To assess the accuracy of a commercially available real-time reverse-transcription-polymerase chain reaction assay for mammaglobin and cytokeratin 19 mRNAs [GeneSearch Breast Lymph Node (BLN) Assay, Veridex LLC, Warren, NJ] in the detection of axillary sentinel lymph nodes (SLNs) metastases in patients with breast carcinoma.
Because of the lack of standardized and widely accepted protocols for a truly accurate histopathologic examination of SLN, the relative merits of alternative assays based on the identification of tumor specific mRNA markers deserve further assessment.
A prospective series of 293 consecutive SLNs from 293 patients was evaluated. The BLN assay results were compared with those of an extensive histopathologic examination of the entire SLNs performed on serial frozen sections cut at 40 to 50 μm intervals.
The BLN assay correctly identified 51 of 52 macrometastatic and 5 of 20 micrometastatic SLNs, with a sensitivity of 98.1% to detect metastases larger than 2 mm, 94.7% for metastases larger than 1 mm, and 77.8% for metastases larger than 0.2 mm. The overall concordance with histopathology was 90.8%, with specificity of 95.0%, positive predictive value of 83.6%, and negative predictive value of 92.9%. When the results were evaluated according to the occurrence of additional metastases to non-SLN in patients with histologically positive SLNs, the assay was positive in 33 (91.7%) of the 36 patients with additional metastases and in 22 (66.6%) of the 33 patients without further echelon involvement.
The sensitivity of the reverse-transcription -polymerase chain reaction assay is comparable to that of the histopathologic examination of the entire SLN by serial sectioning at 1.5 to 2 mm.
A real-time reverse-transcription polymerase chain reaction assay ensures detection of axillary sentinel lymph node metastases from breast carcinoma with a comparable sensitivity to that of the histopathologic examination of the entire lymph node by serial sectioning at 1.5 to 2 mm, and it is correlated with the likelihood of additional metastases to nonsentinel nodes.
From the *Department of Pathology and Laboratory Medicine, European Institute of Oncology; †University of Milan School of Medicine; ‡Department of Breast Surgery; §Department of Nuclear Medicine; ¶Department of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy; and ∥Veridex LLC, Warren, New Jersey.
Reprints: Giuseppe Viale, MD, FRCPath, Department of Pathology, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy. E-mail: firstname.lastname@example.org.