Aspirin may reduce breast cancer recurrence! One of the larger studies is the Nurse's Health Study published in the Journal of Clinical Oncology in March 2010. This was a large observational study performed over a period of up to 30 years that found a 50% reduction in breast cancer mortality with aspirin use. Using aspirin (ASA) 6 to 7 days per week was better than less use. In April, 2015, a meta-analysis of 16 studies (reviewed by researchers at the First Hospital of China Medical University) showed a 25% reduction in recurrence with aspirin use. In the hierarchy of studies, the meta-analysis is better than the observational study. So, I suspect the recurrence reduction will be closer to 20%. There certainly is a lot of validity in these studies. A more recent prospective cohort that was completed at Cardiff University School of Medicine found a 20% reduction in recurrence. Unfortunately data is mixed. In June 2016, a prospective cohort study evaluating ASA and NSAID (non-steroidal anti-inflammatory drugs) use in 34,188 breast cancer patients found no benefit in the 7 year period examined.
Although I'm less than 50 years old, I take a daily aspirin due to the potential benefit. NSAID use such as ibuprofen seems to confer the same benefit. So, if I need an Aleve, I hold my aspirin that day. The one thing these studies did confirm was there were no serious adverse effects in any of the women. Aspirin has several additional benefits for including prevention of heart attacks, strokes, and blood clots. However, there are many contraindications to taking aspirin, so always consult your doctor first. Aspirin must be discontinued at least seven days prior to surgery.
Please see the article on The Aspirin for Breast Cancer (ABC) Trial conducted by researchers at the Dana-Farber Cancer Institute. It will be the first randomized controlled trial assessing aspirin use and risk of recurrence. Please see the other centers involved at this link to the website of the National Cancer Institute. Here's a multi-center phase III trial for aspirin 325 mg daily on the website of the National Cancer Institute.
*Do not take this during chemotherapy, radiation therapy, or after treatment without consulting your doctor.