Background: The utilization of OncotypeDx in the setting of neoadjuvant chemotherapy (NCT) is not well defined. The objective of this study was to determine what proportion of hormone receptor (HR)-positive patients undergoing NCT would not benefit from chemotherapy based on OncotypeDx recurrence scores (RS) and predictors of a high RS as defined by the TAILORx trial.
Methods: The National Cancer Data Base was used to identify patients with unilateral clinical stage I-III HR+/Her2- breast cancer who had an OncotypeDx score and who had undergone NCT. Patients undergoing adjuvant chemotherapy were used as a comparison group.
Results: Of 307,666 patients, 41.8% had testing with OncotypeDx. Of these, 76.6% had no chemotherapy, 22.3% adjuvant chemotherapy, and 1.1% NCT. OncotypeDx testing in NCT patients increased from 4.9% in 2010 to 8.2% in 2015. Of NCT patients with OncotypeDx testing, 11.6% had RS < 11, 44.4% RS 11-25, and 43.9% RS > 25. In patients age ≤ 50 years, 14.5% had RS < 11, 12.4% RS 11-15, 31.4% RS 16-25, and 41.7% RS > 25. Predictors of RS > 25 on multivariable analysis included grade 3 tumors (odds ratio [OR] 3.83) and PR-negative tumors (OR 5.26) but not clinical T or N stage (p > 0.05).
Conclusions: More than half of patients with OncotypeDx testing are being overtreated with NCT, and a third of younger patients are being overtreated. Predictors of a high RS are reliably available at core biopsy, suggesting an application of OncotypeDx in determining the need for NCT for some HR-positive breast cancers.