Neuroendocrine tumors in patients with inflammatory bowel disease: a case series

Purpose The incidence of inflammatory bowel diseases (IBDs) and gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) has increased, but their potential association remains unclear. Chronic inflammation in IBD may contribute to enteroendocrine cell hyperplasia and neoplasia, though evidence for a causal link is limited. This case series describes the characteristics and outcomes of patients with coexisting IBD and GEP-NETs at a tertiary referral center. Methods Retrospective case series including all consecutive IBD patients who were referred to the IBD Unit at the IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy, between January 2019 and December 2024 and who had been diagnosed with a GEP-NET. Results Nine Crohn's disease patients (44.4% female, mean IBD diagnosis age: 51.1 years) also had GEP-NETs. The median interval between IBD and GEP-NET diagnoses was 39.3 months (0-180). In the totality of six cases that underwent surgical intervention, NETs diagnosis was incidental on the surgical specimen. Lesion sites included ileum (3), appendix (3), stomach (2), and rectum (1). Most NETs were G1 (88.8%); one required somatostatin analogues due to metastases. Treatments included surgery (6), endoscopy (2), and one pending. Over a median 24-month follow-up, no recurrences or disease-related deaths occurred. No cases of ulcerative colitis and concomitant GEP-NET 's diagnosis were observed in the patient cohort under consideration. Conclusions Patients with Crohn's disease may have a higher prevalence of GEP-NETs, possibly due to chronic inflammation and immune/microbiota dysregulation. This association does not appear to worsen disease outcomes. Larger studies are needed to explore underlying mechanisms.