A major Swedish trial has found that taking a low dose of aspirin daily after surgery can cut the risk of some colorectal cancers returning by more than half in patients with specific genetic mutations.
The study, led by Prof Anna Martling at the Karolinska Institute, involved over 3,500 patients in Sweden, Norway, Denmark, and Finland. Genetic testing revealed that around 37% of patients had mutations in the PI3K pathway, a key biological route implicated in colorectal cancer. These patients were given 160mg of aspirin daily or a placebo for three years. Those on aspirin were 55% less likely to see their cancer return compared with those taking the placebo.
Aspirin is believed to help by reducing inflammation, interfering with the PI3K pathway, and limiting the ability of blood platelets to shield tumor cells from the immune system.
Prof Martling emphasized that genetic testing for colorectal cancer patients could identify those most likely to benefit. She noted: “It’s a widely available drug that is extremely inexpensive.”
However, aspirin carries risks. In the trial, a few patients experienced severe side effects, including gastrointestinal bleeding and, in one case, possible fatality linked to the drug.
Experts, including Dr Catherine Elliott of Cancer Research UK, said the findings reinforce evidence that low-dose aspirin may protect certain patients from cancer recurrence, while stressing the need for further high-quality studies to confirm who benefits most.
The full results have been published in the New England Journal of Medicine.
