TOPLINE:
Low-dose aspirin use is associated with a reduced risk for colorectal cancer (CRC), confirms a large-scale cohort study, which also suggests that the risk reduction is greatest for metastatic disease and in individuals who take the drug for at least 5 years.
METHODOLOGY:
- Researchers used several population-based registries to identify individuals aged ≥ 50 years living in Norway between 2014 and 2018, excluding those with a prior history of invasive cancer or who had lived in Norway for less than 6 months before study commencement.
- Sociodemographic information was obtained, as well as low-dose aspirin prescription data to determine the prescription date, number of dispensed packages, and defined daily dose.
- Follow-up began 6 months after entering the cohort and continued until CRC diagnosis, another cancer diagnosis, death, emigration, or the end of follow-up on December 31, 2018.
- CRC cases were categorized by site as well as by clinical stage.
TAKEAWAY:
- Of 2,186,390 individuals included, 38,577 (1.8%) were diagnosed with CRC after a median follow-up of 10.9 years. Low-dose aspirin was used at least once by 579,196 (26.5%) individuals.
- Low-dose aspirin use was more common among males, older individuals, those with a lower education or lower income, those of Norwegian origin, and individuals using other medications, including those targeting cardiovascular conditions.
- Duration of current aspirin use was also associated with the degree of CRC risk, at HRs of 0.91 for < 3 years, 0.85 for ≥ 3 and < 5 years, and 0.84 for ≥ 5 years.
- It was estimated that aspirin use averted 1073 cases of CRC over the study period.
IN PRACTICE:
“We believe that new randomized controlled trials are urgently needed to confirm the potential protective effect of aspirin against CRC and to identify subgroups in the population who might benefit the most from the use of aspirin,” the authors wrote.
SOURCE:
The research, led by Edoardo Botteri, PhD, Department of Research, Cancer Registry of Norway, National Institute of Public Health, Oslo, Norway, was published online in The American Journal of Gastroenterology.
LIMITATIONS:
This study is limited by its observational nature. Users and nonusers are also “incomparable,” as aspirin is used for the primary prevention of cardiovascular events. Moreover, information was lacking in the registries about “several known risk factors for CRC,” and so the link between aspirin and CRC risk could have been over- or underestimated. Finally, the defined daily dose may not necessarily reflect the dose actually taken by the individual or how often it was taken.
DISCLOSURES:
No relevant financial relationships were declared. The study was funded by the Norwegian Research Council.
A version of this article appeared on Medscape.com.