A New Diagnostic Method for Rapid Detection of Lymph Node Metastases Using a One-Step Nucleic Acid Amplification (OSNA) Assay in Endometrial Cancer

Background. To improve lymph node (LN) metastasis identification for patients with endometrial cancer (EC), this study assessed the usefulness of molecular biologic techniques using a one-step nucleic acid amplification (OSNA) assay. Methods. Using quantitative reverse transcription polymerase chain reaction (qRT-PCR), an optimal mRNA marker was selected, and its expression was compared between histopathologically positive and negative LNs using an OSNA assay. The authors determined copy number cutoff values and evaluated the diagnostic performance of this OSNA assay using sentinel lymph nodes (SLNs). They also investigated whether an OSNA assay could detect LN metastases with sensitivity and specificity equivalent to the 2-mm-interval histopathology method. Results. For analysis of EC samples, cytokeratin 19 (CK19) was selected as a useful mRNA marker for the OSNA assay. When the cutoff value was set at 250 copies (using 215 LNs from 70 patients), an OSNA assay using CK19 mRNA had a sensitivity of 93.3 %, a specificity of 99.5 %, and a concordance rate of 99.1 %. For performance evaluations using SLNs (120 histopathologically negative LNs and 17 histopathologically positive LNs from 35 patients), a OSNA assay using CK19 mRNA had a sensitivity of 82.4 %, a specificity of 99.2 %, a positive predictive value of 93.3 %, and a concordance rate of 97.1 %. Thus, an OSNA assay using CK19 mRNA provided results equivalent to those with the 2-mm-interval histopathology method. Conclusions. The study data demonstrated that an OSNA assay using CK19 mRNA was applicable for detecting LN metastases in EC. Combined analysis using an OSNA assay and SLNs may improve individualized treatments according to LN metastatic status.