Predictors of Survival in Patients with Small Bowel Neuroendocrine Tumours Associated with Mesenteric Desmoplasia

Background: Small intestinal neuroendocrine tumours (SI NETs) represent 30–50% of small bowel neoplasms and are often associated with diverse fibrotic complications. Mesenteric fibrosis is a hallmark of SI NETs which may cause substantial morbidity and is considered an adverse feature. However, survival analyses in this group of patients are lacking. Methods: The aim of this retrospective study was to determine the overall survival (OS) and factors affecting prognosis in a large cohort of 147 patients with SI NETs and radiological evidence of mesenteric desmoplasia from our centre. The severity of desmoplasia was graded radiologically and its effect on OS and long-term complications was assessed. The median follow-up period was 82 months. Results: The median OS was 8.7 years (95% CI 6.8–9.9) with an overall 5-year survival of 71%. The univariate analysis demonstrated that an age >65 years, a liver tumour burden >50% of the hepatic parenchyma, carcinoid heart disease, chromogranin A levels >10 times the upper limit of normal, and urinary 5-hydroxyindoleacetic acid (5-HIAA) levels >5 times the upper limit of normal were poor prognosticators, while primary resection was associated with a longer OS. However, only an age >65 years and urinary 5-HIAA levels >10 times the upper limit of normal remained statistically significant after multivariate analysis. The severity of mesenteric desmoplasia did not seem to demonstrate a statistically significant relationship to OS or long-term outcomes. Conclusion: This study is the first comprehensive survival analysis of patients with SI NETs associated with mesenteric desmoplasia and has provided important and clinically relevant epidemiological data for this group of patients.