Daily aspirin may reduce risk of breast cancer

Taking aspirin on a daily basis may lower women’s risk of a particular type of breast cancer, according to  large scale study results published in the journal Breast Cancer Research.

Aspirin use was linked to a small reduction in estrogen receptor-positive breast cancers. However, unlike in some previous research, aspirin and related painkillers were not found to reduce the total risk of breast cancer.

About 75% of breast cancers are estrogen receptor-positive (ER+), which means the cancer cells have receptors for the female hormone estrogen on their surface. Estrogen helps the cancer cells grow, so drugs that block the action of estrogen are often used to treat ER+ cancer.

Unlike other NSAIDs, aspirin has irreversible effects on cyclooxygenase (COX) enzymes, so the study authors looked for differences in cancer development according to whether women used aspirin or another kind of NSAID.

NSAID use was not linked to total risk of breast cancer in this study. However, when the team considered different cancer subtypes and specific types of NSAIDs, they found that daily aspirin use was associated with a small reduction (16%) in the risk of ER+ breast cancer. A similar link was not seen in cases of ER- breast cancer.

“In summary, our results do not support an important influence of NSAIDs on total breast cancer risk. Daily aspirin use, however, appeared to offer some protection for ER+ breast cancer in this population. . . . Our results provide support for further evaluating relationships in prospective studies with well-defined measures of NSAID use by NSAID type . . . and by ER status,” the study concludes.