Outcomes of Patients with Small Intestine Adenocarcinoma in a Canadian Province: A Retrospective Multi-Center Population-Based Cohort Study

SIMPLE SUMMARY: Small intestine adenocarcinoma is a rare cancer. Given the rarity of this cancer, the clinicopathological characteristics and the role of chemotherapy in both the early and advanced stages have not been well studied. The aim of this study was to assess the outcomes of all patients who were diagnosed with small intestine adenocarcinoma over a 10-year period in the province of Saskatchewan. Most patients with small intestine adenocarcinoma were diagnosed with advanced-stage disease. We found that advanced-stage disease, poor performance status, lack of curative surgery, and a baseline neutrophil:lymphocyte ratio of >4.5 were significantly correlated with inferior survival. ABSTRACT: Background: Small intestine adenocarcinoma is a rare cancer. The current study aims to determine the outcomes of patients with small intestine adenocarcinoma in a Canadian province. Methods: This retrospective population-based cohort study assessed patients with small intestine adenocarcinoma who were diagnosed from 2008 to 2017 in Saskatchewan. A Cox proportional multivariate regression analysis was performed to determine the correlation between survival and exploratory factors. Results: 112 eligible patients with a median age of 73 years and M:F of 47:53 were identified. Overall, 75% had a comorbid illness, and 45% had a WHO performance status >1. Of the 112 patients, 51 (46%) had early-stage disease and 61 (54%) had advanced-stage disease. The median overall survival (mOS) was as follows: stage one, 59 months; stage two, 30 months; stage three, 20 months; and stage four, 3 months (p < 0.001). The median disease-free survival of patients with stage three disease who received adjuvant chemotherapy was 26 months (95% CI:23.1–28.9) vs. 4 months (0.0–9.1) with observation (p = 0.04). Patients who received chemotherapy for advanced disease had a mOS of 10 months (3.5–16.5) vs. 2 months (0.45–3.6) without chemotherapy (p < 0.001). In the multivariate analysis, stage four disease, hazard ratio (HR), 3.20 (1.84–5.40); WHO performance status >1, HR, 2.22 (1.42–3.45); lack of surgery, HR, 2.10 (1.25–3.50); and a neutrophil:lymphocyte ratio of >4.5, HR, 1.72 (1.10–2.71) were significantly correlated with inferior survival. Conclusions: Most patients with small intestine adenocarcinoma were diagnosed with advanced-stage disease. Advanced-stage disease, poor performance status, lack of surgery and a baseline neutrophil:lymphocyte ratio >4.5 were correlated with inferior survival.