A UNC–led team examined the feasibility of using the function of a gene important in metabolizing tamoxifen, called CYP2D6, to detect a change in tamoxifen drug levels corresponding to a change in tamoxifen dose. They demonstrated that establishing an individual’s dose of tamoxifen based on the function of the gene results in higher drug concentrations in patients with reduced gene function.
William Irvin Jr, MD, first author of the study says, “We showed that doubling the tamoxifen dose in patients whose CYP2D6 function was low increased the concentrations of drug in their system. We do not know if or how this will impact the efficacy of tamoxifen, and I caution strongly against changing clinical practice, but this study shows us that in the future a patient’s individual genetic information may be an important factor in drug dosing.”
Irvin is an assistant professor of medicine who specializes in the treatment of breast cancer at UNC and a member of UNC Lineberger.
Read more about the study, published online ahead of print on July 18, 2011 in the Journal of Clinical Oncology.