Evaluation of intraoperative molecular assay in sentinel lymph node biopsy from breast cancer patients

Objective To evaluate the application of GeneSearchTM breast lymph node assay in intraoperative detection of metastases in sentinel lymph node (SLN) from breast cancer patients. Methods A total of 225 SLN from 88 patients was prospectively studied. Each SLN was cut into 2 mm slabs which were examined by intraoperative imprint cytology (ⅡC) first, followed by GeneSearch assay and postoperative serial sectioning. GeneSearch used real-time fluorescence quantitative RT-PCR technology to detect the expression of CK19 and mammaglobin in SLN. The results of GeneSearch assay were correlated with those of ⅡC and post-operative serial sectioning. Results Amongst the 88 cases studied, 225 SLNs were found, and obvious metastatic carcinoma cells were identified in 27 SLNs and micrometastasis in 9 SLNs.One hundred and eight-nine SLNs were considered as "negative" (with "isolated tumor cells" present in 5 SLNs). The turn-around time of intraoperative GeneSearch assay ranged from 35 to 45 minutes (mean = 40 minutes). The concordance rate between GeneSearch assay and post-operative serial sectioning was 95.6% (215/225), with a sensitivity of 86.1% (31/36), compared with 94.7% (213/225) and 72.2% (26/36)respectively for ⅡC. The size of metastatic foci correlated with the Ct value of CK19 and mammaglobin (P ＜0.01). Conclusions GeneSearch assay for intraoperative detection of metastase in SLN has a satisfactory performance and demonstrates a relatively higher sensitivity than ⅡC. The potential clinical application still requires further evaluation of larger number of cases. Key words: Breast neoplasm; Sentinel lymph node biopsy; Reagent kits,diagnosis; Diagnosis