A new US study suggests that regular taking of aspirin is linked to increased survival after a breast cancer diagnosis and also to a lower risk of the disease recurring. However, as this was an observational study that suggests a possible link and not a clinical trial, the researchers recommended women do not use these findings as a reason to start taking aspirin as a way to increase survival from, and prevent recurrence of, breast cancer.

An article on the study by senior author Dr Michelle Holmes of Brigham and Women’s Hospital and Harvard Medical School in Boston, Massachusetts, and colleagues, appears in the 16 February online issue of the Journal of Clinical Oncology.

According to a Reuters report, Holmes told the press that:

“This is the first study to find that aspirin can significantly reduce the risk of cancer spread and death for women who have been treated for early stage breast cancer.”

Previous studies in animals and lab cultures have suggested that aspirin may reduce the risk of breast cancer spread.

Holmes and colleagues wanted to examine whether aspirin use among women with breast cancer reduced their risk of death from the cancer.

For the prospective observational study, they looked at data on 4,164 women taking part in the Nurses’ Health Study.

The participants, who came from all over the US, had all been diagnosed with stage I, II, or III breast cancer between 1976 and 2002 and were followed until June 2006, or their death, whichever came first, wrote the authors.

They analysed the data to find any links between breast cancer mortality risk and days per week of aspirin use (measured as 0, 1, 2 to 5, or 6 to 7 days per week). This was assessed at least 12 months after diagnosis and updated.

The results showed that:

  • 341 of the participants died of breast cancer.
  • Aspirin use was linked to a decreased risk of dying from breast cancer, showing a significant linear trend (the more days of aspirin use per week, the lower the risk of dying).
  • After adjusting for potential confounders (including demographics and diet), compared to no use at all, the relative risk (RR) of dying from breast cancer after taking aspirin on 1 day per week was 1.07 (95 per cent confidence interval, CI, ranged from 0.70 to 1.63); for 2 to 5 aspirin days per week it was 0.29 (95% CI, 0.16 to 0.52), and for 6 to 7 aspirin days per week it was 0.36 (95% CI, 0.24 to 0.54), with test for linear trend, P < .001.
  • This relationship did not vary with breast cancer stage, menopausal status, body mass index, or estrogen receptor status.
  • There was a similar finding for risk of distant recurrence of breast cancer.
  • For distant recurrence, the adjusted RRs for 1, 2 to 5, and 6 to 7 days per week of aspirin use were respectively: 0.91 (95% CI, 0.62 to 1.33), 0.40 (95% CI, 0.24 to 0.65), and 0.57 (95% CI, 0.39 to 0.82), with test for trend, P = .03.

The authors concluded that:

“Among women living at least 1 year after a breast cancer diagnosis, aspirin use was associated with a decreased risk of distant recurrence and breast cancer death.”

In an interview with Diane Stern on WBZ Newsradio 1030 on Tuesday, Holmes said that they were careful not to include aspirin intake during the first year after cancer diagnosis because women are advised not to take aspirin during the first 12 months after diagnosis with breast cancer because the chemotherapy reduces their blood counts and aspirin carries an increased risk of bleeding, “that’s just not a good combination,” said Holmes.

She also stressed it was important to see if these findings are replicated in other studies before giving advice to women on whether they should take aspirin after being diagnosed with breast cancer.

When asked about the possible reasons for aspirin potentially reducing the risk of dying of breast cancer and making recurrence less likely, Holmes said that the “new thinking” was to view cancer as an inflammatory disease, and aspirin reduces inflammation.

Anyone considering taking aspirin on a regular basis is advised to consult their doctor first, because of the risk of stomach bleeding.

“Aspirin Intake and Survival After Breast Cancer.”
Michelle D. Holmes, Wendy Y. Chen, Lisa Li, Ellen Hertzmark, Donna Spiegelman, Susan E. Hankinson.
JCO, Feb 16 2010.

Sources: JCO, WBZ Newsradio 1030, Reuters.

Written by: Catharine Paddock, PhD