Can aspirin help prevent recurrence of colon and rectal cancer?

A new study from Sweden suggests that aspirin could help prevent colon and rectal cancer from coming back after surgery—but only in patients with specific genetic traits.

Researchers from the Karolinska Institutet and Karolinska University Hospital conducted a large clinical trial to examine whether a low daily dose of aspirin could reduce cancer recurrence in people whose tumors have certain genetic mutations.

Colon and rectal cancers affect nearly 2 million people globally each year. Sadly, up to 40% of patients eventually experience metastasis, where the cancer spreads to other parts of the body—making it more difficult to treat.

Earlier research hinted that aspirin might help reduce the risk of cancer returning, particularly in patients with changes in genes involved in the PIK3 signaling pathway. This pathway regulates cell growth and division, and mutations can cause cells to grow uncontrollably—leading to cancer. However, previous studies were inconclusive, and none had tested the idea in a randomized clinical trial—until now.

The new trial, known as the ALASCCA study, involved over 3,500 colon and rectal cancer patients across 33 hospitals in Sweden, Norway, Denmark, and Finland. After surgery, patients with mutations in the PIK3 pathway were randomly assigned to take either 160 mg of aspirin or a placebo daily for three years.

The results were striking: among patients with the relevant genetic mutation, those who took aspirin had a 55% lower risk of cancer recurrence compared to those who received a placebo.

“This is an exciting step forward in personalized medicine,” said Professor Anna Martling, lead author of the study. “It clearly shows how we can use genetic information to tailor treatments—improving outcomes while also reducing unnecessary treatments and suffering.”

Researchers believe aspirin helps by reducing inflammation, slowing tumor growth, and limiting the activity of platelets—blood cells that can assist cancer in spreading. These combined effects create a less favorable environment for cancer to return.

Although the exact mechanisms are not yet fully understood, the study offers strong evidence that aspirin can be effective in preventing recurrence—but only in patients with the right genetic profile. Given aspirin’s low cost and global availability, this discovery could have significant implications for cancer care worldwide.

In summary, this landmark research supports the use of low-dose aspirin to prevent colon and rectal cancer recurrence in genetically suitable patients. It also highlights the growing importance of genetic testing in guiding more personalized and effective cancer treatments.