To investigate the significance of sentinel lymph node (SLN) biopsy (SLNB) using contrast-enhanced ultrasonography (CEUS) combined with blue dye in neoadjuvant-treated human epidermal growth factor receptor 2 (HER2)-positive or triple-negative breast cancer with initially biopsy-proven nodal metastasis.

From June 2020 to April 2022, HER2-positive or triple negative breast cancer patients with baseline stage cT1~3N1M0 and negative axillary status after neoadjuvant therapy were prospectively included at Sichuan Cancer Hospital. All the patients received SLNB and subsequent axillary lymph node dissection. SLNB was conducted using CEUS combined with blue dye. Using the final pathological results as the golden standard, the detection rate, sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and false negative rate (FNR) of the combination method were calculated.

Twenty-nine patients were included, with a median age of 51 years (range, 28-64 years); 24 cases were HER2 positive and 5 were triple-negative. The overall rate of axillary pathological complete response was 72.4% (21/29). The detection rate of the combination method was 96.6% (28/29). Twenty-eight patients underwent SLNB successfully using the combination method. Compared with the pathological diagnosis, the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and FNR of the combination method were 100% (7/7), 100% (21/21), 100% (7/7), 100% (21/21), 100% (28/28), and 0% (0/7), respectively.

The combination of CEUS with blue dye for SLNB has a meaningful detection rate and FNR in neoadjuvant-treated HER2-positive or triple-negative breast cancer with initial nodal involvement.