Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis




Pharmaceutical Sciences

First Advisor

Dr. Val Adams

Second Advisor

Dr. Jeff Talbert, Dr. Emily Van Meter


The decision for adjuvant therapy in women with early stage breast cancer (ESBC) has historically been guided by the presence or absence of specific biological markers (hormone and HER2 receptors), age, and extent of nodal involvement. Oncotype DX® is a validated assay that quantifies protein expression that can predict the risk of cancer recurrence. This study evaluates if the use of Oncotype DX® impacts chemotherapy prescribing in ESBC. This retrospective, cohort study identified patients with ESBC from a large commercially insured population from January 2007 through June 2009. Patients were identified as having ESBC by utilizing procedure and diagnosis codes to indicate that a sentinel lymph node biopsy had been performed. Hormone receptor status was verified by patients receiving at least one month of hormonal therapy including: tamoxifen, anastrozole, letrozole, or exemestane. Exclusion criteria will include patients less than 18 years of age, procedure codes indicating axillary lymph node dissection, or charges for trastuzumab. The administration of Oncotype DX® was not found to significantly affect a physician’s decision to prescribe chemotherapy. However, there were significant regional differences in Oncotype DX® utilization by region. Future studies should be conducted at a population level to determine the effects of Oncotype DX®.