Cancer Prevention

As diabetes and breast cancer are both common conditions in women and share common risk factors, a special emphasis on obesity as risk factor for cancer incidence and mortality was evident throughout the meeting presentations. Pamela Goodwin, MD (Mount Sinai Hospital, University of Toronto) co-chaired a satellite symposium on diabetes and cancer and incorporated data from her own clinical trial evaluating metformin, a diabetes drug, as breast cancer prevention.

"One of the main reasons why the relationship between cancer and diabetes is of interest is we are in the midst of an obesity epidemic in the developed world," said Dr. Goodwin. "Evolution has not been able to keep up with changes in our lifestyle." Researchers looking at potential associations between diabetes, related factors, and breast cancer risk conducted a comprehensive literature review. They found that key risk factors for breast cancer appear to be body mass index and physical activity -- both of which are related to the risk of developing diabetes and can be modified through lifestyle changes.

While evidence is mounting that certain lifestyle factors can modify risk of developing breast cancer, there are also pharmacologic agents currently available. On a panel "Breast Cancer Chemoprevention: If Not Now, When?" Nancy Davidson, MD (University of Pittsburgh), a member of BCRF's Executive Board of Scientific Advisors, listed much evidence for the validity and benefits of chemoprevention. She highlighted barriers that discourage women from taking tamoxifen and raloxifene, the two FDA-approved drugs for breast cancer prevention, in spite of an abundance of data demonstrating their effectiveness and limited negative side effects. Dr. Davidson noted that the breast cancer field is far behind cardiovascular diseases in prevention and rallied her colleagues to strive towards the latter model to improve patient care.

In addition, Kala Visvanathan, MD, MHS (JHU) collaborated with colleagues in Ireland to explore the potential correlation between aspirin use and breast cancer mortality in women with stage I-III breast cancer. Recent studies have associated aspirin use with large reductions in breast cancer mortality, but why that may be the case is largely unknown. Also, the information on dose and duration of aspirin use are limited. Dr. Visvanathan and colleagues observed no mortality reduction in women who were exposed to low doses of aspirin. The benefits of aspirin exposure were associated with high doses and were greater in early stage, node negative disease. These findings may explain inconsistent results from previous studies and can inform future clinical trials.