A study involving more than a thousand cancer patients has shown that taking a low dose of aspirin can halve the risk of colorectal tumor recurrence after surgery. This affordable and accessible treatment could significantly improve the prognosis for many cancer survivors with certain genetic variants.

Study Process

Researchers from the Karolinska Institute and the University Hospital examined 3,508 patients with stage I, II, or III rectal cancer, as well as stage II or III colon cancer. Among them, 1,103 were found to have a specific variant in the PI3K signaling pathway—a key genetic marker. For this group, a double-blind, randomized, placebo-controlled trial was conducted: 626 patients took 160 mg of aspirin daily for three years, while the rest received a placebo.

Study Features and Significance

The ALASCCA project brought together 33 hospitals across Sweden, Norway, Denmark, and Finland. Special attention was given to patients with mutations in the PIK3CA gene, as well as other significant changes in the PIK3R1 and PTEN genes. These genetic alterations were selected because previous studies indicated a positive effect of aspirin in suppressing tumor growth.

A professor from the Department of Molecular Medicine and Surgery at the Karolinska Institute noted that this is the first time aspirin has been tested in such a context—as a tool of precision medicine. This is a vivid example of how genetic information can be used to personalize therapy, while also reducing costs and alleviating patient suffering.

Results

For patients with a PI3K mutation, aspirin intake reduced the risk of recurrence by 55% compared to placebo. Researchers believe the positive effect is linked to several mechanisms of aspirin action: reducing inflammation, inhibiting platelet function, and slowing tumor growth. Overall, aspirin creates a less favorable environment for cancer cells to establish themselves, especially in people with a genetic predisposition to cellular dysfunction.

Although the molecular mechanisms are not yet fully understood, the data convincingly support the biological rationale for this approach and highlight the particular effectiveness of treatment in certain genetic subgroups of patients. Aspirin is a drug available worldwide and is significantly cheaper than modern anticancer agents, which is a major advantage.

Context and Perspectives

Previously, mainly observational studies also showed a link between aspirin use and reduced recurrence of colorectal cancer, but robust clinical data had been lacking. An additional benefit of aspirin is its well-studied safety profile, making it a promising candidate for clinical recommendations for cancer survivors with specific genetic mutations. Aspirin is also being studied for other types of cancer, including ovarian and gastrointestinal cancers.

Each year, about two million cases of colorectal cancer are diagnosed worldwide, and activating mutations in the PI3K pathway—mainly in the PIK3CA gene—are found in approximately 15–20% of patients.

Key Figures

Researchers noted that the three-year cumulative recurrence rate was 7.7% for those taking aspirin and 14.1% for those on placebo. Aspirin significantly reduced the recurrence rate of colorectal cancer in patients with PIK3CA mutations in exons 9 or 20, and apparently had a similar effect in patients with other somatic changes in PI3K pathway genes.

The study results have been published in The New England Journal of Medicine.