BACKGROUNDTo study the diagnostic value of detection of p16 methylation of sputum exfoliated cells for peripheral lung cancer.

METHODSBefore operation, p16 methylation of the sputum exfoliated cells was detected in 20 normal persons and 50 patients with peripheral pulmonary nodi by p16 methylation-specific PCR (MSP) for judging the nature of the nodi. The results were compared with pathological reports after operation.

RESULTSThe p16 MSP positive rate of sputum exfoliated cells of peripheral lung cancer patients (27/44, 61.4%) was much higher than that of benign pulmonary nodi (1/6, 16.7%) and normal persons (3/20, 15.0%)(Chi-Square=4.281 and 11.869 respectively, both P < 0.05). No significant difference of p16 MSP positive rate of sputum exfoliated cells was found between benign pulmonary nodi and normal persons (Chi-Square= 0.136, P > 0.05). No significant difference of p16 MSP positive rate of sputum exfoliated cells was found between squamous cell carcinoma (13/18, 72.2%) and adenocarcinoma (8/19, 42.1%) (Chi-Square=3.416, P > 0.05 ). If the positive p16 MSP of sputum was chosen as criterion for peripheral lung cancer, its positive predictive value, negative predictive value, sensitivity and specificity were 96.4%, 22.7%, 61.4% and 83.0% respectively.

CONCLUSIONSThe detection of p16 methylation of sputum exfoliated cells is contributable to the diagnosis of lung cancer.