Insights from a Norwegian Cohort Study
In a new study, recently published in the American Journal of Gastroenterology, researchers have identified a possible link between low-dose aspirin usage and a lower risk of developing colorectal cancer (CRC).
The study, Led by Edoardo Botteri, PhD, from the Department of Research at the Cancer Registry of Norway, National Institute of Public Health in Oslo, Norway, was a cohort study examining aspirin’s potential as a preventative measure in this increasingly common form of cancer.
Study Overview
The research team evaluated multiple population-based registries, and identified individuals over the age of 50 living in Norway from 2014 to 2018. The study excluded anyone with a previous invasive cancer diagnosis or those who had lived in Norway for less than six months prior to the study’s initiation.
Participants’ sociodemographic details were collected alongside prescription data for low-dose aspirin, which included the prescription date, number of packages dispensed, and the defined daily dose. The follow-up period began six months after cohort entry, extending until a CRC diagnosis, the diagnosis of another cancer, death, emigration, or until December 31, 2018, marking the study’s conclusion.
Key Findings
The study encompassed 2,186,390 individuals, with 38,577 (1.8%) diagnosed with CRC after a median follow-up of 10.9 years. Notably, 26.5% of the cohort had used low-dose aspirin at least once. The findings revealed that low-dose aspirin usage was more prevalent among males, the elderly, those with lower education or income levels, individuals of Norwegian origin, and unsurprisingly, those taking medication for cardiovascular conditions.
The significant finding was the association between current aspirin use and a reduced risk of CRC, with a hazard ratio (HR) of 0.87. This protective effect was even more pronounced in metastatic CRC cases (HR, 0.79) compared to regionally advanced (HR, 0.89) and localised disease (HR, 0.93).
This means that the probability of developing CRC was 13% lower overall in the cohort of people taking aspirin. Aspirins protective effect against metastatic cancer was even greater, with 21% fewer cases in those taking the drug.
The study also highlighted the importance of duration, showing a decreased CRC risk with longer aspirin use, particularly notable in individuals who had been using aspirin for five years or more.
Over the study period, aspirin use was estimated to have averted 1,073 cases of CRC, underscoring a possible future role in targeted cancer prevention regimes.
Further Research is Needed
Despite the promising results, the authors urge the need for new randomised controlled trials to confirm aspirin’s protective effect against CRC. Such studies would help identify specific population subgroups that might benefit most from aspirin use, optimising preventive strategies against this cancer type.
Study Limitations and Funding
The observational nature of the study brings inherent limitations, including the incomparability between users and non-users of aspirin, primarily due to its use in preventing cardiovascular events. The study also acknowledged the lack of information on several known CRC risk factors within the registries, which could potentially lead to over- or underestimation of the aspirin-CRC risk link. Furthermore, the defined daily dose may not accurately reflect the actual dose consumed by individuals or their usage frequency.
I should also note that aspirin is not free of potential side effects, some of them potentially severe. A few of these include aspirins ability to thin the blood, a capacity than can be beneficial when specifically recommended by a doctor but also potentially risky in terms of an increased bleeding risk. Further aspirin is known to irritate the stomach lining, which could also cause bleeding if not carefully monitored. These and other potential harms mean that no one should seek to take aspirin, of any drug, without first discussing it with a qualified health care professional.
However, this case does provide some interesting initial and hopeful results which should now lead to further study.
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