Small bowel carcinoid: Location isn’t everything!

[Duodenal neuroendocrine tumors]

Significant augmentation of the incidence of duodenal neuroendocrine tumors duodenum has been observed in recent decades. There are 5 histological types of these tumors: gastrinoma (50-60%), somatostatin-producing tumor (15%), inactive serotonin-containing tumors (20%), poorly differentiated neuroendocrine carcinoma (<3%) and gangliocytic paraganglioma (<2%). The majority of tumors are localized within the bulb and postbulbar part of duodenum, 20% are found in periampular area. Treatment strategy depends on dimensions, localization, histological class, stage and type of tumor. It is believed that endoscopic resection is permissible for small inactive tumors (G1) located above major duodenal papilla. The majority of other neoplasms requires surgical resection. Personal experience of various surgeons is limited by small group of patients. Therefore, it is necessary to summarize results for selection of optimal treatment.

The Distal Predilection of Small Bowel Neuroendocrine Tumors

BACKGROUND

The small bowel (SB) is the most common site of neuroendocrine tumors (NETs) of the GI tract. These are described as being predominantly jejunoileal, but their exact locations within the SB have not been well defined. We sought to determine prospectively the spectrum of SBNET locations.

METHODS

Patients undergoing exploration for SBNET primaries had measurement of bowel length, tumor locations, and resection length recorded. Correlations of clinicopathologic factors were performed, and analysis done utilizing Welch's t test, Chi square test, and the Kaplan-Meier method.

RESULTS

Measurements were recorded in 123 patients, 107 of whom had complete information. Multifocal tumors (MTs) were found in 69 (56%) and unifocal (UTs) in 54 (44%) patients. Only 1 of 107 patients had a tumor within 100 cm of the ligament of Treitz (LT), whereas 77 of 107 (72%) had tumors within 100 cm of the ileocecal valve (ICV). No MTs were found within 100 cm of LT, whereas 41 of 60 (68%) patients had all (10) or at least one tumor (31) located within 100 cm of the ICV. MTs required a mean resection length of 108 versus 59 cm for UTs (p < 0.01). Seventy-seven percent of UTs (36/47) were within 100 cm of ICV. Tumors occurring only between > 100 cm from the LT and ICV were seen in 29 of 107 (27%) patients.

CONCLUSIONS

SBNETs are frequently multifocal and most commonly located within 100 cm of the ICV. SBNETs are less prevalent proximally in the small bowel, which may result from anatomic differences in enterochromaffin cell density, hormonal factors, or environmental exposures in the distal SB.

Multifocality in Small Bowel Neuroendocrine Tumors

BACKGROUND

Neuroendocrine tumors (NETs) account for 30% of small bowel (SB) neoplasms. The objectives of this study were to evaluate the incidence of multifocality in primary small bowel neuroendocrine tumors (SBNETs) and to examine the associated outcomes.

METHODS

Patients with multifocal SBNET were compared to those with a solitary lesion. Only patients who underwent diagnostic workup and surgical intervention at our institution were included in this study. The primary aim of our study was surgical outcomes and mortality and recurrence. The second aim of our study was to evaluate the utility of double-balloon enteroscopy (DBE) and capsule endoscopy.

RESULTS

Of 178 patients with SBNETs during the study period, 85 met inclusion criteria. The mean age was 61.0 ± 12.6 years and 44.7% were male. The ileum was the primary tumor site for 66 patients (77.7%). Of DBE patients, 28 (62.2%) had additional lesions identified, of which 23 (82.1%) had NET confirmed on pathology. Average tumor size was 1.8 cm and most were well differentiated (89.9%), with Ki-67 of ≥ 2% (65.8%); 74.4% had nodal metastases and 51% of patients had stage IV disease. Forty-six patients (54.1%) had multifocal disease, of whom 37 (80.5%) had an ileal primary. No differences in survival or recurrence were seen for multifocal versus solitary disease.

CONCLUSIONS

SBNETs have a high incidence of multifocality. DBE can be used in the preoperative assessment to detect multifocal NET. Multifocality has no impact on survival or recurrence outcomes.

Well-Differentiated, Non-Functional, Non-Ampullary Duodenal Neuroendocrine Tumors: Toward Defining Evaluation and Management

INTRODUCTION

Nonfunctional, non-ampullary duodenal neuroendocrine tumors (dNETs) are rare neoplasms, and specific treatment recommendations are less clear than for other NETs.

MATERIALS AND METHODS

We performed a retrospective review of patients (pts) with a diagnosis of dNET, excluding hormonally functional, ampullary, and high-grade tumors. Clinical data were evaluated to identify factors that might impact clinical staging and predictors of metastases.

RESULTS

Thirty-six pts were identified. Surgical resection was performed in 28 and endoscopic resection in 8. LNs were included in specimens of 19/28 (68 %) pts who underwent surgical resection (median #LNs 5, range 1-12). Of these 19 pts, 5 (26 %) were found to be LN+. Of LN+ pts, all had tumors ≤2 cm. When compared to LN- pts, LN+ pts were more likely to have muscularis propria (MP) invasion (80 vs. 23 %, p = 0.04). Tumor size, tumor grade, lymphovascular invasion, and multifocality were similar between LN+ and LN- patients. No pt was found to have distant metastases. Heterogeneity in clinical staging modalities and small number of pts evaluated prohibited meaningful analysis of most appropriate preoperative imaging. At a median follow-up of 25 months (range 9-139), no patient developed recurrence or experienced disease-specific death.

CONCLUSIONS

Non-functional, non-ampullary dNETs, particularly those with MP invasion, have a propensity to metastasize to regional LNs. However, these neoplasms appear to have a favorable prognosis. Further evaluation of preoperative imaging is required to better determine most appropriate clinical staging. A suggested workup and management strategy for prospective evaluation is proposed.

Management of gastric and duodenal neuroendocrine tumors

Gastrointestinal neuroendocrine tumors (GI-NETs) are rare neoplasms, like all NETs. However, the incidence of GI-NETS has been increasing in recent years. Gastric NETs (G-NETs) and duodenal NETs (D-NETs) are the common types of upper GI-NETs based on tumor location. G-NETs are classified into three distinct subgroups: type I, II, and III. Type I G-NETs, which are the most common subtype (70%-80% of all G-NETs), are associated with chronic atrophic gastritis, including autoimmune gastritis and Helicobacter pylori associated atrophic gastritis. Type II G-NETs (5%-6%) are associated with multiple endocrine neoplasia type 1 and Zollinger-Ellison syndrome (MEN1-ZES). Both type I and II G-NETs are related to hypergastrinemia, are small in size, occur in multiple numbers, and are generally benign. In contrast, type III G-NETs (10%-15%) are not associated with hypergastrinemia, are large-sized single tumors, and are usually malignant. Therefore, surgical resection and chemotherapy are generally necessary for type III G-NETs, while endoscopic resection and follow-up, which are acceptable for the treatment of most type I and II G-NETs, are only acceptable for small and well differentiated type III G-NETs. D-NETs include gastrinomas (50%-60%), somatostatin-producing tumors (15%), nonfunctional serotonin-containing tumors (20%), poorly differentiated neuroendocrine carcinomas (< 3%), and gangliocytic paragangliomas (< 2%). Most D-NETs are located in the first or second part of the duodenum, with 20% occurring in the periampullary region. Therapy for D-NETs is based on tumor size, location, histological grade, stage, and tumor type. While endoscopic resection may be considered for small nonfunctional D-NETs (G1) located in the higher papilla region, surgical resection is necessary for most other D-NETs. However, there is no consensus regarding the ideal treatment of D-NETs.

Mesenteric changes in an ultrasound examination can facilitate the diagnosis of neuroendocrine tumors of the small intestine

Neuroendocrine tumors make up an interesting pathology of a variable clinical picture, prognosis, localization, endocrine activity and degree of malignancy.