OBJECTIVETo detect hyper methylation of p16 gene in plasma DNA from patients with lung cancer, and to assess its potential as a malignant marker.

METHODSUsing a modified semi-nested methylation-specific PCR (MSP), the status of methylation of the p16 was investigated in plasma DNA from 137 lung cancer patients and 112 matched tumor tissues.

RESULTSHypermethylation of the p16 was present in 75.2% (103/137) of the plasma samples and 80.4% (90/112) of the tumor tissues. Hypermethylation of the p16 in the plasma was detected in 77.9% squamous-cell carcinoma, 65.1% adenocarcionma, 75.1% adeno-squamous-cell carcinoma, and 91.7% small-cell lung cancer. Only in those patients whose tumor tissues had hypermethylation of p16 gene, similar changes could be detected in their plasma samples. Hypermethylation of the p16 in plasma and the corresponding tumor tissues was not significantly correlated with the clinical stage and pathological type of the tumor.

CONCLUSIONThe result indicates that hypermethylation of the p16 may be a useful marker in the auxiliary diagnosis of lung cancer.