Extent of Lymph Node Dissection for Small Bowel Neuroendocrine Tumors

Mesenteric Fibrosis in Neuroendocrine Neoplasms: a Systematic Review of New Thoughts on Causation and Potential Treatments

PURPOSE OF REVIEW

Mesenteric fibrosis (MF) is a hallmark of small intestinal neuroendocrine neoplasms (SI-NEN) and is frequently associated with significant morbidity due to related complications such as intestinal obstruction, ischemia, and cachexia.

RECENT FINDINGS

Herein we performed a systematic review to discuss the development of MF in SI-NEN. The pathophysiological mechanisms acknowledged as causative for the development of MF include the major components of the tumor microenvironment, such as fibroblasts, endothelial and immune cells and the extracellular matrix, which are involved in a complex interplay activating several signaling pathways that promote profibrotic factors and induce both a desmoplastic reaction and tumor proliferation. Surgery remains the mainstay of treatment, while several medical management options of MF complicating SI-NEN available present rather limited efficacy. MF is a frequent characteristic of SI-NEN that requires particular attention and targeted management to avoid complications.

Lymphatic and vascular anatomy define surgical principles for bowel-sparing radical treatment of ileal tumors

BACKGROUND

There is no consensus on the level of vascular ligation and the extent of lymphadenectomy in the treatment of ileal tumors. This study aims to define lymphovascular bundles of the terminal ileal artery (TIA) and subsequent ileal arteries. It also aims to extrapolate results from two distinct methodologies to define the level of arterial ligation and the dissection area for radical and bowel-sparing surgery.

METHODS

Analysis of 3D-CT mesenteric vascular reconstructions of 104 operated patients. The second dataset consisted of 5 human cadavers for anatomical dissection. In one case, harvested viscera underwent the superior mesenteric artery (SMA) perfusion after ligation of the TIA.

RESULTS

The calibers of the first three ileal arteries were: 2.67 ± 0.98 mm, 2.22 ± 0.78 mm, 2.31 ± 1.24 mm. The distances from the first three ileal arteries to the ileocolic artery (ICA) origin were: 12.45 ± 8.79 mm, 27.45 ± 13.47 mm, and 43.04 ± 16.94 mm. The SMA trifurcated in 61 (59%) of cases and bifurcated in 43 (41%). In 89 cases, the combined ICA + first jejunal artery caliber (6.7 ± 1.6 mm) was greater than the TIA caliber (4.84 ± 1.42 mm). The ileal artery lymphatic clearances were 0.85 mm to the preceding vessel. In the D3 volume at the ICA origin, 3-8 lymph nodes were observed. Internal calibers of the small bowel marginal artery, after selective TIA ligation and the SMA perfusion, were: proximal jejunal part 0.417 mm and distal ileal part 0.291 mm.

CONCLUSIONS

Ileal tumors are irrigated through the TIA, which can be ligated without consequences. Lymphadenectomy should encompass the adjacent vessels (1st jejunal artery, ICA) and can include the central nodes (D3 volume) at the surgeon's preference. Preserving the adjacent vessels and the marginal artery is paramount for bowel-sparing surgery.

Small Bowel Neuroendocrine Neoplasms-A Review

Neuroendocrine neoplasms (NENs) are rapidly evolving small bowel tumors, and the patients are asymptomatic at the initial stages. Metastases are commonly observed at the time of presentation and diagnosis. This review addresses the small bowel NEN (SB-NEN) and its molecular, histological, and imaging features, which aid diagnosis and therapy guidance. Somatic cell number alterations and epigenetic mutations are studied to be responsible for sporadic and familial SB-NEN. The review also describes the grading of SB-NEN in addition to rare histological findings such as mixed neuroendocrine-non-NENs. Anatomic and nuclear imaging with conventional computed tomography, magnetic resonance imaging, computed tomographic enterography, and positron emission tomography are adopted in clinical practice for diagnosing, staging, and follow-up of NEN. Along with the characteristic imaging features of SB-NEN, the therapeutic aspects of imaging, such as peptide receptor radionuclide therapy, are discussed in this review.

Mesenteric sparing approach for advanced nodal extent in small intestinal neuroendocrine tumors. Is there a limit to the vascular resection in order to avoid creating a short small bowel syndrome? An anatomic research study

PURPOSE

By selectively perfusing the first three jejunal arteries (JA), we aim to assess the individual perfusion length of small bowel (SB) and its impact on nodal resection in stage III-up small-intestinal neuroendocrine tumors (SI-NET).

METHODS

Our anatomical research protocol implies a midline laparotomy and three measures of the SB length. We then perform a classical anterior approach of the superior mesenteric vessels. We carry on with the complete dissection and checking of the superior mesenteric artery (SMA) in order to identify the first three JA. Then we selectively perfuse each artery with colored latex solutions and measure the length of small bowel perfused respectively.

RESULTS

We conducted our protocol on six cadaveric subjects. Mean(SD) SB length was 413(5.7), 535(13.2), 485(15), 353(25.1), 730(17.3) and 525(16° cm respectively from subject one to six. Most JA originated from the left side of the SMA. The first JA originated from its posterior wall in two subjects. Mean(SD) distance of origin of the first three JA was 4.6(1.3)cm, 6(1.1)cm and 7.1(0.9)cm respectively. Mean(SD) diameter of SMA was 10.8(3.3)mm. Mean diameter of the three first JA was 4(1.4)mm, 4(1.5)mm and 5(1.2)mm respectively. Mean(SD) SB length perfused by first and second JA was 224(14.9)cm, 175(8.6)cm, 238.3(7.6)cm, 84.3(5.1)cm, 233.3(5.8)cm and 218.3(10.4)cm respectively from subject one to six.

CONCLUSION

We observed a trend suggesting that the first and second JA may sustain a SB length beyond the viable 1.5 m limit, implying the feasibility of stage III-up SI-NET resection with just two JA.

Two synchronous primary mesenteric neuroendocrine tumors in a patient: a case report

Primary mesenteric neuroendocrine tumors represent a rare clinical entity, challenging to manage, while a combination of imaging is demanded in order to differentiate it from metastatic disease, and set the diagnosis. If the tumor is resectable, surgery is the fundament of the therapeutic approach. The appearance of a second primary mesenteric tumor suggests an unacquainted scenario. The current article presents a case of a 40-year-old woman, who underwent laparoscopic excision of a mesenteric tumor located close to the left pararenal space. Pathology with immunohistochemistry examination reported neuroendocrine tumor grade 2. No further treatment was necessary. Seven months later, 68-Gallium DOTATATE detected another primary neuroendocrine tumor located at the right retroperitoneal space without other lesions. The second tumor was also resected laparoscopically, and the pathology confirmed the diagnosis of another neuroendocrine tumor G2. The postoperative course was uneventful, and six months later the patient is disease-free. The adequacy of 68-Gallium DOTATATE for the preoperative diagnosis of primary mesenteric tumors, the role of the laparoscopic approach, and the extent of lymph node resection are matters addressed in this article.

Surgery for advanced neuroendocrine tumours of the small bowel: recommendations based on a consensus meeting of the European Society of Endocrine Surgeons (ESES)

BACKGROUND

Small bowel neuroendocrine tumours often present with locally advanced or metastatic disease. The aim of this paper is to provide evidence-based recommendations regarding (controversial) topics in the surgical management of advanced small bowel neuroendocrine tumours.

METHODS

A working group of experts was formed by the European Society of Endocrine Surgeons. The group addressed 11 clinically relevant questions regarding surgery for advanced disease, including the benefit of primary tumour resection, the role of cytoreduction, the extent of lymph node clearance, and the management of an unknown primary tumour. A systematic literature search was performed in MEDLINE to identify papers addressing the research questions. Final recommendations were presented and voted upon by European Society of Endocrine Surgeons members at the European Society of Endocrine Surgeons Conference in Mainz in 2023.

RESULTS

The literature review yielded 1223 papers, of which 84 were included. There were no randomized controlled trials to address any of the research questions and therefore conclusions were based on the available case series, cohort studies, and systematic reviews/meta-analyses of the available non-randomized studies. The proposed recommendations were scored by 38-51 members and rated 'strongly agree' or 'agree' by 64-96% of participants.

CONCLUSION

This paper provides recommendations based on the best available evidence and expert opinion on the surgical management of locally advanced and metastatic small bowel neuroendocrine tumours.

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.

Accuracy of DOTATATE PET imaging in the preoperative planning of small bowel neuroendocrine tumor resection

BACKGROUND AND OBJECTIVES

We assessed the accuracy of preoperative gallium-68 DOTA-Tyr3-octreotate (DOTATATE) positron emission tomography (PET) imaging in estimating multifocality and nodal metastases of small bowel neuroendocrine tumors (sbNETs).

METHODS

A multicenter analysis was performed on patients with sbNETs who underwent preoperative DOTATATE PET imaging and surgical resection, with manual palpation of the entire length of the small bowel, between January 2016 and August 2022. Preoperative imaging reports and blinded secondary imaging reviews were compared to the final postoperative pathology reports. Descriptive statistics were applied.

RESULTS

One-hundred and four patients met inclusion criteria. Pathology showed 53 (51%) patients had multifocal sbNETs and 96 (92%) had nodal metastases. The original preoperative DOTATATE PET imaging identified multifocal sbNET in 28 (27%) patients and lymph node (LN) metastases in 80 (77%) patients. Based on original radiology reports, sensitivity for multifocal sbNET identification was 45%, specificity was 92%, positive predictive value (PPV) was 86%, and negative predictive value (NPV) was 62%. For the identification of LN metastases, sensitivity was 82%, specificity was 88%, PPV was 99%, and NPV was 29%.

CONCLUSIONS

Although DOTATATE PET imaging is specific and relatively accurate, sensitivity and NPV are insufficient to guide surgical planning. Preoperative use should not replace open palpation to identify additional synchronous lesions or to omit regional lymphadenectomy.

Survival outcome of local versus radical resection for jejunoileal gastrointestinal stromal tumors: a propensity score-matched population-based analysis

PURPOSE

Survival after local resection (LR) versus radical resection (RR) has been revealed comparable for patients with rectal and duodenal gastrointestinal stromal tumors (GISTs), but is unknown for jejunoileal (JI) GISTs. This study aimed to compare the long-term survival between patients with JI GISTs who underwent LR and RR, and to find out the prognostic factors for JI GISTs.

METHODS

Patients diagnosed with JI GISTs in 1975-2019 were identified from Surveillance, Epidemiology, and End Results (SEER) database and grouped according to surgical modality. Propensity score matching (PSM) was performed to balance the LR and RR groups. Overall survival (OS) and disease-specific survival (DSS) were compared in the full and matched cohorts using Kaplan-Meier (KM) analysis. Subgroup sensitivity analyses were also performed. Risk factors associated with DSS were analyzed in multivariate Cox analysis following model selection.

RESULTS

1107 patients diagnosed with JI GISTs were included in the study cohort. After PSM, OS and DSS were comparable in LR and RR groups. Consistently, the two groups had similar DSS in all subgroup analyses. Moreover, multivariate Cox analysis identified lymphadenectomy, older age, larger tumor size, distant metastasis, high and unknown mitotic rate, but not LR, as independent prognostic risk factors for JI GISTs.

CONCLUSIONS

We conducted the first population-based comparison between the effect of different surgical modes on survival for patients with JI GISTs. LR can be carried out safely without compromising oncological outcome, and should be considered as a treatment option in selected patients with JI GISTs.

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.

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.

Prognostic Effect of Lymph Node Metastases and Mesenteric Deposits in Neuroendocrine Tumors of the Small Bowel

Well-differentiated, low-grade neuroendocrine tumors (NETs) are the most frequent tumor types of the small bowel. Despite their generally indolent growth patterns and grade, these tumors tend to metastasize; indeed, at presentation, approximately 50% show nodal metastases and 30% of patients have distant metastases, even though they potentially show long survival. Little is available in the literature concerning the optimal nodal yield in small-bowel resections, and the clinical significance of nodal metastases and lymph node ratio (LNR) at this site is still debated. The aim of this review, through a systematic literature search, is to explore and analyze data regarding nodal status, adequacy of lymphadenectomy, and LNR on the prognosis of small bowel NETs using defined end points (progression-free survival, recurrence-free survival, and overall survival). Some surgical series have demonstrated that extended regional mesenteric lymphadenectomy, together with primary tumor resection, is associated with improved patient survival, and LNR is proving a prognostically important parameter. The new feature of mesenteric tumor deposits (MTDs; neoplastic deposits found in the mesenteric perivisceral adipose tissue that are not LN associated) seems to be a better prognostic predictor in small-bowel NETs compared to nodal metastases, and this feature is explored and critiqued in this review. In particular, increasing number of tumor deposits is correlated with increased risk of disease-specific death, and MTDs seem to correlate with peritoneal carcinomatosis.

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.

Diagnostic value of capsule endoscopy and double-balloon enteroscopy in small bowel diseases

OBJECTIVE

To analyze the diagnostic value of capsule endoscopy (CE) and double-balloon enteroscopy (DBE) in small bowel diseases.

METHODS

The clinical data of 134 cases of CE and 109 cases of DBE examined in our gastroscopy room from January 2016 to December 2019 were retrospectively analyzed. The two groups of patients were compared as to disease diagnostic rate, examination time, examination tolerance, and incidence of adverse reactions.

RESULTS

The two groups showed no significant difference in general data (all P>0.05). The DBE group showed a higher disease diagnostic rate than the CE group (P<0.05). Significantly higher rates of suspected intestinal bleeding were observed in the DBE group than those of the CE group (P<0.05), but no significant differences were found in the diagnosis of unexplained abdominal pain, abdominal distension, and others (all P>0.05). The DBE group required a longer examination time, and had a higher incidence of adverse reactions, and a lower examination tolerance than the CE group (P<0.05).

CONCLUSION

Both DBE and CE are effective in small bowel diseases diagnoses, but DBE demonstrated greater potential in diagnosing small bowel bleeding.

Patterns of Lymph Node Metastasis and Optimal Surgical Strategy in Small (≤20 mm) Gastroenteropancreatic Neuroendocrine Tumors

BACKGROUND

Regional lymph node metastasis (LNM) is crucial for planning additional lymphadenectomy, and is directly correlated with poor prognosis in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). However, the patterns of LNM for small (≤20 mm) GEP-NETs remain unclear. This population-based study aimed at evaluating LNM patterns and identifying optimal surgical strategies from the standpoint of lymph node dissemination.

METHODS

This retrospective cohort study retrieved data from the Surveillance, Epidemiology, and End Results (SEER) 18 registries database for 17,308 patients diagnosed as having localized well-differentiated GEP-NETs ≤ 20 mm between January 1, 2004, and December 31, 2017. The patterns of LNM were characterized in 6,622 patients who underwent extended resection for adequate lymph node harvest.

RESULTS

Of 6,622 patients with localized small GEP-NETs in the current study, 2,380 (36%) presented with LNM after regional lymphadenectomy. Nodal involvement was observed in approximately 7.4%, 49.1%, 13.6%, 53.7%, 13.8%, 7.8%, and 15.4% of gastric (g-), small intestinal (si-), appendiceal (a-), colonic (c-), rectal (r-), non-functional pancreatic (nfp-), and functional pancreatic (fp-) NETs ≤ 20 mm. Patients with younger age, larger tumor size, and muscularis invasion were more likely to present with LNM. Additional lymphadenectomy conferred a significant survival advantage in NETs (≤10 mm: HR, 0.47; 95% CI, 0.33-0.66; p < 0.001; 11-20 mm: HR, 0.54; 95% CI, 0.34-0.85; p = 0.008) and fp-NETs ≤ 20 mm (HR, 0.08; 95% CI, 0.02-0.36; p = 0.001), as well as g-NETs (HR, 0.39; 95% CI, 0.16-0.96; p = 0.041) and c-NETs of 11-20 mm (HR, 0.07; 95% CI, 0.01-0.48; p = 0.007). Survival benefits of additional lymphadenectomy were not found in a-NETs, r-NETs, and nfp-NETs with a small size.

CONCLUSIONS

Given the increased risk for nodal metastasis, primary tumor resection with regional lymphadenectomy is a potential optimal surgical strategy for si-NETs and fp-NETs ≤ 20 mm, as well as g-NETs and c-NETs of 11-20 mm. Local resection is an appropriate and reliable surgical approach for a-NETs, r-NETs, and nfp-NETs ≤ 20 mm.

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.