Contrast-enhanced ultrasonography and blue dye methods in detection of sentinel lymph nodes following neoadjuvant chemotherapy in initially node positive breast cancer

Background Recent studies show that contrast-enhanced ultrasonography (CEUS) using SonoVue has the potential to improve the performance of sentinel lymph node biopsy (SLNB) in patients with early breast cancer. However, the evidence of SLNB using CEUS in patients converting from cN1 to cN0 after neoadjuvant chemotherapy (NAC) is lacking. The aim of this prospective study is to evaluate the feasibility of CEUS using SonoVue for the identification of sentinel lymph node (SLN) and the value of the combination of CEUS and blue dye (BD) for SLNB in patients converting from cN1 to cN0 following NAC. Methods Patients with cytology-proven node positive breast cancer at the initial diagnosis (stage T1-T3N1M0) from January 2018 to January 2019, underwent NAC. Patients converting from cN1 to cN0 following NAC were enrolled and randomized into two groups for SLNB: the combination method group using CEUS and BD together, and the single BD method group. Then all patients underwent complete axillary lymph node dissection (ALND) and primary breast surgery. Compared with the final pathological results, the identification rate, sensitivity, specificity, accuracy, false negative rate, negative predictive value, positive predictive value were recorded and compared between two methods. Results A total of 400 patients with stage T1-T3N1M0 disease underwent NAC between January 2018 to January 2019, among which 134 (33.5%) patients had clinically negative node confirmed by imaging after NAC and randomized into two groups. Each group included 67 cases. In the combination method group, contrast-enhanced lymphatic vessels in 66 cases of 67 were clearly visualized by US soon after the periareolar injection of SonoVue and the SLNs were accurately localized. The identification rate of the combination method was 98.5%%, which was significantly higher than 83.6% (56/67) using the single BD method. The mean numbers of SLNs identified by the combination method was higher than that by the single BD method. Compared with pathological diagnosis, sensitivity, specificity, accuracy, the positive predictive value, the negative predictive value, and the FNR of the combingation method were 84.4%, 100%, 89.4%, 100%, 75%, and 15.6%, respectively. In contrast, sensitivity, specificity, accuracy, the positive predictive value, the negative predictive value, and the FNR using single blue dye were 73.9%, 100%, 89.3%, 100%, 84.6%, and 26.1%, respectively. The FNR using the combination method was significantly lower than that using single BD. Conclusion Identification of SLNs in patients converting from cN1 to cN0 following NAC by CEUS is a technically feasible. The combination of CEUS and BD is more effective than BD alone for SLNB in patients converting from cN1 to cN0 following NAC.