Impact of Body Weight on Pharmacokinetic Analysis of Doxorubicin + Cyclophosphamide in Breast Cancer

This single site study will be conducted at the UT Southwestern Simmons Cancer Center. This study is designed to measure drug concentrations in the blood of 18 female breast cancer patients who require doxorubicin (30 minute infusion) and cyclophosphamide (30 minute infusion) as part of standard medical care. Up to a total of 40 adult female participants will be consented for the study at the cancer center. Eighteen of these participants are needed to complete the study. The others will likely be screen failures. The participants will have no more than 100 ml of blood drawn via a peripheral intravenous catheter just prior to the doxorubicin infusion, and then at 0.5, 1, 1.5, 2, 3, 4, 5, 12-24, and 24-72 h after the beginning of the doxorubicin infusion. The 5 hour blood draw is optional. The intravenous catheter will be removed when the participant is discharged from the cancer center on day 1. The participant will be asked to return to the cancer center at 12-24 and 24-72 hours to have the final 2 blood draws conducted. The participants must be treated with Doxorubicin and Cyclophosphamide in order to participate in this pharmacokinetic analysis study.