Regular Aspirin Use May Reduce Breast Cancer Risk in Black Women

Black women who regularly take aspirin may have a lower risk for breast cancer, a study observed.

Compared to white women, black women are more likely to die from breast cancer and to have estrogen receptor (ER)-negative tumors. Previous studies have observed a correlation between aspirin use and reduced cancer risk. But epidemiologic studies focusing on breast cancer have yielded mixed results, and studies focusing on black women have been scarce, and there has not been research specifically on black women separating ER+ and ER– breast cancer cases.

The present study was an updated analysis of the Black Women’s Health Study, an ongoing study of 59,000 black women. At the time of enrollment in 1995, women were aged between 21 to 69 years (median, 38 years). Women received questionnaires every two years to provide updated information on incident cancer diagnoses and reproductive and behavioral factors. The present analysis excluded diagnosed with breast cancer (n=743) or any other type of cancer aside from non-melanoma skin cancer (n=696) prior to study enrollment, as well as women who did not report their aspirin use on the baseline questionnaire (n=4,399). After exclusions, the present analysis included 53,162 women.

The baseline questionnaire asked about regular medication used, which was defined as at least three days per week. The survey separately asked respondents to report current use of aspirin or acetaminophen three days per week, as well as duration of use: <1, 1, 2, 3 to 4, or ≥5 years. Beginning in 2009, women were also asked about regular use of non-steroidal anti-inflammatory drugs.

According to responses at baseline, regular aspirin users, compared to nonusers, were older (mean age, 44 years vs. 38 years), had a higher body mass index (BMI) (mean BMI, 29.1 kg/m² vs. 27.7 kg/m²), were more likely to consume alcohol (39% vs. 28%), and were less likely to have attained more than a high school education (72% vs. 83%). Reproductive factors did not largely differ between users and nonusers.

When comparing regular aspirin use to nonuse, the multivariable-adjusted hazard ratio (HR) for overall breast cancer risk was 0.92 (95% confidence interval [CI], 0.81 to 1.04). For ER– and ER+ breast cancers, the HRs were 0.81 (95% CI, 0.64 to 1.04) and 0.97 (95% CI, 0.83 to 1.13), respectively, but the researchers stated that “there was no statistically significant heterogeneity by ER status (p = 0.20).”

The risk for ER+ breast cancer risk was reduced even further in women who were regular aspirin users for at least 10 years (HR=0.81; 95% CI, 0.60 to 1.09), but this association was not observed for ER– risk. The HR for triple-negative (TN) breast cancer for regular users compared to nonusers was 0.70 (95% CI, 0.49 to 0.99), with no apparent correlation between longer duration of use and lower risk. No correlation was observed between past aspirin use and breast cancer risk overall or by subtype.

The study was published in Breast Cancer Research.

“The results of this study support the hypothesis that regular aspirin use is associated with reduced breast cancer risk, particularly for ER− and TN breast cancer, in African American women. If findings from this study are confirmed, aspirin may represent a potential opportunity for chemoprevention of ER− and TN breast cancer,” the researchers concluded.