title: Clinical validation of a molecular assay for intra-operative detection of metastases in breast sentinel lymph nodes.
abstract: BACKGROUND
  In breast cancer patients, the status of the sentinel lymph nodes (SLNs) has been shown to accurately reflect the presence of metastases in the axillary lymph nodes (ALNs). Intra-operative SLN evaluation by frozen section histology may miss positive cases, leading to a second surgery for complete ALN dissection. Permanent section histology itself has tissue sampling limitations and is partially dependent on pathologist expertise.
  
  
  METHODS
  A prospective study (N=78) was conducted in our institution to validate a new intra-operative molecular assay, the GeneSearch breast lymph node (BLN) assay. This assay quantifies the expression of mammaglobin and cytokeratin-19 genes using quantitative RT-PCR technology to determine SLN status. Fresh SLN sections (2 mm thick) were analyzed alternatively by BLN assay or post-operative histology (haematoxylin-eosin and immunohistochemistry). The subject was considered positive when histology revealed a focus >0.2 mm.
  
  
  RESULTS
  BLN assay results corroborated with histologic results in 75 out of 78 patients for an overall agreement of 96%, a sensitivity of 92%, and a specificity of 97%. The positive and negative predictive values of the BLN assay were of 86% (12/14) and 98% (63/64), respectively. Interestingly, a statistically significant correlation was observed between the metastases' histologic size and both assay markers' expression levels as represented by cycle time to positivity (rho > or = 0.71, all p<0.0001).
  
  
  CONCLUSIONS
  The performance of the BLN assay in identifying nodal metastases >0.2 mm was similar to that of permanent section histology, with the added advantages of an objective and rapid output that could be used for intra-operative decision to remove additional ALN.
authors.affiliation: Department of Pathology, Jules Bordet Institute, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: M D
authors.initials: MD
authors.lastname: Martin Martinez
authors.forename: I
authors.initials: I
authors.lastname: Veys
authors.forename: S
authors.initials: S
authors.lastname: Majjaj
authors.forename: L
authors.initials: L
authors.lastname: Lespagnard
authors.forename: J C
authors.initials: JC
authors.lastname: Schobbens
authors.forename: G
authors.initials: G
authors.lastname: Rouas
authors.forename: V
authors.initials: V
authors.lastname: Filippov
authors.forename: D
authors.initials: D
authors.lastname: Noterman
authors.forename: D
authors.initials: D
authors.lastname: Hertens
authors.forename: F
authors.initials: F
authors.lastname: Feoli
authors.forename: P
authors.initials: P
authors.lastname: Bourgeois
authors.forename: V
authors.initials: V
authors.lastname: Durbecq
authors.forename: D
authors.initials: D
authors.lastname: Larsimont
authors.forename: J M
authors.initials: JM
authors.lastname: Nogaret
mesh_terms: D001365:Axilla / Q000473:pathology; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000601:surgery*; D002277:Carcinoma / Q000737:chemistry* / Q000556:secondary* / Q000601:surgery; D005260:Female; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D053539:Keratin-19 / Q000032:analysis*; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000737:chemistry / Q000473:pathology; D008207:Lymphatic Metastasis / Q000473:pathology; D060785:Mammaglobin A; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D014598:Uteroglobin / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D053539:Keratin-19; D060785:Mammaglobin A; D009363:Neoplasm Proteins; C556448:SCGB2A2 protein, human; D014598:Uteroglobin