Prediagnostic use of low-dose aspirin and risk of incident metastasis and all-cause mortality among patients with colorectal cancer.

Abstract

Previous studies suggest that the use of low-dose aspirin before a colorectal cancer (CRC) diagnosis may be associated with a decreased risk of CRC progression. Data supporting this association, however, have been inconsistent. We evaluate whether the use of prediagnostic low-dose aspirin is associated with a lower risk of metastases and all-cause mortality in CRC patients. Using a large Italian population-based primary care database, we identified a cohort of 7478 patients newly diagnosed with nonmetastatic CRC between 2000 and 2013. Use of prediagnostic low-dose aspirin was compared with no use of low-dose aspirin. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of incident metastasis and of all-cause mortality associated with prediagnostic low-dose aspirin use, both overall and by duration of use. There were 314 incident metastatic events and 2189 deaths during a mean follow-up time of 4.4 and 4.7 years, respectively. Overall prediagnostic use of low-dose aspirin was not associated with a decreased risk of incident metastasis (HR 0.88; 95% CI 0.63-1.22) or all-cause mortality (HR 1.09; 95% CI 0.96-1.22) in CRC patients. Cumulative duration of aspirin use was not associated with a decreased risk of incident metastasis (P-trend = .22) or all-cause mortality (P-trend = .38). These findings remained consistent in sensitivity analyses. In this real-world, population-based study, the prediagnostic use of low-dose aspirin was not associated with a decreased risk of incident metastasis or all-cause mortality in CRC patients.