Eric P. Winer, M.D. is chief scientific advisor for Susan G. Komen for the Cure®
August 25, 2009 — Tamoxifen is a hormone therapy that has been used for over 30 years to treat breast cancers that are hormone-receptor positive. Since hormone-receptor positive cells need estrogen to grow, tamoxifen can slow or stop the growth of cancer cells. Tamoxifen can be used to treat breast cancer in both pre-menopausal and postmenopausal women.
A new study published in Cancer Research has focused on women who developed a second breast cancer in the opposite breast years after an initial diagnosis of breast cancer. Results from this study suggest that women who took tamoxifen for five years or more were at greater risk of developing an estrogen receptor negative cancer in the other breast than those who did not take tamoxifen. The entire study was relatively small, and the conclusions were based on an even small number of patients.
There is no question that this finding needs to be confirmed in a more definitive study. Even if we accept that there is an increase in estrogen receptor negative cancers, overall there was a 40 percent reduction in the risk of developing breast cancer in the opposite breast. Therefore, the benefits of tamoxifen in preventing contralateral breast cancer would likely outweigh the increased risk of an estrogen receptor negative cancer. More importantly, tamoxifen prevents the development of metastatic breast cancer , which can be life threatening.
We know that the use of tamoxifen in women with hormone receptor positive breast cancer saves lives. Given the established benefits of tamoxifen, the study does not change clinical practice for any patient and, at this time, should not be factored into clinical decision-making.
About Eric P. Winer, M.D.
Eric P. Winer, M.D. is chief scientific advisor for Susan G. Komen for the Cure®. In that role, Dr. Winer leads a group of top-level scientific and medical advisors on Komen’s Scientific Advisory Board, which guides the organization on scientific and medical issues related to breast cancer. He helps shape Komen’s research grants strategy as well as messages regarding emerging breast cancer issues and educational messages.
