Oncotype DX Recurrence Score as a Predictor of Response to Neoadjuvant Chemotherapy.

Background: The Oncotype DX assay has been validated in predicting response to adjuvant chemotherapy in breast cancer. Its role in neoadjuvant chemotherapy (NCT) has not been established.

Methods: The National Cancer Database was used to identify all patients with T1-T3, ER-positive, HER2-negative primary invasive breast cancer diagnosed from 2010 to 2015 who had Oncotype DX recurrence scores (RS) and received NCT. RS were classified as low, intermediate, or high. Unadjusted and adjusted regression analyses were performed to determine the association between pathologic complete response (pCR) and RS.

Results: A total of 989 patients (mean age, 54.6 years) with available RS who underwent NCT were identified. RS were low in 227 (23.0%) patients, intermediate in 450 (45.5%) patients, and high in 312 (31.5%) patients. Most patients had a T1 (431 [43.6%]) or T2 tumor (451 [45.6%]). Most had N0 disease (757 [76.5%]). Tumor grades were 1 (123 [12.4%]), 2 (517 [52.3%]), or 3 (349 [35.3%]). pCR was achieved by 42 (4.3%) patients. Adjusted multivariable analysis showed a significant association between pCR and high RS (odds ratio 4.87; 95% confidence interval 2.01-11.82).

Conclusions: High Oncotype DX RS was associated with pCR after NCT in this national cohort of ER-positive, HER2-negative patients. Oncotype DX testing could help to identify patients most suited for NCT and should be considered for incorporation into the multidisciplinary decision-making process.