Aspirin after adjuvant therapy does not improve colorectal cancer outcomes
Key takeaways:
- Daily aspirin use after adjuvant therapy did not improve outcomes for patients with colorectal cancer.
- Daily aspirin use appeared well tolerated.
Daily aspirin use after standard adjuvant therapy did not improve DFS for patients with colorectal cancer, according to results of a randomized phase 3 study.
Prior studies showed aspirin can reduce incidence of colorectal cancer. One study presented at this year’s ASCO Gastrointestinal Cancers Symposium showed low-dose aspirin significantly reduced risk for colorectal cancer recurrence among patients with mutations in the PI3K pathway.
“We were disappointed that there was no statistically significant benefit of 3 years of aspirin on disease-free survival at 5 years for [patients with colorectal cancer] who had completed standard therapy,” Toh Han Chong, MBBS, senior consultant in the division of medical oncology and deputy chief executive officer of strategic partnerships at National Cancer Centre Singapore, told Healio. “These findings were not unexpected as we calculated a statistical benefit that was optimistic.”
Chia and colleagues conducted a double-blind, placebo-controlled trial to evaluate the efficacy and safety of daily aspirin as secondary prevention of colorectal cancer.
The trial included 1,550 adults (median age, 57 years; 58% men) with Dukes’ C or high-risk Dukes’ B colon cancer, or Dukes’ B or C rectal cancer, treated at 66 centers in 11 countries, including Australia, China and India.
All trial participants had undergone resection and completed at least 3 months of chemotherapy. They had no contraindications to aspirin, no familial syndromes of colorectal cancer, and no clinically significant history of cardiovascular disease or stroke.
Researchers randomly assigned patients to 200 mg aspirin (n = 791) or placebo (n = 759) daily for 3 years.
DFS served as the primary endpoint.
After median follow-up of 59.2 months, results showed no statistically significant difference in 5-year DFS between the aspirin and placebo groups (77% vs. 74.8%; HR = 0.91; 95% CI, 0.73-1.13).
Any-grade adverse events (49% vs. 51%) and serious adverse events (12% vs. 14%) occurred at comparable rates in the aspirin and placebo groups. No treatment-related deaths occurred.
No acute myocardial infarction or ischemic cerebrovascular events occurred in the aspirin group. Two cases of each occurred in the placebo group.
Three patients assigned aspirin developed gastrointestinal bleeds vs. none in the placebo group.
“A key conclusion from our study is that aspirin should not be used in an unselected colorectal cancer population to reduce the risk of colorectal cancer relapse after standard treatment,” he added.
In January — the same month the study by Chong and colleagues was published — results from the ALASCCA trial showed up to 3 years of aspirin use reduced recurrence risk by 50% compared with placebo for people with PIK3CA-mutated colorectal cancer.
“This magnitude of benefit is very impressive and a silver lining for ASCOLT,” Chong said. “ASCOLT laid the foundation and ALASCCA, then revealed an important biomarker for the use of aspirin as adjuvant therapy for colorectal cancer, and together they catalyze crucial next steps for further research.”
For more information:
Toh Han Chong, MBBS, can be reached at toh.han.chong@singhealth.com.sg.
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