February 17, 2010 — Breast cancer survivors who regularly took aspirin after completing treatment were 50% less likely than survivors who did not take aspirin to die or have a recurrence, according to a study published Wednesday in the Journal of Clinical Oncology, USA Today reports (Szabo, USA Today, 2/17). According to the Los Angeles Times, the results were "surprising" because at least five large studies have shown that an aspirin regimen has little to no effect on the risk of developing breast cancer.
Tumor growth is linked to inflammation, which is reduced by aspirin, the Times reports. Previous studies in lab dishes have shown that aspirin can slow the growth and invasiveness of breast cancer cells and stimulate the body's immune system to attack the cells. For the new study, Michelle Holmes of Brigham and Women's Hospital and colleagues analyzed self-reported data from 4,164 female nurses in the Brigham and Women's Nurses' Health Study who were diagnosed with breast cancer from 1976 through 2002. Among these women, there were 400 recurrences and 341 deaths by 2006.
Data were collected on the women's aspirin use starting 12 months after the initial diagnosis, when treatment for the cancer was assumed to be complete. According to the study, participants who took aspirin two to five days per week were 60% less likely to have a recurrence and 71% less likely to die from breast cancer. Women who took aspirin more frequently had a 43% lower risk of recurrence and a 64% lower risk of death. Taking aspirin once per week or taking acetaminophen did not produce a benefit, the study found.
Although the researchers did not monitor the dosages, the majority of women taking aspirin were taking 81 milligrams per day, which is less than a normal dose. Most said they took it for its heart benefits. Experts note that the women in the study who took aspirin were probably more health-conscious than other women, so their improved survival could be related to other lifestyle factors, the Times reports (Maugh, Los Angeles Times, 2/17). Holmes said in a statement, "If these findings are confirmed in other clinical trials, taking aspirin may become another simple, low-cost and relatively safe tool to help women with breast cancer live longer, healthier lives" (Fox, Reuters, 2/16).
Doctors cautioned that women who have not completed treatment for breast cancer should not take aspirin, as it can interfere with treatment and produce severe side effects, the Times reports (Los Angeles Times, 2/17). Laura Hilderley, chief medical officer for the American Cancer Society's New England division, suggested that women discuss the study with their physicians before taking aspirin, the Boston Globe reports (Smith, Boston Globe, 2/17).
John Glaspy, a breast cancer specialist at UCLA's Jonsson Comprehensive Cancer Center, said of the findings, "If true, it would certainly be a relatively easy, inexpensive, potentially safe intervention for women who have had breast cancer." However, he added that researchers "have been tricked by things like this before, especially in cancer epidemiology" (Los Angeles Times, 2/17).
Several breast cancer specialists also called for a review of aspirin and breast cancer after the study's release, the Globe reports. "Studies like today's generally shouldn't change clinical practice, they shouldn't lead to a change in women's health decisions," Eric Winer, head of women's cancer at Dana-Farber Cancer Institute, said. Rather, such studies "provide ... good evidence to move forward with a study asking whether this finding is real and how it should be used in clinical care," he said (Boston Globe, 2/17).