Feasibility of preoperative verification of the sentinel lymph node in patients with breast cancer

Aim. To determine the diagnostic performance and assess the feasibility of verification of the sentinel lymph node (SLN) detected by contrast-enhanced ultrasound in breast cancer patients at the outpatient (preoperative) stage.

Materials and methods. The study included 119 patients with primary breast cancer at stages 0–IIIa (cTis–3N0–1M0). The mean age was 53.0 ± 13.3 years. SLN detection was performed using contrast-enhanced ultrasound with Sonovue (Bracco Swiss SA, Switzerland), administered intradermally in the para-areolar region in a volume of 1 ml. SLN detection was carried out on a Resona 9 diagnostic ultrasound system (Mindray, China) with a linear L14–5WU transducer. Morphological verification was performed using in vivo histological and cytological examinations. Cytological assessment was carried out using the conventional method and a liquid-based technique. Morphological evaluations were performed using a light microscope.

Results. The highest informative value for verification of metastatic involvement of the SLN was demonstrated by the combination of cytological and histological examination: sensitivity – 75.8 % (95 % confidence interval 58.2–88.0 %), accuracy – 92.4 % (95 % confidence interval 86.2–96.0 %), negative predictive value – 91.5 % (95 % confidence interval 84.0–95.7 %). Cytological verification using conventional and liquid-based technologies showed sensitivities of 69.7 % and 63.6 %, respectively, with an accuracy of 92.4 % in both cases. Combining cytological techniques increased sensitivity to 72.7 %, specificity to ~99 %, and positive predictive value to 96 %. Histological verification was inferior to cytology in terms of sensitivity (51.6 %) while maintaining comparable specificity. The diagnostic performance of all morphological techniques clearly depended on the size and type of metastasis: with a combined approach, sensitivity for macrometastases reached 83 %, whereas for micrometastases it decreased to 50 %. The negative predictive value of verification at the outpatient stage ranged from 85 % to 92 %.

Conclusion. For preoperative verification and determination of SLN status in breast cancer patients, it is preferable to use combined biopsy approaches to obtain material for both histological and cytological examination, particularly in patients with moderate and high risk of metastasis, which increases the likelihood of detecting metastases by 10–25 %.