The Importance of Complete Pathologic Response After Neoadjuvant Systemic Treatment in Breast Cancer Research and Practice: Reply

Abstract

We agree with the comments of Dr. Kalogerakos [1] in his letter regarding the recent article [2] in which we describe our nodal response rates following neoadjuvant endocrine therapy and neoadjuvant chemotherapy for breast cancer. Pathologic complete response (pCR) rates following neoadjuvant systemic therapy are predictive of long-term survival benefits [3]. Our results demonstrate that pCR rates may differ between the primary breast tumor and the nodal tissue within an individual patient. Of the 19 patients who had a complete nodal pathologic response to neoadjuvant chemotherapy, only 4 (21%) also had a complete response in the breast. Conversely, there were 12 (17%) patients who had a complete pathological response in the breast following neoadjuvant chemotherapy, but had persistent disease in the nodal tissue. Future neoadjuvant trials will need to address not only the primary breast tumor response but also the nodal response in determining the pCR and its relationship to recurrence rates and overall survival. We recognize the limitations of our single-institution, retrospective study in its inability to identify the patient and tumor characteristics that may predict a pCR following neoadjuvant systemic therapy. The only factor associated with a difference in the rate of a nodal pCR was the type of neoadjuvant therapy used; all 19 patients with a nodal pCR received neoadjuvant chemotherapy and none received neoadjuvant endocrine therapy (P 0.05). The reasons for this absence of a nodal pCR following neoadjuvant endocrine therapy are unclear. Perhaps the mechanism of action for endocrine agents differs in such a way as to result in less tumoricidal activity than that of chemotherapeutic agents. To be able to predict which specific treatments will benefit which specific patients and result in the highest overall pCR rates for all neoadjuvant regimens must be the ultimate goal of future trials. This will allow physicians to personalize individual patient treatment and optimize outcomes.