Histologic Grade and Decrease in Tumor Dimensions Affect Axillary Lymph Node Status after Neoadjuvant Chemotherapy in Breast Cancer Patients

PURPOSE: The purposes our study was to find out any histologic factors associated with negative conversion of axillary lymph node (ALN) after neoadjuvant chemotherapy (NAC). We also evaluated the association between the decrease in size of primary breast tumor and negative conversion of ALN. METHODS: From January 2012 to November 2014, we included 133 breast cancer patients who underwent NAC and who had ALN metastases which were confirmed on fine-needle aspiration or core needle biopsy at initial diagnosis. All 133 patients underwent initial magnetic resonance imaging (MRI) at the time of diagnosis and preoperative MRI after completion of NAC. We measured the longest dimension of primary breast cancer on MRI. RESULTS: Of 133 patients, 39 patients (29%) showed negative conversion of ALN and of these 39 patients, 25 patients (64%) showed pathologic complete remission of primary breast. On univariate analysis, mean percent decrease in longest dimension, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 status and histologic grade were significantly associated with the ALN status after NAC (p<0.001, p=0.001, p< 0.001, p=0.001, p=0.002, respectively). On multivariate logistic regression analysis, percent decrease in longest dimension (odds ratio, 1.026; 95% confidence interval [CI], 1.009-1.044) and histologic grade (odds ratio, 3.964; 95% CI, 1.151-13.657) were identified as being independently associated with the ALN status after NAC. The area under the receiver operating characteristic curve was 0.835 with the best cutoff value of 80% decrease in longest dimension. Combination of high histologic grade and more than 80% decrease in longest dimension showed 64% sensitivity and 92% specificity. CONCLUSION: High histologic grade and more than 80% decrease in primary tumor dimension were associated with negative conversion of ALN after NAC.