Why undergoing this examination?

Tamoxifen is the most selective modulator used in the treatment of breast cancer. One of the main causes of the difference in the interindividual response to tamoxifen is the presence of alleles in the CYP2D6 gene associated with a null, decreased or increased enzyme activity compared to normal. The CYP2D6 gene codes for the enzyme CYP2D6, which converts tamoxifen to endoxifene, its active metabolite and the main responsible for its antineoplastic activity. As a consequence, a decrease in CYP2D6 enzyme activity results in a lower efficacy of tamoxifen treatment.

What is this exam?

The Genetic Profile FG – Onco Tamoxifen studies the 11 major allelic variants of the CYP2D6 gene with known clinical relevance. These 11 allelic variants provide coverage greater than 97% of all alleles described in this gene. The aim of the analysis is to identify those patients with an increased likelihood of less effective tamoxifen treatment and prone to develop serious side effects.

For whom is it indicated?

• Patients on pharmacological treatment who wish to customize medication based on their genetic profile
• Patients in whom pharmacological treatments do not show the expected results


Next Generation Sequencing (NGS)


• Guaranteed from the experience of the Synlab group, the absolute European leader in laboratory diagnosis.
• Detailed report including, in addition to the type of metabolism of each enzyme, which drugs can generate toxic effects and adverse reactions, as well as dose recommendations.
• Information provided by the analysis allows the selection of the most appropriate drug, and determines the most appropriate dose for each patient.
• Genetic counseling available at no additional cost, according to the needs of each client.

Extra information

DOCUMENTATION – Available on Extranet for clients:
• Informed Consent
• Clinical Questionnaire
• Fasting is not necessary for the test.

Delivery Time
20 working days
Type of Sample
5 mL whole blood in EDTA tube

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