GeneSearch™ BLN Assay could replace frozen section and touch imprint cytology for intra-operative assessment of breast sentinel lymph nodes

Abstract

Breast cancer sentinel lymph node (SLN) biopsy has become a common procedure. The GeneSearch™ Breast Lymph Node Assay is a real-time reverse-transcriptase polymerase chain reaction assay for detecting nodal metastases larger than 0.2mm. The trial is a prospective multi-center clinical trial conducted to validate the assay in China. Four hundred and seventy-nine consecutive prospective patients were enrolled from six centers. SLNs were sectioned along the short axis into multiple blocks. Odd blocks were tested by the assay intra-operatively, and even blocks were assessed by post-operative histology. Six 4- to 6-μm-thick sections were taken every 150μm per block. In addition, intra-operative histological assessments were performed on the even blocks of 214 patients by frozen section (FS) and all blocks of 156 patients by touch imprint cytology (TIC). A total of 1046 SLNs were excised. Overall performance of the assay compared to post-operative histology was accuracy of 91.4%, sensitivity of 87.5%, and specificity of 92.9%. There were no significant differences in assay performance of each center. After a learning curve of about 10 cases, the assay could be performed in a median time of about 35min. The sensitivity of the assay was similar to the FS (84.9%, P=0.885) and was significantly higher than the TIC (70.0%, P=0.007) while the specificity of all were comparable. The GeneSearch™ Breast Lymph Node Assay is an accurate and rapid intra-operative assay for breast SLNs and it can replace FS and TIC for application.