Ultrasensitive DNA hypermethylation detection using plasma for early detection of NSCLC: A validation study in Chinese patients.

Abstract

8522 Background: Our previous study revealed that high diagnostic accuracy for early stage lung cancer could be obtained in plasma samples with ultrasensitive DNA hypermethylation detection methods called MOB-qMSP. In this study, we sought to validate and also improve the diagnostic accuracy of lung cancer screening with modified MOB-qMSP approach in Chinese patients. We also develop a lung cancer specific gene panel for Chinese patients. Methods: We included patients with small lung nodules (less than 3cm in diameter) on CT scan screening and conducted a case-control study. Cases (n=138) had pathological confirmation of Non-Small Cell Lung Cancer (NSCLC) lesions staged IA or IB. Controls (n=65) had pathological confirmation of non-cancerous lesions. Plasma samples were obtained pre-operatively. Promoter methylation of eight lung cancer-specific genes (CDO1, TAC1, SOX17, HOXA7, HOXA9, GATA4, GATA5 and PAX5B) was detected using nanoparticle-based DNA extraction (MOB) followed by qMSP. Results: DNA methylation was detected in plasma more frequently in cases compared to controls (p<0.001) for 5 out of 8 genes. The sensitivity and specificity for lung cancer diagnosis using the best individual gene was 64-85% and 55-79% respectively. A three-gene combination of the best individual genes has sensitivity and specificity of 92% and 78%. Area under the Receiver Operating Curve (AUC) for this panel was 0.90, 95% CI (0.86-0.96). Cross validation combining gene methylation with clinical information correctly predicted lung cancer in 86% of subjects using plasma detection. Furthermore, we analyzed the sensitivity and specificity of the same three-gene combination in cases subgroups regarding the tumor size and the results are as follow: in subgroup with tumor size of 2-3cm, the sensitivity and specificity were 94% and 87%, and the AUC was 0.96, 95% CI (0.91-0.99); in subgroup with tumor size of 1-2 cm, the sensitivity and specificity were 92% and 80%, and the AUC was 0.90, 95% CI (0.84-0.96); in subgroup with tumor size less than 1cm, the sensitivity and specificity decreased to 66% and 87%, and the AUC was 0.77, 95% CI (0.64-0.88). Conclusions: This study validates our previous study but in Chinese patients that it is possible to obtain high diagnostic accuracy for early stage NSCLC using a panel of methylated promoter genes in plasma samples with ultrasensitive MOB-qMSP, especially in patients with tumor of larger size. These epigenetic biomarkers could potentially be used to identify patients with high risk of lung cancer development.