This type of study can’t prove conclusively that NSAIDs are responsible for the lower risk of breast cancer. According to the experts, some other factor could be responsible for the reduction in cancer risk.
However, the link is plausible, says coauthor Mahyar Etminan, PharmD, of the University of British Columbia in Vancouver.
“[NSAIDs] are strong inhibitors of the enzyme cyclooxygenase—COX—which is an important enzyme that is responsible for producing inflammatory mediators,” Etminan says. “Inflammation and inflammatory mediators are thought to be important in the pathology of [breast cancer].”
Research in animals suggests that NSAIDs might be more helpful fighting certain types of breast cancer than others—which could explain why past studies in women with breast cancer have had mixed results. For example, there’s some evidence that NSAIDs may be more effective at preventing cancers that over-express the HER2 gene, according to an editorial published with the study.
Etminan says the first randomized controlled trial looking at NSAIDs and cancer is now underway in the United Kingdom. In the study, known as the REACT trial, women at high risk for breast cancer are taking celecoxib to see if the drug can lower their risk. If this and other large trials show that NSAIDs are truly effective, then doctors may start to recommend them to women for breast cancer risk reduction.
“As of today, NSAIDs should not be part of any breast cancer therapy,” Etminan says.