Tamoxifen is the most widely prescribed cancer drug worldwide for women with early-stage estrogen receptor positive (ER+), HER2-negative breast cancer. After finishing their treatment for the cancer, they are prescribed tamoxifen to prevent relapse. A 5- to 10-year treatment delays local and distant recurrence, prolongs overall survival, and reduces the incidence of contralateral breast cancer.

The standard dose of tamoxifen, 20 mg/day, is given to all women independent their BMI, inter-individual variation, liver disease and other drugs.

This could either lead to overdose, causing side effects or too low dose. According to several studies, Tamoxifen adherence to therapy may be as low as 50%, because many women suffer from severe side effects and discontinue medication. Poor adherence and early discontinuation are both associated with an increased risk of breast cancer events.


Therapeutic Drug Monitoring

An individualized prescription based on the concentrations of the drug in the blood would give the women an optimal treatment and reduce the side effects and enhance quality of living. However, the conventional method of TDM of Tamoxifen is complicated and expensive and therefore not widely used.

redhot’s products the rhelise™ kit and the tamoxifen analyzing kit are ideally for TDM

The LC-MS/MS Tamoxifen kit is intended for the quantitative determination of tamoxifen, endoxifen and 4 – hydroxytamoxifen in whole blood.


A Summary of the scientific litteratur

White paper Tamoxifen