Efficacy of intraoperative GeneSearch Breast Lymph Node (BLN) Assay for breast cancer metastasis detection in sentinel lymph node in Chinese patients

Although intraoperative assessment of the sentinel lymph node (SLN) is useful, it has not gained popularity in China as it involves a heavy workload for pathologists. We conducted a prospective clinical feasibility study of the GeneSearch Breast Lymph Node (BLN) Assay performed in 158 SLNs from 97 patients by comparison with postoperative permanent section histopathology, to validate its potential usefulness in China. Every SLN was cut into alternating 1.5 to 3.0 mm slabs. The BLN assay processed 50% of the fresh alternating slabs to detect the presence of cytokeratin 19 and mammaglobin mRNA. Assay results were compared with those for permanent section histopathology and intraoperative imprint cytology. Slides for imprint cytology were prepared from the BLN assay node tissue before it was processed. Full axillary lymph node (ALN) dissections were performed on some patients after a SLN biopsy. The BLN assay was successfully performed on 158 SLNs from 97 patients. Overall performance of the BLN assay compared with permanent section histopathology was sensitivity 83.9% (26/31), specificity 95.5% (63/66), positive predictive value 89.7% (26/29), negative predictive value 92.6% (63/68), and overall agreement 91.8% (89/97). The BLN assay detected about 25% more metastases than imprint cytology. Moreover, the BLN assay correctly identified most of the additional non-sentinel ALNs metastases (P = 0.005). Our results from a large series of Chinese patients with breast cancer indicate that the BLN assay may be a viable alternative for the standard intraoperative procedures used for metastases detection, especially in early stage breast cancer patients. Name of the trial register: GeneSearch Breast Lymph Node (BLN) Assay China Registration Study. Clinical trial registration number: NCT00869674. (Cancer Sci 2010).