A major trial in Sweden suggests that taking a low daily dose of aspirin after colorectal cancer surgery can significantly reduce the risk of the cancer returning in patients with certain gene mutations.
The study, led by Prof. Anna Martling at the Karolinska Institute, focused on patients whose tumours had mutations in the PI3K pathway—a pathway implicated in colorectal cancer. Roughly 40% of colorectal cancer patients carry such mutations. Among these patients, those taking 160mg of aspirin daily for three years were 55% less likely to see their cancer recur compared to those on a placebo.
The protective effect of aspirin is thought to come from reducing inflammation, interfering with the PI3K pathway, and limiting platelet activity, which can shield tumour cells from the immune system.
The trial involved more than 3,500 post-surgery patients from Sweden, Norway, Denmark, and Finland. Genetic tests were performed on 2,980 patients, identifying 1,103 with the PI3K mutations.
While aspirin is inexpensive and widely available, long-term use carries some risks. In the trial, four patients experienced severe side effects potentially linked to aspirin, including gastrointestinal bleeding and bleeding in the brain, with one death possibly associated with the drug.
Experts say these findings could change clinical practice by highlighting the importance of genetic testing in colorectal cancer patients to identify who may benefit from daily aspirin. Dr. Catherine Elliott of Cancer Research UK emphasized the need for larger, high-quality studies to confirm which groups could gain the most benefit.
The full study is published in the New England Journal of Medicine.
