NEW data has shown that frequent aspirin use, defined as use ≥6 days per week, in individuals with and without risk factors, is associated with a reduced risk of ovarian cancer. Lauren Hurwitz, National Cancer Institute, Maryland, USA, and colleagues performed a meta-analysis of nine ovarian cancer cohorts and eight case–control studies, including a total of 491,651 at-risk females and 13,753 females, respectively.
The mean age of participants in the cohort studies ranged from 46.0 years to 68.2 years versus 56.2 years to 60.7 years for the case–control studies. Frequent aspirin use ranged between 9.8% to 38% in the cohort studies and 5.6% to 29.8% in case–control studies. The mean follow-up period for the nine cohort studies was 4.6–14.3 years. Of the 491,651 individuals in the at-risk cohort studies, a total of 2,600 ovarian cancer diagnoses were made during the follow-up period. Within the eight case–control groups, there were a total of 5,726 ovarian cancer cases and 8,027 controls.
Frequent aspirin use was associated with a 10% risk reduction (hazard ratio: 0.90; 95% confidence interval [CI]: 0.81–1.01) in the at-risk cohort studies, and a 16% risk reduction (odds ratio: 0.84; 95% CI: 0.72–0.98) in the case–control studies. This yielded an overall 13% risk reduction (relative risk: 0.87; 95% CI: 0.80–0.94) across all studies included in the meta-analysis. The team also found no significant difference in overall risk reduction between cohort and case–control studies (p=0.48), highlighting that risk is reduced for those with and without ovarian cancer risk factors. Additionally, the researchers also identified that frequent aspirin use was associated with a similarly reduced risk in protective factor subgroups.
Further risk factor subgroup stratification revealed that risk reduction associated with frequent aspirin use was similar across the subgroups, except for endometriosis. Frequent aspirin use was not associated with reduction in ovarian cancer risk for individuals with endometriosis but was associated with reduced risk in those without a diagnosis of endometriosis. This was felt to be secondary to low detection power due to low numbers of patients with endometriosis in the analysis.
In response to these findings, Hurwitz stated that frequent aspirin use “could be incorporated into composite risk-benefit calculations” for patients at-risk of ovarian cancer, and that “future work should explore how chemoprevention programs with aspirin could complement existing preventive strategies.”