Aspirin-Breast Cancer Study Doesn't Prove Cause and Effect
Although provocative, the study only shows an association and does not prove cause and effect, says Steven Isakoff, MD, PhD, a breast cancer specialist at Massachusetts General Hospital Cancer Center in Boston.
Also, long-term use of aspirin carries the risk of serious side effects, such as stomach bleeding and ulcers, he tells WebMD.
Still, if the findings can be confirmed in a large study in which half the women are given aspirin and half aren't and all are followed over time to see how many in each group develop breast cancer, the painkiller could have a huge impact, particularly in underdeveloped nations, Isakoff says.
"As a public health measure, aspirin is cheap and easy," he says.
Previous Studies on Aspirin and Breast Cancer a Mixed Bag
Makubate says the previous studies looking at aspirin use in breast cancer have had conflicting results.
Laboratory work at his institution suggests aspirin could have an effect on breast cancer by blocking the Cox-2 enzyme that promotes inflammation and cell growth.
So Makubate and colleagues combed the medical records of British women aged 25 and older who were cancer-free in 1998. By the end of 2003, 1,420 (1.2%) developed breast cancer.
Prescription records showed one in five women took aspirin during the study period.
Aspirin and Breast Cancer Study: Strengths and Weaknesses
All the analyses were adjusted to take into account a woman's age and socioeconomic status, both of which affect breast cancer risk. But the researchers did not take into account other information, such as family history, that have an impact on risk.
Also, the researchers did not look at what dosages may work best.
A strength of the study is that prescribing records, not faulty memories, were used to gather information on aspirin use, Isakoff says.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.