Breath Test for Women Receiving Tamoxifen in the Prevention or Treatment of Breast Cancer

You may be eligible if

• DISEASE CHARACTERISTICS:
• Eligible to receive tamoxifen for 6 months for either the prevention or treatment of non-invasive or invasive, stage I-III breast cancer
• CYP2D6 genotype known
• * Patients determined to be CYP2D6 poor metabolizers (by determination of a genotype test by their Mayo physician prior to study registration) are eligible to proceed with the initial breath test only
• Hormone receptor status not specified
• PATIENT CHARACTERISTICS:
• Menopausal status not specified
• ECOG performance status 0-2
• Life expectancy \> 6 months
• No known impaired hepatic activity defined as ≥ grade 3 AST, alkaline phosphatase, or total bilirubin
• No pulmonary disease (e.g., asthma or other respiratory disease) associated with hypercapnia
• No uncontrolled metabolic disease (e.g., diabetes in the presence of gastroparesis, uncontrolled congestive heart failure, or uncontrolled gastrointestinal disorders \[e.g., GERD\])
• No prior adverse reaction to dextromethorphan
• No history of chronic liver disease (e.g., hepatitis B or hepatitis C, alcoholic liver disease, cirrhosis, or fibrotic disease)
• Able and willing to fast overnight prior to the study session
• Willing to return to Mayo Clinic for follow-up
• Willing to provide biologic specimens
• PRIOR CONCURRENT THERAPY:
• More than 24 hours since prior medications known to slow gastric emptying or gastrointestinal motility (e.g., alcohol, opioid analgesics, anticholinergics \[e.g., antihistamines\], and loperamide)
• More than 4 weeks since prior and no concurrent CYP2D6 inhibitors or concurrent serotonin-reuptake inhibitors known to be potent CYP2D6 inhibitors (e.g.,paroxetine \[Paxil®\] and fluoxetine \[Prozac®\]
• * If mild to moderate inhibitors of CYP2D6 are medically necessary, patients may go back on after the 8-week time point
• More than 4 weeks since prior and no concurrent monoamine-oxidase inhibitors (e.g., furazolidone, phenelzine, procarbazine, selegiline, and tranylcypromine)