Torrevieja, October 24, 2018. Approximately 7 of every 10 patients diagnosed with breast cancer express the hormonal oestrogen receptor, and are therefore candidates for a treatment to present the appearance of second tumours sensitive to inhibitors of this hormonal receptor. “Most patients are treated with tamoxifen,” explains biologist Elena Martínez, geneticist with the Quirónsalud Torrevieja Oncology Platform, “this treatment, a selective modulator of the oestrogen receptor, consists of taking a tablet for five years after the surgery. This medication helps reduce the annual rate of relapses by at least half, and decides mortality by one third.”
The response of these patients to tamoxifen varies widely, and approximately 35% do not respond to this therapy, and may experience a relapse. This resistance may be due to several factors. As Doctor Martínez explains, “one of the most important factors is the huge genetic diversity of one of the enzymes tasked with transforming tamoxifen into its active form, called CYP2D6. Therefore, depending on the genetic characteristics of this enzyme in each patient, we can classify patients into several categories: those considered fast, intermediate and slow metabolisers.”
Thanks to this innovative test performed at the Molecular Genetics department, in collaboration with the Oncology Department of the Clinical Oncology Platform at Hospital Quirónsalud Torrevieja, it’s possible to establish the characterisation of this enzyme and find the patients that are “slow metabolisers” and incapable of transforming tamoxifen into its active form, and thus would not benefit from this form of prevention of the disease.
This genetic study is endorsed by the international organisation Clinical Pharmacogenetics Implementation Consortium, due to its efficacy in diagnosing the patients who are candidates for substituting tamoxifen treatment for one that would be more effective in their cases.