Neuroendocrine neoplasms diagnosed in the setting of inflammatory bowel disease - A systematic review and proposed management algorithm

Sep 22, 2026

Patients with inflammatory bowel disease (IBD) face elevated malignancy risk, including neuroendocrine neoplasms, yet the clinical specifics remain insufficiently characterized. A systematic review following PRISMA 2020 synthesized PubMed evidence through September 2024, extracting demographics and tumor features such as grade, location, metastasis, and diagnostic detection mode. The study compared ulcerative colitis and Crohn disease and assessed differences using statistical testing.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages7

Reading Time18 min

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Introduction

Methods

Results

Conclusions

® Systematic Review and Meta-Analysis Neuroendocrine neoplasms diagnosed in the setting of inflammatory bowel disease A systematic review and proposed management algorithm Mohamed M. Khamis, MDa ,* , Imad Karam, MDb , Gabriel D. Lang, MDc , Nikolaos A. Trikalinos, MDd | Abstract
Background: Patients with inflammatory bowel disease (IBD) are at higher risk of developing malignancies, including neuroendocrine neoplasms, but the specifics of that are not well known. We reviewed the existing literature to map the evidence surrounding this phenomenon.
Methods: Following PRISMA 2020 guidelines, we searched PubMed from inception to September 2024 for patients with gastrointestinal neuroendocrine neoplasms (NENs) and either Crohn disease (CD) or ulcerative colitis (UC) . Eligible studies included case reports, case series, and larger retrospective IBD cohorts. We extracted demographic and clinical data including tumor grade, location, metastatic status, and mode of detection. Comparative analyses between UC and CD were performed using Fisher exact test, chi-square test, and independent t-tests.
Results: We identified 67 case studies with data available for a total of 108 patients (61 . 1% male), ranging from 14 to 87 years of age. The median duration from IBD diagnosis to NEN detection was 13 years. Fifty-five (50 .9%) patients had CD and 53 (49 . 1%) had UC. UC patients were older at NEN diagnosis (mean 49 vs 40 years, P = .004) and had a higher metastatic rate (39 .6% vs 18.2%, P = .019) . Most NENs were low-grade (69 .4%), while 20 .4% were high-grade and 8.3% were mixed. The most common tumor locations were the rectum (29 .6%) and appendix (27 .8%), with rectal and colonic NENs more prevalent in UC and small bowel or appendiceal NENs more common in CD. At diagnosis, 71.3% of patients had localized disease. For high-grade NENs, 86.4% of cases were metastatic, compared to 9.3% for low-grade tumors. Only 10.2% of NENs were detected via endoscopic surveillance.
Conclusions: NENs in IBD show distinct patterns by IBD type, with significant differences in tumor location, grade, and metastatic rates between UC and CD. These hypothesis-generating observations suggest heightened vigilance after approximately 10 years of IBD or around age 44, focusing on rectal lesions in UC and small bowel/appendiceal lesions in CD. Validation in prospective, population-based studies is needed before these findings can inform clinical practice.
Abbreviations: CD = Crohn disease, CI = confidence interval, GI = gastrointestinal, IBD = inflammatory bowel disease, MiNEN = mixed neuroendocrine/non-neuroendocrine neoplasm, MRE = magnetic resonance enterography, NCCN = National Comprehensive Cancer Network, NEC = neuroendocrine carcinoma, NEN = neuroendocrine neoplasm, NET = neuroendocrine tumor, NICE = National Institute for Health and Care Excellence, PRISMA = preferred reporting items for systematic reviews and meta-analyses, SIR = standardized incidence ratio, UC = ulcerative colitis, WHO = World Health Organization. | | --- | | Keywords: Crohn disease, inflammatory bowel disease, neuroendocrine neoplasms, ulcerative colitis | 1. Introduction The incidence of neuroendocrine neoplasms (NENs) has steadily risen over time,[1] and that trend has been challenging The authors have no funding and conflicts of interest to disclose. The data supporting the findings of this study are available from the corresponding author upon reasonable request. The study protocol (search algorithm) is included in the Appendix. Ethics approval was not required for this study as it is a systematic review of published literature and does not involve human subjects, animal research, or primary data collection. All data were obtained from previously published studies. Supplemental Digital Content is available for this article. a Department of Medicine, Mercy Hospital St. Louis, St. Louis, MO, b Hematology and Medical Oncology, State University of New

FAQs

What clinical question does the review address?

It maps evidence on neuroendocrine neoplasms occurring in the setting of inflammatory bowel disease and characterizes how patterns differ across IBD types.

How were studies identified and data extracted?

Following PRISMA 2020, the review searched PubMed from inception to September 2024 and included case reports, case series, and retrospective IBD cohorts, extracting demographic and tumor characteristics.

What differences were found between ulcerative colitis and Crohn disease?

Ulcerative colitis patients were older at diagnosis and had a higher metastatic rate. Tumor location and grade patterns also differed, with UC showing more rectal/colonic prevalence and CD more small bowel/appendiceal involvement.

Sep 22, 2026

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