ONCOTYPE Dx MAY GUIDE A NEOADJUVANT APPROACH FOR AXILLARY DOWNSTAGING IN ER+/HER2- BREAST CANCER
Few studies have examined the utility of Oncotype Dx Recurrence Score® (RS) in predicting tumor response in the neoadjuvant setting. While neoadjuvant chemotherapy (NAC) or hormonal therapy (NAH) is crucial to downstage the axilla, most patients with ER+/Her2- infrequently result in a complete pathological response (pCR), not sparing patients an axillary node dissection. In the Annals of Surgical Oncology, Pardo and Fan et al. studied the association of RS with axillary pCR in 158 patients. The patients selected from the National Cancer Database all had cT1-2, N1-2, ER+/Her2- invasive ductal carcinoma treated with NAC. Patients with invasive lobular carcinoma were excluded from this study.
Results: In patients with RS > 30, the axillary pCR rate was 28%. This was significantly higher than the 10% axillary pCR rate in those with RS < 30 (p=0.03).
Comments: Whereas there is often some hesitation in using NAC in patients with ER+, Her2- disease. Pardo and Fan's study suggests that the Oncotype Dx Recurrence Score® performed on the initial diagnostic core biopsy can identify patients who would benefit from a neoadjuvant therapy approach. Unfortunately, patients with invasive lobular carcinoma were excluded, and therefore this study may not be applicable.