Association of pathologic non-complete response of axillary node with outcome after neoadjuvant chemotherapy in node positive breast cancer

e12101 Background: The pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) correlates with better outcome in specific subtype of breast cancer and the axillary nodal pCR (N-pCR) rate are more common than breast pCR (B-pCR). While only a few studies to compare the survival in terms of B-pCR and N-pCR, and no study compare between the outcome for those non pCR either in breast or axillary node. Methods: A cohort of 968 cytologically proved nodal metastatic breast cancer (cT1~4N1~2) received NAC in a single medical center between 2005~2017 were analyzed retrospectively. NAC regimen included anthracycline and taxanes in all patients, Trastuzumab was used in 308(70.3%) HER2(+) patients. The percentage of both breast and axillary pCR (T-pCR) 、B-pCR and N-pCR were compared in different subtypes. The impact of T-pCR、B-pCR and N-pCR to DFS and OS were analyzed using univariate and multivariate Cox proportional hazard model. Results: The median follow-up time was 45 months. The median age was 49 years old, average tumor size was 4.2cm, and 543 (56.1%) patients were N1 disease. 382(39.5%) patients were HR(+) HER2(-), 222(22.9%)were HR(+)HER2(+),216(22.3%) were HR(-)HER2(+) and 148(15.3%) were HR(-)HER2(-). After NAC, T-pCR was found in 213 (22.0%) patients, B-pCR and N non-pCR in 31 patients, N-pCR and B non-pCR in 245 patients and T non-pCR in 479 patients. N-pCR rate(47.3%) were significantly higher than B-pCR(25.2%) and this trend found in all subtypes ( P