Pancreatic Neuroendocrine Tumors: an Update

Radiofrequency ablation for the management of pancreatic mass lesions

PURPOSE OF REVIEW

Patients with pancreatic tumors may have limited treatment options. Pancreatic tumor ablation is a novel and emerging treatment modality which can now be performed using endoscopic ultrasound (EUS) guidance. This modality is well suited to guide energy delivery for radiofrequency ablation (RFA) and microwave ablation. These approaches provide minimally invasive, nonsurgical methods for delivering energy to ablate pancreatic tumors in situ. This review summarizes the current data and safety profile for ablation in managing pancreatic cancer and pancreatic neuroendocrine tumors.

RECENT FINDINGS

RFA uses thermal energy to induce cell death by coagulative necrosis and protein denaturation. Studies have reported increased overall survival in patients with pancreatic tumors treated with EUS-guided RFA in a multimodality systemic approach and when used in palliative surgeries. Radiofrequency ablation may have corollary benefits in inducing an immune-modulatory effect. Tumor marker carbohydrate antigen 19-9 has been reported to decrease in response to RFA. Microwave ablation is an emerging modality.

SUMMARY

RFA utilizes focal thermal energy to induce cell death. RFA has been applied through open, laparoscopic, and radiographic modalities. EUS-guided approaches are now allowing RFA and microwave ablation to be performed for pancreatic tumors in situ.

Values of debulking surgery for unresectable well-differentiated metastatic pancreatic neuroendocrine tumors: a comparative study

Background and objective

The value of debulking surgery for unresectable well-differentiated metastatic pancreatic neuroendocrine tumor (m-PNET) remains poorly defined. This study aimed to evaluate the outcomes of m-PNET following debulking surgery in our institute.

Methods

Patients with well-differentiated m-PNET in our hospital between February 2014 and March 2022 were collected. Clinicopathological and long-term outcomes of patients treated with radical resection, debulking surgery, and conservative therapy were compared retrospectively.

Results

Fifty-three patients with well-differentiated m-PNET were reviewed, including 47 patients with unresectable m-PNET (debulking surgery, 25; conservative therapy, 22) and 6 patients with resectable m-PNET (radical resection). Patients undergoing debulking surgery had a post-operative Clavien-Dindo ≥ III complication rate of 16.0% without mortality. The 5-year overall survival (OS) rate of patients treated with debulking surgery was significantly higher than that of those treated with conservative therapy alone (87.5% vs 37.8%, log-rank P = 0.022). Besides, the 5-year OS rate of patients treated with debulking surgery was comparable to that of patients with resectable m-PNET undergoing radical resection (87.5% vs 100%, log-rank P = 0.724).

Conclusions

Patients with unresectable well-differentiated m-PNET who underwent resection had better long-term outcomes than those who received conservative therapy alone. The 5-year OS of patients undergoing debulking surgery and radical resection were comparable. Debulking surgery could be considered for patients with unresectable well-differentiated m-PNET if no contraindication exists.

Malignant pancreatic tumor other than solid pseudopapillary tumor in pediatric patients: A single-center experience

Pancreatic tumors, except solid pseudopapillary tumors (SPTs), are rare in pediatric patients. Herein, we report various types of pancreatic tumors in pediatric patients and review the literature regarding their treatments and prognosis.We retrospectively reviewed the data of pediatric patients who underwent surgery for pancreatic tumors, excluding SPTs, between January 2009 and December 2019 at Seoul National University Children's Hospital. A total of 35 pediatric patients were identified as having undergone surgery for pancreatic tumors. Of these patients, 30 were excluded because the tumor was identified as an SPT.The diagnoses of the five remaining (non-SPT) pancreatic tumors were pancreatic neuroendocrine tumor, mixed acinar neuroendocrine carcinoma, kaposiform hemangioendothelioma, and intraductal papillary mucinous neoplasm. All five patients survived; however, recurrence and liver metastasis were observed in one patient. The detailed demographics, treatments, and prognosis of each patient were reviewed.Despite the rarity and low incidence of pancreatic tumors in pediatric patients, four types of non-SPT tumors are reported here. Hence, the possibility of these should not be overlooked, especially since the diagnosis and adjuvant treatment differ vastly between the tumor types.

The Role of Laparoscopic Surgery in Localized Pancreatic Neuroendocrine Tumours

Pancreatic neuroendocrine tumours (PNETs) are a rare and heterogeneous group of tumours with various clinical manifestations and biological behaviours. They represent approximately 2-4% of all pancreatic tumours, with an incidence of 2-3 cases per million people. PNETs are classified clinically as non-functional or functional, and pancreatic resection is recommended for lesions greater than 2 cm. The surgical approach can involve "typical" and "atypical" resections depending on the number, size and location of the tumour. Typical resections include pancreaticoduodenectomy, distal pancreatectomy enucleation and, rarely, total pancreatectomy. Atypical resections comprise central pancreatectomies or enucleations. Minimally invasive pancreatic resection has been proven to be technically feasible and safe in high-volume and specialized centres with highly skilled laparoscopic surgeons, with consolidated benefits for patients in the postoperative course. However, open and minimally invasive pancreatic surgery remains to have a high rate of complications; there is no specific technical contraindication to minimally invasive pancreatic surgery, but an appropriate patient selection is crucial to obtain satisfactory clinical and oncological outcomes.

Differentiation of atypical non-functional pancreatic neuroendocrine tumor and pancreatic ductal adenocarcinoma using CT based radiomics

PURPOSE

To develop and validate an effective model to differentiate NF-pNET from PDAC.

MATERIALS AND METHODS

Between July 2014 and December 2017, 147 patients (80 patients with PDAC and 67 patients with atypical NF-pNET) with pathology results and enhanced CT were consecutively enrolled and chronologically divided into primary and validation cohorts. Three models were built to differentiate atypical NF-pNET from PDAC, including a model based on radiomic signature alone, one based on clinicoradiological features alone and one that integrated the two. The diagnostic performance of the three models was estimated and compared with the area under the receiver operating characteristic curve (AUC) in the validation cohort. A nomogram was used to represent the model with the best performance, and the associated calibration was also assessed.

RESULTS

In the validation cohort, the AUC for differential diagnosis was 0.884 with the integrated model, which was significantly improved over that of the model based on clinicoradiological features (AUC = 0.775, p value = 0.004) and was comparable to that of the model based on the radiomic signature (AUC = 0.873, p value = 0.512). The nomogram representing the integrated model achieved good discrimination performances in both the primary and validation cohorts, with C-indices of 0.960 and 0.884, respectively.

CONCLUSION

The integrated model outperformed the model based on clinicoradiological features alone and was comparable to the model based on the radiomic signature alone with respect to the differential diagnosis of atypical NF-pNET and PDAC. The nomogram achieved an optimal preoperative, noninvasive differential diagnosis between atypical pNET and PDAC, which can better inform therapeutic choice in clinical practice.

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

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

Expanded criteria for debulking of liver metastasis also apply to pancreatic neuroendocrine tumors

BACKGROUND

Recently, there has been a move toward decreasing the threshold for liver debulking for metastatic carcinoid tumors from 90% to 70%. The debulking threshold and factors that predict outcomes of liver debulking operations specifically among pancreatic neuroendocrine tumors are not well defined.

METHODS

Records of patients with pancreatic neuroendocrine tumors undergoing liver debulking with a threshold of 70% from 2006 to 2016 were reviewed. Extrahepatic metastases and positive margins by enucleation were allowed. Liver progression-free survival and overall survival were calculated by the Kaplan-Meier method for various factors and compared by log-rank. Factors also were correlated with liver progression-free survival and overall survival by multivariate regression analyses.

RESULTS

Forty-two patients underwent 44 operations, of which 24 resulted in 100% debulking, 12 resulted in ≥90% debulking, and 8 resulted in ≥70% debulking. Median liver progression-free survival was 11 months. The 5-year overall survival rate was 81%. There were no significant differences in outcome based on percent debulked. Only liver metastasis ≥5 cm correlated with liver progression-free survival and overall survival.

CONCLUSION

Consideration should be given to expanding the criteria for liver debulking in pancreatic neuroendocrine tumors to include a new threshold of >70% debulking, intermediate grade tumors, positive margins, and extrahepatic metastases; these criteria yield results indistinguishable from complete resection. Using these expanded criteria will increase the number of patients eligible for an operation and maintain high survival rates.

Recent advances in the management of endocrine malignancies associated with hereditary hyperparathyroidism syndromes

Hereditary hyperparathyroidism syndromes, such as multiple endocrine neoplasm type 1, type 2A and the hyperparathyroidism-jaw tumor syndrome, are associated with an increased incidence of malignancies involving the neuroendocrine tissue of the pancreas and thymus, parathyroid and thyroid glands. The natural history of these endocrine tumors can differ from nonhereditary malignancies. The surgical approach, the only potentially curative treatment option for these endocrine malignancies, has evolved considerably in recent years. Newer targeted therapies, such as small molecule kinase inhibitors, somatostatin analogs and peptide receptor radionuclide therapy, are being developed. We provide here a comprehensive review of the current standards of treatment and emerging novel therapies for the endocrine malignancies commonly associated with hereditary hyperparathyroidism syndromes.

Pancreatic Neuroendocrine Tumors (panNETs): Analysis of Overall Survival of Nonsurgical Management Versus Surgical Resection

BACKGROUND

Outcomes of patients with pancreatic neuroendocrine tumors (panNETs) undergoing surgical or nonsurgical management and outcomes of enucleation versus standard resection were compared.

METHODS

MEDLINE, EMBASE, PubMed, Scopus, and Cochrane were queried (2000 to present). All studies comparing patients undergoing surgical versus nonsurgical treatments, or enucleation versus standard resection, were included. Pooled risk ratios and 95% CI for survival were calculated.

RESULTS

Eleven studies met criteria with 1491 resected and 1607 nonsurgically managed patients. Meta-analysis showed improved overall survival with resection at 1 year (risk ratio (RR) = 1.281, CI 1.064-1.542, p = 0.009), 3 years (RR = 1.837, CI 1.594-2.117, p < 0.001), and 5 years (RR = 2.103, CI 1.50-2.945, p < 0.001). OS of patients with resected nonfunctioning panNETs was improved at 3 years (RR = 1.847, CI 1.477-2.309, p < 0.001) and 5 years (RR = 1.767, CI 1.068-2.924, p = 0.027). OS was improved when panNETs ≤2 cm were resected at 3 years (RR = 1.695, CI 1.269-2.264, p < 0.001) and 5 years (RR = 2.210, CI 1.749-2.791, p < 0.001). Fifteen articles met criteria for enucleation versus standard resection (n = 1035; 620 were nonfunctioning). Enucleation had shorter operative time (weighted mean difference (WMD) = -95.6 min, 95% CI -131.4 to -59.8, p < 0.01), less operative blood loss (WMD = -172.6 ml, 95% CI -340 to -5.1, p = 0.04), but increased postoperative pancreatic fistula (POPF) (RR = 2.08, 95% CI 1.39-3.12, p < 0.01).

CONCLUSION

Surgical resection of panNETs, including small and nonfunctioning, appears to be associated with improved OS. Enucleation is associated with shorter operative time, less blood loss, but greater incidence of POPF. Prospective, randomized clinical trials are needed to confirm these results.

Pancreatic neuroendocrine tumors: contemporary diagnosis and management

Pancreatic neuroendocrine tumors (PNETs) are neoplasms that arise from the hormone producing cells of the islets of Langerhans, also known as pancreatic islet cells. PNETs are considered a subgroup of neuroendocrine tumors, and have unique biology, natural history and clinical management. These tumors are classified as 'functional' or 'non-functional' depending on whether they release peptide hormones that produce specific hormone- related symptoms, usually in established patterns based on tumor subtype. This manuscript will review pancreatic neuroendocrine tumor subtypes, syndromes, diagnosis, and clinical management.