Prediction Of The Risk Of Metastasis In Axillary Non-sentinel Lymph Nodes In Patients With Axillary Sentinel Lymph Node Positive For Early Breast Cancer

ObjectiveSentinel lymph node biopsy(SLNB)is the standard treatment in early breast cancer patients with clinical negative axillary lymph node,and no further axillary treatment is required for sentinel lymph node(SLN)negative patients.In SLN positive patients,no more than half have axillary non-sentinel lymph node(nSLN)metastases when axillary dissection is performed.With the evidences from ACOSOG Z0011,IBCSG 23-01 and AMAROS trials,the consensus has been reached that axillary lymph node dissection(ALND)can be omitted in patients with 1-2 positive SLN treated with breast conserving surgery followed by whole breast irradiation.But no agreement was reached regarding how to individualize regional nodal irradiation for them.This study aims to select risk factors of additional disease in nSLN,create a nomogram to predict the risk of nSLN metastases,therefore to provide evidence to guide clinical decision-making of radiation field.MethodsBreast cancer patients in Cancer Hospital Chinese Academy of Medical Sciences treated from April 2002 to December 2017 were retrospectively reviewed.Patients who met the following criteria were included:pathologically confirmed invasive breast cancer,clinically negative axillary lymph node,without neoadjuvant chemotherapy,pathologically confirmed 1-2 positive SLN,completion of ALND and histopathology assessment of dissected lymph nodes.According to the date of surgery,patients were divided into two groups,the first 497 patients for creating a nomogram and the following 420 patients for validation.Risk factors of nSLN metastases were identified and used to create the nomogram.The accuracy was analyzed by receiver operating characteristic(ROC)curve,area under curve(AUC)and caliberation curve.Results917 patients were included,882(96.2%)had nSLN macro-metastases.The median age was 48 years(21-80).420(45.8%)underwent breast conserving surgery.251(27.4%)had nSLN metastases.Univariate analysis showed tumor grade,extra-capsular invasion,number of positive SLN,number of negative SLN and SLN macro-metastases were associated with the risk of nSLN metastases,and lymphovascular invasion was of borderline significance.Logistic regression showed number of positive SLN,number of negative SLN,and SLN macro-metastases were independent risk factors of nSLN metastases.The six risk factors identified from univariate analysis were included in the nomogram.The AUC was 0.718 for the exploration group of 497 patients,and 0.778 for the validation group.ConclusionFor breast cancer patients with 1-2 positive axillay SLN,we created a nomogram to predict the risk of nSLN metastases,and the accuracy was validated.