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Feb. 19, 2010 - Aspirin has anticancer effects, new studies confirm.
The latest of these studies shows that after successful treatment for breast cancer, women who take aspirin regularly have a significantly lower risk of dying from recurrent cancer. Aspirin also cut their risk of having their cancer spread to other sites.
What does this mean for people treated for cancer? What does it mean for people worried about their cancer risk? Here are answers to these and other frequently asked questions about aspirin and cancer.
Only a clinical trial, in which randomly assigned treatment is tested against an inactive placebo, can prove that a treatment is truly effective.
Until such proof is available, the next best thing is a study in which people taking the treatment are observed over time. The Nurses Health Study followed more than 4,000 nurses who had been treated for breast cancer at least 12 months earlier.
The result: Nurses who took aspirin were significantly less likely to die of breast cancer and to have cancer recur at another site. After adjusting for cancer stage, menopausal status, body mass, and hormone sensitivity of the tumor, women who took aspirin seven days a week were 43% less likely to die of breast cancer.
The findings may apply only to women who survive at least four years after breast cancer treatment. But since 90% of women diagnosed with breast cancer survive at least five years, "our findings have considerable clinical importance," conclude researchers Michelle D. Holmes, MD, DrPH, and colleagues at Boston's Brigham & Women's Hospital. Their study is published online in the Journal of Clinical Oncology.
No. If aspirin truly helps prevent breast cancer recurrence, it does so only when combined with recommended cancer therapies.
Some studies suggest that aspirin can cut breast cancer risk in women who do not have the disease. Other studies reach the opposite conclusion.
When data from several studies are combined, there is a hint that aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs, such as ibuprofen) may slightly decrease breast cancer risk.
Most women do not get breast cancer. Taking aspirin every day for a long time carries risks, especially the risk of stomach or intestinal bleeding. This means that for most women, the risks of taking aspirin may exceed the benefit of preventing breast cancer.
However, when taken under a doctor's supervision, regular low-dose aspirin use does cut the risk of heart disease. It's not yet clear whether women at higher risk of breast cancer might get an extra benefit from aspirin.
Aspirin may be sold over the counter, but it's a very powerful drug. It has at least two effects that, in animal studies, fight cancer.
Aspirin is most studied in colon cancer. Human studies strongly suggest that aspirin improves survival in patients treated for colon cancer. Studies also suggest that aspirin decreases the risk of new polyps in patients who have had precancerous intestinal polyps removed, and that regular aspirin use lowers colon cancer risk.
However, the U.S. Preventive Services recommends against the widespread use of aspirin to prevent colon cancer. Again, the risks of aspirin outweigh the benefit for people at normal risk of colon cancer.
Aspirin may also lower the risk of other cancers, particularly prostate cancer and esophageal cancer.
As with breast and colon cancer, the strongest benefits appear to be in patients already treated for cancer. While there is evidence that aspirin has broad anticancer effects, there is no good evidence that this benefit -- even when combined with the benefit of low-dose aspirin in preventing heart disease -- outweighs the risk for people at normal risk of cancer.