Abstract P3-03-29: Evaluation of a direct reverse transcription loop-mediated isothermal amplification method without RNA extraction (direct RT-LAMP) for the detection of lymph node metastasis in early breast cancer

Backgroud: The detection of lymph node metastasis by reverse transcription loop-mediated isothermal amplification method (RT-LAMP) had been studied previously. Even though, RT-LAMP method provides improved performance compared to intraoperative histology sentinel lymph node (SLN) evaluation, direct RT-LAMP method without RNA extraction can be more efficient and easily accessible process. Therefore, we evaluated the performance and efficacy of a direct reverse transcription loop-mediated isothermal amplification (direct RT-LAMP) assay for visual detection of CK19 , CK20 , and CEA mRNAs to identify lymph node metastasis in patients with early breast cancer. Methods: A total of 92 lymph nodes dissected from 40 patients with breast cancer were collected at the breast cancer center of Kyungpook National University Chilgok Hospital between November 2015 and February 2016. All of the samples were analyzed by direct RT-LAMP assay and routine histopathology examination. Cutoff values to distinguish metastasis and nonmetasis were determined by measuring cytokerain 19 (CK19) mRNA in histopathologically positive and negative lymph node using direct RT-LAMP. Results: We set the cutoff value of direct RT-LAMP assay for CK 19 mRNA at 1ng to distinguish status of LN metastasis. The sensitivity and specificity of the RT-LAMP assay were 85.7% and 100%, respectively. The positive predictive value and negative predictive value were 100% and 94.4%. Conclusion: Direct RT-LAMP assay can allow detection of SLN metastasis in breast cancer patients intraoperatively with a good sensitivity through cost-effective and time–saving manner. Citation Format: Lee IH, Jung J, Lee S, Lee J, Lee RK, Park H, Jung J, Kang J, Chae Y. Evaluation of a direct reverse transcription loop-mediated isothermal amplification method without RNA extraction (direct RT-LAMP) for the detection of lymph node metastasis in early breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-03-29.