James N. Ingle, MD
Head, Breast Cancer Research Program, Mayo Clinic Cancer Center
Foust Professor of Oncology, Mayo Medical School
Rochester, MN

Tamoxifen remains one of the most important drugs for the treatment of breast cancer and recent information indicates that a patient's genetic make-up is related to tamoxifen's metabolism (called pharmacogenetics) and the amount of benefit a patient receives. The Mayo Clinic researchers have discovered that the different metabolites of tamoxifen have different effects on the estrogen receptor, explaining the impact of CYP2D6 genotype on clinical outcomes seen in women treated with tamoxifen. This knowledge provides the basis for developing true personalized endocrine therapy of breast cancer.