Seasonal Effect Revealed For Tamoxifen In Breast Cancer Treatment

It appears that low Vitamin D correlates to less effective Tamoxifen, meaning that in winter the Tamoxifen we take might not be working for us as well as it could be.  Interesting to me that the study doesn't recognize the importance of measuring our Vitamin D levels (which the Cancer Centre here has never tested for me despite the already documented link between breast cancer and low Vitamin D - go figure) and neither does it suggest increasing our Vitamin D levels via supplementation. What I infer from this report of the study is that they're suggesting perhaps we need more Tamoxifen during winter months instead. Hmmmm ...

Seasonal Effect Revealed For Tamoxifen In Breast Cancer Treatment:

"For women diagnosed with a form of breast cancer known as estrogen receptor positive (ER+) breast cancer, tamoxifen is an essential drug used in the treatment and prevention of recurring breast cancer. Currently, tamoxifen is used in a one-size-fits-all approach where the same dose is prescribed for every patient.  

New research at Lawson Health Research Institute has found that in addition to patient-specific genetic factors, lack of exposure to vitamin D during the long winter months affects the body's ability to metabolize the drug. The findings, which have been reported in the journal Breast Cancer Research and Treatment, are the first to identify this seasonal effect. Dr. Richard Kim, who is a physician at London Health Sciences Centre (LHSC) and holds the Wolfe Medical Research Chair in Pharmacogenomics at Western University, reports that during the winter months nearly 30 percent of patients are at risk for less than optimal level of the active form of tamoxifen, called endoxifen, and therefore may not benefit as much from the therapy. "  (Read more at the link above)