A daily dose of aspirin can substantially reduce the risk of colorectal cancer returning after surgery in patients with specific genetic mutations, according to groundbreaking results from the Alascca trial conducted by Swedish researchers at the Karolinska Institute in Stockholm.
The major clinical trial found that patients who took a low daily dose of aspirin after having their tumour removed were half as likely to have their cancer return over the next three years compared to patients who received a placebo. The protective effect was specifically observed in cancer patients whose tumours carried genetic mutations that made them susceptible to aspirin's anti-cancer properties.
Significant Risk Reduction in Genetically Defined Population
Prof Anna Martling, who led the Alascca trial, described the results as having "huge effect," with patients experiencing more than 50% reduction in cancer recurrence risk. "I think this will change clinical practice," Martling stated. "If you had these mutations, the risk of the cancer coming back was lowered by more than 50%. It is a huge effect."
The trial recruited more than 3,500 patients who had colorectal tumours removed at hospitals across Sweden, Norway, Denmark, and Finland. Genetic testing on 2,980 patients revealed that 1,103 patients, or 37%, had mutations in genes that make up the PI3K biological pathway, which is implicated in colorectal cancer development.
Patients with the PI3K pathway mutations were randomly assigned to receive either 160mg aspirin daily or a placebo for three years following surgery. Those taking aspirin showed a 55% lower likelihood of cancer recurrence compared to the placebo group.
Mechanism of Action and Clinical Implications
The protective mechanism appears to work through multiple pathways. Aspirin dampens inflammation, interferes with the PI3K pathway, and reduces the activity of blood platelets, which can surround tumour cells and effectively hide them from the patient's immune system.
The findings are particularly significant given that approximately 40% of colorectal cancer patients carry these specific genetic mutations, representing a substantial population that could benefit from this preventive treatment. Nearly 2 million people are diagnosed with colorectal cancer annually worldwide, with more than 40,000 cases occurring in the UK alone.
Safety Profile and Adverse Events
While aspirin has been available for over a century, long-term use carries inherent risks. In the trial, four patients experienced "severe adverse events" potentially linked to aspirin, including allergic reactions, gastrointestinal bleeding, and brain bleeding. Four patients died across both trial arms, with one fatality possibly attributed to aspirin use.
Need for Genetic Testing Implementation
Martling emphasized that the results highlight the critical need for genetic testing of all colorectal cancers to identify patients who would benefit from aspirin therapy. "It's a widely available drug that is extremely inexpensive," she noted, underscoring the accessibility of this potential treatment approach.
The research builds on previous evidence showing aspirin's preventive effects in high-risk populations, including those with hereditary conditions such as Lynch syndrome. However, this study specifically addresses whether aspirin reduces recurrence risk after surgical intervention.
Expert Commentary and Future Directions
Dr Catherine Elliott, director of research at Cancer Research UK, commented on the broader implications: "Preventing cancer cases saves lives, and finding new ways to do this is key to our efforts to beat cancer. There is increasing evidence that in certain groups of people, low-dose aspirin can offer protection from bowel cancer."
Elliott referenced the Cancer Research UK-funded CaPP3 trial, which demonstrated similar protective effects in people with Lynch Syndrome, an inherited condition that increases bowel cancer risk. "We need larger, high-quality studies like CaPP3 and this recent research to confirm who would most benefit from taking aspirin to help them live longer, better lives, free from the fear of cancer," she added.
The study results, published in the New England Journal of Medicine, represent a significant advancement in personalized cancer prevention strategies, potentially offering a cost-effective intervention for a genetically defined subset of colorectal cancer patients.
