By Kathleen Doheny
TUESDAY, Feb. 16 (HealthDay News) -- A new study of more than 4,000 women who were diagnosed with breast cancer shows that taking aspirin appears to significantly increase survival and reduce the risk of recurrence.
"Women who took aspirin were 50 percent less likely to die from breast cancer [during the study follow-up period] than those who did not take it," said study author Dr. Michelle Holmes, an associate professor of medicine and epidemiology at Harvard Medical School and School of Public Health, in Boston.
The study is published online Feb. 16 in the Journal of Clinical Oncology.
The 50 percent reduction is the overall finding when comparing to users to nonusers, she said. "Statistically, the women who took it more days per week had a higher risk reduction," Holmes noted. For instance, those who took it six to seven days a week had a 64 percent reduction in risk of death during the follow-up. For some reason, those who took aspirin two to five days a week had an even greater risk reduction, 71 percent, Holmes found.
But the most important finding, in her view, was the overall 50 percent reduction. She didn't have access to doses, just number of days a week the women took aspirin, she noted.
Aspirin use also reduced the risk of recurrence of the cancer in similar fashion.
"It is a surprisingly strong effect," Holmes said, though she acknowledged that it was an observational study and does not establish definitive cause and effect.
Exactly how aspirin confers a risk reduction is not known, Holmes said. But the new research is in line with some previous studies. "We're appreciating more and more that cancer is an inflammatory disease, and aspirin is an anti-inflammatory," she said.
Aspirin might lower estrogens in the blood or might prevent early spread of cancer, the researchers speculated.
For the study, Holmes and her colleagues evaluated aspirin use among women at least one year after having been diagnosed with breast cancer. The women, diagnosed with stage 1, 2 or 3 breast cancer between 1976 and 2002, were all participants in the Nurses' Health Study.
During the follow-up, which went until a woman's death or June 2006, 341 women died of breast cancer and 400 had distant recurrences, or metastatic disease.
Aspirin would never be a substitute for recommended cancer treatments, Holmes said. And aspirin does have negative effects in some. "It can cause bleeding of the GI tract," she noted.
More study is needed, Holmes said, but for now, "if a woman has breast cancer and is taking aspirin for other reasons [such as arthritis or pain], she may take some comfort in knowing she might be doing something to help prevent her breast cancer from recurring."
"This is the largest study of aspirin use and breast cancer recurrence and survival to date," said Eric Jacobs, director of pharmacoepidemiology for the American Cancer Society. Previous research has produced mixed findings, he noted.
"While the results from this study are exciting, there are some important caveats," he said. Like Holmes, he noted that the findings do not prove cause and effect.
"As noted by the study authors, it is possible that survival results could have been influenced by women with recurrent breast cancer being advised to stop taking aspirin during chemotherapy, resulting in an overestimate of any benefit of aspirin use," Jacobs said.
Both Holmes and Jacobs agreed that it's premature to suggest that breast cancer survivors take aspirin with an aim of reducing breast cancer recurrence or death from the disease. Women should talk to their doctor about what's best for them, they said.
The American Cancer Society has more about breast cancer.
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