Prevalence of Genetic Polymorphisms in Genes Coding for Tamoxifen Metabolising Enzymes, in Postmenopausal ER-positive Breast Cancer Patients According to Uterine and Biochemical Changes and Tolerability of Tamoxifen.
We will study the impact of the 'tamoxifen activity score' - based on functional genetic
polymorphisms for tamoxifen metabolism and the use of drugs that interfere with
tamoxifen-against tamoxifen related endpoints like uterine changes and subjective menopausal
The prevalence of genetic polymorphisms in the CYP2D6 and other genes and differences in
usage of drugs interacting with tamoxifen metabolism will be compared between women with and
those without endometrial thickening on one hand and between women with and those without
hot flashes on the other hand. Tamoxifen use in adjuvant setting.
- "Tamoxifen activity score" (23): The endpoints will be correlated with a predefined
'tamoxifen activity score' which is based on the presence of single nucleotide
polymorphisms (SNP) in relevant genes combined with the effect of well known drugs that
interfere with the metabolism of tamoxifen. The 'tamoxifen activity score' has been
associated with tamoxifen compliance by a group in the US (23). The score will be
adapted to the Belgian situation based on the prevalence of these SNPs in a Belgian
population of volunteers for blood donation and consecutive breast cancer patients.
- The study setting are postmenopausal women with an early ER- positive breast cancer and
not previously treated with an endocrine agent or hormone replacement therapy, with an
intact uterus and clearly measurable thin endometrium/uterus. N =250
Allocation: Non-Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Treatment
change in endometrial thickness or uterine volume
Belgium: Federal Agency for Medicinal Products and Health Products