Abstract 1860: An epigenetic biomarker panel for detection of early stage lung cancer using serum DNA

The use of biomarkers for early detection of lung cancer is promising but still methodologically challenging. Single biomarker approaches have not yet proven to have a strong potential in lung cancer. Clinical validation remains also a major challenge. Here we aimed to perform a phase II validation study in lung cancer specific methylation biomarkers previously reported by our group and others and also to evaluate their potential to identify early stage lung cancer. The gene evaluation set consisted of 205 serum samples from cancer cases and controls. The majority (77%) of cancer patients participating in this study had been diagnosed with stage I lung cancer and both normal and cancer cases had a history of tobacco use. DNA extracted from serum samples was subjected to bisulfite treatment, followed by quantitative methylation specific PCR (qMSP) with primers and probes specifically designed to amplify the promoter region of the genes of interest. All samples were received and assessed blindly. Histology results revealed that the control group included patients with benign lesions and inflammatory histotypes. The relative level of methylated DNA for each gene per sample was determined as the ratio of qMSP for the amplified gene to b-actin multiplied by 1000. No cutoff was used for APC, MGMT, AIM1 and DCC genes. For CDH1, an empiric cutoff was established at 60. A panel with the 5 genes tested (CDH1, APC, AIM1, MGMT and DCC) showed 50% sensitivity and 45.76% specificity in early lung cancer detection when inflammation was considered within the normal cohort. When inflammation was excluded and only other benign conditions were kept in the control group, specificity was increased to 53.33%. Specificity was increased for all the gene combinations when inflammatory conditions were not included in the control group. Combination of APC and CDH1 has a specificity of 69.49% vs 86.67%, CDH1 and AIM1 69.49% vs 86.67%, AIM1 and APC 61.02% vs 73.33% and CDH1, AIM1 and APC 56% vs 75% (inflammatory and benign cases vs only benign cases, respectively). This study confirms and extends previous observations that identification of serum DNA methylation in specific set of genes is a potentially useful approach to detect lung cancer patients. DNA methylation was more frequently observed in patients with early lung cancer than in age-matched controls. The sensitivity for the diagnosis of early stage lung cancer was 50% when analyzed by gene combination approach. All groups had