BACKGROUNDConventional cytology is valuable in diagnosing the cancer cells in pleural fluid of patients with lung cancer. However, the diagnostic value of detecting pleura micrometastasis is limited. The aim of this study is to investigate clinical significance of CK19 mRNA expression in pleural fluid of patients with lung cancer.

METHODSReverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect CK19 mRNA in pleural fluid from 86 patients with lung cancer and 40 patients with benign lung diseases, and the results were compared with the results of conventional cytologic diagnosis.

RESULTSThe positive rates of CK19 mRNA in pleural fluid were 93.0%(80/86) from patients with lung cancer and 20.0% (8/40) from patients with benign lung diseases, which showed an obvious difference between two groups (Chi-square=65.69, P < 0.01). The positive rates of CK19 mRNA in pleural fluid of patients with lung cancer had no correlation with histopathology types (P > 0.05). The sensitivity and accuracy of CK19 mRNA were obviously higher than those of diagnosis of conventional cytology in pleural fluid of patients with lung cancer (P < 0.01).

CONCLUSIONSCK19 mRNA can be taken for a molecular marker to detect pleura micrometastasis, it may be helpful to diagnose the cancer cells in pleural fluid of patients with lung cancer and evaluate the clinical staging more correctly.