Management of Small Bowel Neuroendocrine Tumors

Imaging of Neuroendocrine Neoplasms; Principles of Treatment Strategies. What Referring Clinicians Want to Know

ABSTRACT

Neuroendocrine neoplasms (NENs) are a diverse group of tumors that express neuroendocrine markers and primarily affect the lungs and digestive system. The incidence of NENs has increased over time due to advancements in imaging and diagnostic techniques. Effective management of NENs requires a multidisciplinary approach, considering factors such as tumor location, grade, stage, symptoms, and imaging findings. Treatment strategies vary depending on the specific subtype of NEN. In this review, we will focus on treatment strategies and therapies including the information relevant to clinicians in order to undertake optimal management and treatment decisions, the implications of different therapies on imaging, and how to ascertain their possible complications and treatment effects.

Clinical Intricacies and Advances in Neuroendocrine Tumors: An Organ-Based Multidisciplinary Approach

ABSTRACT

Neuroendocrine neoplasms (NENs) are rare neoplasms originating from neuroendocrine cells, with increasing incidence due to enhanced detection methods. These tumors display considerable heterogeneity, necessitating diverse management strategies based on factors like organ of origin and tumor size. This article provides a comprehensive overview of therapeutic approaches for NENs, emphasizing the role of imaging in treatment decisions. It categorizes tumors based on their locations: gastric, duodenal, pancreatic, small bowel, colonic, rectal, appendiceal, gallbladder, prostate, lung, gynecological, and others. The piece also elucidates the challenges in managing metastatic disease and controversies surrounding MEN1-neuroendocrine tumor management. The article underscores the significance of individualized treatment plans, underscoring the need for a multidisciplinary approach to ensure optimal patient outcomes.

Performance of capsule endoscopy for the detection of small intestinal neuroendocrine tumors in familial carcinoid: a prospective single-site study

BACKGROUND AND AIMS

Small-bowel neuroendocrine tumors (NETs) are slow growing, clinically silent tumors whose prognosis depends on disease stage. Members of kindreds with a familial form of small intestinal NETs (SI-NETs) represent a high-risk population for whom early detection improves disease outcome. Our aim was to determine the utility of small-bowel capsule endoscopy (SB-CE) for screening high-risk asymptomatic relatives from kindreds with familial carcinoid.

METHODS

One hundred seventy-four asymptomatic subjects with a family history (≥2 family members) of SI-NETs were screened under Protocol NCT00646022, Natural History of Familial Carcinoid Tumor at the National Institutes of Health. All patients were imaged with SB-CE and 18fluoro-dihydroxphenylalanine (18F-DOPA) positron emission tomography (PET)/CT, and results were independently analyzed. Patients with a positive imaging study underwent surgical exploration.

RESULTS

Thirty-five of 174 asymptomatic subjects screened for SI-NETs were positive on either SB-CE or 18F-DOPA PET. Thirty-two of 35 patients with a positive study were confirmed at surgery. SB-CE was positive in 28 of 32 patients with confirmed tumors for a per-patient sensitivity of 87.5%. SB-CE had a specificity of 97.3% and a negative predictive value of 96.5%. The average tumor number and size were 7.7 and 5.0 mm, respectively, and 81.2% of patients had multiple tumors. 18F-DOPA PET/CT had a similar sensitivity of 84% versus surgery.

CONCLUSIONS

SB-CE is a sensitive and specific method comparable with 18F-DOPA PET/CT for screening high-risk patients with familial SI-NET. (Clinical trial registration number: NCT00646022.).

Diagnostic Challenge of Small Bowel Neuroendocrine Tumor in a Young Female Patient

Neuroendocrine tumors (NETs) are rare cancers arising from neuroendocrine cells and are characterized by their ability to secrete functional hormones causing distinctive hormonal syndromes. The incidence of NET has increased over the years, and small bowel neuroendocrine tumor (SBNET) is one of the most challenging to detect due to its varied presentation and poor accessibility with traditional endoscopic methods. Patients with SBNET present with variable hormonal symptoms, such as diarrhea, flushing, and nonspecific abdominal pain, which often delay the diagnosis. We present the case of a young patient who underwent multidisciplinary workups leading to a successful diagnosis of SBNET promptly. The patient was a 31-year-old female who presented to the emergency department with complaints of nausea, vomiting, and sudden-onset, severe, sharp abdominal pain. CT scan of her abdomen showed an area of irregular intraluminal soft tissue density suspicious for a mass in the mid-small bowel. The patient's initial enteroscopy was normal. A video capsule endoscopy showed a small bowel mass, which was consistent with SBNET confirmed by pathology later. This case emphasizes the importance of considering SBNET as a differential diagnosis in young patients with nonspecific symptoms of abdominal pain and highlights the role of multidisciplinary approaches in achieving prompt diagnosis and treatment.

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.

High-Contrast Detection of Somatostatin Receptor Subtype-2 for Fluorescence-Guided Surgery

Dye design can influence the ability of fluorescently labeled imaging agents to generate tumor contrast and has become an area of significant interest in the field of fluorescence-guided surgery (FGS). Here, we show that the charge-balanced near-infrared fluorescent (NIRF) dye FNIR-Tag enhances the imaging properties of a fluorescently labeled somatostatin analogue. In vitro studies showed that the optimized fluorescent conjugate MMC(FNIR-Tag)-TOC bound primarily via somatostatin receptor subtype-2 (SSTR2), whereas its negatively charged counterpart with IRDye 800CW had higher off-target binding. NIRF imaging in cell line- and patient-derived xenograft models revealed markedly higher tumor contrast with MMC(FNIR-Tag)-TOC, which was attributed to increased tumor specificity. Ex vivo staining of surgical biospecimens from primary and metastatic tumors, as well as involved lymph nodes, demonstrated binding to human tumors. Finally, in an orthotopic tumor model, a simulated clinical workflow highlighted our unique ability to use standard preoperative nuclear imaging for selecting patients likely to benefit from SSTR2-targeted FGS. Our findings demonstrate the translational potential of MMC(FNIR-Tag)-TOC for intraoperative imaging and suggest broad utility for using FNIR-Tag in fluorescent probe development.

Diagnosis, treatment, and current concepts in the endoscopic management of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are rare tumors derived from the neuroendocrine cell system, which that have increased in incidence and prevalence in recent years. Despite improvements in radiological and metabolic imaging, endoscopy still plays a pivotal role in the number of GEP-NENs. Tumor detection, characterization, and staging are essential in management and treatment planning. Upper and lower gastrointestinal (GI) endoscopy is essential for correct localization of the primary tumor site of GI NENs. Endoscopic ultrasonography (EUS) has an important role in the imaging and tissue acquisition of pancreatic NENs and locoregional staging of GI neuroendocrine tumors. Correct staging and histological diagnosis have important prognostic implications. Endoscopic operating techniques allow the removal of small GI NENs in the early stage of mucosal or submucosal invasion of the intestinal wall. Preoperative EUS-guided techniques may help the surgeon locate small and deep tumors, thus avoiding formal pancreatic resections in favor of parenchymal-sparing surgery. Finally, locoregional ablative treatments have been proposed in recent studies with promising results in selected patients.

From chronic pruritus to neuroendocrine tumor: A case report

Chronic pruritus is a major and distressing symptom of many diseases of dermatological, neurological, psychogenic or systemic origin. This chronic itch could be a presenting sign of malignancy; therefore, paraneoplastic pruritus has also been associated with neuroendocrine tumors (NETs). This article focuses on a patient presenting with chronic pruritus for the past 12 months and who received numerous treatment schemes with very poor clinical improvement, that presented in the hospital for worsening of the chronic pruritus associated with skin rash and significant weight loss (approximately 6 kg over a 2-month period). The laboratory tests showed iron deficiency anemia, eosinophilia and negative tumor markers. In order to investigate the hypoanabolic and anemic syndromes, upper gastrointestinal endoscopy and colonoscopy, which showed no lesions or tumors, were employed. Skin biopsy was performed and antihistaminic and local steroid treatment was initiated. The patient's status worsened within a week and the patient was started on systemic steroid treatment with poor results. Computer tomography was performed to identify any tumor(s) located either in the pelvis or abdomen. A lesion was found in the terminal ileum, identified as a hypervascularized associating bulky lymphadenopathy. The patient was transferred to the surgical ward where right hemicolectomy with manual ileotransverse anastomosis L-L was performed. The histopathological result confirmed NET G2. The patient clinically improved, the skin lesions resolved and the itchiness disappeared. The general status improved significantly. NET G2 diagnosing was possible due to the atypic paraneoplastic sign: chronic pruritus. This case study highlights the association between itch and malignancy and presents an atypical way of NET presentation when all tumor markers remain negative.

OUP accepted manuscript

A 61-year-old woman presented to the hospital with a clinical picture consistent with acute appendicitis. During surgery, the appendix was found to be gangrenous and involved the appendiceal base, so an ileocecectomy was performed. Pathology revealed an incidental neuroendocrine tumor of the terminal ileum involving five of nine lymph nodes. The patient later developed mesenteric venous thrombosis but was diagnosed and treated promptly, and she is now doing well. There have been previous reports of small bowel neuroendocrine tumor resulting in bowel ischemia, usually due to fibrosis which can result in obstruction of the mesenteric vessels. However, this is the first known report of a small bowel neuroendocrine tumor presenting with appendicitis, which most likely was from an ischemic etiology. This case also demonstrates the importance of a high index of suspicion for mesenteric ischemia in patients with small bowel neuroendocrine tumor who present with acute abdominal pain.

Ileal Neuroendocrine Tumor in a Patient with Sclerosing Mesenteritis: Which Came First?

BACKGROUND Jejunoileal neuroendocrine tumors (JI-NETs) are rare tumors that can be associated with mesenteric fibrosis. This case report is of an incidental finding of a JI-NET in a patient who was previously misdiagnosed with sclerosing mesenteritis. CASE REPORT A 42-year-old man was admitted to our institution with diffuse abdominal pain and clinical and radiographic signs of bowel obstruction. He had a previous diagnosis of sclerosing mesenteritis, which had been histologically diagnosed after an exploratory laparoscopy performed in 2009 for recurrent acute abdominal pain. He was also annually monitored through computed tomography scans for an incidentally discovered, gradually enlarging mesenteric mass for which a "wait and watch" management approach was adopted. After a period of fasting and observation, the patient underwent an urgent exploratory laparotomy because of his worsening condition. Intraoperatively, an ileocecal resection was performed, along with excision of the known mesenteric mass. The pathology report revealed an ileal NET with nodal metastases within the mesentery and mesenteric tumor deposits (pT3N1). CONCLUSIONS JI-NETs are rare entities, which are usually encountered as incidental findings or in patients with unspecific abdominal pain. Our case represents a probable delayed diagnosis of JI-NET in the context of sclerosing mesenteritis; therefore, a possible association between these 2 conditions should be investigated.

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.