BACKGROUND.Methylation patterns may be useful biomarkers of cancer detection and risk assessment.METHODS.The methylation status of 6 genes, including a candidate tumor suppressor gene (BLU), the cadherin 13 gene (CDH13), the fragile histidine triad gene (FHIT), the cell cycle control gene p16, the retinoic acid receptor β gene (RARβ), and the Ras association domain family 1 gene (RASSF1A), was examined in plasma samples, corresponding tumor tissues, and normal lung tissues from a group of 63 patients with lung cancer and in plasma samples from 36 cancer‐free individuals. The detection rate of the p16 gene was validated in a test group of 20 patients with lung cancer.RESULTS.The concordance of methylation in tumor tissues and plasma samples was 86%, 87%, 80%, 75%, 76%, and 84% for the BLU, CDH13, FHIT, p16, RARβ, and RASSF1A genes, respectively. The test group showed a similar concordance for p16 methylation detection. Multiple logistic regression analysis showed that the odds ratio for having lung cancer was 10.204 for individuals with p16 methylation (P = .013) and 9.952 for individuals with RASSFIA methylation (P = .019). After several trial tests, the authors established that methylation for ≥2 of the 6 markers met the criterion for an elevated risk of cancer. Comparisons yielded a sensitivity of 73%, a specificity of 82%, and a concordance of 75% between the methylation patterns in tumor tissues and in corresponding plasma samples. The detection rate was relatively high in cigarette smokers with advanced squamous cell lung cancer.CONCLUSIONS.The current results indicated that multiple epigenetic markers in the plasma, especially the p16 and RASSF1A genes, can be used for lung cancer detection. This methylation marker panel should improve the detection of cancer or the risk assessment for lung cancer in combination with conventional diagnostic tools. Cancer 2007. © 2007 American Cancer Society.

Lung cancer is the leading cause of cancer deaths worldwide. This study was designed to select multiple DNA markers, which have high sensitivity and specificity to serve as biomarkers for diagnosis of lung cancer. We examined the promoter hypermethylation of three tumor suppressor genes by methylation-specific PCR (MSP), and the instability of eight microsatellite markers by loss of heterozygosity (LOH) and microsatellite instability (MSI) analyses in lung tumor tissues and matched sputum specimens from 79 lung cancer patients. On the basis of the results of sensitivity, specificity, and concordance from each marker analyzed, we selected seven biomarkers, which are LOH of D9S286, D9S942, GATA49D12, and D13S170, MSI of D9S942, and methylation of p16(INK4a) and RARbeta, from the sputum analyses. These selected etiologically associated biomarkers can potentially be used as supplemental diagnostic biomarkers for early lung cancer detection.