A Norwegian population-based study reported in the Journal of Clinical Oncology by Simer J. Bains, MD, PhD, of the Centre for Molecular Medicine Norway, University of Oslo, and colleagues showed that use of aspirin after diagnosis of colorectal cancer was associated with improved colorectal cancer–specific survival.
In the population-based retrospective cohort study, patients diagnosed with colorectal cancer from 2004 through 2011 in the Cancer Registry of Norway were linked with data on their aspirin use from The Norwegian Prescription Database. The registries cover more than 99% of the Norwegian population and include all patients consecutively. Exposure to aspirin was defined as receipt of aspirin prescriptions for more than 6 months after a colorectal cancer diagnosis.
A total of 23,162 patients diagnosed with colorectal cancer were included in the analysis, with 6,102 (26.3%) having aspirin exposure after diagnosis. Median follow-up was 3.0 years.
Among patients with aspirin exposure, there were 2,071 deaths from all causes (32.9%), including colorectal cancer–specific death in 1,158 (19.0%). Among the 17,060 patients without aspirin exposure, there were 7,218 deaths from all causes (42.3%), including colorectal cancer–specific death in 5,375 (31.5%).
In multivariate analysis, aspirin exposure was associated with significantly improved colorectal cancer–specific survival (hazard ratio [HR] = 0.85, P < .001) and borderline improved overall survival (HR = 0.95, 95% confidence interval [CI] = 0.90–1.01, P = .076). Stratified analysis showed that patients with aspirin exposure both before and after diagnosis had additional improvement in colorectal cancer–specific survival (HR = 0.77, 95% CI = 0.71–0.84) and overall survival (HR = 0.86, 95% CI = 0.81–0.92).
The investigators concluded: “Aspirin use after the diagnosis of colorectal cancer is independently associated with improved [colorectal cancer–specific survival] and [overall survival].”
The study was funded by the Research Council of Norway, the Norwegian Cancer Society, and the K. G. Jebsen Foundation.