External Beam Radiotherapy in the Treatment of Gastroenteropancreatic Neuroendocrine Tumours: A Systematic Review

Gastroenteropancreatic neuroendocrine neoplasms: epidemiology, genetics, and treatment

The incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP NEN) is increasing at a rapid pace and is becoming an increasingly important consideration in clinical care. Epidemiological data from multiple countries indicate that the incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP NEN) exhibits regional, site-specific, and gender-based variations. While the genetics and pathogenesis of some GEP NEN, particularly pancreatic NENs, have been investigated, there are still many mechanisms that require further investigation. The management of GEP NEN is diverse, but surgery remains the primary option for most cases. Peptide receptor radionuclide therapy (PRRT) is an effective treatment, and several clinical trials are exploring the potential of immunotherapy and targeted therapy, as well as combination therapy.

Update in the management of gastroenteropancreatic neuroendocrine tumors

Neuroendocrine neoplasms are a diverse group of neoplasms that can occur in various areas throughout the body. Well-differentiated neuroendocrine tumors (NETs) most often arise in the gastrointestinal tract, termed gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Although GEP-NETs are still uncommon, their incidence and prevalence have been steadily increasing over the past decades. The primary treatment for GEP-NETs is surgery, which offers the best chance for a cure. However, because GEP-NETs are often slow-growing and do not cause symptoms until they have spread widely, curative surgery is not always an option. Significant advances have been made in systemic and locoregional treatment options in recent years, including peptide-receptor radionuclide therapy with α and β emitters, somatostatin analogs, chemotherapy, and targeted molecular therapies.

A Review of the Evolving Role of Radiotherapy in the Treatment of Neuroendocrine Neoplasms

BACKGROUND

Neuroendocrine neoplasms (NENs) are rare tumours that develop from neuroendocrine cells in various parts of the body. The management of this disease poses a significant challenge because of the heterogeneous clinical presentation and varying degrees of aggressiveness. A multidisciplinary approach is often required in complex clinical situations. Radiotherapy (RT) plays a key role in managing NETs in both curative and palliative settings.

SUMMARY

In this review, we summarize and discuss recent developments in the field of advanced RT in early-stage, locally advanced, and metastatic NENs. We highlight limitations in current approaches and discuss future potential treatment strategies for patients with NENs.

Palliative radiotherapy is effective for both well- and poorly differentiated neuroendocrine neoplasms

INTRODUCTION

The outcomes of palliative radiation therapy (RT) for neuroendocrine neoplasms (NEN) are seldom reported. We investigated outcomes following palliative radiotherapy in a cohort of patients with NENs. We hypothesised that well-differentiated NEN will be less likely to have a clinical response than poorly differentiated NEN.

METHODS

Patients who received at least one course of palliative RT were identified using the New Zealand NETwork! Registry. Patients with Merkel cell carcinoma, pulmonary small cell carcinoma or asymptomatic patients were excluded. Clinical response to RT within 90 days and overall survival were analysed alongside clinical variables (fractionation, RT site, tumour differentiation and tumour primary site).

RESULTS

The cohort comprised 79 patients, with 147 courses of palliative RT delivered. Clinical response was measurable for 100 courses, with clinical response rate of 76%. A course delivered to a well-differentiated NEN was associated with 2.02-fold (95% CI 0.67, 6.12; P = 0.21) increase in odds of a clinical response compared to a poorly differentiated NEN. Median overall survival from the first fraction of RT was 94 days (95% CI 80, 138 days). Overall survival was higher in well-differentiated NEN than in poorly differentiated NEN (HR 0.2, 95% CI 0.10-0.40, P-value < 0.001); 30-day mortality was 7%. There were significantly reduced odds of clinical response for non-bone sites, and for courses >10 fractions compared to a single fraction.

CONCLUSION

Palliative RT is an appropriate option for management of symptoms in patients with both well- and poorly differentiated metastatic NEN.

Can Ki-67 predict radiotherapy response in neuroendocrine tumors? Retrospective analysis of a monocentric series of patients

BACKGROUND

The impact of radiotherapy (RT) in neuroendocrine neoplasms is still unknown, and outcomes could be improved by a better insight in RT response predictors. This retrospective analysis investigates the potential correlation between Ki-67 and RT response to evaluate its role as biological marker of radiosensitivity.

MATERIAL AND METHODS

Data from patients treated at an Italian NET-referral center between 2015 and 2020 were retrieved. Inclusion criteria included: histologically-proven diagnosis of NEN, Ki-67 status, indication (symptomatic and/or ablative) and at least one post-RT radiological assessment.

RESULTS

Forty-two patients and 63 different treatment lines were included. Primary tumors presented Ki-67 values < 3% in 21% of cases, between 3 and 20% in 45% and >20% in the remaining 33%. Almost all patients were metastatic at the time of RT, which was performed with symptomatic purpose in 43% of cases. At a median time of three months, a complete response on the target lesion was observed in nine cases (14%), a partial response in 17 (27%), stability in 23 (37%) and local progression in 14 (22%). With median FU of 22.8 months, OS does not show statistically significant differences among three Ki-67 groups. Considering all lines of therapy, the relationship between ORR and Ki-67, did not show statistically significant differences, even following adjustments for drug types and delivered RT doses.

CONCLUSION

No association between Ki67 and local tumor response to RT could be observed in the present cohort, regardless of whether the evaluation was performed on a categorical or continuous scale.

Local disease control after stereotactic body radiotherapy in patients with neuroendocrine neoplasms: a cohort study

BACKGROUND

Neuroendocrine neoplasms represent a diverse group of malignancies. Anatomic origin, histology and aggressiveness vary extensively, from low-grade tumours with an indolent prognosis to highly aggressive conditions with poor outcome. Surgery, with a curative intent, is the standard of treatment when possible. Other treatment regimens include local treatment, or systemic therapy. The role of radiotherapy in treating neuroendocrine neoplasms is not yet established, but studies indicate that a high rate of local control can be achieved by high-dose radiotherapy. Stereotactic body radiotherapy (SBRT) is high dose of radiation delivered to a small volume. We aimed to investigate the one-year local control rate of SBRT in patients with neuroendocrine neoplasms.

MATERIAL AND METHODS

Patients with neuroendocrine neoplasms treated with SBRT between 2003 and 2021 were retrospectively identified. Patient characteristics and SBRT-details were collected by review of patient records and the radiotherapy planning charts. All types except for small cell lung cancer and brain metastases were allowed. The prescribed dose was 45-67.8 Gy in three fractions. Progression, both within the target-site and in other sites, was determined based on existing imaging reports. One-year local control rate and systemic control rate was calculated. Descriptive analyses of local response duration, progression-free survival and overall survival were performed.

RESULTS

Twenty-one patients were included. The one-year local control rate was 94%. Four of the patients had local progression. All patients receiving SBRT towards their primary tumour (n = 11) had a bronchopulmonary neuroendocrine neoplasm, and a one-year local control rate of 100%. In patients treated at a metastatic target, 80% developed systemic progression but the local control remained high.

CONCLUSION

Our study suggests that SBRT may offer a feasible and effective treatment of neuroendocrine neoplasms in selected cases. SBRT provides long-term local stability and may be useful in treating patients with localised disease not fit for surgery.

Precision radiotherapy using MR-linac for pancreatic neuroendocrine tumors in MEN1 patients (PRIME): a protocol for a phase I-II trial, and systematic review on available evidence for radiotherapy of pNETs

Background

Surgical resection is the standard of care for the treatment of pancreatic neuro-endocrine tumors (pNETs) in patients with Multiple Endocrine Neoplasia Type 1 (MEN1). However, surgery can cause significant short- and long-term morbidity. Magnetic resonance-guided radiotherapy (MRgRT) is a potential effective treatment with little side effects. With traditional radiotherapy techniques, irradiation of pancreatic tumors to high dose levels was hampered by poor visibility of the tumor during treatment. MRgRT uses onboard MRI to guide the treatment, thereby enabling delivery of ablative irradiation doses to the tumor, while sparing surrounding tissues. In this study, we describe results from a systematic review assessing efficacy of radiotherapy in pNET and present the protocol of the PRIME study.

Methods

PubMed, Embase and Cochrane Library were searched for articles assessing efficacy and side effects of radiotherapy for the treatment of pNETs. Risk of bias was assessed using the ROBINS-I Risk of Bias Tool for observational studies. Descriptive statistics were used to describe results of included trials.

Results

Four studies comprising of 33 patients treated by conventional radiotherapy were included. Despite the heterogeneity of studies, radiotherapy appeared to be effective for the treatment of pNETs with most patients responding (45.5%) or stabilizing (42.4%) in tumor size.

Conclusion and trial design

Due to the limited literature available and concerns about damage to surrounding tissue, conventional radiotherapy is currently little used for pNETs. The PRIME study is a phase I-II trial with a single arm prospective cohort study design, investigating the efficacy of MRgRT in MEN1 patients with pNET. MEN1 patients with growing pNETs with a size between 1.0 and 3.0 cm without malignant features are eligible for inclusion. Patients are treated with 40 Gy in 5 fractions on the pNET, using online adaptive MRgRT on a 1.5T MR-linac. The primary endpoint is the change in tumor size at MRI 12 months follow-up. Secondary endpoints include radiotoxicity, quality of life, endocrine and exocrine pancreas function, resection rate, metastatic free and overall survival. When MRgRT is found effective with low radiotoxicity, it could reduce the need for surgery for pNET and preserve quality of life.

Systematic Review Registration

PROSPERO https://clinicaltrials.gov/, (CRD42022325542).

Adaptive Tomotherapy for locally advanced unresectable pancreatic neuroendocrine tumor: Case report and literature review

BACKGROUND

Pancreatic neuroendocrine tumor (NET) is rare, and the majority presents late in their clinical course. Here, we present a huge locally advanced pancreatic NET having Hi-Art helical Tomotherapy that resulted in a 68% reduction in target volume during adaptive image-guided radiotherapy (IGRT).

CASE SUMMARY

A 63-year-old man without any history of systemic disease developed voiding difficulty for several months. Associated symptoms included poor appetite, nausea, distended abdomen, and body weight loss. Further magnetic resonance imaging showed a large multilobulated tumor in the left upper abdomen. Tumor biopsy revealed well-differentiated, grade 2, neuroendocrine tumor. Complete resection was unattainable. Therefore, Lanreotide was prescribed initially. However, tumor progression up to the greatest diameter of 18 cm was noted on computed tomography 5 months later. Thus, he stopped Lanreotide and commenced on concurrent chemoradiotherapy (CCRT). With a total dose of 70 Gy in 35 fractions, we generated two adaptive treatment plans during the whole course. Laparoscopic subtotal pancreatectomy with spleen preservation was performed after neoadjuvant CCRT. It has been more than 3 years after IGRT, and he remains cancer free and reports no side effects during regular follow-ups.

CONCLUSION

Tomotherapy caused tumor size reduction and hence facilitated surgical possibility for this originally unresectable pancreatic NET. Neoadjuvant IGRT incorporated with adaptive treatment planning enhanced delivery accuracy. In this case of pancreatic NET resistant to Lanreotide, inter-fractional tumor regression from 1910 to 605 cc (68%) was documented.

Radioligand therapy (RLT) as neoadjuvant treatment for inoperable pancreatic neuroendocrine tumors: a literature review

In the last 10 years, several literature reports supported radioligand therapy (RLT) in neoadjuvant settings for pancreatic neuroendocrine tumors (PanNETs). Indeed, primary tumor shrinkage has been frequently reported following RLT in unresectable or borderline resectable PanNETs. Moreover, RLT-induced intratumoral modifications facilitate surgery, both on primary tumor and metastasis, having a great impact on progression free survival (PFS), overall survival (OS) and quality of life (QoL). However, prospective controlled investigations are necessary to confirm preliminary data and to define the best RLT scheme and the ideal patient that, in a multidisciplinary approach, should be referred to neoadjuvant RLT.

Pediatric Neuroendocrine Neoplasms: Rare Malignancies with Incredible Variability

Neuroendocrine neoplasms (NENs) encompass a variety of neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) which can arise anywhere in the body. While relatively rare in the pediatric population, the incidence of NENs has increased in the past few decades. These neoplasms can be devastating if not diagnosed and treated early, however, symptoms are variable and can be indolent for many years. There is a reported median of 10 years from the appearance of the first symptoms to time of diagnosis. Considering some of these neoplasms have a mortality rate as high as 90%, it is crucial healthcare providers are aware of NENs and remain vigilant. With better provider education and easily accessible resources for information about these neoplasms, awareness can be improved leading to earlier disease recognition and diagnosis. This manuscript aims to provide an overview of both the most common NENs as well as the rarer NENs with high lethality in the pediatric population. This review provides up to date evidence and recommendations, encompassing recent changes in classification and advances in treatment modalities, including recently completed and ongoing clinical trials.

Multimodal Management of Grade 1 and 2 Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (p-NETs) are rare tumors with a recent growing incidence. In the 2017 WHO classification, p-NETs are classified into well-differentiated (i.e., p-NETs grade 1 to 3) and poorly differentiated neuroendocrine carcinomas (i.e., p-NECs). P-NETs G1 and G2 are often non-functioning tumors, of which the prognosis depends on the metastatic status. In the localized setting, p-NETs should be surgically managed, as no benefit for adjuvant chemotherapy has been demonstrated. Parenchymal sparing resection, including both duodenum and pancreas, are safe procedures in selected patients with reduced endocrine and exocrine long-term dysfunction. When the p-NET is benign or borderline malignant, this surgical option is associated with low rates of severe postoperative morbidity and in-hospital mortality. This narrative review offers comments, tips, and tricks from reviewing the available literature on these different options in order to clarify their indications. We also sum up the overall current data on p-NETs G1 and G2 management.

Localization Defines Streptozotocin/5-FU Response in Primary Pancreatic Neuroendocrine Tumours

INTRODUCTION

Incidence of pancreatic neuroendocrine tumours (pNETs) is on the rise. The only curative treatment is surgical resection in localized or oligo-metastatic disease. However, patients may present with locally advanced or unresectable primary tumours. So far, no conversion therapy to achieve resectability has been established, which is partly due to lack of data on primary tumour response to therapies. Here, we specifically evaluate the primary tumour response to streptozocin/5-FU in a large cohort of metastatic pNET patients.

METHODS

Five ENETS centres in Germany contributed 84 patients to the study cohort for retrospective analysis.

RESULTS

Overall response rate (ORR) in primary tumours was 34% and disease control rate (DCR) 88%. ORR was different in metastases at 44% and DCR at 70%. Partial remission in primary tumours was more frequent among those located in pancreatic tail than that in pancreatic head (49% vs. 14%, p = 0.03). Correspondingly, metastases from tumours originating from pancreatic tail responded more frequently than metastases originating from pancreatic head (88.5% vs. 41.7%, p = 0.005). The median PFS of the primary tumours was longer than that in metastases (31 months vs. 16 months; p = 0.04). Considerable downsizing of the primary tumour was rare and occurred primarily in tumours located in the pancreatic tail.

CONCLUSION

STZ/5-FU can achieve disease stabilization in a high proportion of metastatic pNET patients. In the majority of cases however it does not induce substantial downsizing of the primary tumour, thus possibly limiting its potential as conversion chemotherapy. Furthermore, the difference in response rate observed between different primary tumour locations warrants further exploration.

Stereotactic Ablative Radiotherapy for the Management of Liver Metastases from Neuroendocrine Neoplasms: A Preliminary Study

INTRODUCTION

Liver metastases are common in patients with neuroendocrine neoplasms. The role of stereotactic ablative radiotherapy (SABR) is not well understood in this population.

OBJECTIVE

The objective of this study was to evaluate the safety and efficacy of SABR in treating well-differentiated neuroendocrine liver metastases (WD-NELM).

METHODS

A retrospective review of patients with WD-NELM treated with SABR was conducted between January 2015 and July 2019. Demographic, treatment, and clinical/radiographic follow-up data were abstracted. RECIST 1.1 criteria were applied to each individual target to evaluate the response to treatment. Local control (LC) and progression-free survival (PFS) were determined using the Kaplan-Meier methodology. Toxicity was reported according to the CTCAE v5.0.

RESULTS

Twenty-five patients with a total of 53 liver metastases treated with SABR were identified. Most patients (68%) had midgut tumors, were grade 2 (80%), and had high-volume intrahepatic and/or extrahepatic disease (76%). The median number of liver metastases treated was 2, with a median size of 2.5 cm. The median radiation dose delivered was 50 Gy/5 fractions. The median follow-up was 14 months; 24 of the 25 patients were alive at the time of analysis. The objective response rate was 32%, with improvement or stability in 96% of lesions treated. The median time to best response was 9 months. The 1-year LC and PFS were 92 and 44%, respectively. No grade 3/4 acute or late toxicity was identified.

CONCLUSIONS

Liver SABR is a safe and promising means of providing LC for WD-NELM. This treatment modality should be evaluated in selected patients in concert with strategies to manage systemic disease.

Implementation of robot-assisted curative resection for rare anorectal tumours on the basis of individualised treatment

PURPOSE

To evaluate the validity of robot-assisted curative operation for rare anorectal tumours, characterised by biological heterogeneity and anatomical complexity.

METHODS

The present study evaluated 16 consecutive patients including three with anorectal squamous cell carcinoma (ARSCC), four with anorectal mucosal melanoma (ARMM), seven with anorectal neuroendocrine tumour (ARNET), and two with other types of anorectal tumours.

RESULTS

Of the three patients with ARSCC after chemoradiotherapy, two underwent abdominoperineal resection (APR), and one underwent ultralow anterior resection (uLAR)/total intersphincteric resection (ISR), surviving 56-76 months without recurrence. Of the four ARMM patients, APR and uLAR/total ISR were conducted in two patients, respectively, with variable survival outcomes. All seven patients with ARNET were treated with uLAR/ISR and LAR, surviving for 5-106 months to date.

CONCLUSIONS

Because most anorectal tumours are confined to the dermal and submucosal layers, robotic anorectal function preserving ISR is expected to achieve R0 resection.

Outcomes after high-dose radiation in the management of neuroendocrine neoplasms

BACKGROUND

Neuroendocrine neoplasms (NENs) comprise a rare and heterogenous group of cancers, for which the role of radiation therapy continues to evolve. The purpose of this study is to analyze oncologic outcomes after the use of high-dose radiation in management of NENs at a tertiary hospital.

MATERIALS AND METHODS

We performed a retrospective review of patients who received high-dose radiation with intent to cure or provide durable local control (defined as biologically effective dose (BED) ≥40, α/β = 10) for a localized or metastatic NEN from 2006 to 2019. Evaluation of disease status after radiation was performed according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria when possible. Patients were grouped by differentiation (well-differentiated (WD) or poorly-differentiated (PD)) and stage (localized/locally advanced disease (L) or metastatic (M)) in analysis of probabilities of progression after radiation.

RESULTS

45 patients completed a radiation course with BED ≥40 for a NEN (median BED 72). With a median follow-up of 24 months after radiation, the 2-year actuarial rates of local relapse-free survival, new metastasis-free survival, progression-free survival, and overall survival after radiation were 98%, 45%, 41%, and 69%, respectively. 25 patients (56%) developed new metastases after completion of radiation, including 33% (n = 3) of patients with WD-L disease, 44% (n = 8) of WD-M, 77% (n = 10) of PD-L, and 80% (n = 4) of PD-M, with progressively shorter median times to progression (26, 9, 8, and 3 months, respectively; p = 0.093). Of the 25 patients evaluable by RECIST, 68% (n = 17) achieved either a complete or partial best response in the irradiated lesion.

CONCLUSIONS

These data suggest that focal, high-dose radiation has a role in the management of selected patients with NENs. Local failure is rare in patients with both well-differentiated and poorly-differentiated disease, although the predominant pattern of failure remains development of new metastases.

Knowns and unknowns of bone metastases in patients with neuroendocrine neoplasms: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to develop an evidence-based summary of current knowledge of bone metastases (BMs) in neuroendocrine neoplasms (NENs), inform diagnosis and treatment and standardise management between institutions.

METHODS

PubMed, Medline, EMBASE and meeting proceedings were searched for eligible studies reporting data on patients with BMs and NENs of any grade of differentiation and site; poorly-differentiated large/small cell lung cancer were excluded. Data were extracted and analysed using STATA v.12. Meta-analysis of proportions for calculation of estimated pooled prevalence of BM and calculation of weighted pooled frequency and weighted pooled mean for other variables of interest was performed .

RESULTS

A total of 149 studies met the eligibility criteria. Pooled prevalence of BMs was 18.4% (95% CI 15.4-21.5). BMs were mainly metachronous with initial diagnosis of NEN (61.2%) and predominantly osteoblastic; around 61% were multifocal, with a predisposition in axial skeleton. PET/CT seemed to provide (together with MRI) the highest sensitivity and specificity for BM detection. Almost half of patients (46.4%) reported BM-related symptoms: pain (66%) and skeletal-related events (SREs, fracture/spinal cord compression) (26.2%; weightedweighted mean time-to-SRE 9.9 months). Management of BMs was multimodal [bisphosphonates and bone-modifying agents (45.2%), external beam radiotherapy (34.9%), surgery (14.8%)] and supported by little evidence. Overall survival (OS) from the time of diagnosis of BMs was long [weighted mean 50.9 months (95% CI 40.0-61.9)]. Patients with BMs had shorter OS [48.8 months (95% CI 37.9-59.6)] compared to patients without BMs [87.4 months (95% CI 74.9-100.0); p = 0.001]. Poor performance status and BM-related symptoms were also associated with worse OS.

CONCLUSIONS

BMs in patients with NENs remain underdiagnosed and undertreated. Recommendations for management of BMs derived from current knowledge are provided. Prospective studies to inform management are required.

Radiation treatment for adult rare cancers: Oldest and newest indication

AIM

Aim of this analysis is to review the role of RT in the management of several rare tumors for adult patients.

METHODS

Collection data regarding RT and rare tumors was made by Pubmed.

RESULTS

For mucosal melanomas, RT is prescribed, being associated with lower local recurrence rate. For trachea tumors, RT was used as adjuvant or salvage treatment for unresectable disease. For pNET, RT can be a suitable option for post-surgical or unresectable/borderline. For bronchopulmonary neuroendocrine tumors the role of adjuvant treatments is uncertain. For hepatobiliary and ovarian malignancy, stereotactic body RT (SBRT) is a promising approach. For soft tissue sarcoma, perioperative treatments are indicated, and a growing role of SBRT in oligometastatic disease is recognized. For endocrine tumors, adjuvant RT has demonstrated benefits through reducing recurrence risk.

CONCLUSION

The radiotherapy is a frequent indication in adult rare cancers; thus the role of Radiation Oncologist must not be neglected.

The North American Neuroendocrine Tumor Society Consensus Guidelines for Surveillance and Medical Management of Pancreatic Neuroendocrine Tumors

This article is the result of the North American Neuroendocrine Tumor Society consensus conference on the medical management of pancreatic neuroendocrine tumors from July 19 to 20, 2018. The guidelines panel consisted of medical oncologists, pathologists, gastroenterologists, endocrinologists, and radiologists. The panel reviewed a series of questions regarding the medical management of patients with pancreatic neuroendocrine tumors as well as questions regarding surveillance after resection. The available literature was reviewed for each of the question and panel members voted on controversial topics, and the recommendations were included in a document circulated to all panel members for a final approval.

Unexpected response to palliative radiotherapy for subcutaneous metastases of an advanced small cell pancreatic neuroendocrine carcinoma: a case report of two different radiation schedules

Background

Skin metastases from pancreatic neuroendocrine carcinoma (PNEC) are rare and their palliative treatment is challenging. We report our experience in the multimodal management of one of the few reported cases of metastatic PNEC with multiple visceral and subcutaneous secondary lesions, focusing on the effectiveness of palliative radiotherapy for skin metastases.

Case presentation

A 61-years old woman affected by a metastatic PNEC – with subcutaneous growing and bleeding secondary lesions (at the scalp, right scapular region and at the back of the left thoracic wall, respectively) – obtained a successful control of visceral metastases with the use of chemotherapy and an unexpected local response of her skin metastases with palliative radiotherapy. In particular, two subsequent radiation treatments were performed using different fractionation schedules (30 Gy in 10 fractions and 20 Gy in 5 fractions, respectively). Both radiation treatments were well-tolerated and patient’s quality of life was improved. Local response was maintained until patient’s death – that occurred due to cachexia.

Conclusions

The presented case highlights the effectiveness and the good tolerance of radiotherapy in the treatment of subcutaneous metastases; nevertheless, further knowledge of the optimal local palliative approach for PNEC metastatic sites is necessary. The experience gained in this work is the occasion to encourage a routine integrated multidisciplinary team management of metastatic PNECs because of their clinical complexity. The aim is to guarantee the optimization of the care with personalized and more effective systemic and local treatments – also including supportive cares and treatment-related side effects management.

Management of Gastrointestinal Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are derived from neuroendocrine cell system and can have benign or malignant characteristics. They are rare tumors, but have been increasing in incidence over the past 40 years. Patients with NENs may develop symptoms due to primary tumor invasion, metastasis, or from secretion of hormonally active tumor substances. Multiple imaging modalities are used for diagnosis and staging, including specialty scans such as ¹¹¹In pentetreotide (Octreoscan) and ⁶⁸Gallium-DOTATATE, along with endoscopy, endoscopic ultrasound, and biochemical marker testing. Treatment involves both surgical approach, for both primary and metastatic lesions, as well as medical management for symptom management and disease progression. This article will review the current clinical knowledge regarding the diagnosis, treatment, and prognosis of these fascinating neoplasms and the associated hormonal syndromes.

Treatment Options for Pancreatic Neuroendocrine Tumors

The management of pancreatic neuroendocrine tumors (PanNETs) involves classification into non-functional or functional PanNET, and as localized or metastatic PanNET. In addition, while most PanNETs are sporadic, these endocrine neoplasms can also be manifestations of genetic syndromes. All these factors may assist in forming a risk stratification system permitting a tailored management approach. Most PanNETs are classified as non-functional because they are not associated with clinical sequelae of hormone excess. They are characterized by non-specific symptoms, such as abdominal pain or weight loss, resulting from mass effect related to the pancreatic tumor or secondary to distant metastases. Accurate staging of the disease is essential for determining the appropriate approach to therapy. As cure is only potentially possible with surgical resection of the tumor, it is recommended to remove all localized and limited metastatic disease. However, many patients present with metastatic and/or advanced local disease. In such instances, the goal of therapy is to control tumor growth and/or decrease tumor burden, lengthen survival, and palliate local symptoms and those of hormone excess. This typically requires a multimodal approach, including surgery, liver-directed treatment, and systemic medical therapy.

Current treatment strategies for patients with advanced gastroenteropancreatic neuroendocrine tumors (GEP-NETs)

Background

Neuroendocrine tumors (NETs) are rare neoplasms, with an estimated annual incidence of ~ 6.9/100,000. NETs arise throughout the body from cells of the diffuse endocrine system. More than half originate from endocrine cells of the gastrointestinal tract and the pancreas, thus being referred to as gastroenteropancreatic NETs (GEP NETs). The only treatment that offers a cure is surgery, however most patients are diagnosed with metastatic disease, and curative surgery is usually not an option.Since the majority of patients are not candidate for curative surgery, they can be offered long-term systemic treatment, for both symptomatic relief and tumor growth suppression. Evidence based treatment options include somatostatin analogues, everolimus (an mTOR inhibitor), sunitinib (a tyrosine kinase inhibitor), peptide receptor radionuclide therapy (PRRT), chemotherapy, etc., alone or combined with cytoreductive procedures (surgery or liver directed procedures). However, there is an increasing need for novel therapies. Other treatment options being investigated are immunotherapy and epigenetic assessment that may lead to more personalized interventions. Following first line therapy with somatostatin analogues, there is no clear information to date indicating a preferred treatment sequence, and therefore the treatment approach should be individualized based on each NET patient characteristics.

Conclusions

NET patients are increasingly diagnosed throughout the world, usually with metastatic disease and requiring systemic therapy. We believe that each patient should be therefore thoroughly evaluated and individually discussed by a multidisciplinary and dedicated NET-expert team, updated with all treatment options including ongoing clinical trials, and before selecting the proper treatment sequence.