Predicting level 2 axillary lymph node metastasis in a Chinese breast cancer population post-neoadjuvant chemotherapy: development and assessment of a new predictive nomogram

// Caigang Liu 1,* , Yanlin Jiang 1,2,* , Xin Gu 3,* , Zhen Xu 2 , Liping Ai 2 , Hao Zhang 2 , Guanglei Chen 2 , Lisha Sun 4 , Yue Li 2 , Hong Xu 5 , Huizi Gu 6 , Ying Yu 7 , Yangyang Xu 8 and Qiyong Guo 9 1 Department of Breast Surgery, Shengjing Hospital of China Medical University, Shenyang, China 2 Department of Breast Disease and Reconstruction Center, Breast Cancer Key Lab of Dalian, the Second Hospital of Dalian Medical University, Dalian, China 3 Department of Head and Neck Surgery, Harbin Medical University Cancer Hospital, Harbin, China 4 Department of Surgical Oncology, the First Hospital of China Medical University, Shenyang, China 5 Department of Breast Surgery, Liaoning Cancer Hospital & Institute, Shenyang, China 6 Department of Internal Neurology, the Second Hospital of Dalian Medical University, Dalian, China 7 Liaoning Medical Device Test Institute, Shenyang, China 8 Department of Urinary Surgery, Harbin Medical University Cancer Hospital, Harbin, China 9 Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China * Co-first authors Correspondence to: Qiyong Guo, email: // Yangyang Xu, email: // Keywords : breast cancer, neoadjuvant chemotherapy, level 2 axillary lymph node metastasis, nomogram, level 2 axillary lymph node dissection Received : November 18, 2016 Accepted : February 22, 2017 Published : March 15, 2017 Abstract Background: We aimed to develop a new nomogram to predict the probability of level 2 axillary lymph node metastasis (L-2-ALNM) in breast cancer (BC) patients treated with neoadjuvant chemotherapy (NAC). Methods: Data were collected from 709 patients who received neoadjuvant chemotherapy and then underwent axillary lymph node (ALN) dissection between May 2009 and December 2015 at the Liaoning Cancer Hospital. The level 2 axillary lymph node metastasis (L-2-ALNM ) nomogram was created from the logistic regression model. An additional set of 141 consecutive patients treated at the same institution between January 2015 and December 2015 were enrolled as the validation group. The predictive accuracy of the L-2-ALNM nomogram was measured by calculating the area under the receiver operating characteristic curve (AUC). Results: In multivariate analysis, age, tumor size, histological grade, skin invasion, and response to neoadjuvant chemotherapy were identified as independent predictors of L-2-ALNM. The new model was accurate and discriminating for both the modeling and validation groups (AUC: 0.819 vs 0.849). The false-negative rates of the L-2-ALNM nomogram were 4.44% and 7.69% for the predicted probability cut-off points of 10% and 20%. Conclusion: The L-2-ALNM nomogram shows reasonable accuracy for making clinical decisions. The omission of level 2 axillary lymph node dissection after neoadjuvant chemotherapy might be possible if the probability of level 2 lymph node involvement was < 10% or < 20% in accordance with the acceptable risk determined by medical staff and patients.