Clinical use of an intra-operative RT-PCR assay for the detection of metastases in sentinel lymph nodes of breast cancer patients at the Institut Jules Bordet

Abstract

11100 Background: A molecular assay (GeneSearch™ BLN Assay, Veridex, LLC), CE marked and approved by the FDA, has been in clinical use at our institution for over 18 months to intra-operatively detect metastases ≥0.2 mm in the sentinel lymph nodes (SLNs) in breast cancer patients. After a small validation study (N=78, sensitivity = 92.3%, specificity = 96.9%) the assay was adopted as the only intra-operative SLN test used at the Institut Jules Bordet. This is the first report of the post-market assay performance. Methods: One SLN per patient is cut into approximately 2 mm sections. Alternating sections are processed fresh in the BLN assay. The assay detects mRNA expression of mammaglobin and CK19. Predetermined cutoffs are set to detect metastases ≥0.2 mm. The BLN Assay results are used to make intra-operative decisions for same surgery axillary lymph node dissections (ALND). The remaining alternating sections of the SLN are examined later by permanent section H&E. Results: Since August 2006, the BLN Assay has been used for intra-operative ALND decision-making on 100 patients. The assay intra-operatively detected all 15 H&E-positive SLNs. The assay was in agreement with 93% of the H&E-negative SLNs (79 of 85) and was positive when H&E was negative for 6 SLNs. One of these 6 SLNs had a 0.3 mm size metastasis detected by IHC alone. The average turn around time for the assay was 39 minutes for all 100 patients, and was 35 minutes for the second 50 patients. Conclusions: The BLN Assay results shows high correlation to permanent section H&E results that take 2–3 days, and its timing permits same-surgery ALND when nodes are found positive for metastases. In clinical use, agreement of assay results and permanent section H&E results (94%, 94/100) is similar to the agreement found in an earlier validation study (96.2%, 75/78). Perfect agreement is not expected since the two tests are evaluating different sections of the node. The BLN Assay is beneficial to our patients by reducing the need for second surgeries while being practical and cost effective for the institution to perform. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Veridex Veridex