medwireNews: The ABC (Aspirin after Breast Cancer) trial has ruled out the adjuvant use of daily high-dose aspirin for the prevention of breast cancer recurrence in people with high-risk, HER2-negative disease.
Speaking at the ASCO Plenary Series, study author Wendy Chen (Dana-Farber Cancer Institute, Boston, Massachusetts, USA) noted that invasive disease-free survival (IDFS) was comparable among the aspirin and placebo groups in the study.
If anything, there appeared to be a trend, albeit not statistically significant, towards worse IDFS with the use of aspirin, she highlighted.
Discussant Angela DeMichele, from the University of Pennsylvania in Philadelphia, USA, agreed that a potential for harm with adjuvant aspirin could not be ruled out, especially in light of the ASPREE trial results that showed numerically higher all-cause mortality with aspirin than placebo in older adults.
She therefore believes that “at this time aspirin should not be used simply to prevent breast cancer recurrence,” and “decisions about aspirin use for other indications should definitely include an individualized risk–benefit discussion between physician and patient.”
The double-blind trial enrolled 3021 individuals aged up to 70 years with high-risk, HER2-negative breast cancer. The majority of participants were postmenopausal (81.2%), had hormone receptor-positive (89.0%) and node-positive (85.7%) disease, and had previously received chemotherapy (83.3%).
In a preplanned interim analysis, conducted at a median follow-up of 20 months, IDFS did not differ significantly between the 1511 participants who were randomly assigned to receive aspirin 300 mg/day for 5 years and their 1510 counterparts who instead received placebo.
The stratified hazard ratio (HR) for aspirin versus placebo was 1.25, and as this was greater than the prespecified HR for futility of 1.03, the data monitoring committee advised early closure of the trial, Chen told the audience.
She noted that compliance with the study treatment – defined as taking more than 80% of doses in the last 6 months – was high in both arms, at more than 80% in months 6–11 and more than 90% in months 12–24. Conversely, off-protocol use of aspirin and other nonsteroidal anti-inflammatory drugs was low, at rates of around 10–13% over the course of the study.
The incidence of adverse events of grade 3 or worse was similar in the aspirin and placebo groups, at 7.7% and 8.3%, respectively, and this was also the case for grade 4 or worse events, at 1.0% and 1.4%. A comparable 2.0% of aspirin-treated participants and 1.7% of those given placebo required a dose reduction to 100 mg/day.
Chen concluded that “[d]espite the study results, inflammation may still play a key role in cancer,” and added that “it’s also important to remember that aspirin may have different effects in other cancers, such as colon, or in different settings, such as primary versus secondary prevention.”
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