S338 The Impact of Concurrent Bevacizumab Therapy on Adverse Outcomes in Patients Undergoing Colonic Luminal Stenting for Malignant Obstruction: A Retrospective Multicenter U.S. Comparative Cohort Study

Introduction: Malignant colonic obstruction is a critical complication of advanced colorectal cancer, often managed with self-expandable metallic stents (SEMS). Bevacizumab (Avastin), an anti-angiogenic therapy for metastatic colorectal cancer, is associated with a risk of gastrointestinal (GI) perforation and other adverse events like peritonitis and sepsis. The concurrent use of SEMS and bevacizumab has raised concerns regarding an increased risk of such complications, with existing literature presenting conflicting evidence and methodological limitations. The study aimed to assess the risk of adverse outcomes in patients undergoing colonic luminal stenting while receiving bevacizumab therapy. Methods: A retrospective cohort study was conducted using de-identified patient data from the TriNetX database. Adult patients (≥18 years old) who underwent colonic luminal stenting were identified using the International Classification of Diseases, Tenth Revision codes. Patients were then stratified into 2 groups based on receiving or not receiving bevacizumab. To minimize selection bias and hidden confounders, 1:1 propensity score matching was performed, adjusting for patient demographics and relevant comorbidities. Odds ratios (OR) for perforation, peritonitis, sepsis, septic shock, emergent exploratory laparotomy and all-cause mortality at one year were calculated to compare the matched cohorts. Results: The initial cohorts consisted of 478 patients receiving bevacizumab therapy and 2,036 patients not receiving bevacizumab therapy. After propensity score matching, each group comprised 474 patients. At the 1-year follow-up, patients receiving bevacizumab therapy had significantly higher odds of perforation (OR 2.17, 95% confidence interval [CI] 1.41-3.33), peritonitis (OR 1.79, 95% CI 1.24-2.59), and sepsis (OR 1.49, 95% CI 1.07-2.07) compared to the no bevacizumab group. Conversely, the odds for all-cause mortality (OR 0.99, 95% CI 0.74-1.30), emergent exploratory laparotomy (OR 1.37, 95% CI 0.62-3.02), and septic shock requiring pressors (OR 1.04, 95% CI 0.57-1.90) were not significantly different between the 2 groups. Conclusion: In this large real-world cohort study, colonic luminal stenting was associated with a higher risk of perforation in patients receiving bevacizumab compared to the control group. These findings underscore the importance of a careful risk-benefit assessment and heightened vigilance for specific adverse events when considering luminal stenting in this patient population.