P323 Nomogram predicting axillary PCR after neoadjuvant chemotherapy in node-positive breast cancer

Abstract

Goals: The purpose of this study was to investigate the factors that predict the axillary pathologic complete response (pCR) and develop a nomogram predicting the probability of axillary pCR in cytologically-proven axillary node-positive breast cancer patients who received neoadjuvant chemotherapy. Methods: We reviewed the records of 415 patients with cytologically-proven node-positive breast cancer who were treated with neoadjuvant chemotherapy and followed by surgery between 2008 and 2012. Baseline patient and tumor characteristics, chemotherapy regimen, tumor and nodal response were analyzed. Nomogram was developed using a multivariable logistic regression model in a training cohort and validated in an external cohort of 110 patients between 2013 and 2014. Results: Axillary pCR was achieved in 38.8% of the patients who underwent ALND after NCT. Axillary pCR was associated with early clinical nodal status, negative estrogen receptor status, positive HER2 status treated with trastuzumab, clinical nodal response and clinical tumor response on the multivariate analysis. Nomogramwas developed on the basis of significant and predefined predictors. It had good performancewith discrimination (AUC 0.822, 95%CI 0.781–0.862) and calibration (P = 0.8806). The nomogram was validated (AUC 0.828, 95%CI 0.754–0.903), indicating good predictive power of the model when applied to the external validation data set. Conclusion: Our nomogram may be useful to predict the axillary pCR after neoadjuvant chemotherapy in patients with node-positive breast cancer. Patients with a high probability of achieving axillary pCR could be spared axillary lymph node dissection, avoiding postoperative morbidity. Disclosure of Interest: No significant relationships.