A randomized trial showed no significant difference in the rate of invasive melanoma between patients taking daily aspirin and those taking a placebo.
However, researchers said these results don’t rule out the possibility that aspirin might have a chemopreventive effect on melanoma incidence.
The results, from the ASPREE trial, were published in Cancer Prevention Research.
The trial (ClinicalTrials.gov Identifier: NCT01038583) enrolled 19,114 adults — 16,703 from Australia and 2411 from the United States. Patients were randomly assigned to receive aspirin at 100 mg daily (n=9525) or placebo (n=9589).
In both treatment groups, the median age was 74 years, and 44% of patients were men. Three percent of patients in the aspirin group and 4% in the placebo group had a personal history of melanoma, and 3% in each group had a family history of melanoma.
The rate of intervention adherence was 62.1% in the aspirin group and 64.1% in the placebo group.
At a median follow-up of 4.7 years, the trial was terminated. Throughout the follow-up, there were 366 melanoma events and 170 invasive melanoma events.
There were slightly fewer melanoma events in the aspirin group than in the placebo group — 177 and 189, respectively — but the difference between the groups was not statistically significant (hazard ratio [HR], 0.94; 95% CI, 0.77-1.16; P =.58).
Similarly, there were slightly fewer invasive melanoma events in the aspirin group than in the placebo group — 76 and 94, respectively — but the between-group difference was not significant (HR, 0.81; 95% CI, 0.60-1.10; P =.18).
After the trial was terminated, participants were invited to enroll in the ASPREE eXTension (ASPREE-XT) trial, an observational study designed to evaluate the delayed effect of aspirin.
With additional observation and a median follow-up of 6.3 years, there were 268 invasive melanoma events.
Again, there were slightly fewer invasive melanoma events in the aspirin group than in the placebo group — 119 and 194, respectively — but the between-group difference was not significant (HR, 0.81; 95% CI, 0.63-1.03; P =.08).
“The hypothesis that aspirin has a chemopreventive effect on melanoma incidence is not contradicted by evidence from this large [trial], but nor have we found strong support for that hypothesis,” the researchers concluded. “Further studies are required to investigate this association.”
Yan MK, Orchard SG, Adler NR, et al. Effect of aspirin on melanoma incidence in older persons: extended follow-up of a large randomised double-blind placebo-controlled trial. Cancer Prev Res. Published online February 22, 2022. doi:1940-6207.CAPR-21-0244