Amendment on the CYPTAM documentation study: effect of CYP2D6 genotype on pharmacokinetics and clinical outcome in tamoxifen treated breast cancer patients:;(P07.234 CYPTAM study) Validation and optimization of 13C-dextrometorphan breath test (DM-BT) for CYP2D6 phenotyping

Completed

• Conditions: breast cancer; 10006291

• Registration Number: NL-OMON38059
• Lead Sponsor: eids Universitair Medisch Centrum

Brief Summary

Not available

Detailed Description

Not available

Study Timeline

• Last Update Posted: 18 June 2024

Recruitment & Eligibility

• Status: Completed
• Sex: Not specified
• Target Recruitment: 6

Inclusion Criteria

1. Pre- and postmenopausal women who have already been using tamoxifen as part of a standard adjuvant therapy for newly diagnosed breast cancer;2. Willing and able to give written informed consent ;3. Age >= 18 years;4. Women who have already been enrolled in the first amendment on the CYPTAM documentation study ((P.07.234): Addition of CYP2D6 phenotyping by a 13C-dextrometorphan breath test (DM-BT)) and are currently on tamoxifen therapy for at least two months.

Exclusion Criteria

Inability or unwillingness to fast overnight prior to the study session.
Inability or willingness to abstain from drinking alcohol for 24 h prior to the DM-BT.
A diagnosis of pulmonary disease such as asthma or other respiratory disease associated with hypercapnia.
Existence of metabolic or gastrointestinal disorders which influence absorption and/or gastric emptying.
A demonstrated adverse reaction to previous dextromethorphan exposure.
Impaired hepatic function as defined by >= Grade 3 AST, alkaline phosphatase or total bilirubin or a history of liver chirrosis
Renal insufficiency
Use of medication known to slow gastric emptying or gastrointestinal motility within 24 hours of the breath test (known to slow gastric emptying or gastrointestinal motility •
The use of MAO inhibitors in the last two weeks
Use of dextrometorphan cough syrup/tablets within 24 hours of the breath test.

Study & Design

• Study Type: Interventional
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
<p>Correlation between CYP2D6 phenotype (by 13C-dextromethorphan breath test) and<br /><br>endoxifen serum levels.</p><br>

Secondary Outcome Measures

Name	Time	Method
<p>none</p><br>