Method for dissection of mesenteric metastases in mid-gut carcinoid tumors

Long-Term Survival Outcomes After Minimally Invasive Surgery for Ileal Neuroendocrine Tumors

BACKGROUND

Ileal neuroendocrine tumors (i-NETs) are characterized by their multifocality and bulky mesenteric mass. Having shown that minimally invasive surgery (MIS) utilizing a hand-access port device has favorable short-term outcomes and achieves the goals of surgery for i-NETs, we sought to analyze long-term survival outcomes of MIS.

METHODS

One hundred and sixty-eight patients who underwent resection of primary i-NETs at a single institution between January 2007 and February 2023 were retrospectively studied. Patients were categorized into the MIS or open surgery cohorts on an intention-to-treat basis. Open surgery was selected mainly based on the need for hepatectomy or bulky mesenteric mass resection. Overall survival was analyzed using log-rank tests with propensity score matching (PSM) and Cox proportional hazards regression. PSM was performed to reduce standardized mean differences of the variables to <0.2.

RESULTS

Overall, 129 (77%) patients underwent MIS and 39 (23%) underwent open surgery. Twenty-seven MIS patients were converted to an open procedure. The median follow-up time was 49 months (interquartile range 23-87 months). In the PSM cohorts, overall survival did not differ significantly between the MIS and open surgery cohorts {median 99 months (95% confidence interval [CI] 91-not applicable [NA]) vs. 103 months (95% CI 86-NA), p = 0.77; hazard ratio 0.87 (95% CI 0.33-2.2), p = 0.77}.

CONCLUSIONS

MIS is an alternative to open surgery for i-NETs, achieving similar short- and long-term oncological outcomes. Bulky mesenteric mass and a plan for concurrent liver resection are potential criteria for open surgery.

[Local resection of small intestine neuroendocrine neoplasms (SI-NEN) : Current principles]

BACKGROUND

Neuroendocrine tumors of the small bowel (small intestine neuroendocrine neoplasms, SI-NEN) are the most frequent tumors of the small intestine and approximately 30-40% are still surgically treatable with curative intent at the time of diagnosis. Certain surgical principles must be followed for optimal oncological outcomes and good postoperative quality of life.

METHODS

Based on international guidelines and own experiences, the locoregional surgical treatment of SI-NENs is presented.

RESULTS

Locoregional SI-NENs should always be resected if technically feasible, as only this approach can achieve a long-term cure and even small primary tumors (< 10 mm) often already show lymphatic metastasis. The resectability of SI-NENs and their difficulty depend on the extent of lymphatic metastasis, which should be assessed based on preoperative imaging of the extent around the superior mesenteric artery. Currently, the surgical gold standard for SI-NENs is open surgery with bidigital palpation of the entire small intestine followed by primary tumor resection via small bowel segment resection, right hemicolectomy or ileocecal resection and vessel-sparing, and therefore organ-preserving lymphadenectomy (≥ 8 lymph nodes). The guidelines consider that laparoscopic or robotic approaches are justified only for early stages of SI-NENs.

CONCLUSION

Guideline-compliant surgical treatment of locoregional SI-NEN enables recurrence-free long-term survival with good quality of life.

ASO Practice Guidelines Series: Surgical Management of Gastrointestinal (Midgut) Neuroendocrine Neoplasms

Gastrointestinal midgut neuroendocrine neoplasms (NENs) are a heterogeneous group of uncommon malignancies. For well-differentiated NENs, known as neuroendocrine tumors (NETs), surgery is a cornerstone of management in localized and metastatic disease. Because of heterogeneous tumor behaviour, association with endocrine syndrome, and prognosis, the management of NETs must be individualized to all these factors in addition to the primary site. With the fast pace of advancement in the field, both for therapies and understanding of tumoral etiology and behaviour, it is important for surgical oncologists to remain updated on guidelines recommendations and suggested treatment pathways. Those guidelines provide important guidance for management of NETs but are largely based on expert opinions and interpretation of retrospective evidence. This article reviews highlights of most recent practice guidelines for midgut (gastric, duodenal, small intestinal, and appendiceal) NETs.

Diagnosis and staging of small intestinal neuroendocrine tumors with CT enterography and PET with Gallium-68: preoperative risk stratification protocol

PURPOSE

Pre-operative diagnosis and staging of small intestine neuroendocrine tumors (SI-NETs) remain sub-optimal, with open palpation during surgery still considered the gold standard. This limits a standardized implementation of minimally invasive surgery (MIS). The aim of this single-center retrospective study was to assess a tailored diagnostic work-up to identify candidates at low risk of undetected disease who may benefit from MIS.

METHODS

Patients diagnosed with SI-NETs between 2013 and 2022 who underwent contrast-enhanced computed tomography enterography (CTE) and Ga68-DOTATOC-positron emission tomography-CT (68 Ga DOTATATE PET/CT) preoperatively and subsequently underwent open surgical resection were included. Imaging studies were reassessed by two radiologists. Combined use of CTE and 68 Ga DOTATATE PET/CT in determining primary lesion disease burden (number of lesions) and LN disease stage (distal and proximal relative to superior mesenteric vessels) was assessed, using surgical reports and pathology as gold standard.

RESULTS

Overall, 56 patients were included. Sensitivity of CTE and 68 Ga DOTATATE PET/CT for at least one primary SI-NET was 100% and 94%, respectively. In the presence of concordance between studies, combined use of CTE and 68 Ga DOTATATE PET/CT for detection of single primary tumors improved specificity to 89% (n = 25/28) with a positive predictive value of 87.5% (n = 21/24). Distal LN disease was identified in 89.2% of cases (n = 33/37). The association of single lesion and distal LN disease was found pre-operatively in 32% of patients (n = 18).

CONCLUSION

Combined use of CTE and 68 Ga DOTATATE PET/CT enables identifying low-risk surgical candidates (single SI-NET lesions with distal LN disease).

Surgery as a Principle and Technical Consideration for Primary Tumor Resection of Small Bowel Neuroendocrine Tumors

Small bowel neuroendocrine tumors (SB-NETs) are increasingly identified and have become the most frequent entity among small bowel tumors. An increasing incidence, a high prevalence, and a prolonged survival with optimal modern multidisciplinary management makes SB-NETs a unique set of tumors to consider for surgical oncologists. The major goals of surgical treatment in the setting of SB-NET include control of tumor volume, control of endocrine secretion, and prevention of locoregional complications. Key considerations include assessment of multifocality and resection of mesenteric nodal masses with the use of mesenteric-sparing approaches and acceptance of R1 margins if necessary to clear disease while avoiding short bowel syndrome. A description through eight steps for consideration is presented to allow for systematic surgical planning and execution of resection. Moreover, some controversies and evolving considerations to the surgical principles and technical procedures remain. The role of primary tumor resection in the presence of (unresectable) liver metastasis is still unclear. Reports of feasibility of minimally invasive surgery are emerging, with undetermined selection criteria for appropriateness or long-term outcomes. Resection of SB-NETs should be considered in all patients fit for surgery and should follow principles to achieve surgical oncological control that is appropriate for the stage and tumor burden, considering the age and comorbidity of the individual patient.

Management Strategies and Outcomes for Small Intestinal Neuroendocrine Tumours with Involvement of the Superior Mesenteric Vessels: A Systematic Review

Small intestinal neuroendocrine tumours (SI-NETs) are the most common small intestinal tumours. A particularly challenging subset of these tumours is those that involve the superior mesenteric artery or vein for which the role and feasibility of surgery are often questioned. This systematic review aimed to identify and evaluate the management strategies used for these complex SI-NETs. The identified studies showed positive outcomes with surgery and multimodality therapy.

Management of Small Bowel Neuroendocrine Tumours: 10 Years' Experience at a Tertiary Referral Centre

BACKGROUND

Neuroendocrine tumours (NET) arising from the small bowel are clinically challenging and are often diagnosed at advanced stages. Disease control with surgery alone can be demanding. Multimodal treatment concepts integrating surgery and non-surgical modalities could be of benefit.

METHOD

Retrospective review of consecutive adult patients with SB NET treated at Imperial College Healthcare NHS Trust between 1 January 2010 and 31 December 2019. Data regarding clinicopathological characteristics, treatments, and disease trajectory were extracted and summarised. Overall and progression/recurrence-free survival were estimated at 5 and 10 years.

RESULTS

154 patients were identified, with a median age of 64 years (range 33-87); 135/154 (87.7%) had stage III/IV disease at diagnosis. Surgery was used in 125 individuals (81.2%), typically with either segmental small bowel resection (60.8%) or right hemicolectomy (33.6%) and mesenteric lymphadenectomy for the primary tumour. Systemic and/or liver-directed therapies were used in 126 (81.8%); 60 (47.6%) had more than one line of non-surgical treatment. Median follow-up was 67.2 months (range 3.1-310.4); overall survival at 5 and 10 years was 91.0% (95% CI: 84.9-94.7%) and 82.5% (95% CI: 72.9-88.9%), respectively. Imaging-based median progression-free survival was 42.7 months (95% CI: 24.7 to 72.4); 5-year progression-free survival was 63.4% (95% CI: 55.0-70.6%); 10-year progression-free survival was 18.7% (95% CI: 12.4-26.1). Nineteen patients (12.3%) reached 10 years follow-up without disease recurrence and therefore were considered cured.

CONCLUSIONS

Most patients with SB NET present in a metastasised stage. Multimodal treatment concepts may be associated with excellent clinical outcomes. Future work should explore optimal approaches to treatment sequencing and patient selection.

Prognostic differences in grading and metastatic lymph node pattern in patients with small bowel neuroendocrine tumors

PURPOSE

Neuroendocrine tumors of the small intestine (si-NET) describe a heterogenous group of neoplasms. Based on the Ki67 proliferation index si-NET are divided into G1 (Ki67 < 2%), G2 (Ki67 3-20%) and rarely G3 (Ki67 > 20%) tumors. However, few studies evaluate the impact of tumor grading on prognosis in si-NET. Moreover, si-NET can form distinct lymphatic spread patterns to the mesenteric root, aortocaval lymph nodes, and distant organs. This study aims to identify prognostic factors within the lymphatic spread patterns and grading.

METHODS

Demographic, pathological, and surgical data of 208 (90 male, 118 female) individuals with si-NETs treated at Charité University Medicine Berlin between 2010 and 2020 were analyzed retrospectively.

RESULTS

A total of 113 (54.5%) specimens were defined as G1 and 93 (44.7%) as G2 tumors. Interestingly, splitting the G2 group in two subgroups: G2 low (Ki67 3-9%) and G2 high (Ki67 10-20%), displayed significant differences in overall survival (OS) (p = 0.008) and progression free survival (PFS) (p = 0.004) between these subgroups. Remission after surgery was less often achieved in patients with higher Ki67 index (> 10%). Lymph node metastases (N +) were present in 174 (83.6%) patients. Patients with isolated locoregional disease showed better PFS and OS in comparison to patients with additional aortocaval and distant lymph node metastases.

CONCLUSION

Lymphatic spread pattern influences patient outcome. In G2 tumors, low and high grading shows heterogenous outcome in OS and PFS. Differentiation within this group might impact follow-up, adjuvant treatment, and surgical strategy.

Surgical aspects of small intestinal neuroendocrine tumors

Small intestinal neuroendocrine tumors (NETs) are a heterogeneous group of epithelial tumors with a predominant neuroendocrine differentiation. Although NETs are usually considered rare neoplasms, small intestinal NETs are the most common primary malignancy of the small bowel, with an increasing prevalence worldwide during the course of the past few decades. The indolent nature of these tumors often leads to a delayed diagnosis, resulting in over one-third of patients presenting with synchronous metastases. Primary tumor resection remains the only curative option for this type of tumor. In this review article, the various surgical aspects for the excision of small intestinal NETs are discussed.

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.

Neuroendocrine neoplasm imaging: protocols by site of origin

With the relatively low incidence of neuroendocrine neoplasms (NEN), most radiologists are not familiar with their optimal imaging techniques. The imaging protocols for NENs should be tailored to the site of origin to accurately define local extension of NEN at time of staging. Patterns of spread and recurrence should be taken into consideration when choosing protocols for detection of recurrence and metastases. This paper will present the recommended CT and MRI imaging protocols for gastro-enteric and pancreatic NENs based on site of origin or predominant pattern of metastatic disease, and explain the rationale for MRI contrast type, contrast timing, as well as specific sequences in MRI. We will also briefly comment on PET/CT and PET/MRI imaging protocols.

Small bowel neuroendocrine neoplasm: what surgeons want to know

Neuroendocrine neoplasms of the small bowel are a diverse group of tumors with a broad spectrum of imaging findings and clinical implications. Most tumors originate in close proximity to the ileocecal valve and most commonly metastasize to the mesentery and liver. This review will highlight the imaging findings of primary and metastatic small bowel neuroendocrine neoplasm that are most relevant to the surgical team.

Association of lymph node metastases, grade and extent of mesenteric lymph node dissection in locoregional small intestinal neuroendocrine tumors with recurrence-free survival

We aimed to assess the prognostic impact of tumor- and patient-related parameters in patients with stage I-III small intestinal neuroendocrine tumors (SI-NETs), who underwent locoregional resective surgery (LRS) with curative intent. We included 229 patients with stage I-III SI-NETs diagnosed from June 15, 1993, through March 8, 2021, identified using the SI-NET databases from five European referral centers. Mean ± SD age at baseline was 62.5 ± 13.6 years; 111/229 patients were women (49.3%). All tumors were well-differentiated; 160 were grade 1 (G1) tumors, 51 were G2, two were G3 and 18 tumors were of unspecified grade (median Ki-67: 2%, range 1%-50%). One-hundred and sixty-three patients (71.2%) had lymph node (LN) involvement. The median number of retrieved lymph nodes was 10 (0-63), whereas the median number of positive LNs was 2 (0-43). After a mean ± SD follow-up of 54.1 ± 64.1 months, 60 patients experienced disease recurrence at a median (range) of 36.2 (2.5-285.1) months. The 5- and 10-year recurrence-free survival (RFS) rates were 66.6% and 49.3% respectively. In univariable analysis, there was no difference in RFS and overall survival (OS) between LN-positive and LN-negative patients (log-rank, p = .380 and .198, respectively). However, in stage IIIb patients who underwent mesenteric lymph node dissection (MLND) with a minimum of five retrieved LN (n = 125), five or more LN metastases were associated with shorter RFS (median RFS [95% CI] = 107.4 [0-229.6] vs. 73.7 [35.3-112.1] months; log-rank, p = .048). In addition, patients with G2 tumors exhibited shorter RFS compared to patients with G1 tumors (median RFS [95% confidence interval (CI)] = 46.9 [36.4-57.3] vs. 120.7 [82.7-158.8] months; log-rank, p = .001). In multivariable Cox-regression RFS analysis in stage IIIb patients, the Ki-67 proliferation index (hazard ratio = 1.08, 95% CI = 1.035-1.131; p < .0001) and the number of LN metastases (hazard ratio = 1.06, 95% CI = 1.001-1.125; p = .047) were independent prognostic factors for RFS. In conclusion, LRS with a meticulous MLND and a minimum number of five harvested LNs appears to be critical in the surgical management of SI-NET patients with locoregional disease. In patients who underwent LRS and MLND, the Ki-67 proliferation index and the LN metastases count were independent predictors of RFS.

Vessel-Sparing Lymphadenectomy Should Be Performed in Small Intestine Neuroendocrine Neoplasms

Simple Summary

Primary tumor resection with lymphadenectomy in small intestine neuroendocrine neoplasms potentially requires extensive small bowel resections due to central lymph node metastases and mesenteric fibrosis. Retrograde vessel-sparing lymphadenectomy (VS-LA) might be a sufficient method for avoiding local recurrence and for sparing the small bowel at the same time. We retrospectively analyzed clinical, surgical and pathological data of 50 patients with SI-NENs who exclusively underwent small bowel resections; half of them received conventional lymphadenectomy and 25 underwent VS-LA. VS-LA resulted in shorter resected bowel segments (median 40 cm vs. 65 cm, p = 0.007) with similar rates of local R0 resections (72% vs. 84%) and number of resected lymph nodes (median 13 vs. 13). Postoperative complications occurred significantly less in the vessel-sparing group. VS-LA should be the preferred surgical method in small bowel resections for SI-NENs.

Abstract

Introduction: The goal of primary tumor resection with lymphadenectomy (PTR) in small intestine neuroendocrine neoplasms (SI-NENs) is to avoid local recurrence while sparing as much of the small bowel as possible, even in the case of extensive mesenteric fibrosis. The results of PTR with retrograde vessel-sparing lymphadenectomy (VS-LA) were compared to those of conventional lymphadenectomy (Con-LA). Methods: Prospectively collected clinical, surgical and pathological data of consecutive patients with SI-NENs who underwent small bowel resections were retrospectively analyzed regarding the resection technique performed. Results: In a 7-year period, 50 of 102 patients with SI-NENs had only small bowel resections; of those, 25 were VS-LA and 25 were Con-LA. Patients with VS-LA had tendentially more advanced diseases with slightly higher rates of abdominal pain, mesenteric shrinkage and more level III lymph node involvement compared to patients with Con-LA. VS-LA, however, resulted in shorter resected bowel segments (median 40 cm vs. 65 cm, p = 0.007) with similar rates of local R0 resections (72% vs. 84%) and resected lymph nodes (median 13 vs. 13). Postoperative clinically relevant complications occurred in 1 of 25 (4%) in the VS-LA and in 7 of 25 (28%) patients in the Con-LA group (p = 0.02). Three months after surgery, 1 of 25 (4%) patients of the VS-LA group and 10 of 25 (40%) patients in the Con-LA group (p = 0.002) complained about abdominal pain. One of eight patients in the VS-LA group and two of thirteen patients in the Con-LA group who had completely resected stage III disease complained about diarrhea (p = 0.31). Conclusion: VS-LA seems to be oncologically safe and should be considered in small bowel resections for SI-NENs.

Immuno-histochemical correlation of fibrosis-related markers with the desmoplastic reaction of the mesentery in small intestine neuroendocrine neoplasms

INTRODUCTION

Small intestine neuroendocrine neoplasms (siNENs) will attain more importance due to their increasing incidence. Moreover, siNENs might lead to a desmoplastic reaction (DR) of the mesentery causing severe complications and deteriorating prognosis. The expression of fibrosis-related proteins appears to be the key mechanisms for the development of this desmoplastic reaction. Therefore, this study aimed to investigate the association of the desmoplastic mesentery with specific fibrosis-related protein expression levels.

MATERIALS AND METHODS

By immunohistochemistry, the protein expression levels of four fibrosis-related markers (APLP2, BNIP3L, CD59, DKK3) were investigated in primary tumors of 128 siNENs. The expression levels were correlated with the presence of a desmoplastic reaction and clinico-pathological parameters.

RESULTS

In the primary tumor, APLP2, BNIP3L, CD59 and DKK3 were highly expressed in 29.7% (n = 38), 64.9% (n = 83), 92.2% (n = 118) and 80.5% (n = 103), respectively. There was no significant correlation of a single marker or the complete marker panel to the manifestation of a desmoplastic mesentery. The desmoplastic mesentery was significantly associated with clinical symptoms, such as flushing and diarrhea. However, neither the fibrosis-related marker panel nor single marker expressions were associated with clinical symptoms.

DISCUSSION

The expression rates of four fibrosis-related markers in the primary tumor display a distinct pattern. However, the expression patterns are not associated with desmoplastic altered mesenteric lymph node metastases and the expression patterns did not correlate with prognosis. These findings suggest alternative mechanisms being responsible for the desmoplastic reaction.

Concept of reintervention with thorough lymphadenectomy after suboptimal resection of small-intestine neuroendocrine neoplasms: A multicentre preliminary study

Complete surgical resection is the only hope to cure small intestine neuroendocrine neoplasms (SiNENs). However, inadequate lymphadenectomy or entire small bowel palpation for multiple primary tumours renders at least 20% of resections suboptimal. This study was undertaken to investigate reintervention outcomes after initial suboptimal resections (ISORs), and agreement between residual tumour identification on interval imaging and during reintervention. This retrospective, multicentre study included all patients undergoing reintervention within 18 months post ISOR. Disease-free survival (DFS) was defined as the time from reintervention resection date to recurrence or any-cause of death. The kappa coefficient assessed agreement rates between suspected residual tumour on interval imaging and its presence at reintervention. A total of 21 patients underwent reintervention for nonmetastatic SiNENs (median follow-up 2.3 [IQR 0.6-3.75] years). Residual tumour, suspected in 17/21 (81%) patients based on interval imaging, was found in 20/21 (95%) during reintervention. Interval imaging-intraoperative detection agreement was fair for residual primary tumours (kappa = 0.28, 95% CI: 0.05-0.62; p = .09) and residual lymph node metastases (kappa = 0.17, 95% CI: 0.28-0.62; p = .45). Reintervention achieved complete tumour clearance in 16/21 (76%) patients, among whom 5/16 (31%) developed liver metastases during follow-up. Median DFS was 70.6 months (IQR 39.7-not reached). Reintervention post-ISOR can obtain tumour clearance and prolonged remission. It should be systematically discussed after suspected ISOR, even when postoperative imaging does not find any residual tumour. To maximize detection of potentially resectable residual disease, imaging modalities after "curative" surgery should be redefined.

Relevant prognostic factors in patients with stage IV small intestine neuroendocrine neoplasms

There are few, but controversial data on the prognostic role of upfront primary tumour resection and mesenteric lymph node dissection (PTR) in patients with diffuse metastatic small intestinal neuroendocrine neoplasia (SI-NEN). Therefore, the prognostic role of PTR and other factors was determined in this setting. This retrospective cohort study included patients with stage IV SI-NETs with unresectable distant metastases without clinical and radiological signs of acute bowel obstruction or ischaemia. Patients diagnosed from January 2002 to May 2020 were retrieved from a prospective SI-NEN database. Disease specific overall survival (OS) was analysed with regard to upfront PTR and a variety of other clinical (e.g., gender, age, Hedinger disease, carcinoid syndrome, diarrhoea, laboratory parameters, metastatic liver burden, extrahepatic and extra-abdominal metastasis) and pathological (e.g., grading, mesenteric gathering) parameters by uni- and multivariate analysis. A total of 138 patients (60 females, 43.5%) with a median age of 60 years, of whom 101 (73%) underwent PTR and 37 (27%) did not, were included in the analysis. Median OS was 106 (95% CI: 72.52-139.48) months in the PTR group and 52 (95% CI: 30.55-73.46) in the non-PTR group (p = 0.024), but the non-PTR group had more advanced metastatic disease (metastatic liver burden ≥50% 32.4% vs. 13.9%). There was no significant difference between groups regarding the rate of surgery for bowel complications during a median follow-up of 51 months (PTR group 10.9% and non-PTR group 16.2%, p = 0.403). Multivariate analysis revealed age < 60 years, normal C-reactive protein (CRP) at baseline, absence of diarrhoea, less than 50% of metastatic liver burden, and treatment with PRRT as independent positive prognostic factors, whereas PTR showed a strong tendency towards better OS, but level of significance was missed (p = 0.067). However, patients who underwent both, PTR and peptide radioreceptor therapy (PRRT) had the best survival compared to the rest (137 vs. 73 months, p = 0.013). PTR in combination with PRRT significantly prolongs survival in patients with stage IV SI-NEN. Prophylactic PTR does also not result in a lower reoperation rate compared to the non-PTR approach regarding bowel complications.

International survey on opinions and use of minimally invasive surgery in small bowel neuroendocrine neoplasms

INTRODUCTION

Although minimally invasive surgery is becoming the standard technique in gastrointestinal surgery, implementation for small bowel neuroendocrine neoplasms (SB-NEN) is lagging behind. The aim of this international survey was to gain insights into attitudes towards minimally invasive surgery for resection of SB-NEN and current practices.

METHODS

An anonymous survey was sent to surgeons between February and May 2021 via (neuro)endocrine and colorectal societies worldwide. The survey consisted of questions regarding experience of the surgeon with minimally invasive SB-NEN resection and training.

RESULTS

A total of 58 responses from five societies across 20 countries were included. Forty-one (71%) respondents worked at academic centers. Thirty-seven (64%) practiced colorectal surgery, 24 (41%) endocrine surgery and 45 (78%) had experience in advanced minimally invasive surgery. An open, laparoscopic or robotic approach was preferred by 23 (42%), 24 (44%), and 8 (15%) respondents, respectively. Reasons to opt for a minimally invasive approach were mainly related to peri-operative benefits, while an open approach was preferred for optimal mesenteric lymphadenectomy and tactile feedback. Additional training in minimally invasive SB-NEN resection was welcomed by 29 (52%) respondents. Forty-three (74%) respondents were interested in collaborating in future studies, with a cumulative median (IQR) annual case load of 172 (86-258).

CONCLUSIONS

Among respondents, 69% applies minimally invasive surgery for resection of SB-NEN. Arguments for specific operative approaches differ, and insufficient training in advanced laparoscopic techniques seems to be a barrier. Future collaborative studies can provide better insight in selection criteria and optimal technique.

Management of Small Bowel Neuroendocrine Tumors

Small bowel neuroendocrine tumors (SBNETS) are slow-growing neoplasms with a noted propensity toward metastasis and comparatively favorable prognosis. The presentation of SBNETs is varied, although abdominal pain and obstructive symptoms are the most common presenting symptoms. In patients with metastases, hypersecretion of serotonin and other bioactive amines results in diarrhea, flushing, valvular heart disease, and bronchospasm, termed carcinoid syndrome. The treatment of SBNETs is multimodal and includes surgery, liver-directed therapy, somatostatin analogues, targeted therapy, and peptide receptor radionuclide therapy.

Multifocal neuroendocrine tumour of the small bowel presenting as an incarcerated incisional hernia: a surgical challenge in a high-risk patient

Neuroendocrine tumours (NET) of the small bowel present significant clinical challenges, such as their rate of metastasis at initial presentation, common multifocality and understaging even with gold standard imaging. Here, we present a case of a high-risk surgical patient with a complex medical history initially presenting as an acute abdomen due to an incarcerated incisional hernia. He was found at emergency laparotomy to have three small NET deposits in a 30-cm segment of incarcerated ileum which was resected. Postoperative morphological and functional imaging and biochemical markers were unremarkable, but due to clinical suspicion for undetected residual tumour bulk given the non-systematic palpation of the entire small bowel at initial operation, underwent re-operation where a further 70 cm of ileum was found to harbour multiple tumour deposits (n = 25) and was resected. There was no surgical morbidity and the patient remains tumour-free at 9-month follow-up.

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.

Evaluating Nationwide Application of Minimally Invasive Surgery for Treatment of Small Bowel Neuroendocrine Neoplasms

Aim

Open resection of small bowel neuroendocrine neoplasms (SB-NEN) is still considered standard-of-care, mainly because of frequently encountered multifocality and central mesenteric masses. The aim of this study was to evaluate surgical approach for SB-NEN at a national level and determine predictors for overall survival.

Methods

Patients with SB-NEN who underwent resection between 2005 and 2015 were included from the Netherlands Cancer Registry. Patient and tumor characteristics were compared between laparoscopic and open approach. Overall survival was assessed by Kaplan–Meier and compared with the Log-rank test. Independent predictors were determined by Cox proportional hazards model.

Results

In total, 482 patients were included, of whom 342 (71%) underwent open and 140 (29%) laparoscopic resection. The open resection group had significantly more multifocal tumors resected (24% vs. 14%), pN2 lymph nodes (18% vs. 7%) and stage IV disease (36% vs. 22%). Overall survival after open resection was significantly shorter compared to laparoscopic resection (3-year: 81% vs. 89%, 5-year: 71% vs. 84%, p = 0.004). In multivariable analysis, age above 60-years (60–75, HR 3.38 (95% CI 1.84–6.23); > 75 years, HR 7.63 (95% CI 3.86–15.07)), stage IV disease (HR 1.86 (95% CI 1.18–2.94)) and a laparoscopic approach (HR 0.51 (95% CI 0.28–0.94)) were independently associated with overall survival, whereas multifocal primary tumor, grade and resection margin status were not.

Conclusion

Laparoscopic resection was the approach in 29% of SB-NEN at a national level with selection of the more favorable patients. Laparoscopic resection remained independently associated with better overall survival besides age and stage, but residual confounding cannot be excluded.

Evaluation of the prognosis for N2 status in patients with small bowel neuroendocrine tumors

BACKGROUND

The 8th edition AJCC Staging for small bowel neuroendocrine tumors created a novel N2 classification. This study investigates if it is independently prognostic.

METHODS

Records of patients from 2008 to 2019 were reviewed. Survival rates were estimated by Kaplan-Meier method and compared by log-rank. The Cox Proportional Hazards model was used to determine factors associated with overall survival (OS) via multivariate analysis.

RESULTS

Among 300 patients, 225 were N2 and 60 were N1. No differences were seen in pathologic markers for N1 compared to N2. N2 were more likely to have liver metastases (LM) (p = 0.048) but rates of resectability were similar. Median OS for N1 with >70% liver cytoreduction was not yet reached compared to 121 months for N2 (p = 0.005). On multivariate analysis, LM was associated with shorter survival (p = 0.028), but nodal status was not.

CONCLUSIONS

Unlike LM, N2 status is not independently prognostic, but a marker for aggressive LM.

A combination of surgery, theranostics, and liquid biopsy - a personalised oncologic approach to treatment of patients with advanced metastatic neuroendocrine neoplasms

Rationale: Neuroendocrine neoplasia (NEN) of small bowel (SBNEN) frequently present with metastatic disease. Theranostics (molecular imaging followed by targeting therapy) allow for personalised medicine. Liquid biopsies enable precise identification of residual disease and real-time monitoring of therapeutic response. Our aim was to determine the clinical utility of a combination of surgery, theranostics, and a multigene blood measurement in metastasised SBNEN. Methods: Inclusion criteria were SBNEN, G1/G2 NEN, initial tumour diagnosis, stage IV NEN, positivity on 68Ga somatostatin analogue PET/CT, eligible for surgery, and 177Lu peptide receptor radionuclide therapy (PRRT). Blood samples for NETest were collected longitudinally. Progression-free survival (PFS) and overall survival (OS) were calculated. NETest results were assessed prior to surgery and during clinical follow-up. Results: A surgical cohort of 39 SBNEN patients met eligibility criteria. Thirty-two patients underwent ileal resection and 7 right hemicolectomy. The mean number of 177Lu PRRT cycles was 4. Mortality was nil. Surgical morbidity was 10.3%. Transient grade 1/2 toxicity occurred in 41% (PRRT). NETest scores (n=9 patients) decreased in 100% following treatment and correlated with diminished tumour volume and disease stabilization following surgery and PRRT. Median follow-up: 78 months. Median PFS and OS: 42.7 and 110 months, respectively. Progression-free survival at 1-, 3-, and 5-years was 79.4%, 57.1% and 40.5%, respectively. Overall survival at 1-, 3-, and 5-years was 97.4%, 97.4%, and 94.1%, respectively. Conclusions: Surgery combined with 177Lu PRRT is safe and provides favourable PFS and OS in selected patients with advanced SBNEN. Liquid biopsy (NETest) has the potential to accurately delineate disease status.

Fluorescence angiography guided resection of small bowel neuroendocrine neoplasms with mesenteric lymph node metastases

BACKGROUND

Surgery for small bowel neuroendocrine neoplasms (SB-NEN) might result in vascular compromise of the remaining bowel due to resection of lymph node metastases in close proximity to main mesenteric vessels. Fluorescence angiography (FA) has been described as a safe technique to assess perfusion during gastro-intestinal surgery. This study aimed to evaluate the potential value of intraoperative FA during surgery for SB-NEN.

METHODS

This study included patients undergoing surgery for SB-NEN of any stage. The planned level of transection was marked by the surgeon, after which FA using indocyanine green (ICG) was performed. The primary study outcome was change in management due to FA.

RESULTS

Ten consecutive patients with SB-NEN were included, all with metastatic lymph nodes close to main mesenteric vessels. FA use led to management changes in eight patients (80%); four patients had less bowel resected with a preserved length of 5-35 cm. The other four patients had more extended bowel resections with an additional length varying from 3 to 25 cm. The median postoperative stay was 4 days (interquartile range 4-6). No anastomotic leakage occurred.

CONCLUSION

This is the first known series describing preliminary results of FA during SB-NEN surgery. FA led to a management change in 80% of patients with better tailoring the extent of resection of small bowel. Structural implementation of FA to assess small bowel perfusion after dissection for small bowel NET results in change of management, either by preserving small bowel or resecting ill-perfused small bowel.

The Landmark Series: Management of Small Bowel Neuroendocrine Tumors

Surgical resection is the foundation for treatment of small bowel neuroendocrine tumors (SBNETs). Guidelines for surgical management of SBNETs rely on retrospective data, which suggest that primary tumor resection and cytoreduction improve symptoms, prevent future complications, and lengthen survival. In advanced NETs, improvement in progression-free survival has been reported in large, randomized, controlled trials of various medical treatments, including somatostatin analogues, targeted therapy, and peptide receptor radionuclide therapy. This review discusses important studies influencing the management of SBNETs and the limitations of current evidence regarding surgical interventions for SBNETs.

Prognostic Factors in Curative Resected Locoregional Small Intestine Neuroendocrine Neoplasms

BACKGROUND

Small intestinal neuroendocrine neoplasms (SI-NEN) are rare, and only about 40% of patients are diagnosed without distant metastases. Aim of the study was to identify prognostic factors in patients with potentially curative resected locoregional SI-NEN.

METHODS

Patients with curative resected locoregional SI-NEN (ENETS stages I-III) were retrieved from a prospective data base. Demographic, surgical and pathological data of patients with and without disease recurrence were retrospectively analyzed using univariate and multivariate analysis.

RESULTS

In a 20-year period, 65 of 203 (32%) patients with SI-NEN were operated for stages I-III disease. Thirty-eight (58.5%) patients were men, and the median age at surgery was 59 (range 37-87) years. After median follow-up of 65 months, 14 patients experienced disease relapse median 28.5 (range 6-122) months after initial surgery, of which 2 died due to their disease. Multivariate analysis revealed age ≥ 60 years (HR = 6.41, 95% CI 1.38-29.67, p = 0.017), tumor size ≥ 2 cm (HR = 26.54, 95% CI 4.46-157.62, p < 0.001), lymph node ratio > 0.5 (HR 7.18, 95% CI 1.74-29.74, p = 0.007) and multifocal tumor growth (HR = 6.98, 95% CI 1.66-29.39, p = 0.008) as independent negative prognostic factors and right hemicolectomy compared to segmental small bowel resection (HR = 0.04, 95% CI 0.01-0.24, p < 0.001) as independent protector against recurrence.

CONCLUSION

Patients with locoregional SI-NEN with an age ≥ 60 years, tumor size ≥ 2 cm, lymph node ratio > 0.5 and multiple small bowel tumor foci have an increased risk for recurrence and might benefit from adjuvant treatment. In contrast, right hemicolectomy of ileal SI-NEN seems to reduce the risk of recurrence.

Surgical Principles in the Management of Small Bowel Neuroendocrine Tumors

OPINION STATEMENT

Small bowel neuroendocrine tumors (SB NETs) are increasing in frequency and becoming more common in surgical practice. It is often difficult to make the diagnosis of a SB NET at an early stage, as the primary tumor tends to be small and patients are asymptomatic until there is regional or distant metastasis, when they develop abdominal pain, partial obstruction, or bleeding and/or develop carcinoid syndrome. Despite this advanced presentation at the time of diagnosis, patients with metastatic SB NETs, as compared to other gastrointestinal malignancies, have favorable survival, which can be improved by appropriate surgical interventions. With the lack of randomized studies, there is reasonable controversy surrounding the optimal management of patients with SB NETs. As such, treatment of these patients is driven primarily by physician experience and available data based predominantly on retrospective studies. Based on this, current recommendations advocate for patients with SB NETs (localized or metastatic) to be managed at experienced centers by a multidisciplinary team. Eligible patients should undergo surgical resection of primary and regional disease as outlined in this article. Additionally, patients with metastatic disease should be evaluated on a case by case basis to evaluate surgical options that may mitigate bowel symptoms (i.e., pain, intestinal angina, obstruction) and carcinoid symptoms (flushing, diarrhea, hemodynamic instability) and prolong survival. Unlike other gastrointestinal malignancies, aggressive surgical management of these patients, even in the context of unresectable metastatic disease, can improve patients' symptoms and long-term survival. The principles outlined in this article are geared to guide appropriate management of SB NET patients with improvement in quality of life and overall survival outcomes.

Role of Primary Tumor Resection for Metastatic Small Bowel Neuroendocrine Tumors

While small bowel resection is well established as standard of care for curative-intent management of localized and loco-regional small bowel neuroendocrine tumors (SB-NETs), resection of the primary tumor in the setting of metastatic disease is debated. This review addresses the role of primary tumor resection for stage IV well-differentiated grade 1 and 2 SB-NETs. While survival benefits have been reported for primary tumor resection in the setting of metastatic disease, these studies are limited by selection bias and thus controversial. The main clinical benefits of primary tumor resection for stage IV disease involve the prevention of potentially debilitating complications associated with mesenteric fibrosis, including intestinal obstruction, mesenteric ischemia and angina, venous congestion, malabsorption, and malnutrition. Patients with metastases undergoing initial resection of the primary SB-NETs appear to have fewer episodes of care and re-intervention for loco-regional complications than those who do not undergo resection. As recommended by the NANETS and ENETS guidelines, resection of the primary tumor for stage IV SB-NETs should be strongly considered to avoid future loco-regional complications and potentially to improve survival. All patients with stage IV SB-NETs should be assessed by a surgeon experienced in the management of NETs to consider surgical therapies, including resection of the primary tumor despite metastatic disease.

Extent of Lymph Node Dissection for Small Bowel Neuroendocrine Tumors

The management of nodal disease remains controversial for small bowel neuroendocrine tumors (SB-NETs). Debates remain regarding the therapeutic role and extent of routine lymph node dissection (LND) for localized SB-NETs, as well as the need for aggressive resection of advanced loco-regional SB-NETs with mesenteric nodal masses. This review will address these questions regarding lymph node dissection for well-differentiated WHO grade 1 and 2 SB-NETs. In general, the aggressiveness and radicality of resection should be balanced against the length of bowel resected and post-operative functional outcomes. In localized SB-NETs with clinically negative lymph nodes, a nodal harvest of ≥ 8 lymph nodes provides accurate staging, but has not been shown to confer survival benefit. For loco-regional SB-NETs with clinically positive lymph nodes identified on imaging, 4 stages of nodal extent have been described: stage 1 nodes are located near to the intestinal border, stage 2 on arterial branches close to the origin of the SMA, stage 3 along the SMA itself, and stage 4 extend in the retroperitoneum under the pancreatic neck. In SB-NETs, every attempt should be made at resection of the primary tumor and the nodal mesenteric mass for curative-intent management and to prevent debilitating complications from mesenteric fibrosis. A mesenteric-sparing approach is favored to allow for resection for complex proximal nodal masses while preserving intestinal length and function. All patients with SB-NETs with nodal mesenteric mass should be assessed by a surgeon for resection; if deemed unresectable, consideration should be given to assessment in high-volume NETs centres to confirm proximal mesenteric-sparing resection is not feasible.

Pathogenesis and Clinical Management of Mesenteric Fibrosis in Small Intestinal Neuroendocine Neoplasms: A Systematic Review

Mesenteric fibrosis (MF) constitutes an underrecognized sequela in patients with small intestinal neuroendocrine neoplasms (SI-NENs), often complicating the disease clinical course. The aim of the present systematic review, carried out by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, is to provide an update in evolving aspects of MF pathogenesis and its clinical management in SI-NENs. Complex and dynamic interactions are present in the microenvironment of tumor deposits in the mesentery. Serotonin, as well as the signaling pathways of certain growth factors play a pivotal, yet not fully elucidated role in the pathogenesis of MF. Clinically, MF often results in significant morbidity by causing either acute complications, such as intestinal obstruction and/or acute ischemia or more chronic conditions involving abdominal pain, venous stasis, malabsorption and malnutrition. Surgical resection in patients with locoregional disease only or symptomatic distant stage disease, as well as palliative minimally invasive interventions in advanced inoperable cases seem clinically meaningful, whereas currently available systemic and/or targeted treatments do not unequivocally affect the development of MF in SI-NENs. Increased awareness and improved understanding of the molecular pathogenesis of MF in SI-NENs may provide better diagnostic and predictive tools for its timely recognition and intervention and also facilitates the development of agents targeting MF.

A novel stratification of mesenteric mass involvement as a predictor of challenging mesenteric lymph node dissection by minimally invasive approach for ileal neuroendocrine tumors

BACKGROUND AND OBJECTIVES

We classified the extent of mesenteric mass (MM) involvement that predicts challenging mesenteric lymph node dissection (mLND) by minimally invasive surgery (MIS) for ileal neuroendocrine tumors (i-NETs).

METHODS

Patients who underwent surgery for i-NETs were retrospectively reviewed. MM involvement was classified as region-0: no MM; region-1: >2 cm from the origins of the ileocolic artery/vein; region-2: ≤2 cm from the origins; and region-3: more proximal superior mesenteric artery/vein. Logistic regression analysis was used to evaluate the predictive value of MM regions for gross positive mesenteric margin (mR2) and/or conversion among the MIS cohort. The open surgery cohort was used as a reference for mR2 rates.

RESULTS

Of 108 patients, 83 patients (77%) underwent MIS. MMs in region-2 and region-3 were independent risk factors for mR2 and/or conversion (odds ratio [95% confidence interval]: 4.25 [1.17-16.4] and 8.51 × 10⁷ [11.0-], respectively, against regions-0 and 1]. mR2 rates of MIS and open surgery cohorts per region did not differ significantly (4% and 7% for regions-0 and 1; 17% and 25% for region-2; and 100% and 83% for region-3).

CONCLUSIONS

The novel stratification of MM regions was predictive of challenging mLND by MIS. Surgeons should have a low threshold for conversion for MMs in proximal regions.

Does the addition of adjuvant intraoperative tumor bed chemotherapy during midgut neuroendocrine tumor debulking procedures benefit patients?

Background

Midgut neuroendocrine tumor (NET) patients are often diagnosed at advanced stages with extensive mesenteric nodal and hepatic metastasis. The only potentially curative treatment is surgical tumor eradication. Despite an aggressive resection, macro and microscopic residual disease still may remain in the resection bed. We hypothesize that the application of 5-fluorouracil (5-FU) within the tumor bed will help eliminate microscopic residual disease.

Methods

Records of 189 patients who underwent extensive cytoreductive surgeries during 2003-2012 for advanced, midgut NETs with extensive mesenteric lymphadenopathy were reviewed. Eighty-six patients (46%) who had 5-FU saturated gel foam strips secured into their mesenteric resection sites served as the study group and a matching 103 patients (54%) who did not have such an intra-operative chemotherapy served as controls. Survival from the time of diagnosis and post-operative complications between the two groups were compared.

Results

Mortality rates at 30, 60 and 90 days post-operatively were 4%, 0%, 0% versus 2%, 0%, 2% for study and control groups, respectively. Major complications (Grades III & IV) at the same intervals were 0, 0, 1 versus 2, 3, 2 for study and control groups, respectively. Median survival was 236 months versus 148 months for the study and control groups, respectively 24 (P=0.15).

Conclusions

Intraoperative tumor resection bed chemotherapy is a safe adjuvant without discernible toxicity. This procedure may provide survival benefits to midgut NET patients with extensive mesenteric lymphadenopathy undergoing extensive cytoreductive surgery. Further study in prospective trials must be conducted to determine definitive benefit to the NET patient.

Association of a Prophylactic Surgical Approach to Stage IV Small Intestinal Neuroendocrine Tumors With Survival

Importance

Primary tumor resection and mesenteric lymph node dissection in asymptomatic patients with stage IV small intestinal neuroendocrine tumors (SI-NETs) are controversial.

Objective

To determine the association of locoregional surgery (LRS) performed at diagnosis with outcomes in patients with asymptomatic SI-NETs and distant metastases.

Design, Setting, and Participants

This cohort study included asymptomatic patients with stage IV SI-NETs diagnosed from January 1, 1985, through December 31, 2015, and identified using the prospective database of SI-NETs from Uppsala University Hospital, Uppsala, Sweden. Patients included were treated at a tertiary referral center and followed up until May 31, 2016, with data from the Swedish National Patient Register. The 363 patients with stage IV SI-NETs without abdominal symptoms were divided between those who underwent prophylactic up-front surgery within 6 months from diagnosis combined with oncologic treatment (hereafter referred to as LRS group [n = 161]) and those who underwent nonsurgical treatment or delayed surgery as needed combined with oncologic treatment (hereafer referred to as delayed LRS group [n = 202]).

Exposures

Prophylactic up-front surgery within 6 months from diagnosis combined with oncologic treatment vs nonsurgical treatment or delayed surgery as needed combined with oncologic treatment.

Main Outcomes and Measures

Overall survival (OS), length of hospital stay (LOS), postoperative morbidity and mortality, and reoperation rates measured from baseline. Propensity score matching was performed between the 2 groups.

Results

The 363 patients included 173 women (47.7%) and 190 men (52.3%), with a mean (SD) age at diagnosis of 62.4 (11.1) years. Two isonumerical groups with 91 patients in each resulted after propensity score matching. The LRS and delayed LRS groups were comparable in median OS (7.9 years [range, 5.1-10.7 years] vs 7.6 years [range, 5.8-9.5 years]; hazard ratio [HR], 0.98; 95% CI, 0.70-1.37; log-rank P = .93) and cancer-specific survival (7.7 years [range, 4.5-10.8 years] vs 7.6 years [range, 5.6-9.7 years]; HR, 0.99; 95% CI, 0.71-1.40; log-rank P = .99). No difference was found in 30-day mortality (0 patients in both matched groups) or postoperative morbidity (2 [2.2%] vs 1 [1.1%]; P > .99), median LOS (73 days [range, 2-270 days] vs 76 days [range, 0-339 days]; P = .64) or LOS due to local tumor-related symptoms (7.0 days [range, 0-90 days] vs 11.5 days [range, 0-69 days]; P = .81), or incisional hernia repairs (4 patients [4.4%] in both groups; P > .99). Patients in the LRS group underwent more reoperative procedures (13 [14.3%]) compared with those in the delayed LRS group (3 [3.3%]) owing to intestinal obstruction (P < .001).

Conclusions and Relevance

Prophylactic up-front LRS conferred no survival advantage in asymptomatic patients with stage IV SI-NETs. Delayed surgery as needed was comparable in all examined outcomes and was associated with fewer reoperations for intestinal obstruction. The value of a priori LRS in the presence of distant metastases is challenged and needs to be elucidated in a randomized clinical study.

EndoVascular Occlusion and Tumor Excision (EVOTE): a Hybrid Approach to Small-Bowel Neuroendocrine Tumors with Mesenteric Metastases

BACKGROUND

Mesenteric metastases from small-bowel neuroendocrine tumors (SBNETs) present a surgical challenge due to encasement of mesenteric vessels. In this study, we evaluate the feasibility and safety of a new, hybrid surgical approach to these mesenteric masses, EndoVascular Occlusion and Tumor Excision (EVOTE).

METHODS

From 2014 to 2018, 13 patients underwent the EVOTE procedure after being referred to our institution for primary SBNETs with "unresectable" mesenteric metastases. During stage 1 of the hybrid EVOTE procedure, angiographic evaluation of the mesenteric mass is performed. If adequate collateralization is demonstrated, the encased mesenteric vessel(s) is embolized. Mass excision is performed the following day during stage 2 of the EVOTE procedure.

RESULTS

Preoperative embolization was successful in 86% of cases; 2 cases were aborted for persistent abdominal pain following occlusion testing. Complete surgical excision of the mesenteric mass was achieved in 86% of cases. The 30-day overall morbidity and mortality rate was 29% and 0%, respectively. There was one local recurrence at 31.8 months post-op; this patient underwent a repeat EVOTE procedure with successful complete excision.

DISCUSSION

EVOTE represents a new technique that aids in preoperative planning and surgical resection of SBNETs with mesenteric metastases.

Surgery Provides Long-Term Survival in Patients with Metastatic Neuroendocrine Tumors Undergoing Resection for Non-Hormonal Symptoms

INTRODUCTION

Patients with metastatic neuroendocrine tumor (NET) often have an indolent disease course yet the outcomes for patients with metastatic NET undergoing surgery for non-hormonal (NH) symptoms of GI obstruction, bleeding, or pain is not known.

METHODS

We identified patients with metastatic gastroenteropancreatic NET who underwent resection from 2000 to 2016 at 8 academic institutions who participated in the US Neuroendocrine Tumor Study Group.

RESULTS

Of 581 patients with metastatic NET to liver (61.3%), lymph nodes (24.1%), lung (2.1%), and bone (2.5%), 332 (57.1%) presented with NH symptoms of pain (n = 223, 67.4%), GI bleeding (n = 54, 16.3%), GI obstruction (n = 49, 14.8%), and biliary obstruction (n = 22, 6.7%). Most patients were undergoing their first operation (85.4%) within 4 weeks of diagnosis. The median overall survival was 110.4 months, and operative intent predicted survival (p < 0.001) with 66.3% undergoing curative resection. Removal of all metastatic disease was associated with the longest median survival (112.5 months) compared to debulking (89.2 months), or palliative resection (50.0 months; p < 0.001). The 1-, 3-, and 12-month mortality was 3.0%, 4.5%, and 9.0%, respectively. Factors associated with 1-year mortality included palliative operations (OR 6.54, p = 0.006), foregut NET (5.62, p = 0.042), major complication (4.91, p = 0.001), and high tumor grade (11.2, p < 0.001). The conditional survival for patients who lived past 1 year was 119 months.

CONCLUSIONS

Patients with metastatic NET and NH symptoms that necessitate surgery have long-term survival, and goals of care should focus on both oncologic and quality of life impact. Surgical intervention remains a critical component of multidisciplinary care of symptomatic patients.

Neuroendocrine tumors of the small intestine causing a desmoplastic reaction of the mesentery are a more aggressive cohort

BACKGROUND

Desmoplastic reaction of the mesentery is commonly seen in patients with neuroendocrine tumors of the small intestine. However, it is not clear whether desmoplastic reaction is associated with tumor-specific characteristics and diminished prognosis. Therefore, the aim of this study was to investigate whether the presence of a desmoplastic reaction correlates with prognostic and molecular markers of neuroendocrine tumors of the small intestine.

METHODS

Patients with neuroendocrine tumors of the small intestine operated at our department from 2000 to 2016 were analyzed. Patient and tumor characteristics were evaluated. Kaplan-Meier and multivariate analyses were performed.

RESULTS

In total, 148 patients underwent surgery, and preoperative imaging was available in 113 patients. A total of 45 patients showed desmoplastic reaction of the mesentery and progression-free survival was significantly impaired (26 months versus 65.4 months) compared with patients without desmoplastic reaction. These patients had significantly more often distant metastases (84.4% vs 39.7%), lymphatic vessel (68.9% vs 44.1%), and perineural tissue infiltration (57.8% vs 17.6%) compared with patients without desmoplastic reaction. However, proliferation index (positive desmoplastic reaction 4.1% versus negative desmoplastic reaction 3.3%) and tumor size (positive desmoplastic reaction 2 cm versus negative desmoplastic reaction 1.9 cm) were not diverging significantly.

CONCLUSION

This study revealed that tumors leading to desmoplastic reaction are more aggressive, despite similar Ki67 indices.

Flushing Disorders Associated with Gastrointestinal Symptoms: Part 1, Neuroendocrine Tumors, Mast Cell Disorders and Hyperbasophila

Flushing is the subjective sensation of warmth accompanied by visible cutaneous erythema occurring throughout the body with a predilection for the face, neck, pinnae, and upper trunk where the skin is thinnest and cutaneous vessels are superficially located and in greatest numbers. Flushing can be present in either a wet or dry form depending upon whether neural-mediated mechanisms are involved. Activation of the sympathetic nervous system results in wet flushing, accompanied by diaphoresis, due to concomitant stimulation of eccrine sweat glands. Wet flushing is caused by certain medications, panic disorder and paroxysmal extreme pain disorder (PEPD). Vasodilator mediated flushing due to the formation and release of a variety of biogenic amines, neuropeptides and phospholipid mediators such as histamine, serotonin and prostaglandins, respectively, typically presents as dry flushing where sweating is characteristically absent. Flushing occurring with neuroendocrine tumors accompanied by gastrointestinal symptoms is generally of the dry flushing variant, which may be an important clinical clue to the differential diagnosis. A number of primary diseases of the gastrointestinal tract cause flushing, and conversely extra-intestinal conditions are associated with flushing and gastrointestinal symptoms. Gastrointestinal findings vary and include one or more of the following non-specific symptoms such as abdominal pain, nausea, vomiting, diarrhea or constipation. The purpose of this review is to provide a focused comprehensive discussion on the presentation, pathophysiology, diagnostic evaluation and management of those diseases that arise from the gastrointestinal tract or other site that may cause gastrointestinal symptoms secondarily accompanied by flushing. This review is divided into two parts given the scope of conditions that cause flushing and affect the gastrointestinal tract: Part 1 covers neuroendocrine tumors (carcinoid, pheochromocytomas, vasoactive intestinal polypeptide, medullary carcinoma of the thyroid), polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes (POEMS), and conditions involving mast cells and basophils; while Part 2 covers dumping syndrome, mesenteric traction syndrome, rosacea, hyperthyroidism and thyroid storm, anaphylaxis, panic disorders, paroxysmal extreme pain disorder, and food, alcohol and medications.

Small intestinal neuroendocrine tumours and fibrosis: an entangled conundrum

Small intestinal neuroendocrine tumours (SI-NETs) are neoplasms characterized by their ability to secrete biogenic amines and peptides. These cause distinct clinical pathology including carcinoid syndrome, marked by diarrhoea and flushing, as well as fibrosis, notably mesenteric fibrosis. Mesenteric fibrosis often results in significant morbidity by causing intestinal obstruction, oedema and ischaemia. Although advancements have been made to alleviate symptoms of carcinoid syndrome and prolong the survival of patients with SI-NETs, therapeutic options for patients with mesenteric fibrosis are still limited. As improved insight in the complex pathogenesis of mesenteric fibrosis is key to the development of new therapies, we evaluated the literature for known and putative mediators of fibrosis in SI-NETs. In this review, we discuss the tumour microenvironment, growth factors and signalling pathways involved in the complex process of fibrosis development and tumour progression in SI-NETs, in order to elucidate potential new avenues for scientific research and therapies to improve the management of patients suffering from the complications of mesenteric fibrosis.

Mesenteric fibrosis and palliative surgery in small intestinal neuroendocrine tumours

Mesenteric fibrosis (MF) surrounding a mesenteric mass is a hallmark feature of small intestinal neuroendocrine tumours (SI-NETs). Since this can induce intestinal obstruction, oedema and ischaemia, prophylactic resection of the primary tumour and mesenteric mass is often recommended. This study assessed the predictors for mesenteric metastasis and fibrosis and the effect of MF and palliative surgery on survival. A retrospective analysis of 559 patients with pathologically proven SI-NET and available CT-imaging data was performed. Clinical characteristics, presence of mesenteric mass and fibrosis on CT imaging and the effect of palliative abdominal surgery on overall survival were assessed. We found that MF was present in 41.4%. Older age, 5-HIAA excretion ≥67 μmol/24 h, serum CgA ≥121.5 μg/L and a mesenteric mass ≥27.5 mm were independent predictors of MF. In patients ≤52 years, mesenteric mass was less often found in women than in men (39% vs 64%, P = 0.002). Corrected for age, tumour grade, CgA and liver metastasis, MF was not a prognostic factor for overall survival. In patients undergoing palliative surgery, metastasectomy of mesenteric mass or prophylactic surgery did not result in survival benefit. In conclusion, we confirmed known predictors of MF and mesenteric mass and suggest a role for sex hormones as women ≤52 years have less often a mesenteric mass. Furthermore, the presence of MF has no effect on survival in a multivariate analysis, and we found no benefit of metastasectomy of mesenteric mass or prophylactic surgery on overall survival.

Surgical Treatment of Small Intestinal Neuroendocrine Tumors G1/G2

Although the majority of neuroendocrine tumors of the small intestine (siNETs) classified as low-grade G1 or G2 show slow local growth, they are frequently diagnosed at an advanced stage of metastatic disease. The surgical treatment is curative in stages I-III or palliative in stage IV in an attempt to avoid local complications of bowel obstruction and ischemia of the small bowel by unremoved lymph node metastases. Individualized surgical procedures performed by experienced surgeons considering tumor multifocality and the primary extent of lymph node metastases along the mesenteric vessels are recommended to remove as much tumor volume as possible, while avoiding major complications intraoperatively and small bowel syndrome postoperatively.

Neoadjuvant peptide receptor radionuclide therapy and modified multivisceral transplantation for an advanced small intestinal neuroendocrine neoplasm: an updated case report

Small intestinal neuroendocrine neoplasms (SI-NEN) frequently metastasise to regional lymph nodes, and surgery is the mainstay of therapy for such patients. However, despite the possible use of advanced surgical techniques, the resection of both primary and locoregional diseases is not always attainable. Intestinal and multivisceral transplantation has been performed in a small number of patients with conventionally nonresectable, slow-growing tumours threatening the mesenteric root but has remained controversial. The use of donor skin in “sentinel flaps” in transplantation theoretically offers advantages in tailoring immunosuppression and monitoring for rejection. We represent (with extended follow-up) the first case of a patient with inoperable extensive mesenteric metastases from SI-NEN, who underwent neoadjuvant peptide receptor radionuclide therapy before a modified multivisceral transplant with a concomitant vascularised sentinel forearm flap. At 48 months after transplantation, our patient remained at full physical activity with no evidence of disease recurrence on either tumour biochemistry or radiological imaging.

The Surgical Management of Small Bowel Neuroendocrine Tumors: Consensus Guidelines of the North American Neuroendocrine Tumor Society

Small bowel neuroendocrine tumors (SBNETs) have been increasing in frequency over the past decades, and are now the most common type of small bowel tumor. Consequently, general surgeons and surgical oncologists are seeing more patients with SBNETs in their practices than ever before. The management of these patients is often complex, owing to their secretion of hormones, frequent presentation with advanced disease, and difficulties with making the diagnosis of SBNETs. Despite these issues, even patients with advanced disease can have long-term survival. There are a number of scenarios which commonly arise in SBNET patients where it is difficult to determine the optimal management from the published data. To address these challenges for clinicians, a consensus conference was held assembling experts in the field to review and discuss the available literature and patterns of practice pertaining to specific management issues. This paper summarizes the important elements from these studies and the recommendations of the group for these questions regarding the management of SBNET patients.

Aggressive Surgical Approach to the Management of Neuroendocrine Tumors: A Report of 1,000 Surgical Cytoreductions by a Single Institution

BACKGROUND

Neuroendocrine tumors (NETs) are rare neoplasms. Our group has treated more than 2,000 NET patients and has performed more than 1,000 surgical cytoreductive procedures.

STUDY DESIGN

Records of 834 NET patients who underwent surgical cytoreduction at our institution were reviewed. Demographic information, intraoperative findings, extent of disease, complications, and survival rates were calculated.

RESULTS

Eight hundred patients underwent 1,001 cytoreductive operations. Sixty-five percent had small bowel primaries. One hundred and thirty-eight patients presented with an unknown primary site, which was localized intraoperatively in 89% of these cases. The intraoperative complication rate was 9%. The incidence of intraoperative carcinoid crisis was 1%. Mean ± SD operative time was 368 ± 146 minutes. Mean ± SD hospital stay was 9 ± 10 days. Minor postoperative complications occurred after 43% of procedures and major postoperative complications were noted after 19% of procedures. The 30-day postoperative mortality rate was 2%. Median overall survival (OS) for patients with pancreatic NETs was 124 months. The 5-, 10-, and 20-year OS rates for patients with pancreatic NETs were 67%, 51%, and 36%, respectively. The life expectancy difference (between OS and actuarial survival) after surgical cytoreduction for patients with pancreatic NETs was 16.6 years. Median OS for patients with small bowel NETs was 161 months. The 5-, 10-, and 20-year OS rates for patients with small bowel NETs were 84%, 67% and 31%, respectively. The life expectancy difference after surgical cytoreduction for patients with small bowel NETs was 11.7 years.

CONCLUSIONS

Surgical cytoreduction in NET patients has low morbidity and mortality rates and results in prolonged survival. We believe that surgical cytoreduction should play a major role in the care of patients with NETs.

Surgical Treatment of NEN of Small Bowel: A Retrospective Analysis

BACKGROUND

Neuroendocrine Neoplasms of the small intestine have been noticed more frequently over the past 35 years. They constitute about 25% of all NENs and 29% of all tumors of the small intestine. Due to the predominantly indolent nature and overall good prognosis, the benefit of surgical treatment is still debated.

METHODS

In a retrospective study, data of 83 surgically treated patients with neuroendocrine neoplasms of the small intestine, 48 males and 35 females with a median age of 62 years (range 25-86 years) were analyzed. Patient data were documented in the MaDoc database for neuroendocrine tumors of the University Medical Center of Mainz. IBM SPSS Statistics 20 was used for statistical analysis. Kaplan-Meier survival curves and Log-Rank tests, censoring patients at the time of last follow-up, were used to compare the overall survival depending on potential prognostic factors (stage, grade, surgical treatment).

RESULTS

At the time of diagnoses, the most common clinical symptoms were abdominal pain (n = 31, 37.3%), bowel obstruction (n = 11, 13.3%), bowel perforation and peritonitis (n = 3, 3.6%), gastrointestinal bleeding (n = 9, 10.8%), weight loss (n = 11, 13.3%), and carcinoid syndrome (n = 27, 32.5%). 65 patients (78.3%) had lymph node metastasis and in 58 patients (69.9%) distant metastasis were present. Segmental bowel resection (44) was the most common surgical procedure, followed by right hemi-colectomy (32) and explorative laparotomy (7). In most patients (78.9%), lymphadenectomy (systematic/selective) was performed. The 5-year survival of patients who underwent a systematic or a selective lymphadenectomy differed significantly (82.2 vs. 40.0%). The overall 3-, 5-, and 10-year survival rates were 88.2, 80.3, and 71.0%, respectively.

CONCLUSION

Mesenteric lymph node metastases are almost invariably present and have significant impact on patients' prognosis. Systematic lymphadenectomy prevents complications and improves the survival. Early surgical treatment should be the goal in order to prevent complications.

Gastroenteropancreatic Well-Differentiated Grade 3 Neuroendocrine Tumors: Review and Position Statement

: In 2010, the World Health Organization (WHO) classification of neuroendocrine neoplasms was reviewed and validated the crucial role of the proliferative rate. According to the WHO classification 2010, gastroenteropancreatic neuroendocrine neoplasms are classified as well-differentiated neuroendocrine tumors (NETs) of grade 1 or 2 in up to 84%, or poorly differentiated neuroendocrine carcinomas in 6%-8%. Neuroendocrine carcinomas are of grade G. Recently, a proportion of neuroendocrine tumors presenting a number of mitoses or a Ki-67 index higher than 20% and a well-differentiated morphology have been identified, calling for a new category, well-differentiated grade 3 NET (NET G-3). Studies that have reported the characteristics of neuroendocrine neoplasms have identified more well-differentiated NET G-3 than neuroendocrine carcinomas. The main localizations of NET G-3 are the pancreas, stomach, and colon. Treatment for NET G-3 is not standardized and is balanced between G-1/2 neuroendocrine tumor and neuroendocrine carcinoma treatments. In nonmetastatic neuroendocrine tumors, the European and American guidelines recommended a surgical resection for localized neuroendocrine neoplasm, irrespective of the tumor grading. In NET G-3, chemotherapy is the benchmark if the main treatment goal is reduction of the tumor mass, particularly if it would allow a secondary surgery. In the present work, we review the epidemiology and make recommendations for the management of NET G-3.

IMPLICATIONS FOR PRACTICE

Neuroendocrine tumors presenting a number of mitoses or a Ki-67 index higher than 20% and a well-differentiated morphology have been identified and named well-differentiated grade 3 neuroendocrine tumors (NET G-3). The main localizations of NET G-3 are the pancreas, stomach, and colon. The prognosis is worse than that for NET G-2. In nonmetastatic NET G-3, surgery appeared to be the first option. The chemotherapy regimen in pancreatic NET G-3 should be in line with that implemented in NET G-1/2 when the Ki-67 index is below 55% and should be in line with that implemented for neuroendocrine carcinoma when Ki-67 is above 55%.