Clinical validation of a molecular assay for intra-operative detection of metastases in breast sentinel lymph nodes

Eur J Surg Oncol. 2009 Apr;35(4):387-92. doi: 10.1016/j.ejso.2008.05.008. Epub 2008 Jul 17.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Axilla / pathology
  • Biomarkers, Tumor / analysis*
  • Breast Neoplasms / surgery*
  • Carcinoma / chemistry*
  • Carcinoma / secondary*
  • Carcinoma / surgery
  • Female
  • Humans
  • Intraoperative Care / methods
  • Keratin-19 / analysis*
  • Lymph Node Excision
  • Lymph Nodes / chemistry
  • Lymph Nodes / pathology
  • Lymphatic Metastasis / pathology
  • Mammaglobin A
  • Middle Aged
  • Neoplasm Proteins / analysis*
  • Predictive Value of Tests
  • Prospective Studies
  • Reverse Transcriptase Polymerase Chain Reaction / methods*
  • Sensitivity and Specificity
  • Sentinel Lymph Node Biopsy / methods*
  • Uteroglobin / analysis*


  • Biomarkers, Tumor
  • Keratin-19
  • Mammaglobin A
  • Neoplasm Proteins
  • SCGB2A2 protein, human
  • Uteroglobin