This study will examine how the body handles etoposide, a drug used to treat breast cancer.
The knowledge gained may lead to more effective use of the drug with fewer side effects in
Breast cancer patients who are receiving etoposide as part of their treatment may
participate in this study. Patients will have 18 blood samples (about a teaspoon or less
each) drawn over a 72-hour period during and after their infusion of etoposide. The initial
blood samples cannot be taken from the same intravenous line (small tube placed in a vein)
used to deliver the etoposide, so a second line may have to be placed temporarily to obtain
Etoposide is a topoisomerase II inhibitor that has a broad range of anticancer activity at
conventional doses (100 mg/m(2) daily x 5 days) and is administered in high doses (greater
than 1200 mg/m(2)) as a component of pre-transplant myeloablative chemotherapy regimens.
Etoposide pharmacokinetics are linear over a 30-fold dose range, but disposition is highly
variable. Etoposide is highly protein bound (95%) to albumin, but protein binding (and
therefore free drug concentrations) vary widely in cancer patients. Etoposide is eliminated
by metabolism and renal excretion, which may also contribute to the variability. The
pharmacokinetics of etoposide will be studied in patients receiving high-dose etoposide as
part of their pre-transplant preparative regimen, and pharmacokinetic parameters generated
from pharmacokinetic modeling will be correlated with clinical and laboratory
characteristics and toxicity in order to develop more rational dosing methods.
Age greater than or equal to 18 years.
Patients with breast cancer who are entered on existing Medicine Branch protocols that
include high-dose etoposide.
Must be able to provide informed consent.