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

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)