Aspirin linked to reduced metastasis in bowel cancer patients with a PIK3 mutation

Aspirin, a long-standing and inexpensive medication, may reduce the risk that bowel cancer spreads after surgery in patients who carry a specific genetic mutation, according to a large randomized trial.

Researchers reported that among people with a mutation in the PIK3 signaling pathway, taking 160 milligrams of aspirin daily for three years following tumor removal reduced the risk of metastasis by 55% compared with a placebo. The findings, published in The New England Journal of Medicine, come from a study of more than 3,500 bowel cancer patients treated at 33 hospitals across Sweden, Norway, Denmark and Finland. About 40% of participants were found to have the PIK3 mutation.

Lead study author Anna Martling, a professor at the Department of Molecular Medicine and Surgery at Karolinska Institutet and a senior consultant at Karolinska University Hospital, said aspirin could help reduce both suffering and the cost of cancer care. “Aspirin is a drug that is readily available globally and extremely inexpensive compared to many modern cancer drugs, which is very positive,” she said. “This is a completely new context for aspirin as a precision medicine treatment.” She added that the results demonstrate how genetic information can guide therapy while potentially easing the burden on healthcare systems.

The trial represents the first randomized evidence to confirm observational hints that aspirin might lower the risk of recurrence in bowel cancer patients with the PIK3 mutation. Researchers suggested the benefit likely stems from aspirin’s anti-inflammatory effects and its ability to make the internal environment less favorable for cancer cells, though the precise molecular links are not yet fully understood. Martling noted that the benefit may be greatest in genetically defined subgroups, pointing to the promise of personalized cancer care based on tumor genetics.

Bowel cancer, which encompasses colorectal cancer, is among the most aggressive to treat and carries a substantial risk of metastasis to other body sites. Patients may notice blood in stool, changes in bowel habits, or a lump that can cause obstruction. Worldwide, colorectal cancer affects nearly two million people each year, with metastases occurring in 20% to 40% of cases at diagnosis or during follow-up. In the United Kingdom, roughly 44,000 cases are diagnosed annually, while the United States sees about 130,000 new cases each year. The disease remains a leading cause of cancer deaths in both countries, with survival diminishing as metastasis develops.

Aspirin’s potential role in cancer care has long been explored, particularly in prevention. It is commonly prescribed in low doses to reduce blood clots, but its use in oncology has been limited by concerns about side effects, such as stomach ulcers and bleeding disorders. The current study underscores the potential for repurposing an inexpensive, widely available drug to benefit a specific genetic subgroup of patients who have undergone curative surgery for bowel cancer. Still, experts caution that the findings apply to patients with the PIK3 mutation and should not be generalized to all bowel cancer patients. Further research is needed to confirm long-term outcomes and to define any risks associated with extended aspirin use in this population.