A Prospective Validation Cohort Study of a Prediction System on nSLN Metastasis in Early Breast Cancer

In the previous study, a predictive model for non-sentinel lymph node involvement in early breast cancer (cT1-2cN0, 1-2 SLNs involvement) was established. This model was designed for predicting the status of non-sentinel lymph node in cT1-2cN0 with 1-2 SLNs involvement breast cancer based on peripheral blood CK19 and contrast-enhanced ultrasound. The investigator previously tested this model comparing with MSKCC model in a same population and confirmed a result of satisfactory low false-negative rate and high AUC. This model had a potential practise value in clinic applying. For further validation, the research group design the CK19B trial to prospectively using this model in decision strategy of whether receiving ALND in 1-2SLNs+ patients. If the model predictive result is negative, the risk of nSLNs involvement is estimated very low and the patients should be avoid ALND, even radiotherapy no matter the surgery is mastectomy or conserving. If the model result is positive, then further ALND or radiotherapy should be accepted by patients to decrease the risk of local and regional recurrent. A prospectively and conditional grouping method is planned for this cohort study. The primary endpoint is disease-free survival (DFS) in two groups, the second primary endpoint is local recurrent rate (LRR) and overall survival (OS).