Possible Interaction Identified Between Tamoxifen and Hot Flash Drug

Date: June 1, 2004

Journal of National Cancer Institute, December 3, 2003

Researchers are investigating interactions between the commonly used breast cancer drug tamoxifen and the antidepressant drug paroxetine, used to treat hot flashes. The interactions could potentially alter the effectiveness of tamoxifen. A team of scientists from the Johns Hopkins Kimmel Cancer Center, Indiana University and the University of Michigan found that women taking both drugs had decreased levels of a newly identified molecule called endoxifen, a byproduct of tamoxifen in its processed form, which could indicate that the tamoxifen is not being fully metabolized in these people.  

“Right now, these results do not change current treatment recommendations for women on adjuvant tamoxifen therapy who are dealing with hot flashes,” says Vered Stearns, M.D., assistant professor of oncology at the Kimmel Cancer Center and lead investigator in the study.  “We need larger studies to understand the impact of endoxifen and CYP2D6 on tamoxifen’s effectiveness.”

Check our Web site and the next issue of Promise & Progress for new updates on this and other research presented at the 2004 American Society of Clinical Oncology (ASCO) meeting.

This research was funded by the National Institutes of Health, the Damon Runyon Cancer Research Foundation, Fashion Footwear Association of New York and GlaxoSmithKline Pharmaceuticals.