University of Toronto, Toronto, ON, Canada
Sean Bennett , Natalie Coburn , Calvin Law , Victoria Zuk , Alyson Mahar , Simron Singh , Sten Myrehaug , Haoyu Zhao , Laura E Davis , Vaibhav Gupta , Julie Hallet
Background: Early resection of the primary tumor in metastatic small bowel neuroendocrine (SB-NET) remains controversial. Conflicting data exist regarding its clinical and survival benefits. We compared the long-term outcomes of upfront small bowel resection (USBR) and non-operative management (NOM) for metastatic SB-NETs. Methods: A population-based analysis of patients with SB-NET metastatic at diagnosis between 2001-2017 was conducted by linking administrative datasets. USBR was defined as resection within 6 months of diagnosis. Primary outcomes were subsequent unplanned acute care admissions and small bowel related surgery. Secondary outcome was overall survival (OS). USBR and NOM patients were matched 2:1 using a propensity-score including age, sex, year of diagnosis, socioeconomic status, institution academic status, and functional status. We used time-to-event analyses with cumulative incidence functions and univariate Andersen-Gill regression for primary outcomes, and Kaplan-Meier methods and univariate Cox regression for OS. E-value methods assessed the potential for residual confounding. Results: Of 1000 patients identified, 785 (78.5%) had USBR. The matched cohort included 348 patients with USBR and 174 with NOM. Matched groups were well balanced with standardized mean differences <10% for matched variables. Patients with USBR had lower 3-year risk of subsequent admissions (72.6% vs 86.4%, p<0.001) than those with NOM, with hazard ratio (HR) 0.72 (95%CI 0.57-0.91). USBR was associated with lower risk of subsequent small bowel related surgery (15.4% vs 40.3%, p<0.001), with HR 0.41 (95%CI 0.30-0.56). OS was superior for USBR patients compared to NOM (HR 0.55, 95%CI 0.41-0.74). E-values indicated it was unlikely that the observed risk estimates could be explained by an unmeasured confounder. Sensitivity analysis excluding emergent resections to define USBR did not alter the results. Conclusions: USBR for metastatic SB-NETs was associated with clinical benefits over NOM, in terms of decreased subsequent admissions and interventions, and improved survival. USBR should be considered for metastatic SB-NETs to improve patient outcomes.
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