A Study Of Sentinel Lymph Node Biopsy In The Axilla And Internal Breast After Neoadjuvant Chemotherapy For Breast Cancer

PurposeThis study aims to identify the pathologic complete response(pCR)among different tumor subtypes for patients underwent neoadjuvant chemotherapeutic(NAC)as well as access whose patients would benefit more from axillary downstaging surgery after NAC,determine the optimal time to perform axillary-sentinel lymph node biopsy(A-SLNB)for cN0 patients with NAC,and evaluate the feasibility of internal mammary-sentinel lymph node biopsy(IM-SLNB)in breast cancer patients who underwent NAC.MethodsFrom October 2010 to November 2017,206 patients with breast cancer underwent operation after NAC were included in this study in our breast cancer center.Patients with cN0 before and ycN0 after NAC received A-SLNB and axillary lymph node dissection(ALND)in case of positive axillary sentinel lymph node(ASLN).Patients with cN+ before and ycN0 after NAC received A-SLNB and ALND.Patients with ycN+ after NAC received ALND without A-SLNB.IM-SLNB would be performed on patients with internal mammary sentinel lymph node(IMSLN)visualization.ResultsAmong the 183 cN+ patients,the overall axillary nodal pathologic complete response(apCR)rate was 33.3%,and the apCR rates were significantly higher in patients with HER2+(62.1% with and 34.5% without targeted therapy respectively)and triple-negative(TN)disease(41.0%)than that in patients with hormone receptor positive/HER2 negative(HR+/HER2-)(19.8%,p<0.001).Among the 23 cN0 patients,the positive rate of SLN was 26.1%(6/23).Among 179 patients who tried to perform IM-SLNB,the visualization rate of IMSLN was 31.8%(57/179),and the detection rate of IMSLN was 31.3%(56/179).The success rate of IM-SLNB was 98.2%(56/57).The IMSLN metastasis rate was 7.1%(4/56),and all of them were accompanied by ALN metastasis.ConclusionThe pCR rates were significantly related to tumor subtype.Combining the pCR rates in different tumor subtypes of cN+ patients and excellent locoregional control of AOSOG Z0011 and AMAROS trials in cN0 patients,it would be preferable to perform SLNB prior to NAC for cN0 patients with HR+/HER2-subtype,and SLNB after NAC for those with TN and HER2+ subtype to increase the chance of avoiding ALND.As for patients with initial cN+ converting to ycN0,TN and HER2+ subtypes would benefit more from axillary downstaging surgery with NAC than HR+/HER2-subtype.Patients with visualization of IMSLN should perform IM-SLNB after NAC,especially for patients with cN+ disease,in order to complete lymph nodal staging.IM-SLNB could further improve the definition of nodal pCR and guide internal mammary node irradiation.