Prediction of axillary pathologic response with breast pathologic complete response after neoadjuvant chemotherapy

Many breast cancer patients receive sentinel lymph node biopsy after neoadjuvant chemotherapy (NAC). We evaluated the axillary pathologic complete response (pCR) in relation to achievement of breast pCR. We evaluated 1044 patients who were diagnosed with invasive breast cancer and were treated with NAC followed by curative surgery at the Samsung Medical Center between January 2008 and December 2016. The pathologic node-positive rates in breast pCR patients were compared for different breast cancer subtypes and clinical nodal stages. Axillary pCR was achieved in 51.9% of the patients after NAC. In this case, the axillary pCR was associated with a biologic subtype (P < 0.0001), initial clinical tumor stage (P < 0.0001), clinical nodal stage (P = 0.0071), and breast pCR (P < 0.0001). In particular, axillary pCR correlated more than 80% with breast pCR (87.1%) or clinical nodal stage N0 (81.0%). Patients with breast pCR had 96.4% axillary pCR in clinical nodal stage N0, 86.1% in N1, and 84.7% in N2/N3. Our study may help to predict node-positive rates in patients with breast pCR after NAC according to clinical node stage. Patients with a high probability of achieving pCR might be suitable candidates for more minimal surgery.