CYP2D6 Genotype Should Not Be Used for Deciding About Tamoxifen Therapy in Postmenopausal Breast Cancer
Year: 2013
Type: article
Abstract: al 1 regarding our current knowledge about the importance of CYP2D6 status when prescribing tamoxifen concluded that results from ongoing prospective studies in the metastatic/neoadjuvant setting will not help to close the circle on this topic.We do agree with their conclusion that published retrospective studies-so far-do not provide sufficient evidence to determine whether or not CYP2D6 testing should be performed in daily practice.However, we believe that two registered, ongoing, prospective studies in the neoadjuvant/metastatic setting (the European CYPTAMBRUT-2 study [Study to Assess Response to Tamoxifen in (cT3)/Inoperable Locally Advanced/Metastatic Estrogen Receptor-Positive Breast Cancer by the "Tamoxifen Activity Score" Based on Drug Interaction and Polymorphisms in Genes Coding for Tamoxifen Metabolising Enzymes] and the study of the Eastern Cooperative Oncology Group E3108 [Tamoxifen Citrate in Treating Patients With Metastatic or Recurrent Breast Cancer]) will provide answers that are not available from retrospective studies and which are likely to be relevant in the adjuvant setting.Although metastatic breast cancer differs in many respects from early breast cancer, in which tamoxifen helps to eradicate subclinical disseminated disease, metabolic pathways of tamoxifen for efficacy are disease-stage independent.It is unlikely that endoxifen levels matter in the adjuvant setting if they do not matter in the metastatic setting.However, if endoxifen levels do matter in metastatic disease, it does probably but not necessarily follow that this applies in the adjuvant setting.As principal investigators of the European CYPTAMBRUT-2 study, we would like to stress that this study includes only patients in the first-line metastatic/neoadjuvant setting.Patients with hormoneinsensitive or aromatase inhibitor-refractory disease were excluded from this study, as were premenopausal women.The study has so far recruited 240 of 260 patients.
Source: Journal of Clinical Oncology
Language: English
Subfield: Pharmacology
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2065571980