Determining the benefit of neoadjuvant chemotherapy in reduction of axillary dissection rates in Z0011 trial cohort with high nodal burden.

Background: In breast cancer patients fulfilling the Z0011 trial criteria, axillary lymph node dissection (ALND) is reserved for patients with a high nodal burden of ≥3 metastatic nodes. In this group of patients, to avoid an ALND, neoadjuvant chemotherapy (NACT) could be given instead to achieve nodal pathological complete response (pCR). However, the benefit of NACT in achieving nodal pCR and avoiding ALND in this group of patients is unknown. We aimed to determine the nodal pCR rate in this group of patients who otherwise would have needed an ALND. Methods: cT1-2N0 breast cancer patients, with histologically proven nodal metastasis, who underwent NACT were identified from a prospectively maintained database. The sonographic criteria of ≥3 abnormal nodes, which has been reported as highly predictive of high nodal burden, was then used to identify the high nodal burden group. Nodal pCR was determined based on the ALND following NACT. Results: Twenty-four patients with high nodal burden were identified. Mean age was 55.2 years. 91.7% had invasive ductal carcinoma and 29.2% had grade III cancer. 54.2% achieved nodal pCR which was associated with ypT (P=0.006). Nodal pCR was 75%, 70% and 30% in the triple negative, human epidermal growth factor receptor2 (HER2) positive and ER/PR+HER2- tumors, respectively. Conclusions: In the postulated T1-2 breast cancer patients with high nodal burden, needing an upfront ALND, NACT could result in nodal pCR of 54.2%, with higher pCR in certain subtypes. Hence, to minimize ALND risk, NACT should be offered in this high nodal burden group.