Does adding an aspirin improve outcomes to treatment for localized prostate cancer?


The clinical research community in the UK (with access to relevant government funding) still appears to be able to do the types of trial of older drugs that would rarely if ever get done here in America today.

A trial we have just heard about is the so-called Add-Aspirin trial, which has been designed to test the hypothesis that putting patients on daily aspirin after treatment with curative intent for four different types of cancer may be an effective (and almost certainly cost-effective) form of adjuvant treatment. Prostate cancer is one of the four types of cancer in which this strategy is being tested. The trial started enrolling patients about a year ago, in October 2015.

The idea that taking a daily aspirin could help to improve long-term outcomes for many patients after first-line therapy for some cancers has been around for years. If aspirin does indeed have such an effect, it would be highly cost-effective too. The “New” Prostate Cancer InfoLink is therefore delighted to see this trial being implemented.

The Add-Aspirin study is a phase III, multi-center, double-blind, placebo-controlled, randomized trial. It has been designed to enroll patients who have had potentially curative, first-line treatment for breast cancer (n = 3,100), colorectal cancer (n = 2,600), prostate cancer (n = 2,100), or gastroesophageal cancer (n = 2,100). The patients will be registered in four, parallel, tumor-specific cohorts, and the total number of patients to be enrolled will probably be > 10,000. The first 1,000 patients have already been successfully enrolled and randomized.

Patients who are eligible and who agree to be randomized for participation in the trial will:

  • Have an active run-in period when they take 100 mg aspirin/day for about 8 weeks.
  • Patients who can adhere to and tolerate this initial aspirin regimen will then be randomized 1:1:1 to one of the three following regimens
    • 100 mg aspirin once daily for a minimum of 5 years
    • 300 mg aspirin once daily for a minimum of 5 years
    • A matched placebo once daily for a minimum of 5 years
  • Trial participants who are ≥ 75 years of age will only be eligible for randomization to either the 100 mg aspirin or placebo arms because of the increased risk of toxicity for higher doses of aspirin among older patients.

The primary outcome measures for this trial are

  • Invasive disease-free survival for the breast cancer cohort
  • Disease-free survival for the colorectal cancer cohort
  • Biochemical recurrence-free survival for the prostate cancer cohort
  • Overall survival for the gastroesophageal cancer cohort

A co-primary endpoint will be overall survival across all four cohorts (which could take many years to be identified), and other secondary outcomes and endpoints will include things like include adherence to treatment, toxicity (including serious hemorrhage), cardiovascular events, and some cohort specific measures. The final outcome of this trial is not expected until late 2026 according to the trial information on the ClinicalTrials.gov web site.

This is a trial that we would encourage men in the UK who are having potentially curative, first-line treatment for localized prostate cancer to participate in (unless of course they are already taking a daily aspirin for other medical reasons). To find detailed eligibility criteria for prostate cancer patients, please click here.

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