Root of mesentery and small bowel tumours also the domain of HPB surgeons: a single UK centre outcome

Abstract

Background: Primary malignant tumours of the small bowel represent 1-3% of all malignant gastrointestinal tumours. Neuroendocrine tumours (NET) are the predominant histological subtype with adenocarcinoma and gastrointestinal stromal tumours (GIST) also recognised. Method: Retrospective cohort study of patients with histologically confirmed small bowel tumours operated at Oxford university hospitals from January 2012 to the present day. Results: 87 patients underwent surgery for small bowel malignancy. 24 patients required emergency surgery, primarily due to bowel obstruction. NET was the most common subtype (41 patients) followed by adenocarcinoma (28) and GIST (18). Ileal tumours were more frequently NET than adenocarcinoma or GIST (24.3%, 10.7% and 5.6%, p< 0.0001) and patients with adenocarcinoma were more frequently anaemic pre-operatively (Hb 110.7±4.7g/dL, 129.9±3.4 and 117.6±5.9 for adenocarcinoma, NET and GIST, p< 0.0005). NETs were significantly smaller than adenocarcinoma or GIST (21.8±2.0mm, 42.6±6.2 and 82.6 ±17.7, p< 0.0001) however, a greater proportion had metastatic disease (39.0%, 3.6% and 11.1%, p=0.0004), perineural invasion (73.2% for NET, 21.4% for adenocarcinoma, p=0.0002) and R1 resection status (22.0% for NET, 3.6% for adenocarcinoma, p=0.047). Tumour grade, nodal status and histopathological subtype were independent predictors of outcome on multivariate analysis, with NET demonstrating significantly longer overall survival compared with adenocarcinoma or GIST (HR2.9 95%CI 1.5-5.3). Conclusion: Despite the relatively advanced stage of NETs at presentation, these tumours demonstrated better overall survival than adenocarcinomas of the small bowel. De bulking procedures with R1 resection is an acceptable approach for NET as compared to adenocarcinoma or GIST.