Frequent Aspirin Use and Risk of Ovarian Cancer

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In an individual-level meta-analysis reported in the Journal of Clinical Oncology, Hurwitz et al found that frequent aspirin use was associated with reduced risk of ovarian cancer, including high-grade serous ovarian cancer and among women with multiple risk factors.

Study Details

The analysis included: nine cohort studies from the Ovarian Cancer Cohort Consortium with 491,651 women at risk, of whom 2,600 developed ovarian cancer over follow-up; and eight case-control studies from the Ovarian Cancer Association Consortium with 5,726 ovarian cancer cases and 8,027 controls. Frequent aspirin use was defined as use for ≥ 6 d/wk or ≥ 28 d/mo and for a duration of ≥ 6 months without regard to dose.

Key Findings

Overall, frequent aspirin use was associated with a 13% reduction in ovarian cancer risk (relative risk = 0.87, 95% confidence interval [CI] = 0.80–0.94). This included a hazard ratio of 0.90 (95% CI = 0.81–1.01) in cohort studies and an odds ratio of  0.84 ( 95% CI = 0.72–0.98) in case-control studies, with no significant heterogeneity by study design (P = .48).

With regard to histotype, relative risks were 0.80 (95% CI = 0.67–0.96) for endometrioid, 0.86 (95% CI = 0.78–0.94) for high-grade serous, 0.93 (95% CI = 0.71–1.22) for clear cell, 1.00 (95% CI = 0.73–1.36) for mucinous, and 0.94 (95% CI = 0.81–1.10) for other/unknown or epithelial histology, with no significant heterogeneity by histotype (P = .60).

With regard to risk factors, relative risks were: 0.82 (95% CI = 0.73–0.92) among women without endometriosis, but 1.15 (95% CI = 0.80–1.65) among those with endometriosis (P for heterogeneity = .08); 0.79 (95% CI = 0.67–0.93) among obese women and 0.91 (95% CI = 0.80–1.03) among non-obese women (P for heterogeneity = .18); and 0.86 (95% CI = 0.79–0.94) among women with a family history of breast or ovarian cancer and 0.88 (95% CI = 0.72–1.06) among those without family history (P for heterogeneity = .88). The relative risk was 0.81 (95% CI = 0.73–0.90) among women with at least two risk factors.

The investigators concluded: “This study, the largest to date on aspirin use and ovarian cancer, provides evidence that frequent aspirin use is associated with lower ovarian cancer risk regardless of the presence of most other ovarian cancer risk factors. Risk reductions were also observed among women with multiple risk factors, providing proof of principle that chemoprevention programs with frequent aspirin use could target higher-risk subgroups.”

Lauren M. Hurwitz, PhD, MHS, of the Division of Cancer Epidemiology and Genetics, National Cancer Institute, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was funded by the US Department of Defense Ovarian Cancer Research Program and others. For full disclosures of the study authors, visit


The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.