Further characterization of a ¹³C-dextromethorphan breath test for CYP2D6 phenotyping in breast cancer patients on tamoxifen therapy

• Published in: Journal of breath research Vol. 9; no. 2; p. 026003
• Main Authors: Opdam, F L, Modak, A S, Gelderblom, H, Guchelaar, H J
• Format: Journal Article
• Language: English
• Published: England 20-04-2015
• Subjects: Antineoplastic Agents, Hormonal - metabolism; Antineoplastic Agents, Hormonal - therapeutic use; Breast Neoplasms - drug therapy; Breath Tests - methods; Carbon Isotopes; Cytochrome P-450 CYP2D6 - genetics; Cytochrome P-450 CYP2D6 - metabolism; Dextromethorphan - pharmacokinetics; Excitatory Amino Acid Antagonists - pharmacokinetics; Female; Humans; Phenotype; Prospective Studies; Reproducibility of Results; Tamoxifen - analogs & derivatives; Tamoxifen - metabolism; Tamoxifen - therapeutic use
• ISSN: 1752-7163
• DOI: 10.1088/1752-7155/9/2/026003

In a previous study, we found that the CYP2D6 phenotype determined by (13)C-dextromethorphan breath test (DM-BT) might be used to predict tamoxifen treatment outcome in breast cancer patients in the adjuvant setting. However, large variation in the delta-over-baseline (DOB) values was observed in the extensive metabolizer predicted phenotype group based on single point measures. In the present work we aimed to analyze the variability of phenotype results and determine reproducibility to further characterize the clinical utility of DM-BT by introducing multiple breath sampling instead of single breath sampling and by administration of a fixed dose of (13)C-DM.