[295] Use of the Veridex GeneSearch BLN Assay in Clinical Practice To Evaluate Breast Sentinel Lymph Nodes

N Sidiropoulos, LJ Tafe, MC Schwab, EJ Rizzo, SN Schutz, SH Boyle, PP Seery, WA Wells, GJ Tsongalis. Dartmouth Medical School, Dartmouth Hitchcock Medical Center, and Norris Cotton Cancer Center, Lebanon, NH

Background: Sentinel lymph node (SLN) analysis is considered standard of practice for breast cancer patients. New methodologies utilizing gene expression profiling for SLN analysis have been explored and recently the FDA approved a real time PCR assay, the Veridex GeneSearch Breast Lymph Node (BLN) Assay, for this application. In this study, we describe our experience with this test as applied in a routine clinical setting.
Design: Seventeen consecutive eligible SLNs from 9 patients were assessed. The lymph nodes were serially sectioned perpendicular to the long axis and the first and last sections submitted for molecular analysis. This sampling method differs from the manufacturer's recommended sampling of half the node. We wanted to assess a sampling method that would still allow for the evaluation of deposit size and location by routine H&E and IHC. RNA extraction and RT-PCR were performed using the GeneSearch BLN Assay reagents on the Cepheid SmartCycler to generate expression data for 3 target genes (mammaglobin, cytokeratin 19, and porphobilinogen deaminase). Gene expression results were then applied against predetermined criteria to provide a qualitative result.
Results: Of the 17 SLNs, 4 were not submitted for molecular studies (3 nodes <0.8 mm, 1 node with macrometastasis (0.7 cm)). The remaining 13 SLNs were negative by H&E and one was positive by IHC for cytokeratin 19 (<0.1 mm focus). The GeneSearch BLN Assay of these cases revealed 12 negative and one positive result concordant with the H&E/IHC results.
Conclusions: While this new molecular assay is performed in less than 40 minutes and has intraoperative claims, we have opted to use it as part of a SLN algorithm where only portions of H&E negative SLNs are tested. This has resulted in a drastic reduction of H&E slides reviewed per SLN and has maintained our ability to assess other morphologic features of the node. This assay has been an excellent adjunct to traditional pathologic examination of breast SLNs.
Category: Breast

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 49, Monday Morning