Role of liver transplantation in the management of unresectable neuroendocrine liver metastases

Long-Term Outcomes of Liver Transplantation for the Management of Neuroendocrine Neoplasms: A Systematic Review

Liver transplantation is an uncommonly used, controversially debated therapeutic approach for highly selected individuals with neuroendocrine liver metastases. Synthesising evidence regarding outcomes from this approach is crucial to understand its position within the broad neuroendocrine liver metastases armamentarium. In this narrative systematic review of studies published in PubMed, Scopus and OVID until 1 July 2021, we summarise and critically appraise the existing literature regarding this modality, with a special focus on long-term outcomes data where possible. Fourteen studies were identified that reported outcomes from the use of liver transplantation for metastatic neuroendocrine neoplasms. No randomised trials were identified. Generally, indications and selection criteria were poorly articulated, with the notable exception of studies using the Milan criteria. The median 5-year overall survival was 65% (ranging from 36% to 97.2%, 11 studies), and the median 10-year overall survival was 50% (ranging from 46.1% to 88.8%, 3 studies). One additional study focussed on treatments and outcomes following post-transplant recurrence. No studies reported outcomes past 10 years. Further follow-up of the largest series with explicit selection criteria will deepen our understanding of the role that transplantation has to play in this setting.

Surgical Approaches to the Management of Neuroendocrine Liver Metastases

Surgical approaches to hepatic metastases occupy an important role in the management of patients with neuroendocrine neoplasms and may have curative or palliative intentions. Resection of hepatic disease with curative intent is the only modality offering potential cure for patients with liver metastases; however, only a minority of patients are eligible. Regardless of resection margin, disease recurrence almost invariably occurs and novel adjuvant/neoadjuvant therapies are mandated to be included within multimodal treatment concepts. Liver transplantation in meticulously selected patients may be associated with excellent outcomes, but unfortunately demands on donated organs limit the wider utilization of this approach.

Con: Liver transplantation for expanded criteria malignant diseases

Organ shortage requires policies and guidelines to aid organ allocation along the principles of urgency or utility. Identifying patients with significant benefit and withholding liver transplantation (LT) from patients too sick for transplantation are ongoing challenges, in particular in patients with malignancies. An arbitrary threshold of >50% 5-year overall survival (OS) is broadly considered a minimum standard for LT. In patients transplanted for intrahepatic cholangiocarcinoma (iCC), this was only achieved in select cases and when the tumor had a diameter of <2 cm. In patients with extrahepatic and hilar cholangiocarcinoma (CCC), strict selection criteria and combined preoperative radiotherapy/chemotherapy according to the Mayo protocol showed that acceptable longterm results can be achieved in a single high-volume center but are difficult to repeat elsewhere. Furthermore, only rigorously selected patients with neuroendocrine tumors (NETs) meeting the NET Milan criteria adopted by United Network for Organ Sharing can also have >50% 5-year OS. A prospective study in patients with unresectable colorectal cancer metastases in the liver has shown promising OS rates, but further prospective trials are warranted. Current evidence shows that none of the proposed expanded malignant criteria justify deviation of scarce donor organs to patients with hilar CCC, iCC > 2 cm, metastatic NET beyond NET Milan criteria, or metastatic colorectal cancer (CRC) outside clinical trials. Liver Transplantation 24 104-111 2018 AASLD.

Rectal Carcinoid Tumor With Liver Metastases Treated by Local Excision and Orthotopic Liver Transplant With Long-term Follow-up

In patients affected by unresectable liver metastases from neuroendocrine tumor, liver transplant represents currently the only realistic chance for cure. The first attempt to establish selection criteria for liver transplant in patients affected by neuroendocrine tumor liver metastases was made by Mazzaferro and associates in 2007. We report the case of a 46-year-old man who came to our institution in 2006 with right upper quadrant abdominal pain. Diagnosis of rectal neuroendocrine tumor with bilobar liver nodules was made; the patient underwent transanal local resection. A liver biopsy confirmed the metastatic nature of the hepatic lesion, showing a low-grade neuroendocrine tumor (G1, proliferation index Ki-67 <2%). The patient underwent 2 sessions of transarterial chemoembolization that resulted in stable disease. Afterward, the patient underwent a liver transplant, using the piggyback technique without a venous-venous bypass. His postoperative course was uneventful. The patient has been disease-free for 3 years. Posttransplant treatment has played a key role in increasing the overall survival of the patient and assuring him a good quality of life. He died 9 years (102 mo) after liver transplant.

Liver Ablation: Best Practice

Tumor ablation in the liver has evolved to become a well-accepted tool in the management of increasing complex oncologic patients. At present, percutaneous ablation is considered first-line therapy for very early and early hepatocellular carcinoma and second-line therapy for colorectal carcinoma liver metastasis. Because thermal ablation is a treatment option for other primary and secondary liver tumors, an understanding of the underlying tumor biology is important when weighing the potential benefits of ablation. This article reviews ablation modalities, indications, patient selection, and imaging surveillance, and emphasizes technique-specific considerations for the performance of percutaneous ablation.

Liver transplantation for metastatic neuroendocrine tumors: Outcomes and prognostic variables

BACKGROUND

Patient selection for liver transplantation for metastatic neuroendocrine tumors remains a topic of debate. There is no established MELD exception, making it difficult to obtain donor organs.

METHODS

A multicenter database was created assessing outcomes for liver and multivisceral transplantation for metastatic neuroendocrine tumors and identifying prognostic factors for survival. Demographic, transplant, primary tumor site and management, pathology, recurrent disease and survival data were collected and analyzed. Survival probabilities were calculated using the Kaplan-Meier method.

RESULTS

Analysis included 85 patients who underwent liver transplantation November 1988-January 2012 at 28 centers. One, three, and five-year patient survival rates were 83%, 60%, and 52%, respectively; 40 of 85 patients died, with 20 of 40 deaths due to recurrent disease. In univariate analyses, the following were predictors of poor prognosis: large vessel invasion (P < 0.001), extent of extrahepatic resection at liver transplant (P = 0.007), and tumor differentiation (P = 0.003). In multivariable analysis, predictors of poor overall survival included large vessel invasion (P = 0.001), and extent of extrahepatic resection at liver transplant (P = 0.015).

CONCLUSION

In the absence of poor prognostic factors, metastatic neuroendocrine tumor is an acceptable indication for liver transplantation. Identification of favorable prognostic factors should allow assignment of a MELD exception similar to hepatocellular carcinoma.

Liver transplantation for metastatic neuroendocrine tumors

Neuroendocrine tumors are a heterogeneous group of rare epithelial tumors. Most of them are metastatic at the time of initial diagnosis. Liver transplantation (LT) has been proposed in selected patients with diffuse liver involvement. Rationale for LT in this indication is based on the frequently indolent nature of neuroendocrine tumors, the propensity for liver-only metastasis and the high rate of intrahepatic recurrence after resection. However, indications for LT for neuroendocrine liver metastases remain controversial, and patient selection criteria is still a matter of debate. The aim of this review is to summarize data regarding LT for neuroendocrine liver metastases by answering frequently asked questions about this issue.

Role of surgery and transplantation in the treatment of hepatic metastases from neuroendocrine tumor

Neuroendocrine tumors (NET) are a heterogeneous group of cancers, with indolent behavior. The most common primary origin is the gastro-intestinal tract but can also appear in the lungs, kidneys, adrenals, ovaries and other organs. In general, NET is usually discovered in the metastatic phase (40%-80%). The liver is the most common organ involved when metastases occur (40%-93%), followed by bone (12%-20%) and lung (8%-10%).A number of different therapeutic options are available for the treatment of hepatic metastases including surgical resection, transplantation, ablation, trans-arterial chemoembolization, chemotherapy and somatostatin analogues. Recently, molecular targeted therapies have been used, usually in combination with other treatment options, to improve outcomes in patients with metastases. This article emphasizes on the role of surgery in the treatment of liver metastases from NET.

Therapeutic strategies for neuroendocrine liver metastases

Patients who have neuroendocrine tumors frequently present with liver metastases. A wide panel of treatment options exists for these patients. Liver resection with curative intent achieves the best long-term results. Highly selected patients may be considered for liver transplantation. Substantial recurrence rates reported after surgical approaches call for neoadjuvant and adjuvant concepts. Liver-directed, locally ablative procedures are recommended for patients with limited, nonresectable tumor burden. Angiographic liver-directed techniques, such as transarterial embolization, transarterial chemoembolization, and selective internal radiotherapy, offer excellent palliation for patients with liver-predominant disease. Peptide receptor radionuclide therapy is a promising palliative procedure for patients with hepatic and/or extrahepatic metastases. The efficacy of these treatment options needs to be evaluated in randomized trials. Somatostatin analogues have demonstrated effectiveness not only for symptomatic relief in patients with secreting tumors but also for the control of proliferation in small intestinal neuroendocrine tumors and most recently also in those originating from the pancreas. Chemotherapy is an option mainly for those with pancreatic neuroendocrine tumors and high-grade tumors irrespective of the origin. Novel drugs targeting specific pathways within the tumor cell have produced improved progression-free survival compared with placebo in patients with pancreatic neuroendocrine tumors. Despite such a diverse armamentarium, there is uncertainty with regard to the optimal treatment regimens. Newly introduced molecular-based markers, along with the conduction of clinical trials comparing the efficacy of treatment modalities, offer a chance to move the treatment of neuroendocrine tumor disease toward personalized patient care. In this report, the authors review the approaches for treatment of neuroendocrine liver metastases, identify shortcomings, and anticipate future perspectives. Furthermore, clinical practice recommendations are provided for currently available treatment options. Although multiple modalities are available for the treatment of neuroendocrine liver metastases, optimal management is unclear. The current knowledge pertaining to these treatment options is analyzed.

Management of patients with hepatic metastases from neuroendocrine tumors

Neuroendocrine tumors have a disposition toward metastasis to the liver. A range of treatment modalities for neuroendocrine liver metastases is available in the clinical arena, the indications for which depend on tumor characteristics such as patterns of metastasis, tumor grade, and anatomical origin. The complete surgical resection of liver deposits represents the only option with the intent to cure and is the gold standard approach, whereas cytoreductive resection (debulking) presents another surgical option aiming to ameliorate the symptoms and prolong survival. Liver transplantation is generally an accepted option for highly selected patients. For patients ineligible for radical surgery, liver-directed therapies-transarterial embolization/chemoembolization, selective internal radiotherapy, and local tumor ablation-present alternative strategies. Systemic therapies include peptide receptor radiotherapy, somatostatin analogues, cytotoxic chemotherapeutics, and novel molecularly targeted drugs. However, despite the variety of treatments available, there exists little evidence to guide optimal clinical practice with currently available data predominantly retrospective in nature. In this review, we discuss the diagnostic procedures that influence the trajectory of treatment of patients with neuroendocrine liver metastases before critically appraising the evidence pertaining to these therapeutic strategies.

Liver transplantation for neuroendocrine tumors in Europe-results and trends in patient selection: a 213-case European liver transplant registry study

OBJECTIVE

The purpose of this study was to assess outcomes and indications in a large cohort of patients who underwent liver transplantation (LT) for liver metastases (LM) from neuroendocrine tumors (NET) over a 27-year period.

BACKGROUND

LT for NET remains controversial due to the absence of clear selection criteria and the scarcity and heterogeneity of reported cases.

METHODS

This retrospective multicentric study included 213 patients who underwent LT for NET performed in 35 centers in 11 European countries between 1982 and 2009. One hundred seven patients underwent transplantation before 2000 and 106 after 2000. Mean age at the time of LT was 46 years. Half of the patients presented hormone secretion and 55% had hepatomegaly. Before LT, 83% of patients had undergone surgical treatment of the primary tumor and/or LM and 76% had received chemotherapy. The median interval between diagnosis of LM and LT was 25 months (range, 1-149 months). In addition to LT, 24 patients underwent major resection procedures and 30 patients underwent minor resection procedures.

RESULTS

Three-month postoperative mortality was 10%. At 5 years after LT, overall survival (OS) was 52% and disease-free survival was 30%. At 5 years from diagnosis of LM, OS was 73%. Multivariate analysis identified 3 predictors of poor outcome, that is, major resection in addition to LT, poor tumor differentiation, and hepatomegaly. Since 2000, 5-year OS has increased to 59% in relation with fewer patients presenting poor prognostic factors. Multivariate analysis of the 106 cases treated since 2000 identified the following predictors of poor outcome: hepatomegaly, age more than 45 years, and any amount of resection concurrent with LT.

CONCLUSIONS

LT is an effective treatment of unresectable LM from NET. Patient selection based on the aforementioned predictors can achieve a 5-year OS between 60% and 80%. However, use of overly restrictive criteria may deny LT to some patients who could benefit. Optimal timing for LT in patients with stable versus progressive disease remains unclear.

Recent advances in understanding pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) are uncommon and have an incidence of approximately 4-5 per 1 000 000 people, accounting for 1%-2% of all pancreatic neoplasms. They usually grow slowly, eventually metastasize and lead to death. PETs can be classified as functioning or non-functioning tumors based on clinical manifestation. The pathogenesis of PETs may involve abnormal expression of CD10, CD44, CD99, p27, COX2, Ki-67, KIT, CK19, ARHI, RUNX1T1, and survivin genes, loss of heterozygosity on chromosomes, hypermethylation of tumor suppressor genes, and overexpression of ghrelin. Chromogranin A (CgA) has long been used as an important broad-spectrum marker for the identification of PETs. KIT and endoglin are new independent prognostic markers for PETs. The diagnosis is based on histopathology demonstrating neuroendocrine features such as positive staining for chromogranin A and specific hormones such as gastrin, proinsulin, vasoactive intestinal peptide (VIP) and glucagon. In addition to standard localization procedures, radiology diagnosis including computed tomography (CT), positron emission tomography and computed tomography (PET/CT), magnetic resonance imaging (MRI), ultrasound (US), endoscopic ultrasound (EUS), laparoscopic ultrasound (LUS), dynamic enhanced spiral CT, selective arterial stimulation and venous sampling (ASVS), and somatostatin receptor scintigraphy (SRS) are performed. Surgery is still one of the cornerstones in the management of PETs. Laparoscopy, and drugs of somatostatin analogs are routinely used. Understanding of the recent advances of PETs has important implications for the early diagnosis and treatment of PETs.

Liver transplantation for hepatic metastases of neuroendocrine pancreatic tumors: a survival-based analysis

BACKGROUND

Liver transplantation (LT) has been accepted as a treatment in selected cases of neuroendocrine tumors (NETs) with hepatic metastases.

PATIENTS AND METHODS

A systematic review of the literature was conducted to evaluate long-term patient survival in the instances of LT for pancreatic NET. Univariate and multivariate regression analyses and survival analysis were performed.

RESULTS

Fifty-three clinical studies were screened. Data from 20 studies encompassing 89 transplanted patients were included in the study. Most primary tumors were endocrine pancreatic tumors (n=69), with gastrinomas representing the most frequent diagnosis (n=21). There were 61 functioning pancreatic NET. Simultaneous LT and pancreatic NET resections were performed in 45 instances. Cumulative 1-, 3-, and 5-year survival was 71%, 55%, and 44%, respectively, with a calculated mean survival of 54.45±6.31 months. Vasoactive intestinal peptide (VIPomas) had the best overall survival. Recurrence-free survival at 1, 3, and 5 years was 84%, 47%, and 47%, respectively. Recipient age more than or equal to 55 years (P=0.0242) and simultaneous LT-pancreatic resection (P=0.0132) were found to be significant predictors of worse survival by both univariate and multivariate Cox proportional hazard analyses. A scoring system was developed, with prognostic points assigned as follows: age more than or equal to 55 years:age less than 55 years=1:0 points and simultaneous LT-pancreatic resection:LT alone=1:0 points. This stratification delineated three separate population samples corresponding to patients with scores of 0, 1, and 2, respectively. The calculated 5-year survival for scores 0, 1, and 2 was 61%, 40%, and 0%, respectively (P=0.0023).

CONCLUSIONS

Despite the limitations of this retrospective analysis, good results can be achieved even for pancreatic NET primaries if the above-proposed scoring system is applied.

Multimodal management of neuroendocrine liver metastases

BACKGROUND

The incidence of neuroendocrine tumours (NET) has increased over the past three decades. Hepatic metastases which occur in up to 75% of NET patients significantly worsen their prognosis. New imaging techniques with increasing sensitivity enabling tumour detection at an early stage have been developed. The treatment encompasses a panel of surgical and non-surgical modalities.

METHODS

This article reviews the published literature related to management of hepatic neuroendocrine metastases.

RESULTS

Abdominal computer tomography, magnetic resonance tomography and somatostatin receptor scintigraphy are widely accepted imaging modalities. Hepatic resection is the only potentially curative treatment. Liver transplantation is justified in highly selected patients. Liver-directed interventional techniques and locally ablative measures offer effective palliation. Promising novel therapeutic options offering targeted approaches are under evaluation.

CONCLUSIONS

The treatment of neuroendocrine liver metastases still needs to be standardized. Management in centres of expertise should be strongly encouraged in order to enable a multidisciplinary approach and personalized treatment. Development of molecular prognostic factors to select treatment according to patient risk should be attempted.

Liver transplantation for primary or secondary endocrine tumors

Endocrine tumors comprise a heterogeneous group of rare neoplasms. Liver metastatic endocrine tumors (MET) are amenable to various therapeutic modalities including liver transplantation (LT). However, LT for MET remains controversial because of the lack of clear selection criteria. The purpose of this study based on thorough perusal of English and French literature since 1989 was to identify prognostic factors and propose recommendations for selecting patients most likely to benefit LT for primary and secondary endocrine tumors.

Surgical management of liver metastases from gastrointestinal endocrine tumors

Liver metastases from endocrine tumors can reduce 5-year survival from 90% to 40% and, in cases of functional gastrointestinal endocrine tumors, lead to a carcinoid syndrome. Complete resection of cancerous disease should be considered in all cases. Indeed, after hepatectomy, prolonged survival (41-86% at five years) can be achieved, with low rates of surgery-related mortality (0-6.7%). Extended liver resection is required in most cases. Percutaneous portal embolization increases the volumetric feasibility of resection, and sequential hepatectomy techniques enable a two-stage resection of both bilobar metastases and the primary tumor. For carcinoid syndrome that does not respond to medical therapy, incomplete resection of liver metastases, by reducing tumor volume, may be indicated to reduce symptoms and halt the progression of carcinoid heart disease. In cases of non-resectable liver metastases in selected patients, liver transplantation can lead to 5-year survival rates as high as 77%.

Liver transplantation and pancreatic resection: a single-center experience and a review of the literature

Liver transplantation may occasionally be indicated in patients with unique clinical scenarios. Little is known regarding the outcomes of patients who have had a pancreatic resection prior to, in combination with, or after liver transplantation. A retrospective review of all patients undergoing liver transplantation from March 1998 to March 2008 identified 17 patients who also underwent pancreatic resection. An additional literature review was performed. Five underwent pancreatic resection prior to liver transplantation (1.7, 3.6, 3.8, 6.8, and 8.1 years), another 9 underwent pancreatic resection together with liver transplantation, and 3 underwent pancreatic resection after liver transplantation (2.2, 2.6, and 3.8 years). Indications for pancreatic resection included cholangiocarcinoma (n = 6), neuroendocrine tumor (n = 5), pancreatic cancer (n = 2), gastrointestinal stromal tumor (n = 1), periampullary adenocarcinoma (n = 1), duodenal adenomas (n = 1), and benign pancreatic mass (n = 1). Indications for liver transplantation were metastatic neuroendocrine tumor disease (n = 5), primary sclerosing cholangitis (n = 5), hepatitis C virus (n = 2), metastatic gastrointestinal stromal tumor (n = 1), Klatskin tumor (n = 1), alcohol cirrhosis (n = 1), alpha-1 antitrypsin deficiency (n = 1), and chemotherapy-induced cirrhosis (n = 1). One patient died intraoperatively, 7 patients died of tumor recurrence, 2 patients died from transplant complications, and 7 patients are still alive. Pancreatic resection-related complications included 4 pancreatic fistulas. A literature review confirmed liver transplantation/pancreatic resection-related complications. In conclusion, liver transplantation and pancreatic resection remain uncommon, and a good outcome can be achieved. Recurrence of malignant disease is the main factor limiting survival, and specific morbidity may be related to pancreatic resection and liver transplantation.

Placebo-controlled, double-blind, prospective, randomized study on the effect of octreotide LAR in the control of tumor growth in patients with metastatic neuroendocrine midgut tumors: a report from the PROMID Study Group

PURPOSE

Somatostatin analogs are indicated for symptom control in patients with gastroenteropancreatic neuroendocrine tumors (NETs). The ability of somatostatin analogs to control the growth of well-differentiated metastatic NETs is a matter of debate. We performed a placebo-controlled, double-blind, phase IIIB study in patients with well-differentiated metastatic midgut NETs. The hypothesis was that octreotide LAR prolongs time to tumor progression and survival.

PATIENTS AND METHODS

Treatment-naive patients were randomly assigned to either placebo or octreotide LAR 30 mg intramuscularly in monthly intervals until tumor progression or death. The primary efficacy end point was time to tumor progression. Secondary end points were survival time and tumor response. This report is based on 67 tumor progressions and 16 observed deaths in 85 patients at the time of the planned interim analysis.

RESULTS

Median time to tumor progression in the octreotide LAR and placebo groups was 14.3 and 6 months, respectively (hazard ratio [HR] = 0.34; 95% CI, 0.20 to 0.59; P = .000072). After 6 months of treatment, stable disease was observed in 66.7% of patients in the octreotide LAR group and 37.2% of patients in the placebo group. Functionally active and inactive tumors responded similarly. The most favorable effect was observed in patients with low hepatic tumor load and resected primary tumor. Seven and nine deaths were observed in the octreotide LAR and placebo groups, respectively. The HR for overall survival was 0.81 (95% CI, 0.30 to 2.18).

CONCLUSION

Octreotide LAR significantly lengthens time to tumor progression compared with placebo in patients with functionally active and inactive metastatic midgut NETs. Because of the low number of observed deaths, survival analysis was not confirmatory.

A fuller understanding of pancreatic neuroendocrine tumours combined with aggressive management improves outcome

BACKGROUND

Neuroendocrine tumours of the pancreas (PNETs) represent 1-2% of all pancreatic tumours. The terms 'islet cell tumours' and 'carcinoids' of the pancreas should be avoided. The aim of this review is to offer an overview of the history and diagnosis of PNETs followed by a discussion of the available treatment options.

METHODS

A search on PubMed using the keywords 'neuroendocrine', 'pancreas' and 'carcinoid' was performed to identify relevant literature over the last 30 years.

RESULTS

The introduction of a revised classification of neuroendocrine tumours by the World Health Organisation (WHO) in 2000 significantly changed our understanding of and approach to the management of these tumours. Advances in laboratory and radiological techniques have also led to an increased detection of PNETs. Surgery remains the only treatment that offers a chance of cure with increasing number of non-surgical options serving as beneficial adjuncts. The better understanding of the behaviours of PNETs together with improvements in tumour localisation has resulted in a more aggressive management strategy with a concomitant improvement in symptom palliation and a prolongation of survival.

CONCLUSION

Due to their complex nature and the wide range of therapeutic options, the involvement of specialists from all necessary disciplines in a multidisciplinary team setting is vital to provide optimal treatment of this disease.