Detection of micrometastases of lung cancer by using lunx mRNA specific reverse transcription-polymerase chain reaction

Objective: To detect of lung cancer micrometastases in peripheral blood and regional lymphatic nodes by using lunx mRNA specific reverse transcription-polymerase chain reaction (RT-PCR). Methods: RT-PCR was used to detect lunx mRNA in peripheral blood of 26 patients with lung cancer. We also detected 44 regional lymphatic nodes obtained from 25 patients with lung cancer who underwent curative lobectomy. All the 44 regional lymphatic nodes were also examined by histopathology. Micrometastatic tumor cells in the peripheral blood and regional lymphatic nodes were semiquantitatively determined with the ratio of lunx band intensity to the glyceraldehydes-3-phosphate dehydrogenase band intensity. Results: The positive detection rate of lunx mRNA in peripheral blood for non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) patients were 60% (12/20) and 67% (4/6) respectively. 16 (36.4%) of regional lymphatic nodes from 44 lung cancer patients were positive by RT-PCR while 6 (13.6%) were positive by histopathology (x 2=6.06, P=0.014). However, no blood samples and lymphatic nodes from patients with benign pulmonary diseases or normal volunteers were positive for lunx mRNA. The positive detection rate of lunx mRNA in bone marrow of NSCLC amd SCLC patients were 65% (13/20) and 67% (4/6) respectively. Conclusion: RT-PCR amplification of lunx mRNA is an sensitive and specific means to detect early haematogenous and regional lymphatic nodes dissemination of cancer cells for patients with lung cancer.