Small bowel cancers: A population-based analysis of epidemiology, treatment and outcomes in Ontario, Canada from 2005-2020

Introduction

Small bowel cancers are uncommon malignancies comprised of several histologies with variable treatments and prognoses. The current study describes the epidemiology, treatment, and outcomes of a large, population-based cohort of patients with small bowel cancers.

Methods

We performed a retrospective cohort study using linked administrative healthcare data from Ontario, Canada. Patients diagnosed with a small bowel cancer between 2005–2020 were included. Trends in incidence, treatments, and survival were explored by histology (adenocarcinoma, neuroendocrine tumors (NET), gastrointestinal stromal tumors (GIST), and lymphoma).

Results

A total of 5306 patients with small bowel cancers were identified. The most common histologies were NET (40.5 %) and adenocarcinoma (31.6 %). Over the study period the annual incidence of small bowel cancers increased from 1.54 to 2.78 per 100 000 and the likelihoods of receiving surgery and systemic therapy within one year of diagnosis both increased for all histologic subtypes except lymphoma. Median overall survival from diagnosis was 1.0 year for adenocarcinoma, 13.2 years for NET, 14.2 years for GIST, and 10.1 years for lymphoma. There was no trend towards improved median survival for adenocarcinoma by year of diagnosis; 0.94 years (2005–2010), 1.07 years (2011–2015), and 0.98 years (2016–2020).

Discussion

Small bowel cancers are increasing in incidence, with increasing use of surgery and systemic therapies. While survival is favourable for many small bowel cancers, it remains poor for adenocarcinoma. Better availability of cancer stage data and detailed histopathology within the database would facilitate future research.

Synopsis

This study of small bowel cancer in Ontario from 2005 to 2020 demonstrated increasing incidence, use of surgery, and systemic treatments. The most common histologies are neuroendocrine tumors and adenocarcinoma, with median survivals of 13.2 and 1.0 years respectively.