic biopsies, it also offers the ability to precisely assess the depth of invasion and lymphovascular involvement and thus stage NENs accurately. EUS-directed locoregional ablative therapies are increasingly recognized as highly effective, minimally invasive treatment modalities for NENs, particularly pancreatic NENs. Advanced endoscopic resection techniques like endoscopic submucosal dissection (ESD), endoscopic submucosal resection (EMR), and endoscopic full-thickness resection (EFTR) have been increasingly used over the past decade with excellent results in achieving curative resection of various early-stage gastrointestinal luminal lesions including NENs. In this article, we aim to delineate NENs of the different segments of the gastrointestinal (GI) tract (esophagus, gastric, pancreatic, and small and large intestine) and their management with emphasis on the endoscopic management of these tumors.

Prognostic factors after resection of locally advanced non-functional pancreatic neuroendocrine neoplasm: an analysis from the German Cancer Registry Group of the Society of German Tumor Centers

OBJECTIVE

The available literature regarding outcome after pancreatic resection in locally advanced non-functional pNEN (LA-pNEN) is sparse. Therefore, this study evaluates the current survival outcomes and prognostic factors in after resection of LA-pNEN.

MATERIALS AND METHODS

This population-based analysis was derived from 17 German cancer registries from 2000 to 2019. Patients with upfront resected non-functional non-metastatic LA-pNEN were included.

RESULTS

Out of 2776 patients with pNEN, 277 met the inclusion criteria. 137 (45%) of the patients were female. The median age was 63 ± 18 years. Lymph node metastasis was present in 45%. G1, G2 and G3 pNEN were found in 39%, 47% and 14% of the patients, respectively. Resection of LA-pNEN resulted in favorable 3-, 5- and 10-year overall survival of 79%, 74%, and 47%. Positive resection margin was the only potentially modifiable independent prognostic factor for overall survival (HR 1.93, 95% CI 1.71-3.69, p value = 0.046), whereas tumor grade G3 (HR 5.26, 95% CI 2.09-13.25, p value < 0.001) and lymphangiosis (HR 2.35, 95% CI 1.20-4.59, p value = 0.012) were the only independent prognostic factors for disease-free survival.

CONCLUSION

Resection of LA-pNEN is feasible and associated with favorable overall survival. G1 LA-pNEN with negative resection margins and absence of lymph node metastasis and lymphangiosis might be considered as cured, while those not fulfilling these criteria might be considered as a high-risk group for disease progression. Herein, negative resection margins represent the only potentially modifiable prognostic factor in LA-pNEN but seem to be influenced by tumor grade.

Efficacy and predictive factors of endoscopic ultrasound-guided ethanol ablation in benign solid pancreatic tumors

BACKGROUNDS AND OBJECTIVES

Endoscopic ultrasound-guided ethanol ablation (EUS-EA) has recently been introduced for the management of solid pancreatic tumors, including pancreatic neuroendocrine tumors (PNETs) and solid pseudopapillary tumors (SPTs). The study aims to evaluate the efficacy and predictive factors for response of EUS-EA in solid pancreatic tumors.

METHODS

Between October 2015 and July 2021, 72 patients who underwent EUS-EA for solid pancreatic tumors were included. The study outcomes were to evaluate the efficacy of EUS-EA with complete remission (CR) and objective response, and their predictive factors.

RESULTS

During follow-up, 47 patients were diagnosed with PNETs and 25 with SPTs. Eight cases reached CR and 48 reached objective response. When compared with SPTs, PNETs showed similar duration to reach CR (median not reached; p = 0.319), but shorter duration to reach objective response (PNETs: median 20.6 months, 95%CI 10.26-30.88; SPTs: median 47.7 months, 95%CI 18.14-77.20; p = 0.018). Ethanol dosage > 0.35 ml/cm³ shortened the duration to reach CR (median not reached; p = 0.026) and objective response (median 42.5 months, 95%CI 25.34-59.66 vs. 19.6 months, 95%CI 10.17-29.09; p = 0.006). CR had no significant predictive factors, but PNETs showed significant predictive factors for objective response (HR 3.34, 95%CI 1.07-10.43; p = 0.038). Twenty-seven patients experienced adverse events, and there were two severe cases.

CONCLUSION

EUS-EA for pancreatic solid lesions seems feasible as a local treatment for patients who refuse or are unfit for surgery. Additionally, PNETs seem to be the better candidate for EUS-EA.

Status of Surveillance and Nonsurgical Therapy for Small Nonfunctioning Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) occur in < 1/100,000 patients and most are nonfunctioning (NF). Approximately 5% occur as part of multiple endocrine neoplasia type 1. Anatomic and molecular imaging have a pivotal role in the diagnosis, staging and active surveillance. Surgery is generally recommended for nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) >2 cm to prevent metastases. For tumors ≤2 cm, active surveillance is a viable alternative. Tumor size and grade are important factors to guide management. Assessment of death domain-associated protein 6/alpha-thalassemia/mental retardation X-linked and alternative lengthening of telomeres are promising novel prognostic markers. This review summarizes the status of surveillance and nonsurgical management for small NF-PNETs, including factors that can guide management.

Pancreatic Neuroendocrine Neoplasms Larger than 4 cm: A Retrospective Observational Study of Surgery, Histology, and Outcome

BACKGROUND

Pancreatic neuroendocrine neoplasms (pNENs) are often detected as large primary lesions, even with distant metastases, and their prognosis may be difficult to predict.

METHODS

In this retrospective study, we retrieved data of patients treated for a large pNEN in our Surgical Unit (1979-2017) to evaluate the possible prognostic role of clinic-pathological features and surgery. Cox-proportional hazard regression models were used to find possible associations among some variables (clinical features, surgery, and histology) and survival at univariate and multivariate analyses.

RESULTS

Among 333 pNENs, we identified 64 patients (19%) with a lesion > 4 cm. Patients' median age was 61 years, median tumor size was 6.0 cm, and 35 (55%) patients had distant metastases at diagnosis. There were 50 (78%) nonfunctioning pNENs, and 31 tumors localized in the body/tail region of the pancreas. Overall, 36 patients underwent a standard pancreatic resection (with 13 associated liver resection/ablation). Regarding histology, 67% of pNENs were N1, and 34% were grade 2. After a median follow-up of 48 months (up to 33 years), 42 patients died of disease. Median survival after surgery was 79 months, and six patients experienced recurrence (median DFS 94 months). At multivariate analysis, distant metastases were associated with a worse outcome, while having undergone radical tumor resection was a protective factor.

CONCLUSIONS

In our experience, about 20% of pNENs have a size > 4 cm, 78% are nonfunctioning, and 55% show distant metastases at diagnosis. Nevertheless, a long-term survival of more than five years may be achieved after surgery.

Reprint of: The Diagnostic and Prognostic Utility of Incorporating DAXX, ATRX, and Alternative Lengthening of Telomeres (ALT) to the Evaluation of Pancreatic Neuroendocrine Tumors (PanNETs)

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and an ill-defined pathobiology. Although many PanNETs are indolent and remain stable for years, a subset may behave aggressively and metastasize widely. Thus, the increasing and frequent detection of PanNETs presents a treatment dilemma. Current prognostic systems are susceptible to interpretation errors, sampling issues, and do not accurately reflect the clinical behavior of these neoplasms. Hence, additional biomarkers are needed to improve the prognostic stratification of patients diagnosed with a PanNET. Recent studies have identified alterations in death domain-associated protein 6 (DAXX) and alpha-thalassemia/mental retardation X-linked (ATRX), as well as alternative lengthening of telomeres (ALT), as promising prognostic biomarkers. This review summarizes the identification, clinical utility, and specific nuances in testing for DAXX/ATRX by immunohistochemistry and ALT by telomere-specific fluorescence in situ hybridization in PanNETs. Furthermore, a discussion on diagnostic indications for DAXX, ATRX, and ALT status is provided to include the distinction between PanNETs and pancreatic neuroendocrine carcinomas (PanNECs), and determining pancreatic origin for metastatic neuroendocrine tumors in the setting of an unknown primary.

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.

Reconsideration of operative indications in pancreatic neuroendocrine neoplasms

BACKGROUND

The incidence of pancreatic neuroendocrine neoplasm (PNEN) has been increasing. Resection is typically indicated for PNEN, regardless of its size; however, the indications for its resection are controversial. This study aimed to evaluate the treatment results of surgical resection of PNEN at our institute.

METHODS

In this single-center, retrospective, case-control study, 87 patients who underwent PNEN resection and 17 patients with PNEN who did not undergo surgical resection between 1993 and 2020 were included in this study. Clinical characteristics and outcomes were reviewed and statistically compared. Survival was also estimated for the patients in each cohort.

RESULTS

Seventeen patients who underwent resection (20%) had lymph node metastasis. Tumors measuring ≥ 2.0 cm and multiple lesions were identified as independent predictors for lymph node metastasis (odds ratio [OR] 17.3, 95% confidence interval [CI] 3.0-100.0, p = 0.001 and OR 8.7, 95% CI 1.5-52.0, p = 0.018, respectively). There was a significant difference in the survival curves depending on the presence or absence of lymph node metastasis (5-year overall survival 74.7% vs. 94.3%, p < 0.001; 5-year recurrence-free survival: 66.3% vs. 93.6%, p < 0.001). All 17 PNEN cases under observation with a median 8 mm (range 5-23) tumor size for a median of 34 (range 2.4-114) months showed slight morphological change with a median tumor growth rate of 0.15 mm (range 0-3.33) per year.

CONCLUSION

Patients with tumors measuring ≥ 2.0 cm have a high probability of lymph node metastasis or recurrence, thereby requiring resection. PNEN measuring < 1.0 cm may be acceptable for observation.

The diagnostic and prognostic utility of incorporating DAXX, ATRX, and alternative lengthening of telomeres to the evaluation of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and an ill-defined pathobiology. Although many PanNETs are indolent and remain stable for years, a subset may behave aggressively and metastasize widely. Thus, the increasing and frequent detection of PanNETs presents a treatment dilemma. Current prognostic systems are susceptible to interpretation errors, sampling issues, and do not accurately reflect the clinical behavior of these neoplasms. Hence, additional biomarkers are needed to improve the prognostic stratification of patients diagnosed with a PanNET. Recent studies have identified alterations in death domain-associated protein 6 (DAXX) and alpha-thalassemia/mental retardation X-linked (ATRX), as well as alternative lengthening of telomeres (ALT), as promising prognostic biomarkers. This review summarizes the identification, clinical utility, and specific nuances in testing for DAXX/ATRX by immunohistochemistry and ALT by telomere-specific fluorescence in situ hybridization in PanNETs. Furthermore, a discussion on diagnostic indications for DAXX, ATRX, and ALT status is provided to include the distinction between PanNETs and pancreatic neuroendocrine carcinomas (PanNECs), and determining pancreatic origin for metastatic neuroendocrine tumors in the setting of an unknown primary.

Long-term Outcomes of Parenchyma-sparing and Oncologic Resections in Patients With Nonfunctional Pancreatic Neuroendocrine Tumors <3 cm in a Large Multicenter Cohort

INTRODUCTION

The role of parenchyma-sparing resections (PSR) and lymph node dissection in small (<3 cm) nonfunctional pancreatic neuroendocrine tumors (PNET) is unlikely to be studied in a prospective randomized clinical trial. By combining data from 4 high-volume pancreatic centers we compared postoperative and long-term outcomes of patients who underwent PSR with patients who underwent oncologic resections.

METHODS

Retrospective review of prospectively collected clinicopathologic data of patients who underwent pancreatectomy between 2000 and 2021 was collected from 4 high-volume institutions. PSR and lymph node-sparing resections (enucleation and central pancreatectomy) were compared to those who underwent oncologic resections with lymphadenectomy (pancreaticoduodenectomy, distal pancreatectomy). Statistical testing was performed using χ 2 test and t test, survival estimates with Kaplan-Meier method and multivariate analysis using Cox proportional hazard model.

RESULTS

Of 810 patients with small sporadic nonfunctional PNETs, 121 (14.9%) had enucleations, 100 (12.3%) had central pancreatectomies, and 589 (72.7%) patients underwent oncologic resections. The median age was 59 years and 48.2% were female with a median tumor size of 2.5 cm. After case-control matching for tumor size, 221 patients were selected in each group. Patients with PSR were more likely to undergo minimally invasive operations (32.6% vs 13.6%, P <0.001), had less intraoperative blood loss (358 vs 511 ml, P <0.001) and had shorter operative times (180 vs 330 minutes, P <0.001) than patients undergoing oncologic resections. While the mean number of lymph nodes harvested was lower for PSR (n=1.4 vs n=9.9, P <0.001), the mean number of positive lymph nodes was equivalent to oncologic resections (n=1.1 vs n=0.9, P =0.808). Although the rate of all postoperative complications was similar for PSR and oncologic resections (38.5% vs 48.2%, P =0.090), it was higher for central pancreatectomies (38.5% vs 56.6%, P =0.003). Long-term median disease-free survival (190.5 vs 195.2 months, P =0.506) and overall survival (197.9 vs 192.6 months, P =0.372) were comparable. Of the 810 patients 136 (16.7%) had no lymph nodes resected. These patients experienced less blood loss, shorter operations ( P <0.001), and lower postoperative complication rates as compared to patients who had lymphadenectomies (39.7% vs 56.9%, P =0.008). Median disease-free survival (197.1 vs 191.9 months, P =0.837) and overall survival (200 vs 195.1 months, P =0.827) were similar for patients with no lymph nodes resected and patients with negative lymph nodes (N0) after lymphadenectomy.

CONCLUSION

In small <3 cm nonfunctional PNETs, PSRs and lymph node-sparing resections are associated with lower blood loss, shorter operative times, and lower complication rates when compared to oncologic resections, and have similar long-term oncologic outcomes.

[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.

Sporadic nonfunctional pancreatic neuroendocrine tumors: Risk of lymph node metastases and aggressiveness according to tumor size: A multicenter international study

BACKGROUND

Although the correlation between tumor size and aggressiveness is clearly established in sporadic nonfunctional pancreatic neuroendocrine tumors, the management of tumors ≤2 cm remains debated. In recent guidelines, the cut-off size to operate ranged from 1 to 2 cm. The aim of this retrospective study was to report the rate of lymph nodes metastases in resected sporadic nonfunctional pancreatic neuroendocrine tumors, according to tumor size and, second, to identify risk factors of lymph node metastases and disease-free survival.

METHODS

Resected sporadic nonfunctional pancreatic neuroendocrine tumors from 9 international expert centers were included (1999-2017). Functional pancreatic neuroendocrine tumors, genetic syndromes, and R2 resection were excluded. Aggressiveness was defined as microvascular invasion, perineural invasion, lymph node metastases, G3 grading, distant metastases, and/or recurrence.

RESULTS

Overall, 495 resected sporadic nonfunctional pancreatic neuroendocrine tumors were included. For tumors up to 5 cm, the risk of lymph node metastases was increased by 1.73 for every 1 cm increase in size (odds ratio = 1.73; 95% confidence interval = 1.46-2.03). Tumor size >2 cm (P < .001), perineural invasion (P = .002), microvascular invasion (P < .001), and distant metastases (P = .008) were independently associated with lymph node metastases. Tumor size >2 cm (P = .003), R1 status (P = .004), lymph node metastases (P < .001), and World Health Organization grade 3 (P = .002) were independently associated with disease-free survival. Aggressiveness rate was 13.1% in tumors ≤1 cm and 29% in tumors between 1.1 and 2 cm.

CONCLUSION

In resected sporadic nonfunctional pancreatic neuroendocrine tumors, the risk of lymph node metastases is correlated to tumor size. Considering that sporadic nonfunctional pancreatic neuroendocrine tumors between 1.1 and 2 cm had a higher risk of lymph node metastases and recurrence compared to tumors ≤1 cm, the decision to perform surgery in this subgroup of patients should be individualized in surgically fit patients.

Facility type and size-stratified analysis of management patterns and outcomes of patients with localized non-functional pancreatic neuroendocrine tumors

BACKGROUND

Non-functional neuroendocrine tumors of the pancreas (NF-pNETs) are uncommon. Consensus guidelines have conflicting recommendations. We performed a nationwide analysis of patterns in management and outcomes based on facility type and tumor size.

METHODS

The National Cancer Database (2004-2016) was queried for patients with localized NF-pNETs (<1 cm, 1-2 cm, >2 cm) stratified by facility type. Management decisions, operative outcomes, and survival were compared.

RESULTS

A total of 7170 patients were included in the analysis (<1 cm = 916; 1-2 cm = 2180; >2 cm = 4074). Most patients were treated at academic facilities (62.8%). Over 67% of patients with tumors <1 cm underwent resection, independent of facility type (p = 0.443). There was no association between facility type and operative vs non-operative management of patients with NF-pNETs 1-2 cm in size. Patients treated at academic facilities were more likely to undergo resection for tumors >2 cm compared to other facility types. Resection was associated with improved survival among patients with tumors 1-2 cm (HR = 0.43,p < 0.001) and >2 cm (HR = 0.32,p < 0.001), but not <1 cm (HR = 0.64,p = 0.054), as compared to non-operative management.

CONCLUSION

There is heterogeneity in management of NF-pNETs across facility types. Treatment at academic facilities appears to be associated with higher resection rates for tumors >2 cm. There appears to be an independent association between operative management and improved survival for tumors ≥1 cm in size.

Fate of Surgical Patients with Small Nonfunctioning Pancreatic Neuroendocrine Tumors: An International Study Using Multi-Institutional Registries

Simple Summary

No consensus has been reached regarding whether nonmetastatic nonfunctioning neuroendocrine tumors of the pancreas (NF-pNETs) ≤ 2 cm should be resected or observed. In this retrospective international multicenter study, 483 patients who underwent resection for NF-pNETs ≤ 2 cm in 18 institutions from 2000 to 2017 were enrolled and their medical records were reviewed. Tumor size > 1.5 cm, Ki-67 index ≥ 3%, and nodal metastasis were independent adverse prognostic factors for survival after multivariable analysis. NF-pNET patients with tumors ≤ 1.5 cm can be observed if the preoperative Ki-67 index is under 3%, and if nodal metastasis is not suspected in preoperative radiologic studies. These findings support the clinical use to make decisions about small NF-pNETs.

Abstract

Several treatment guidelines for sporadic, nonmetastatic nonfunctioning neuroendocrine tumors of the pancreas (NF-pNETs) have recommended resection, however, tumors ≤ 2 cm do not necessarily need surgery. This study aims to establish a surgical treatment plan for NF-pNETs ≤ 2 cm. From 2000 to 2017, 483 patients who underwent resection for NF-pNETs ≤ 2 cm in 18 institutions from Korea and China were enrolled and their medical records were reviewed. The median age was 56 (range 16–80) years. The 10-year overall survival rate (10Y-OS) and recurrence-free survival rate (10Y-RFS) were 89.8 and 93.1%, respectively. In multivariable analysis, tumor size (>1.5 cm; HR 4.28, 95% CI 1.80–10.18, p = 0.001) and nodal metastasis (HR 3.32, 95% CI 1.29–8.50, p = 0.013) were independent adverse prognostic factors for OS. Perineural invasion (HR 4.36, 95% CI 1.48–12.87, p = 0.008) and high Ki-67 index (≥3%; HR 9.06, 95% CI 3.01–27.30, p < 0.001) were independent prognostic factors for poor RFS. NF-pNETs ≤ 2 cm showed unfavorable prognosis after resection when the tumor was larger than 1.5 cm, Ki-67 index ≥ 3%, or nodal metastasis was present. NF-pNET patients with tumors ≤ 1.5 cm can be observed if the preoperative Ki-67 index is under 3%, and if nodal metastasis is not suspected in preoperative radiologic studies. These findings support the clinical use to make decisions about small NF-pNETs.

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

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

Prognostic Factors of Small Non-Functional Pancreatic Neuroendocrine Tumors and the Risk of Lymph Node Metastasis: A Population-Level Study

BACKGROUND

Small non-functional neuroendocrine tumors (NF-PNETs) are a heterogeneous subset of tumors with controversy regarding their optimal management. We aimed to analyze the prognostic factors of patients with small NF-PNETs and create a risk score for lymph node metastasis (LNM).

METHODS

Data of 751 patients with NF-PNETs ≤ 2 cm were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Multivariate survival analysis was performed to analyze the prognostic factors. Logistic regression was used to identify risk factors for LNM.

RESULTS

Of the 751 patients, 99 (13.2%) were confirmed to have LNM. In multivariate survival analysis, LNM (hazard ratio [HR], 2.12; 95% CI, 1.04-4.32, p = 0.040) was independently associated with disease-specific survival. Logistic regression identified that tumor location in the head of the pancreas (odds ratio [OR], 4.33; 95% CI, 2.75-6.81; p < 0.001), size ≥ 1.5-2 cm (OR, 1.84; 95% CI, 1.17-2.87; p = 0.009), and grade III-IV (OR, 7.90; 95% CI, 1.79-34.90; p = 0.006) were independent risk factors of LNM. According to the OR value, the risk of LNM was scored as follows: a score of 1 for tumors located in the body/tail of the pancreas and 4 for those located in the head; a score of 1 for tumors <1 cm and 2 for those ≥1.5-2 cm; and a score of 1 for tumors with grade I-II and 8 for those with grade III-IV. Finally, the median score for this cohort was 4, with an interquartile range of 3-6. Therefore, patients were classified as three groups based on the risk score system: a total score of 1-3 for low risk, 4-6 for intermediate risk (OR, 2.98; 95% CI, 1.59-5.60; p = 0.001), and 7-14 for high risk (OR, 8.94; 95% CI, 4.50-17.7; p < 0.001), with an incidence of LNM 5.0%, 13.5%, and 31.8%, respectively (p < 0.001).

CONCLUSION

Surgical resection with regional lymphadenectomy is recommended for small NF-PNETs with malignant potential of LNM. A risk score for LNM based on tumor grade, location, and size may preoperatively predict LNM of small NF-PNETs and guide clinical practice.

Predicting Progression, Recurrence, and Survival in Pancreatic Neuroendocrine Tumors: A Single Center Analysis of 174 Patients

INTRODUCTION

The European Neuroendocrine Tumor Society, ENETS, reports variables of prognostic significance in pancreatic neuroendocrine tumors (PNET). However, studies have short follow-ups, and the optimal treatment remains controversial. We aimed to determine overall survival (OS), progression-free survival (PFS) after conservative treatment, and recurrence-free survival (RFS) after surgery and further to find predictors of aggressive PNET behavior to support treatment decisions.

METHODS

174 patients with PNET treated at Aarhus University Hospital from 2011 to 2021 were included in a retrospective cohort study. Patients were divided into surgically resected (SUR, n=91) and medically or conservatively treated (MED, n=83). Variables were tested in univariate and multivariate survival analysis. Median follow-up time was 3.4 years in the MED group and 4.5 years in the SUR group.

RESULTS

The 5-year OS was 95% and 65% for the SUR and MED groups, respectively. The 5-year RFS in the SUR group was 80% whereas the 5-year PFS in the MED group was 41%. Larger tumor size, Ki67 index, tumor grade, and stage were predictive of shorter OS, RFS, and PFS. Further, chromogranin A was a predictor of OS. Larger tumor size was associated with higher stage and grade. Only 1 of 28 patients with stage 1 disease and size ≤2 cm developed progression on a watch-and-wait strategy during a median follow-up of 36 months.

CONCLUSION

This study supported the ENETS staging and grading system to be useful to predict OS, PFS, and RFS in PNET. Further, our data support that small, localized, low-grade PNETS can be followed with active surveillance.

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.

Small pancreatic neuroendocrine tumours: observe and monitor or prompt surgical resection

Over recent decades there has been a significant increase in the annual incidence of neuroendocrine tumors of the pancreas (PanNets), from 0.4 to 0.8 per 100,000 inhabitants, due to the more widespread use of more sensitive imaging techniques (cross-sectional and functional imaging).

Progress in the Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous and orphan group of neoplasms that vary in their histology, clinical features, prognosis, and management. The treatment of PNETs is highly dependent on the stage at presentation, tumor grade and differentiation, presence of symptoms from hormonal overproduction or from local growth, tumor burden, and rate of progression. The US Food and Drug Administration has recently approved many novel treatments, which have altered decision making and positively impacted the care and prognosis of these patients. In this review, we focus on the significant progress made in the management of PNETs over the past decade, as well as the active areas of research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Prognostic factors for relapse in resected gastroenteropancreatic neuroendocrine neoplasms: A systematic review and meta-analysis

BACKGROUND

Gastroenteropancreatic neoplasms (GEP-NENs)can potentially be cured through surgical resection, but only 42-57% achieve 5-year disease-free survival.There is a lack of consensus regarding the factorsassociated withrelapse followingresection ofGEP-NENs.

METHODS

Asystematic review identified studies reporting factors associated with relapse in patients with GEP-NENs following resection of a primary tumour. Meta-analysis was performed to identify the factors prognostic for relapse-free survival (RFS)oroverall survival (OS).

RESULTS

63 studies comprising 13,715 patients were included; 56 studies reported on pancreatic NENs (12,418 patients), 24 reported on patients with grade 1-2 tumours (4,735 patients). Median follow-up was 44.2 months, median RFS was 32 months. Pooling of multivariable analyses of GEP-NENs (all sites and grades) found the following factors predicted worse RFS (all p values < 0.05): vascular resection performed, metastatic disease resected, grade 2 disease, grade 3 disease, tumour size > 20 mm, R1 resection, microvascular invasion, perineural invasion, Ki-67 > 5% and any lymph node positivity. In a subgroup of studies comprising exclusively of grade 1-2 GEP-NENs, R1 resection, perineural invasion, grade 2 disease, any lymph node positivity and tumour size > 20 mm predicted worse RFS (all p values < 0.05). Few OSdata were available for pooling; in univariableanalysis(entire cohort), grade 2 predicted worse OS (p = 0.007), whileR1 resectiondid not (p = 0.14).

CONCLUSIONS

The factors prognostic for worse RFS following resection of a GEP-NEN identified in this meta-analysis could be included in post-curative treatment surveillance clinical guidelines and inform the stratification and inclusion criteria of future adjuvant trials.

Clinical Prognosticators of Metastatic Potential in Patients with Small Pancreatic Neuroendocrine Tumors

BACKGROUND

While observation of T1(≤2cm) nonfunctioning pancreatic neuroendocrine tumors (NF-PanNETs) is an accepted practice, an ill-defined subgroup of patients with T1 tumors develops metastases. This study aimed to identify those patients via clinical factors.

METHODS

Patients from the Surveillance, Epidemiology, and End Results (SEER) registry who were diagnosed with NF-PanNET with size ≤2cm between 1998 and 2014 and who underwent primary tumor resection were identified. Binary logistic regression analyses were performed to evaluate factors associated with pathological nodal and systemic metastatic disease.

RESULTS

A total of 612 patients with T1 NF-PanNETs were identified. Of those, 72 (11.7%) developed nodal metastasis and 35 (5.7%) distant metastasis (M1). In the multivariable analysis, tumor location in the pancreatic body (OR 1.903, p=0.03) (OR 1.407, p=0.038) or tail (OR 1.258, p=0.04) (OR 1.612, p=0.021); tumor grade III-IV (OR 2.042, p=0.022) (OR 5.379, p≤0.001); and younger age (OR 0.963, p=0.01) (OR 0.919, p=0.009) were associated with nodal metastases and the presence of M1 disease, respectively.

CONCLUSION

While the low metastatic potential of ≤2cm NF-PanNET implies watchful waiting to be an appropriate strategy for most patients, the increased risk of metastatic disease in younger patients with high grade (III-IV) body/tail tumors suggests individualized risk stratification to be optimal.

Sunitinib-Loaded Chondroitin Sulfate Hydrogels as a Novel Drug-Delivery Mechanism for the Treatment of Pancreatic Neuroendocrine Tumors

BACKGROUND

Pancreatic neuroendocrine tumors (PanNETs) are increasingly common. Experts debate whether small tumors should be resected. Tumor destruction via injection of cytotoxic agents could offer a minimal invasive approach to this controversy. We hypothesize that a new drug delivery system comprising chondroitin sulfate (CS) hydrogels loaded with sunitinib (SUN) suppresses tumor growth in PanNET cells.

METHODS

Injectable hydrogels composed of CS modified with methacrylate groups (MA) were fabricated and loaded with SUN. Loading target was either 200 µg (SUN200-G) or 500 µg (SUN500-G) as well as sham hydrogel with no drug loading (SUN0-G). SUN release from hydrogels was monitored in vitro over time and cytotoxicity induced by the released SUN was evaluated using QGP-1 and BON1 PanNET cell lines. QGP-1 xenografts were developed in 35 mice and directly injected with 25 µL of either SUN200-G, SUN500-G, SUN0-G, 100 µL of Sunitinib Malate (SUN-inj), or given 40 mg/kg/day oral sunitinib (SUN-oral).

RESULTS

SUN-loaded CSMA hydrogel retained complete in vitro cytotoxicity toward the QGP-1 PanNET and BON-1 PanNET cell lines for 21 days. Mouse xenograft models with QGP-1 PanNETs showed a significant delay in tumor growth in the SUN200/500-G, SUN-inj and SUN-oral groups compared with SUN0-G (p = 0.0014). SUN500-G hydrogels induced significantly more tumor necrosis than SUN0-G (p = 0.04). There was no difference in tumor growth delay between SUN200/500G, SUN-inj, and SUN-oral.

CONCLUSIONS

This study demonstrates that CSMA hydrogels loaded with SUN suppress PanNETs growth. This drug delivery could approach represents a novel way to treat PanNETs and other neoplasms via intratumoral injection.

Reappraisal of a 2-Cm Cut-off Size for the Management of Cystic Pancreatic Neuroendocrine Neoplasms: A Multicenter International Study

OBJECTIVE

The aim of this study was to characterize an international cohort of resected cystic pancreatic neuroendocrine neoplasms (cPanNENs) and identify preoperative predictors of aggressive behavior.

BACKGROUND

The characteristics of cPanNENs are unknown and their clinical management remains unclear. An observational strategy for asymptomatic cPanNENs ≤2 cm has been proposed by recent guidelines, but evidence is scarce and limited to single-institutional series.

METHODS

Resected cPanNENs (1995-2017) from 16 institutions worldwide were included. Solid lesions (>50% solid component), functional tumors, and MEN-1 patients were excluded. Aggressiveness was defined as lymph node (LN) involvement, G3 grading, distant metastases, and/or recurrence.

RESULTS

Overall, 263 resected cPanNENs were included, among which 177 (63.5%) were >2 cm preoperatively. A preoperative diagnosis of cPanNEN was established in 162 cases (61.6%) and was more frequent when patients underwent endoscopic ultrasound [EUS, odds ratio (OR) 2.69, 95% confidence interval (CI) 1.52-4.77] and somatostatin-receptor imaging (OR 3.681, 95% CI 1.809-7.490), and for those managed in specialized institutions (OR 3.12, 95% CI 1.57-6.21). Forty-one cPanNENs (15.6%) were considered aggressive. In the whole cohort, LN involvement on imaging, age >65 years, preoperative size >2 cm, and pancreatic duct dilation were independently associated with aggressive behavior. In asymptomatic patients, older age and a preoperative size >2 cm remained independently associated with aggressiveness. Only 1 of 61 asymptomatic cPanNENs ≤2 cm displayed an aggressive behavior.

CONCLUSIONS

The diagnostic accuracy of cPanNENs is increased by the use of EUS and somatostatin-receptor imaging and is higher in specialized institutions. Preoperative size >2 cm is independently associated with aggressive behavior. Consequently, a watch-and-wait policy for sporadic asymptomatic cPanNENs ≤2 cm seems justified and safe for most patients.

Serotonin immunoreactive pancreatic neuroendocrine neoplasm associated with main pancreatic duct dilation: a recognizable entity with excellent long-term outcome

OBJECTIVES

Dilatation of the main pancreatic duct (MPD) is rare in pancreatic neuroendocrine neoplasm (panNEN) and may be due to different mechanisms. We compared the imaging and pathological characteristics as well as the outcome after resection of positive (S+) and negative (S-) serotonin immunoreactive panNENs causing MPD dilatation.

METHODS

This retrospective study included patients with panNEN, with MPD dilatation (≥ 4 mm) on preoperative CT/MRI and resected between 2005 and 2019. Clinical, radiological, and pathological features were compared between S+ and S- panNENs. Imaging features associated with S+ panNEN were identified using logistic regression analysis. The diagnostic performance of imaging for the differentiation of S+ and S- panNENs was assessed by ROC curve analysis. Recurrence-free survival (RFS) was compared between the two groups.

RESULTS

The final population of 60 panNENs included 20/60 (33%) S+ panNENs. S+ panNENs were smaller (median 12.5 mm vs. 33 mm; p < 0.01), more frequently hyperattenuating/intense on portal venous phase at CT/MRI (95% vs. 25%, p < 0.01), and presented with more fibrotic stroma on pathology (60.7 ± 16% vs. 40.7 ± 12.8%; p < 0.01) than S- panNENs. Tumor size was the only imaging factor associated with S+ panNEN on multivariate analysis. A tumor size ≤ 20 mm had 95% sensitivity and 90% specificity for the diagnosis of S+ panNEN. Among 52 patients without synchronous liver metastases, recurrence occurred in 1/20 (5%) with S+ panNEN and 18/32 (56%) with S- panNEN (p < 0.01). Median RFS was not reached in S+ panNENs and was 31.3 months in S- panNENs (p < 0.01).

CONCLUSIONS

In panNENs with MPD dilatation, serotonin positivity is associated with smaller size, extensive fibrotic stroma, and better long-term outcomes.

KEY POINTS

• S+ panNENs showed a higher percentage of fibrotic stroma, higher microvessel density, and lower proliferation index (Ki-67) compared to S- panNENs. • Radiologically, S+ panNENs causing dilatation of the MPD were characterized by a small size (< = 20 mm) and a persistent enhancement on portal phase on both CT and MRI. • Patients with S+ panNENs presented with longer RFS when compared to those with S- panNENs.

A novel risk factor panel predicts early recurrence in resected pancreatic neuroendocrine tumors

BACKGROUND

Pancreatic neuroendocrine tumors (PanNETs) are indolent pancreatic tumors derived from neuroendocrine cells in pancreatic islets. To date, reliable predictors for identifying patients at high risk for recurrence after curative cancer resection are lacking. We aimed to determine independent predictors for high-risk PanNETs and patient outcomes after surgery.

METHODS

We analyzed relevant clinicopathological parameters in 319 consecutive patients of derivation cohort 1 and 106 patients of validation cohort 2 who underwent pancreatectomy and were diagnosed with PanNETs. Association of tumor characteristics with recurrence-free survival (RFS) and overall survival (OS) was evaluated using Cox regression.

RESULTS

PanNET grade 3 (G3), pancreatic duct dilatation, and perineural invasion were independent prognostic factors for RFS and were significantly associated with early recurrence (within 1.5 years) of PanNETs after curative resection (P = 0.019, P < 0.001, and P < 0.001, respectively). Using these factors, we established a novel risk factor panel (R-panel), which predicted early recurrence (P < 0.001, HR = 15.02, 95% CI 5.76-39.19). Predictive accuracy of this R-panel was favorable, with a C-index of 0.853, higher than AJCC TNM staging (0.713). We further built an integrated staging system combining R-panel scoring and TNM staging, which improved predictive probability of TNM staging. Finally, we showed that adjuvant therapy with long-acting somatostatin analogs (SSAs) significantly reduced postoperative recurrence (P < 0.001) and prolonged long-term survival (P = 0.021) in patients with the above risk factors.

CONCLUSION

We identified a novel risk factor panel, which includes PanNET G3, pancreatic duct dilatation, and perineural invasion; this panel predicted early recurrence of PanNETs after curative resection. Patients with these risk factors can benefit from adjuvant therapy with SSAs.

Watchful waiting for small non-functional pancreatic neuroendocrine tumours: nationwide prospective cohort study (PANDORA)

This prospective nationwide cohort study examined the feasibility of a watchful-waiting protocol for non-functional pancreatic neuroendocrine tumours (NF-pNET) of 2 cm or smaller. In total, 8 of 76 patients (11 per cent) with a NF-pNET no larger than 2 cm showed significant tumour progression (more than 0.5 cm/year) during 17 months of follow-up, of whom two opted for resection. No patient developed metastases. Quality of life was poorer than in the reference population. Watchful waiting seems a safe alternative to upfront surgery in patients with a NF-pNET no larger than 2 cm, although longer follow-up is necessary.

Prognostic Impact of Tumor Size on Pancreatic Neuroendocrine Tumor Recurrence May Have Racial Variance

OBJECTIVE

The incidence of pancreatic neuroendocrine tumors (PNETs) has increased over the last decade. Black patients have worse survival outcomes. This study investigates whether oncologic outcomes are racially disparate at a single institution.

METHODS

Retrospective analysis was performed on 151 patients with resected PNETs between 2010 and 2019.

RESULTS

More White males and Black females presented with PNETs (P = 0.02). White patients were older (65 years vs 60 years; P = 0.03), more likely to be married (P < 0.01), and had higher median estimated yearly incomes ($28,973 vs $17,767; P < 0.01) than Black patients. Overall and disease-free survival were not different. Black patients had larger median tumor sizes (30 mm vs 23 mm; P = 0.02). Tumor size was predictive of recurrence only for White patients (hazard ratio, 1.02; P = 0.01). Collectively, tumors greater than 20 mm in size were more likely to have recurrence (P = 0.048), but this cutoff was not predictive in either racial cohort independently.

CONCLUSIONS

Black patients undergoing curative resection of PNETs at our institution presented with larger tumors, but that increased size is not predictive of disease-free survival in this population.

Role of Somatostatin Receptor in Pancreatic Neuroendocrine Tumor Development, Diagnosis, and Therapy

Pancreatic neuroendocrine tumors (pNETs) are rare and part of the diverse family of neuroendocrine neoplasms (NENs). Somatostatin receptors (SSTRs), which are widely expressed in NENs, are G-protein coupled receptors that can be activated by somatostatins or its synthetic analogs. Therefore, SSTRs have been widely researched as a diagnostic marker and therapeutic target in pNETs. A large number of studies have demonstrated the clinical significance of SSTRs in pNETs. In this review, relevant literature has been appraised to summarize the most recent empirical evidence addressing the clinical significance of SSTRs in pNETs. Overall, these studies have shown that SSTRs have great value in the diagnosis, treatment, and prognostic prediction of pNETs; however, further research is still necessary.

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

Background

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

Methods

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

Results

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

Conclusions

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