Aspirin Fails to Prevent Recurrence After Colorectal Cancer Liver Metastases

A widely available drug did not show the hoped-for benefit

Aspirin did not prevent cancer recurrence after treatment for colorectal cancer liver metastases in a randomized clinical trial, according to researchers at the University of Oslo and Oslo University Hospital.

The result addresses a difficult stage of colorectal cancer care. Colorectal cancer is among the most common cancers in Norway, and the researchers note that about 30% of patients develop liver metastases during the course of their illness. Once the cancer has spread, it is much more difficult to treat than disease confined to the bowel.

For some patients, surgery offers the best chance of cure. Yet recurrence remains a central challenge: even after tumors are removed surgically, the cancer returns in more than half of patients, according to Sheraz Yaqub, a professor at the University of Oslo and consultant hepatobiliary surgeon at Oslo University Hospital.

Why aspirin was tested

Aspirin has long been used for pain, fever and inflammation. Because it is inexpensive, widely available and has well-known effects and side effects, it has attracted sustained interest as a possible way to reduce cancer recurrence.

Earlier observational studies had suggested that aspirin use after colorectal cancer treatment might be associated with a lower risk of recurrence and improved survival. More recent randomized trials have examined whether the drug could offer benefits, particularly for patients whose tumors have certain molecular alterations.

The question for the Norwegian team was whether a similar preventive effect might apply to patients whose colorectal cancer had spread to the liver. Metastatic disease, rather than the primary tumor itself, is generally the life-threatening component of the illness, the researchers said.

The ASAC trial

To test the idea, the researchers conducted ASAC, a randomized, double-blind, placebo-controlled trial. Such a design assigns participants to treatment or placebo by chance and keeps both participants and investigators unaware of the assignment during the study, helping limit bias in comparisons between groups.

The trial examined whether aspirin could prevent recurrence after treatment for colorectal cancer liver metastases. Its finding was negative: aspirin did not prevent recurrence in this setting.

The study has been published in The Lancet Gastroenterology & Hepatology. Its outcome is an important corrective to expectations built from observational evidence. Associations seen in earlier studies can identify promising possibilities, but randomized trials are needed to determine whether an intervention itself produces the hoped-for result.

What the result means

The result does not diminish the need for better ways to prevent recurrence after treatment of colorectal cancer liver metastases. Instead, it indicates that aspirin should not be assumed to provide that protection for this patient group on the basis of earlier evidence alone.

It also underscores how difficult it is to improve outcomes after metastatic colorectal cancer. Surgery can offer a route to cure for selected patients, but the high rate of return after surgery means recurrence prevention remains a major unmet need.

Aspirin’s familiarity made it an appealing candidate: it is a medicine used for more than a century, accessible in many settings and extensively studied for other purposes. The ASAC result shows that those advantages do not guarantee effectiveness against recurrence after liver metastases have been treated.

Questions that remain

The supplied study information does not establish that aspirin has no role in every colorectal cancer setting, nor does it resolve questions about patients with particular tumor characteristics that have been explored in other trials. It does provide a direct answer for the clinical situation studied: aspirin did not prevent recurrence after treatment for colorectal cancer liver metastases.

For patients and clinicians, the finding reinforces the importance of basing recurrence-prevention strategies on evidence from the population and disease stage under consideration. Decisions about aspirin use should remain individualized and be discussed with the treating clinical team, particularly because aspirin also has known side effects.

Key points

• About 30% of people with colorectal cancer develop liver metastases during their illness, according to the researchers.
• Recurrence occurs in more than half of patients even after surgical removal of tumors, the team said.
• The ASAC study was randomized, double-blind and placebo-controlled.
• Aspirin did not prevent recurrence after treatment for colorectal cancer liver metastases.

This article is based on reporting by Medical Xpress. Read the original article.