Prediagnostic Prescription Antibiotics Use and Survival in Patients with Colorectal Cancer: A Swedish National Register-Based Study

Abstract

Background: Antibiotics use is associated with higher colorectal cancer risk, but little is known regarding any potential effects on survival. Methods: We conducted a nationwide cohort study, using complete-population data from Swedish national registers between 2005 and 2020, to investigate prediagnostic prescription antibiotics use in relation to survival in colorectal cancer patients. Results: We identified 36 061 stage I-III and 11 242 stage IV colorectal cancer cases diagnosed between 2010 and 2019. For stage I-III, any antibiotics use (binary yes/no variable) was not associated with overall or cancer-specific survival. Compared to no use, moderate antibiotics use (total 11-60 days) was associated with slightly better cancer-specific survival (adjusted hazard ratio (aHR) = 0.93, 95% confidence interval (CI) 0.86-0.99), whereas very high use (>180 days) was associated with worse survival (overall survival aHR = 1.42, 95% CI 1.26-1.60, cancer-specific survival aHR =1.31, 95% CI 1.10-1.55). In analyses by different antibiotic types, although not statistically significant, worse survival outcomes were generally observed across several antibiotics, particularly macrolides and/or lincosamides. In stage IV colorectal cancer, inverse relationships between antibiotics use and survival were noted. Conclusions: Overall, our findings do not support any substantial detrimental effects of prediagnostic prescription antibiotics use on cancer-specific survival after colorectal cancer diagnosis, with the possible exception of very high use in stage I-III colorectal cancer. Further investigation is warranted to confirm and understand these results. Impact: Although the study findings require confirmation, physicians probably do not need to factor in prediagnostic prescription antibiotics use in prognosticating colorectal cancer patients.