Background: Peptide nucleic acid (PNA)-mediated real-time PCR clamping was recently used to detect mutations because it has higher sensitivity than conventional direct sequencing. Pleural effusion and serum samples could be good sources of detecting the epidermal growth factor receptor (EGFR) mutational status of non-small cell lung cancer (NSCLC) patients. Methods: We studied 37 NSCLC patients with malignant pleural effusion. In each patient, EGFR mutational status was measured from the samples of tumor tissue, cell block, pleural effusion and serum using both PNA clamping and direct sequencing. The concordance between PNA clamping and direct sequencing, and the diagnostic performance of pleural effusion was investigated. Results: The detection rate of EGFR mutation in the pleural effusion and the serum was 27% and 2.8%, respectively by both PNA clamping and direct sequencing. The κ coefficient between the two methods were 0.68 (p-value = 0.0007), 0.91 (p-value < 0.0001), 0.75 (p-value < 0.0001) and -0.01 (p-value = 0.8639) in tissue, cell block, pleural effusion and serum, respectively. The diagnostic performance of pleural effusion compared with combined tumor tissue plus cell block showed sensitivity 89%, specificity 100%, positive predictive value 100% and negative predictive value 95% with PNA clamping, and sensitivity 67%, specificity 90%, positive predictive value 75% and negative predictive value 86% with directing sequencing. Interestingly, a patient who was confirmed EGFR mutation only with the PNA clamping showed significant response to EGFR TKI (tyrosine kinase inhibitor). Conclusion: Despite the limited role of serum samples, pleural effusion had a diagnostic performance comparable with tumor tissue and cell block to detect EGFR mutational status in NSCLC. Although the diagnostic performance of PNA clamping was similar to that of direct sequencing, additional benefit is expected considering the response to the EGFR TKI.

Citation Format: Chan Kwon Park, Chang Dong, Jin Woo Jin Woo, Kwan Hyoung Kim, Jick Hwan Ha, Chin Kook Rhee, Young Kyoon Kim, Sang Haak Lee, Mi Sun Park, Hyeon Woo Yim, Seung Joon Kim. Detection and comparison of EGFR mutations in matched tumor tissue, cell block, pleural effusion and serum with PNA clamping and direct sequencing in NSCLC with malignant pleural effusion. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 62. doi:10.1158/1538-7445.AM2013-62