‘Disappointing’ data confirm aspirin does not reduce risk for breast cancer relapse
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Key takeaways:
- Daily aspirin use did not reduce breast cancer recurrence.
- Research into aspirin’s impact on other cancer types should continue.
Daily aspirin use did not reduce disease recurrence, progression or mortality in patients with high-risk breast cancer, according to extended follow-up results of a terminated study published in JAMA.
Researchers examined more than 3,000 individuals in the phase 3 randomized trial, and those in the aspirin cohort had a higher number of invasive DFS events, although the authors determined the results to be statistically insignificant.
“Patients with history of early breast cancer should not be encouraged to take aspirin routinely to improve their breast cancer outcomes,” Wendy Y. Chen, MD, MPH, senior physician and assistant professor at Dana-Farber Cancer Institute, told Healio.
Background and methodology
Previous research indicated aspirin use could increase survival for individuals with breast cancer. The numbers showed greater promise in studies involving cardiovascular disease, according to background information provided by researchers.
“In a pooled analysis of five large, randomized trials of aspirin to prevent vascular disease with data on cancer outcomes, participants randomized to aspirin had a reduced risk [for] cancer with distant metastasis, mainly due to a reduced risk [for] metastatic adenocarcinoma,” they wrote. “Furthermore, patients with adenocarcinoma who did not have metastasis at initial diagnosis and who continued receiving aspirin up to or after diagnosis had a reduced risk [for] metastasis ... particularly a possible reduced breast cancer mortality.”
Chen and colleagues investigated aspirin’s benefit further in a phase 3, double-blind trial conducted in the U.S. and Canada.
Participants had to be between the ages of 18 and 70 with a history of ERBB2-negative breast cancer to be included. Patients with hormone receptor-positive and -negative tumors had different enrollment criteria.
Researchers randomly assigned study participants in a 1:1 ratio to receive 300 mg of aspirin or placebo once daily for 5 years. The study occurred between Jan. 6, 2017, and Dec. 4, 2020, with follow-up extended to March 4, 2023.
The trial finished with 3,020 patients (more than 99.5% women; most aged 50 to 59 years and white). Each cohort consisted of 1,510 participants and had a median follow-up of 33.8 months.
Chen and colleagues evaluated invasive DFS as the study’s primary endpoint, with OS serving as a secondary outcome measurement.
They previously stopped the trial in November 2021 because the futility boundary had been reached.
“Follow-up is always required to gather data on any potential adverse events and recurrences and to give the study sites time to finalize and send in their final data,” Chen said.
Results and next steps
Researchers observed 253 invasive DFS events between the two groups with 55% occurring in the aspirin cohort (HR = 1.27; 95% CI, 0.99-1.63).
The aspirin group had more deaths (12), invasive progressions (104) and new primary events (25), but those numbers did not achieve statistical significance.
“The study showed no benefit to aspirin among breast cancer survivors,” Chen said. “These were disappointing [results] and not what we were expecting.”
Researchers wrote aspirin’s impact on other cancers should still be researched.
“Our study was not powered to see if there were potential benefits to aspirin among tumor subtypes, but we hope to pool our results with other studies to answer this question,” Chen said. “It is important to remember that aspirin may still have an important role in other cancers, such as colorectal cancer.”
In an accompanying editorial, Jeanne S. Mandelblatt, MD, MPH, founder and director of Georgetown Lombardi Institute for Cancer and Aging Research; Candice Mainor, MD, oncologist at MedStar Georgetown Cancer Institute at MedStar; and Barry I. Hudson, PhD, associate professor of oncology of Georgetown University Hospital School of Medicine, mentioned several “critical issues” raised by this trial — most notably questions about health equity.
“Persons recruited to an intervention trial may not be representative of the broader target population,” they wrote. “This limitation does not affect the internal validity of comparisons across study groups. However, limits in external generalizability may mean that subgroups that might benefit from aspirin use may not have been included or were included in insufficient numbers.”
References:
Chen WY, et al. JAMA. 2024;doi:10.1001/jama.2024.4840.
Mandelblatt JS, et al. JAMA. 2024;doi:10.1001/jama.2024.4828.
For more information:
Wendy Y. Chen, MD, MPH, can be reached at wendy_chen@dfci.harvard.edu.
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Chen WY, et al. JAMA. 2024;doi:10.1001/jama.2024.4840.
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