Tamoxifen is prescribed to patients with breast cancer who have estrogen receptors that stimulate the growth of breast cancer.
It is also important to keep in mind that this treatment can be managed between 5 and 10 years.
Some of the women in the sample had heavy bleeding and hot flashes after initiating treatment with this drug, which can stop the growth of some tumors by blocking the activity of estrogen in breast tissue.
"Because the tumor cells have different estrogen receptors in the membrane that overexpress and the patients naturally produce estrogens, tamoxifen competes with them and blocks the receptors," explains Viviana Ariza Márquez, a student of biotechnology at the National University of Colombia ( VN).
"Within 30 patients, two poor metabolisers were identified, which means that they will not experience the therapeutic benefit with the given dose because they will not reach the limit of concentration in the blood", PhD student.
Another patient, who stopped the medication prematurely, was considered an ultrametabolizer.
The other women continued the dose and some changed treatment in aromatase inhibitors and anastrozole (commercial Arimidex).
These two drugs are alternatives that inhibit aromatases, responsible for converting androgens into estrogens, sex hormones involved in the appearance of female sex characteristics.
Patients were followed for this study and intermediary metabolites, genotyping and side effects were then identified.
The follow-up was performed in 30 women older than 54 years on average, 20 of them postmenopausal and 10 premenopausal, who consumed the drug four months before taking the sample.
Subsequently, the quantification of intermediate metabolites was performed in each of the patients.
"We evaluated the molecules in the blood produced by the cytochromes, to show whether they metabolized in the right way and there was a correlation with the intermediate metabolites," explains the researcher.
Subsequently, the symptoms referred by the patients were validated and followed up to identify whether they had responded to the treatment or not, and whether they had experienced side effects or a kind of relapse or recurrence of the disease.
"The biggest annoyance they experienced was bleeding, indicating that there is a possible thickening of the uterine lining, which is beneficial at the level of estrogen receptors in breast cancer, especially in breast tissue, because it blocks it, but it can block estrogen receptors stimulate the uterine lining, causing cancer, "explains the researcher.
As a result of the results of the research, the PhD student of U.N. It suggests a previous genotyping in patients to adjust the dose or to choose a therapeutic direction, as this is one of the most chronic diseases.