Impact of Genomic Assay Testing and Clinical Factors on Chemotherapy Use After Implementation of Standardized Testing Criteria

Abstract

Purpose: For clinically appropriate early-stage breast cancer patients, reflex criteria for Oncotype DX ordering (“the intervention”) was implemented at our comprehensive cancer center, which reduced time-to-adjuvant chemotherapy initiation. Our objective was to evaluate Oncotype DX ordering practices and chemotherapy use pre- and post-intervention. Methods: We examined medical records for 498 patients who had definitive breast cancer surgery at our center. The post-intervention cohort consisted of 232 consecutive patients who had Oncotype DX testing after reflex criteria implementation and were compared to a retrospective cohort of 266 patients, including those who did and did not have Oncotype DX ordered before reflex criteria implementation. Factors associated with Oncotype DX ordering pre- and post- intervention were examined. We used multivariate logistic regression to evaluate factors associated with chemotherapy receipt among patients with Oncotype DX testing. Results: The distribution of Oncotype DX scores, the proportion of those having Oncotype DX testing (28.9% vs. 34.1%) and those receiving chemotherapy (14.3% vs 19.4%) did not significantly change between pre- and post-intervention. Age <65 years, stage II, grade II, 1-3+ nodes, and tumor size >2cm were associated with higher odds of Oncotype DX testing. Among patients having Oncotype DX testing, node status and Oncotype DX scores were significantly associated with chemotherapy receipt. Conclusion: Our criteria for reflex Oncotype DX ordering appropriately targeted patients for whom Oncotype DX would typically be ordered by providers. No significant change in the rate of Oncotype DX ordering or chemotherapy use was observed after reflex testing implementation.