LOS ANGELES – Women who take aspirin regularly after their breast cancer goes into remission are about 50 percent less likely to suffer a recurrence or to die from the disease, according to new findings from the ongoing Nurses’ Health Study.
The results, reported Tuesday in the Journal of Clinical Oncology, are surprising because at least five large studies have shown that taking aspirin regularly has no effect on the risk of developing breast cancer in the first place. The study’s authors described the findings as surprising and worthy of follow-up, but even they cautioned that survivors shouldn’t yet begin prophylactic aspirin use.
The new results could be because the process of metastasis of breast cancer is different than that of initiation and could thus be susceptible to influence by aspirin. Or it could be simply that there is some other shared characteristic of women who took aspirin that produced the beneficial effect.
Nonetheless, if the findings can be replicated in a large controlled trial in which women are randomly assigned to take either aspirin or a placebo, the common drug could provide an important way to reduce deaths from the disease, said Dr. Lori Pierce of the University of Michigan, a spokeswoman for the American Society for Clinical Oncology. Breast cancer is expected to strike more than 192,000 American women this year, killing more than 40,000 of them.
Whether aspirin ultimately proves beneficial or not, doctors cautioned that women being treated for breast cancer should not take the medication. It can interfere with the therapy, producing severe side effects.
The research is not without foundation. Metastasis is clearly linked to inflammation, and aspirin reduces inflammation. Studies in laboratory dishes show that aspirin can inhibit the growth and invasiveness of breast cancer cells and stimulate the immune system to attack the cells.
Based on these lab studies, Dr. Michelle Holmes of Brigham and Women’s Hospital in Boston and her colleagues studied self-reported data from 4,164 female nurses enrolled in the hospital’s Nurses’ Health Study who were diagnosed with breast cancer between 1976 and 2002. By 2006, there had been 400 recurrences and 341 deaths among the nurses.
The team collected data on the women’s aspirin use beginning 12 months after diagnosis. They found that women who took aspirin two to five days per week were 60 percent less likely to have a recurrence and 71 percent less likely to die from breast cancer. Those taking it more frequently had a 43 percent lower risk of recurrence and a 64 percent lower risk of death.