A major Swedish trial has found that taking a low daily dose of aspirin can significantly reduce the risk of colorectal cancer recurrence in certain post-surgery patients.
The study, led by Prof. Anna Martling at the Karolinska Institute, involved more than 3,500 patients across Sweden, Norway, Denmark, and Finland. Researchers focused on patients whose tumors carried genetic mutations in the PI3K pathway, which makes them particularly responsive to aspirin. Around 37–40% of colorectal cancer patients have these mutations.
Participants with the mutations were given either 160mg of aspirin daily or a placebo for three years after surgery. Results showed that those on aspirin were 55% less likely to experience a cancer recurrence than those on placebo. Aspirin is thought to work by reducing inflammation, interfering with the PI3K pathway, and inhibiting platelets that can shield tumor cells from the immune system.
Prof. Martling highlighted the importance of genetic testing for colorectal cancer patients to identify those who could benefit from aspirin therapy, calling it “a widely available drug that is extremely inexpensive.”
While aspirin is generally safe, long-term use carries risks. In the trial, four participants experienced severe adverse events potentially linked to aspirin, including gastrointestinal bleeding, allergic reactions, and intracranial bleeding, with one death possibly associated with the drug.
Dr. Catherine Elliott of Cancer Research UK said the findings add to growing evidence that low-dose aspirin can offer protection for certain groups, echoing results from previous trials such as the CaPP3 study involving patients with Lynch Syndrome. She stressed the need for larger, high-quality studies to determine which patients will benefit most.
The trial’s findings are published in the New England Journal of Medicine and may influence clinical practice for post-surgery colorectal cancer care.
