Neuroendocrine liver metastasis: The chance to be cured after liver surgery

Comprehensive single-cell atlas of colorectal neuroendocrine tumors with liver metastases: unraveling tumor microenvironment heterogeneity between primary lesions and metastases

BACKGROUND

Colorectal neuroendocrine tumors with liver metastases (CRNELM) are associated with a poorer prognosis compared to their nonmetastatic counterparts. A comprehensive understanding of the tumor microenvironment (TME) heterogeneity between primary lesions (PL) and liver metastases (LM) could provide crucial insights for enhancing clinical management strategies for these patients.

METHODS

We utilized single-cell RNA sequencing to analyze fresh tissue samples from CRNELM patients, aiming to elucidate the variations in TME between PL and LM. Complementary multidimensional validation was achieved through spatial transcriptomics, bulk RNA sequencing, and multiplex immunohistochemistry/immunofluorescence.

RESULTS

Our single-cell RNA sequencing analysis revealed that LM harboured a higher proportion of CD8 + T cells, CD4 + T cells, NK cells, NKT cells, and B cells exhibiting a stress-like phenotype compared to PL. RGS5 + pericytes may play a role in the stress-like phenotype observed in immune cells within LM. MCs in PL (PL_MCs) and LM (LM_MCs) exhibit distinct activation of tumor-associated signaling pathways. Notably, COLEC11 + matrix cancer-associated fibroblasts (COLEC11_mCAFs) were found to be significantly associated with LM_MCs. Cell communication analysis unveiled potential targetable receptor-ligand interactions between COLEC11_mCAFs and LM_MCs. Multidimensional validation confirmed the prominence of the characteristic stress-like phenotypes, including HSPA6_CD8_Tstr, HSPA6_NK, and COLEC11_mCAFs in LM. Moreover, a higher abundance of COLEC11_mCAFs correlated with poorer survival rates in the neuroendocrine tumor patient cohort.

CONCLUSION

Overall, our study provides the first single-cell analysis of the cellular and molecular differences between PL and LM in CRNELM patients. We identified distinct cell subsets and receptor-ligand interactions that may drive TME discrepancies and support metastatic tumor growth. These insights highlight potential therapeutic targets and inform strategies for better managing CRNELM patients.

Surgical microwave ablation of 397 neuroendocrine liver metastases: a retrospective cohort analysis of 16 years of experience

BACKGROUND

Neuroendocrine tumors (NET) constitute a heterogeneous group of malignancies whose incidence has been on the rise over the past two decades, currently documented at 5.25 per 100,000. Liver metastasis develops in over 60% of NET patients. Even after resection recurrence rates are high, underscoring the importance of parenchymal-sparing interventions. In this study, we conducted 105 surgical microwave ablations and examined outcomes related to survival and local recurrence.

METHODS

Retrospective review of patients who underwent a surgical microwave ablation (MWA) at a single-center, high-volume institution from September 2007 through December 2022 using a prospective database. Primary outcome was overall survival.

RESULTS

A total of 105 operations were performed on 94 patients, with 397 tumors undergoing MWA. Median tumor size was 1.3 cm (range 0.3-8.0), and the median number of tumors ablated was 2 (range 1-12). Laparoscopic approach was utilized 69.5% of the time. The most common concomitant procedure performed was hepatectomy (33.3%) and cholecystectomy (23.8%). Clavien-Dindo grade III or IV complications occurred in 9 patients (9.6%). Mortality within 30 days occurred in 1 patient (1.1%). The rate of incomplete ablation was 0.3% per tumor. Local recurrence occurred in 2.8% of tumors. Median OS was 9.43 years [95% CI 4.23-14.63 years], with a 5- and 10-year survival probability of 70.2% and 48.2%, respectively.

CONCLUSION

Surgical MWA offers an efficacious, parenchymal-sparing treatment of hepatic metastasis of NET, with low rates of incomplete ablation and local recurrence per tumor.

Improvement of Laboratory Hepatic Parameters After Treatment With 177 Lu-DOTATATE : Cohort in an Oncology Reference Center

PURPOSE

Well-differentiated neuroendocrine neoplasms (NETs) overexpress the somatostatin receptor, which is the target for the peptide receptor radionuclide therapy (PRRT). NETs have a slow growth rate and can metastasize to liver, bone, and lungs. In NETs patients, liver metastasis is an important prognostic marker because liver failure is one of the most common causes of death in this population. In this regard, we aimed to describe the changes in laboratorial parameters in patients submitted to PRRT with 177 Lu-DOTATATE, focusing on hepatic parameters.

PATIENTS AND METHODS

One hundred ten patients treated with 1 to 4 cycles of 7.4 GBq (200 mCi) of 177 Lu-DOTATATE from January 2011 to December 2021 were analyzed in this retrospective observational single-center study. Patients were submitted to blood tests before and after each cycle of PRRT. Laboratory measurements were collected to assess liver function, cholestasis, kidney, and bone marrow function.

RESULTS

In the general population (n = 110), ALP ( P = 0.013) and GGT ( P < 0.001) showed a statistically significant reduction. Patients with high liver disease volume showed a statistically significant reduction in ALT ( P = 0.016), whereas patients with low liver disease volume showed a statistically significant reduction in GGT ( P = 0.013). All parameters for bone marrow function showed a statistically significant decrease in all population subsets.

CONCLUSIONS

Patients treated with 177 Lu-DOTATATE showed a significant improvement in liver function and cholestasis parameters, and a consistent decrease in bone marrow function, even in the presence of advanced liver disease.

Impact of primary tumor resection in the management of metastatic well-differentiated neuroendocrine tumors of the small bowel and pancreas

Patients with gastroenteropancreatic (GEP) neuroendocrine tumors (NET) often present with advanced disease. Primary tumor resection (PTR) in the setting of unresectable metastatic disease is controversial. Most studies evaluating the impact of PTR on overall survival (OS) have been performed using large population-based databases, with limited treatment related data. This study aims to determine whether PTR improves OS and progression-free survival (PFS) in patients with metastatic well-differentiated GEP-NET. This is a retrospective single-institution study of patients with metastatic well-differentiated GEP-NET between 1978 and 2021. The primary outcome was OS. The secondary outcome was PFS. Chi-squared tests and Cox regression were used to perform univariate and multivariate analyses (MVA). OS and PFS were estimated using the Kaplan-Meier method and log-rank test. Between 1978 and 2021, 505 patients presented with metastatic NET, 151 of whom had well-differentiated GEP-NET. PTR was performed in 31 PNET and 77 SBNET patients. PTR was associated with improved median OS for PNET (136 vs. 61 months, p = .003) and SBNET (not reached vs. 79 months, p<.001). On MVA, only higher grade (HR 3.70, 95%CI 1.49-9.17) and PTR (HR 0.21, 95%CI 0.08-0.53) influenced OS. PTR resulted in longer median PFS for patients with SBNET (46 vs. 28 months, p = .03) and a trend toward longer median PFS for patients with PNET (20 vs. 13 months, p = .07). In patients with metastatic well-differentiated GEP-NET, PTR is associated with improved OS and may be associated with improved PFS and should be considered in a multidisciplinary setting. Future prospective studies are needed to validate these findings.

Surgical debulking is associated with improved survival for patients with neuroendocrine liver metastases of unknown primary

BACKGROUND

Resection of neuroendocrine tumors (NET) with surgical debulking of liver metastasis (NETLM) is associated with improved survival. In patients with an unknown primary (UP-NETLM), the effects of debulking remains unclear.

METHODS

The National Cancer Database (2004-2016) was queried for patients with small intestine (SI) and pancreas (P) NETLMs. If the liver was listed as the primary site, the patient's disease was classified as UP-NETLM.

RESULTS

Patients with UP-NETLM, SI-NETLM, and P-NETLM who were managed non-operatively demonstrated a significant difference in 5-year overall survival (OS) (21.5% vs. 39.2% vs. 17.1%; p < 0.0001). OS in patients who underwent debulking was higher (63.7% vs. 73.2% vs. 54.2%). Patients with UP-NETLMs who underwent debulking had similar OS to patient with SI-NETLM (p = 0.051), but significantly higher OS, depending on tumor differentiation, compared to patients with P-NETLMs. If well-differentiated, surgery for UP-NETLMs was associated with a higher rate of OS (p = 0.009), while no difference was observed if moderately (p = 0.209) or poorly/undifferentiated (p = 0.633). P-NETLMs were associated with worse OS (p < 0.001) on multivariate analysis.

DISCUSSION

Debulking in patients with UP-NETLMs was associated with similar OS compared to patients with SI-NETLMs and better or similar OS compared to patient with P-NETLMs.

The Evolving Landscape of Neuroendocrine Tumors

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

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

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

Survival Benefit of Resection Surgery for Pancreatic Ductal Adenocarcinoma with Liver Metastases: A Propensity Score-Matched SEER Database Analysis

Simple Summary

Pancreatic ductal adenocarcinoma is a devastating illness but guidelines consider it unresectable once metastasized. However, resection of the primary tumor is carried out in select cases and retrospective analyses indicate that this may improve survival. Even so, these analyses are limited to single centers or fail to account for biased patient selection. We overcome these limitations with a propensity score-matched SEER database analysis that reliably demonstrates surgery can extend overall survival. Furthermore, we identify prognostic factors that could aid the selection of patients for randomized controlled trials. Thus, this study paves the way for future work that aims to update treatment guidelines in accordance with surgical developments.

Abstract

Guidelines do not recommend resection surgery for oligometastatic pancreatic ductal adenocarcinoma (PDAC). However, reports in small samples of selected patients suggest that surgery extends survival. Thus, this study aims to gather evidence for the benefits of cancer-directed surgery (CDS) by analyzing a national cohort and identifying prognostic factors that aid the selection of candidates for CDS or recruitment into experimental trials. Data for patients with PDAC and hepatic metastasis were extracted from the population-based Surveillance, Epidemiology, and End Results database (SEER). The bias between CDS and non-CDS groups was minimized with Propensity Score Matching (PSM), and the prognostic role of CDS was investigated by comparing Kaplan-Meier estimators and Cox proportional hazard models. A total of 12,018 patients were extracted from the database, including 259 patients who underwent CDS that were 1:1 propensity score-matched with patients who did not receive CDS. CDS appeared to significantly prolong median overall survival from 5 to 10 months. Multivariate analysis revealed chemotherapy as a protective prognostic, whilst survival was impaired by old age and tumors that were poorly differentiated (Grades III–IV). These factors can be used to select patients likely to benefit from CDS treatment, which may facilitate recruitment into randomized controlled trials.

How to Manage Small Intestine (Jejunal and Ileal) Neuroendocrine Neoplasms Presenting with Liver Metastases?

PURPOSE OF REVIEW

Small intestinal neuroendocrine neoplasms (siNENs) are slowly growing tumours with a low malignant potential. However, more than half of the patients present with distant metastases (stage IV) and nearly all with locoregional lymph node (LN) metastases at the time of surgery. The value of locoregional treatment is discussed controversially.

RECENT FINDINGS

In stage I to III disease, locoregional surgery was currently shown to be curative prolonging survival. In stage IV disease, surgery may prolong survival in selected patients with the chance to cure locoregional disease besides radical/debulking liver surgery. It may improve the quality of life and may prevent severe local complications resulting in a state of chronic malnutrition and severe intestinal ischaemia or bowel obstruction. Locoregional tumour resection offers the opportunity to be curative or to focus therapeutically on liver metastasis, facilitating various other therapeutic modalities. Risks and benefits of the surgical intervention need to be balanced individually.

Chemoembolization Versus Radioembolization for Neuroendocrine Liver Metastases: A Meta-analysis Comparing Clinical Outcomes

BACKGROUND

Studies have shown intra-arterial therapies to be effective in controlling neuroendocrine liver metastases (NELMs), but the evidence supporting the selection of specific methods is limited. This meta-analysis is the first to compare survival outcomes between transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) in the treatment of NELM.

METHODS

A systematic search according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in PubMed and Embase databases was conducted in February 2020 for published studies comparing survival outcomes between TACE and TARE in the treatment of NELM.

RESULTS

Six eligible cohort studies with a total of 643 patients were identified. The TACE and TARE groups were similar in terms of age, sex, hepatic tumor burden, tumor grade, and Eastern Cooperative Oncology Group (ECOG) score. The patients treated with TACE had significantly better overall survival (odds ratio [OR], 1.92; 95% confidence interval [CI] 1.14-3.22, p = 0.014) than those treated with TARE. Overall survival ranged from 16.8 to 81.9 months with TACE and from 14.5 to 66.8 months with TARE. No significant differences in hepatic progression-free survival (OR, 1.01; 95% CI 0.75-1.35; p = 0.96) or tumor response were observed within the first 3 months (OR, 2.87; 95% CI 0.81-10.21; p = 0.10) or thereafter (OR, 0.98; 95% CI 0.12-7.86; p = 0.99). The complication rates were similar between the two groups, with 6.9% of the TACE patients versus 8.5% of TARE patients reporting major complications (OR, 1.16; 95% CI 0.54-2.48; p = 0.71) and respectively 44.6% and 58.8% of the TACE and TARE patients reporting minor adverse events (OR, 1.08; 95% CI 0.39-2.99; p = 0.88).

CONCLUSIONS

Despite similar tumor responses, an overall survival benefit was associated with TACE treatment of NELM compared with TARE treatment. Randomized controlled trials are warranted to confirm this finding and clarify whether certain subpopulations benefit from different transarterial methods.

Operative Microwave Ablation for the Multimodal Treatment of Neuroendocrine Liver Metastases

Background and Purpose: Operative microwave ablation (MWA) is a safe modality for treating hepatic tumors. The aim of this study is to present our 10-year, single-center experience of operative MWA for neuroendocrine liver metastases (NLM). Methods: A single-institution retrospective review of patients who underwent operative MWA for NLM was performed (2008-2018). Demographics, primary tumor site, operative approach, combined surgical operations, and carcinoid symptoms were recorded. Clinical outcomes for major complications, readmission, and mortality were analyzed 30 days postoperatively. Postablation imaging was evaluated for incomplete ablation/missed lesions, and surveillance imaging reviewed for local, regional, and metastatic recurrence. Results: Of the 50 patients (166 targeted lesions) who received MWA for NLM, 41 (82%) were treated with a minimally invasive approach, and 22 (44%) underwent MWA concomitant with hepatectomy and/or primary tumor resection. Within the study cohort 70% of patients were treated with curative intent with a 77% (27/35) success rate. Carcinoid symptoms were reported in 40% (20/50) of patients preoperatively, and MWA treatment improved symptoms in 19/20 patients. Incomplete ablation occurred in 1/166 treated lesions. Recurrence-free survival at 1 and 5 years was 86% and 28%, respectively. Overall survival at 1 and 5 years was 94% and 70%, respectively (median follow-up 32 months, range 0-116 months). Conclusion: Operative MWA is a versatile modality, which can be safe and effectively performed alone or combined with hepatectomy for NLM, preferably using a minimally invasive approach, to achieve symptom control and possibly improve survival.

[Gastroenteropancreatic neuroendocrine neoplasms-Heterogeneity, management and perspectives of treatment and research]

The term neuroendocrine neoplasms (NEN) encompasses a molecularly and biologically very heterogeneous group of tumors, which have in common their origin in neuroendocrine cells. The also very heterogeneous subgroup of gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) is the best classified and investigated group. This article provides a systematic review of the current classification, diagnostics and treatment options of GEP-NEN. In order to achieve a better overview, it was consciously decided not to use an approach based on the primary localization. Instead, a thematic organization according to classification, clinical phenotype, diagnostics and treatment was chosen.

Surgical management of pancreatic neuroendocrine liver metastases

Pancreatic neuroendocrine tumors (PNET) are a heterogeneous group of neoplasms that vary in their clinical presentation, behavior and prognosis. The most common site of metastasis is the liver. Surgical resection of neuroendocrine liver metastases (NELM) is thought to afford the best long-term outcomes when feasible. Initial preoperative workup should include surveillance for carcinoid syndrome, screening for evidence of liver insufficiency, and performance of imaging specific to neuroendocrine tumors such as a somatostatin receptor positron emission tomography scan. Standard surgical principles apply to hepatic surgery for NELM, namely prioritizing low central venous pressure anesthesia, minimizing blood loss, knowledge of liver anatomy, generous use of intraoperative ultrasound, as well as safe parenchymal transection techniques and practices to avoid bile leakage. Knowledge of established prognostic factors may assist with patient selection, which is important for optimizing short- and long-term outcomes of hepatic resection. Adjunct therapies such as concomitant liver ablation are used frequently and are generally safe when used appropriately. For patients with synchronous resectable NELM, resection of the primary either in a staged or combined fashion is recommended. Primary tumor resection in the setting of unresectable metastatic disease is more controversial, however generally recommended if morbidity is acceptable. For patients who are not surgical candidates, due to either patient performance status or burden of liver disease, several liver-directed therapies such as transarterial embolization, chemoembolization, and radioembolization are available to assist with locoregional control, extend progression-free survival (PFS), and improve symptoms of carcinoid syndrome. Multiple systemic therapy options exist for patients with metastatic PNET which are often prioritized for those patients with advanced or progressive disease. A systematic approach in a multi-disciplinary setting is likely to result in the best long-term outcomes for patients with pancreatic NELM. Ongoing research is needed to determine the optimal patient selection for hepatic surgery as well as the ideal treatment sequencing for those patients with NELM.

Residual tumor volume discriminates prognosis after surgery for neuroendocrine liver metastasis

BACKGROUND AND OBJECTIVES

We developed objective measurements of preoperative and residual tumor volume, and debulking rate, to evaluate their prognostic value for neuroendocrine liver metastasis (NELM).

METHODS

Seventy-three patients who underwent surgery for NELM were analyzed retrospectively. Indices of preoperative and postoperative residual tumor volume (pre-volume index [VI] and post-VI) were calculated as the sum of the cubes of individual tumor diameters on preoperative and postoperative imaging, respectively. The debulking rate (%) was calculated as 100 - 100 × post-VI/pre-VI. The classification and regression trees method was used to classify pre-VI and post-VI.

RESULTS

Overall survival (OS) was discriminated by preoperative tumor volume (5-year OS rates, 87.8% for low pre-VI and 60.1% for high pre-VI; P = .037) and residual tumor volume (5-year OS rates, 88.1% for low post-VI and 24.8% for high post-VI; P < .001). In contrast, debulking rates of 100%, ≥90%, and <90% did not discriminate OS (5-year OS rates, 88.0%, 61.9%, and 58.9%, respectively, not significant). In multivariate analysis, residual tumor volume (high post-VI, hazard ratio, 6.40; 95% confidence interval, 1.45-32.3) was an independent prognostic factor for OS.

CONCLUSIONS

Objective measurement of tumor volume demonstrates that residual tumor volume is prognostic after surgery for NELM.

Resection of pancreatic neuroendocrine tumors: defining patterns and time course of recurrence

BACKGROUND

To define recurrence patterns and time course, as well as risk factors associated with recurrence following curative resection of pNETs.

METHOD

Patients who underwent curative-intent resection for pNET between 1997 and 2016 were identified from the US Neuroendocrine Tumor Study Group. Data on baseline and tumor-specific characteristics, overall survival (OS), timing and first-site of recurrence, predictors and recurrence management were analyzed.

RESULTS

Among 1020 patients, 154 (15.1%) patients developed recurrence. Among patients who experienced recurrence, 76 (49.4%) had liver-only recurrence, while 35 (22.7%) had pancreas-only recurrence. The proportion of liver-only recurrence increased from 54.3% within one-year after surgery to 61.5% from four-to-six years after surgery; whereas the proportion of pancreas-only recurrence decreased from 26.1% to 7.7% over these time periods. While liver-only recurrence was associated with tumor characteristics, pancreas-only recurrence was only associated with surgical margin status. Patients undergoing curative resection of recurrence had comparable OS with patients who had no recurrence (median OS, pancreas-only recurrence, 133.9 months; liver-only recurrence, not attained; no recurrence, 143.0 months, p = 0.499) CONCLUSIONS: Different recurrence patterns and timing course, as well as risk factors suggest biological heterogeneity of pNET recurrence. A personalized approach to postoperative surveillance and treatment of recurrence disease should be considered.

Is hepatectomy safe following Yttrium-90 therapy? A multi-institutional international experience

BACKGROUND

Single institution reports demonstrate variable safety profiles when liver-directed therapy with Yttrium-90 (Y-90) is followed by hepatectomy. We hypothesized that in well-selected patients, hepatectomy after Y90 is feasible and safe.

METHODS

Nine institutions contributed data for patients undergoing Y90 followed by hepatectomy (2008-2017). Clinicopathologic and perioperative data were analyzed, with 90-day morbidity and mortality as primary endpoints.

RESULTS

Forty-seven patients were included. Median age was 59 (20-75) and 62% were male. Malignancies treated included hepatocellular cancer (n = 14; 30%), colorectal cancer (n = 11; 23%), cholangiocarcinoma (n = 8; 17%), neuroendocrine (n = 8; 17%) and other tumors (n = 6). The distribution of Y-90 treatment was: right (n = 30; 64%), bilobar (n = 14; 30%), and left (n = 3; 6%). Median future liver remnant (FLR) following Y90 was 44% (30-78). Resections were primarily right (n = 16; 34%) and extended right (n = 14; 30%) hepatectomies. The median time to resection from Y90 was 196 days (13-947). The 90-day complication rate was 43% and mortality was 2%. Risk factors for Clavien-Dindo Grade>3 complications included: number of Y-90-treated lobes (OR 4.5; 95% CI1.14-17.7; p = 0.03), extent of surgery (p = 0.04) and operative time (p = 0.009).

CONCLUSIONS

These data demonstrate that hepatectomy following Y-90 is safe in well-selected populations. This multi-disciplinary treatment paradigm should be more widely studied, and potentially adopted, for patients with inadequate FLR.

Management of Small Bowel Neuroendocrine Tumors

Several important landmark trials have reshaped the landscape of non-surgical management of small bowel neuroendocrine tumors over the last few years, with the confirmation of the antitumor effect of somatostatin analogue therapy in PROMID and CLARINET trials as well as the advent of therapies with significant potential such as mammalian target of rapamycin inhibitor (mTor) everolimus (RADIANT trials) and peptide receptor radionuclide therapy (PRRT) with 177-Lutetium (NETTER-1 trial). This narrative summarizes the recommended management strategies of small bowel neuroendocrine tumors. We review the main evidence behind each recommendation as well as compare and contrast four major guidelines, namely the 2016 Canadian Consensus guidelines, the 2017 North American Neuroendocrine Tumor Society guidelines, the 2018 National Comprehensive Cancer Network guidelines, and the 2016 European Neuroendocrine Tumor Society guidelines. Different clinical situations will be addressed, from loco-regional therapy to metastatic unresectable disease. Carcinoid syndrome, which is mostly managed by somatostatin analogue therapy and the serotonin antagonist telotristat etiprate for refractory diarrhea, as well as neuroendocrine carcinoma will be reviewed. However, several questions remain unanswered, such as the optimal management of neuroendocrine carcinomas or the effect of combining and sequencing of the aforementioned modalities where more randomized controlled trials are needed.

Liver transplantation in patients with liver metastases from neuroendocrine tumors

The prevalence of metastatic disease in neuroendocrine tumors (NETs) is very high (60-80%) and cancer-related death among these patients is generally due to metastatic disease. Numerous treatment options for cure and disease control have been investigated for patients with neuroendocrine liver metastases (NELM). Despite the success of liver directed therapy on slowing tumor progression and palliating symptoms, the chance of being cured by liver resection is 40-50% and only roughly 20% of patients have potentially resectable disease. As such, there has been interest in liver transplantation (LT) as a potentially curative option for patients with unresectable disease. Several criteria have been proposed in order to balance long-term outcomes of patients with NELM and the problem of organ shortage including the Milan-NET criteria, the UNOS criteria and the ENETS guidelines. In the most representative studies, recurrence rate after LT has ranged from 30% to 60% with a 5-year OS ranging from 50% to 97%. This large variability is due to the retrospective nature of the studies available, which used different inclusion criteria. As such, outcomes and the prognostic factors associated with LT for NELM warrant further investigation.

[Oligometastases of neuroendocrine tumors-extent of surgery]

Neuroendocrine tumors (NETs) are rare neoplasms, which represent complex challenges in diagnosis and treatment. Even in the metastatic stage there are important differences in the type of tumor in comparison to gastrointestinal and pancreatic adenocarcinomas. Therefore, the disease courses are substantially different depending on the grade of differentiation. Even in the metastatic stage the 5‑year survival rates of G1 tumors is up to 83%. Approximately 20% of small intestine NETs additionally show hormone activity, which can compromise survival and the quality of life. For individual treatment decisions the special tumor biology of these tumors must be taken into consideration more so than for other tumor entities. Surgery always becomes important for these tumors when a R0 resection appears possible. Oligometastasis of the liver and the lymph drainage system can be meaningfully approached by surgical treatment. In selected patients with an isolated liver involvement, a liver transplantation can be considered; however, even tumor debulking can lead to improvement in the quality of life and survival, especially for hormone active tumors with a carcinoid syndrome which cannot be conservatively controlled. The aim of this review is to present the value of surgical treatment options in the case of (oligo)metastasized NETs.

Minimally invasive versus open distal pancreatectomy for pancreatic neuroendocrine tumors: An analysis from the U.S. neuroendocrine tumor study group

BACKGROUND

To determine short- and long-term oncologic outcomes after minimally invasive distal pancreatectomy (MIDP) with open distal pancreatectomy (ODP) for the treatment of pancreatic neuroendocrine tumor (pNET).

METHODS

The data of the patients who underwent curative MIDP or ODP for pNET between 2000 and 2016 were collected from a multi-institutional database. Propensity score matching (PSM) was used to generate 1:1 matched patients with MIDP and ODP.

RESULTS

A total of 576 patients undergoing curative DP for pNET were included. Two hundred and fourteen (37.2%) patients underwent MIDP, whereas 362 (62.8%) underwent ODP. MIDP was increasingly performed over time (2000-2004: 9.3% vs 2013-2016: 54.8%; P < 0.01). In the matched cohort (n = 141 in each group), patients who underwent MIDP had less blood loss (median, 100 vs 200 mL, P < 0.001), lower incidence of Clavien-Dindo ≥ III complications (12.1% vs 24.8%, P = 0.026), and a shorter hospital stay versus ODP (median, 4 versus 7 days, P = 0.026). Patients who underwent MIDP had a lower incidence of recurrence (5-year cumulative recurrence, 10.1% vs 31.1%, P < 0.001), yet equivalent overall survival (OS) rate (5-year OS, 92.1% vs 90.9%, P = 0.550) compared with patients who underwent OPD.

CONCLUSION

Patients undergoing MIDP over ODP in the treatment of pNET had comparable oncologic surgical metrics, as well as similar long-term OS.

Outcomes of laparoscopic tumor ablation for neuroendocrine liver metastases: a 20-year experience

BACKGROUND

Since neuroendocrine tumors have an indolent behavior, studies looking at oncologic outcomes should report a long-term follow-up. Over the years, we have been treating selected patients with neuroendocrine liver metastases (NELM) with laparoscopic ablation (LA) and reported favorable local tumor control. The aim of this study is to see whether this local efficacy translates into long-term oncologic outcomes.

METHODS

This was an IRB-approved study of patients who underwent LA for NELM at a single center. Overall and progression-free survivals were analyzed using Kaplan-Meier and Cox proportional hazards model.

RESULTS

Study included 58 women and 71 men with a median age of 58 (IQR 47-67) years. Tumor type included carcinoid (n = 92), pancreatic islet cell (n = 28), and medullary thyroid cancer (n = 9). There was a median of 6 (IQR 3-8) tumors, measuring 1.6 (IQR 1.1-2.4) cm. At a median follow-up of 73 (IQR 34-135) months, local liver recurrence per patient, new liver recurrence, and new extrahepatic recurrence rates were 22, 68, and 33%, respectively. Local tumor recurrence per lesion was 5% (n = 42/770). Median overall survival was 125 months, with 5-year, and 10-year overall survivals being, 76%, and 59%, respectively; and median disease-free survival was 13 months, with 5-year, and 10-year progression-free survivals being 26%, and 6%, respectively. On Cox proportional hazards model, overall survival was independently predicted by tumor size, grade, and resection status of primary.

CONCLUSION

To our knowledge, this is the largest single-center experience with the longest follow-up regarding the utilization of LA for NELM. Our results demonstrate that in selected patients, LA achieves a 95% local tumor control and 59% 10-year overall survival.

Primary Tumor Site Affects Survival in Patients with Gastroenteropancreatic and Neuroendocrine Liver Metastases

BACKGROUND

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are commonly present with metastatic disease, and the liver is the most frequent metastatic site. Herein, we studied whether primary tumor site affects survival in patients with GEP-NETs and liver metastases (NELM). As a secondary endpoint, we studied whether extrahepatic disease and surgical resection impact survival in this patient population.

METHODS

Patients with NELM diagnosed from 2006 to 2014 were identified from the National Cancer Database. Kaplan-Meier curves and nested Cox proportional hazards were used to assess variables associated with survival.

RESULTS

2947 patients with well- or moderately differentiated GEP-NETs and NELM met the inclusion criteria for this study. Patients with small bowel NETs survived the longest of all GEP-NETs with NELM (median not reached). Rectal and gastric NETs with NELM had the shortest survival (median 31 months). Patients with extrahepatic metastases who underwent any operation survived longer than those managed nonoperatively (median survival 38.7 months vs. 18.6 months, p = 0.01). On multivariable analysis, operations on the primary tumor and distant metastatic site (HR 0.23-0.43 vs. no surgery), treatment at an academic/research hospital, Charlson comorbidity index of 0, no extrahepatic metastases, and younger age were associated with prolonged survival (p < 0.01).

CONCLUSIONS

Primary tumor site affects survival in patients with GEP-NETs and NELM. Surgical resection seems beneficial for all GEP-NETs with NELM, even in the presence of extrahepatic metastases.

Carcinoid syndrome: update on the pathophysiology and treatment

Approximately 30-40% of patients with well-differentiated neuroendocrine tumors present with carcinoid syndrome, which is a paraneoplastic syndrome associated with the secretion of several humoral factors. Carcinoid syndrome significantly and negatively affects patients' quality of life; increases costs compared with the costs of nonfunctioning neuroendocrine tumors; and results in changes in patients' lifestyle, such as diet, work, physical activity and social life. For several decades, patients with neuroendocrine tumors and carcinoid syndrome have been treated with somatostatin analogues as the first-line treatment. While these agents provide significant relief from carcinoid syndrome symptoms, there is inevitable clinical progression, and new therapeutic interventions are needed. More than 40 substances have been identified as being potentially related to carcinoid syndrome; however, their individual contributions in triggering different carcinoid symptoms or complications, such as carcinoid heart disease, remain unclear. These substances include serotonin (5-HT), which appears to be the primary marker associated with the syndrome, as well as histamine, kallikrein, prostaglandins, and tachykinins. Given the complexity involving the origin, diagnosis and management of patients with carcinoid syndrome, we have undertaken a comprehensive review to update information about the pathophysiology, diagnostic tools and treatment sequence of this syndrome, which currently comprises a multidisciplinary approach.

Can echogenic appearance of neuroendocrine liver metastases on intraoperative ultrasonography predict tumor biology and prognosis?

BACKGROUND

Determining the biologic behavior of neuroendocrine liver metastases (NELM) is important when managing patients with this disease. We sought to define the intraoperative ultrasound (IOUS) characteristics of NELM and correlate with tumor biology and prognosis.

METHODS

Prospective data on patients who underwent IOUS and surgical intervention for NELM were collected, with images digitally recorded, blindly reviewed, and scored for echogenicity. Association between sonographic appearance, clinicopathologic factors and long-term outcomes was analyzed.

RESULTS

A total of 216 lesions from 65 patients were analyzed, with IOUS identifying at least one additional metastasis than preoperative imaging in 41 patients (63.1%) with subsequent change of surgical strategy in 14 patients (21.5%). Most NELM appeared hypoechoic (49.1%) on IOUS, while 38.9% demonstrated hyperechogenicity and 12% isoechogenicity. Hypoechoic lesions were associated with poorly-differentiated tumor (p = 0.005) and smaller tumor size (p = 0.004). Patients with hypoechoic metastases demonstrated significantly shorter median disease-free survival compared with isoechoic or hyperechoic lesions (9 vs 20 vs 18 months, p = 0.049).

DISCUSSION

In addition to improved tumor detection of NELM, IOUS was found to be associated with features of tumor biology, specifically tumor grade and risk-of-recurrence. Echogenicity should be considered a potential prognostic factor in the management of patients with neuroendocrine tumors.

Neuroendocrine Liver Metastasis: Prognostic Implications of Primary Tumor Site on Patients Undergoing Curative Intent Liver Surgery

BACKGROUND

Neuroendocrine tumors typically arise from pancreatic (PNET) vs. gastrointestinal or thoracic origins (non-PNET). The impact of primary tumor site on long-term prognosis following resection of neuroendocrine liver metastasis (NELM) remains poorly defined. The objective of the current study was to define the association of primary tumor location on prognosis of patients undergoing curative intent liver resection for NELM.

METHODS

Between 1990 and 2014, 421 patients who underwent resection of NELM were identified from a multi-institutional database. Clinicopathological characteristics, operative details, and outcomes were stratified and analyzed by location of the primary tumor (PNET vs. non-PNET). A propensity score-matched analysis was utilized to assess the impact of primary tumor location on long-term survival.

RESULTS

Among the 421 patients, 197 (46.8%) patients had NELM from a PNET primary while 224 (53.2%) had a non-PNET primary (small bowel, n = 145; rectal, n = 10; bronchial, n = 22; other, n = 47). There were no differences in tumor burden and tumor site, while presence of extrahepatic disease was more common among patients with non-PNET NELM (extrahepatic disease, PNET NELM, n = 11 27.5% vs. non-PNET NELM, n = 29 72.5%; p = 0.010). Patients with PNET NELM were more likely to have non-functional disease compared with patients who had non-PNET NELM (non-functional, PNET NELM, n = 117 54.9% vs. non-PNET NELM, n = 96 45.1%; p = 0.011). On the final pathological specimen of the resected NELM, patients with PNET NELM were more likely to have a moderately differentiated tumor (59.3%), while patients with non-PNET NELM were more likely to have a poorly differentiated tumor (67.8%) (p = 0.005). Patients with PNET NELM had a worse 5-year DFS and 5-year OS compared with patients who had non-PNET NELM (DFS, PNET 36.2% vs. non-PNET 55.2%; p = 0.001 and OS, PNET 79.5% vs. non-PNET 83.4%; p = 0.008). After propensity score matching, both 5-year DFS and 5-year OS of the PNET and non-PNET groups were comparable (DFS, PNET 46.2% vs. non-PNET 55.9%; p = 0.22 and OS, PNET 81.5% vs. non-PNET 84.3%; p = 0.19).

CONCLUSION

PNET patients more often present with non-functional NELM and moderately differentiated tumors. On propensity-matched analysis, factors such as extrahepatic disease and tumor grade, but not primary tumor location, were associated with prognosis of patients undergoing curative intent liver surgery for NELM.

Early Recurrence of Neuroendocrine Liver Metastasis After Curative Hepatectomy: Risk Factors, Prognosis, and Treatment

BACKGROUND

Early tumor recurrence after curative resection typically indicates a poor prognosis. The objective of the current study was to investigate the risk factors, treatment, and prognosis of early recurrence of neuroendocrine tumor (NET) liver metastasis (NELM) after hepatic resection.

METHODS

A total of 481 patients who underwent curative-intent resection for NELM were identified from a multi-institutional database. Data on clinicopathological characteristics, intraoperative details, and outcomes were documented. The optimal cutoff value to differentiate early and late recurrence was determined to be 3 years based on linear regression.

RESULTS

With a median follow-up of 60 months, 223 (46.4%) patients developed a recurrence, including 158 (70.9%) early and 65 (29.1%) late recurrences. On multivariable analysis, pancreatic NET, primary tumor lymph node metastasis, and a microscopic positive surgical margin were independent risk factors for early intrahepatic recurrence. While recurrence patterns and treatments were comparable among patients with early and late recurrences, early recurrence was associated with worse disease-specific survival than late recurrences (10-year NELM-specific survival, 44.5 vs 75.8%, p < 0.001). Among the 34 (21.5%) patients who underwent curative treatment for early recurrence, post-recurrence disease-specific survival was better than non-curatively treated patients (10-year NELM-specific survival, 54.2 vs 26.3%, p = 0.028), yet similar to patients with late recurrences treated with curative intent (10-year NELM-specific survival, 54.2 vs 37.4%, p = 0.519).

CONCLUSIONS

Early recurrence after surgery for NELM was associated with the pancreatic type, primary lymph node metastasis, and extrahepatic disease. Re-treatment with curative intent prolonged survival after recurrence, and therefore, operative intervention even for early recurrences of NELM should be considered.

Defining Long-Term Survivors Following Resection of Intrahepatic Cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is an aggressive primary tumor of the liver. While surgery remains the cornerstone of therapy, long-term survival following curative-intent resection is generally poor. The aim of the current study was to define the incidence of actual long-term survivors, as well as identify clinicopathological factors associated with long-term survival.

METHODS

Patients who underwent a curative-intent liver resection for ICC between 1990 and 2015 were identified using a multi-institutional database. Overall, 679 patients were alive with ≥ 5 years of follow-up or had died during follow-up. Prognostic factors among patients who were long-term survivors (LT) (overall survival (OS) ≥ 5) were compared with patients who were not non-long-term survivors (non-LT) (OS < 5).

RESULTS

Among the 1154 patients who underwent liver resection for ICC, 5- and 10-year OS were 39.6 and 20.3% while the actual LT survival rate was 13.3%. After excluding 475 patients who survived < 5 years, as well as patients were alive yet had < 5 years of follow-up, 153 patients (22.5%) who survived ≥ 5 years were included in the LT group, while 526 patients (77.5%) who died < 5 years from the date of surgery were included in the non-LT group. Factors associated with not surviving to 5 years included perineural invasion (OR 4.78, 95% CI, 1.92-11.8; p = 0.001), intrahepatic metastasis (OR 3.75, 95% CI, 0.85-16.6, p = 0.082), satellite lesions (OR 2.12, 95% CI, 1.15-3.90, p = 0.016), N1 status (OR 4.64, 95% CI, 1.77-12.2; p = 0.002), ICC > 5 cm (OR 2.40, 95% CI, 1.54-3.74, p < 0.001), and direct invasion of an adjacent organ (OR 3.98, 95% CI, 1.18-13.4, p = 0.026). However, a subset of patients (< 10%) who had these pathological characteristics were LT.

CONCLUSION

While ICC is generally associated with a poor prognosis, some patients will be LT. In fact, even a subset of patients with traditional adverse prognostic factors survived long term.

Management Options for Advanced Low or Intermediate Grade Gastroenteropancreatic Neuroendocrine Tumors: Review of Recent Literature

Our understanding of the biology, genetics, and natural history of neuroendocrine tumors (NETs) of the gastrointestinal tract and pancreas has improved considerably in the last several decades and the spectrum of available therapeutic options is rapidly expanding. The management of patients with metastatic low or intermediate grade NETs has been revolutionized by the development of new treatment strategies such as molecular targeting therapies with everolimus and sunitinib, somatostatin analogs, tryptophan hydroxylase inhibitors, and peptide receptor radionuclide therapy that can be used alone or as a multimodal approach with or without surgery. To further define and clarify the utility, appropriateness, and the sequence of the growing list of available therapies for this patient population will require more high level evidence; however, data from well-designed randomized phase III clinical trials is rapidly accumulating that will further stimulate development of new management strategies. It is therefore important to thoroughly review emerging evidence and report major findings in frequent updates, which will expand our knowledge and contribute to a better understanding, characterization, and management of advanced NETs.