Insufficient vitamin D exposure may hinder metabolism of drug
Breast cancer patients may not metabolize tamoxifen well if they, along with patient-specific genetic factors, lack exposure to vitamin D during the winter months, according to new research.
Lawson Health Research Institute reports that almost 30% of patients are at risk of producing inadequate levels of endoxifen, the active form of tamoxifen, during the winter months, so the therapy may not be as beneficial.
Richard Kim, who is a physician at London Health Sciences Centre (LHSC) and holds the Wolfe Medical Research Chair in Pharmacogenomics at Western University says, “Our research has shown that patients with normal CYP2D6 activity can easily convert tamoxifen to endoxifen, whereas patients with no CYP2D6 activity have a significantly limited ability to convert tamoxifen to endoxifen.”
A patient’s ability to metabolize endoxifen levels can also be significantly reduced by the concurrent use of a common antidepressant, Kim discovered.
“These new clinical and genetic markers can aid physicians to better identify patients who will benefit from tamoxifen, as well as those patients at risk for suboptimal benefit,” says Kim.
Study results are published in the journal Breast Cancer Research and Treatment.
Source: Lawson Health Research Institute.