Analysis of RTEL1 and PCDHGB6 promoter methylation in circulating-free DNA of lung cancer patients using liquid biopsy: A pilot study.

Background: Analysis of epigenetic alterations such as methylation of circulating-free DNA (cf-DNA) expression significantly broadened perspectives of lung cancer (LC) screening. Moreover, methylation of tumor suppressor genes may be analyzed with non-invasive manner in patients' blood samples (liquid biopsy), what underline necessity of detailed investigation of tumor cf-DNA.
Material and Methods: The purpose of current study was to assess methylation of RTEL1 and PCDHGB6 promoter regions in cf-DNA of 70 LC patients and 80 healthy individuals using qMSP-PCR technique. Methylation status of both genes has not been investigated in cf-DNA of LC patients before.
Results: PCDHGB6 promoter methylation was found in 41.4% of LC patients and in 1.3% of healthy individuals, whereas promoter of RTEL1 was found methylated in 51.4% of LC patients and in 8.8% of healthy individuals. Combined analysis of two markers improved test sensitivity up to 62.9% and specificity up to 90% with area under the curve (AUC) in receiver operating curve (ROC) of 0.755.
Conclusions: The evaluation of RTEL1 and PCDHGB6 promoter methylation may be an useful tool for non-invasive diagnosis of LC in liquid biopsy.