PARTⅠ. EVALUATION OF THE DIAGNOSTIC TEST Background and aims: Since traditional RT-PCR technology is at best semiquantitative, it has been difficult to differentiate between baseline level of gene expression in normal tissues and increased level of gene expression associated with cancer, rising the concerning for false-positive results. This study aimed to set up a quantitative method (i.e. Fluorescent Quantitative Reverse Transcriptase –Polymerase Chain reaction, fqRT-PCR) and determine the possibility to use easily accessible body fluids as a source for MMD detection enabling longitudinal observation of the disease, therapy monitoring and initial diagnosis. Methods: Using CK19 mRNA as a marker, the assay (real-time fluorescent quantitative RT-PCR), standard curve and receiver operator characteristic (ROC) curve were set up through detection of the target transcription in peripheral blood of patients with lung cancer and healthy subjects. Results: The area under the ROC curve was 0.965,indicating high accuracy. The reproducibility of the technique was established with the Ct value obtained for each dilution (105~108) from the standard curve in different assays and within an assay. The intraassay and interarray CVs of the threshold cycle were 2.2 and6.5%, respectively, on average. Nine positive samples were found in the stage Ⅳ lung cancer patients(n=15), whereas, 14 / 23 operable lung cancer patients were positive prior to operation. Conclusion: The specificity of a tissue-specific marker could be restored by the use of a quantitative assay with subtraction of background transcription. Real-time quantitative PCR is a sensitive method, which can offer several advantages over classical RT-PCR techniques. This method may help rapidly assess the efficacy of anticancer treatment, redefine cancer staging, and facilitate the design of better therapeutic strategies for the cancer patients. PARTⅡ. OBSERVATION OF CTCs IN PATIENTS WITH NON-SMALL CELL LUNG CANCER IN PEROPERATIVE PERIOD Background and aims: The detachment of cancer cells from the primary tumour is one of the early sequential events in the metastatic cascade. Therefore surgeons are always concerned that the manual manipulation of a tumour during an operating might enhance the shedding of cancer cells into the bloodstream, resulting in an increase in the incidence of distant metastases. In the present study, we aimed to assess whether surgical manoeuvre or resection of lung cancer could lead to haematogenous dissemination of malignant cells. The quantity and timing of the shedding of lung cancer cells into the circulation of patients were also monitored by FQ-RT-PCR before, during and after surgery. In the mean time, the relationship between the sequence of vessel ligation and the haematogenous dissemination of cancer cells during operation was determined. Methods: Exploiting CK19/CEA mRNA as markers, 69 peripheral blood samples were collected during preoperative, intraoperative and postoperative period from 23 consecutive patients with lung cancer who underwent surgical resection with curative intention. All patients were randomly assigned before the operation to one of two surgical procedure groups according to the order of vessel ligation, PV-first group and PA-first group. Additionally, the 10 patients with benign lung disease served as control subjects undergoing surgical resection. All the peripheral blood samples were subjected to FQ-RT-PCR. Results: The CK19 diagnostic test (1) The level in operation was significantly higher than that of preoperational(5.246±0.196 vs. 4.472±0.164,P=0.000) and post operation (5.246±0.196 vs. 4.694±0.177,P=0.013). (2) The value of poor grade was higher than that of well/mediate grade(5.0337±1.1058 vs. 4.2257 ± 0.4519,t=2.534,P=0.019). Meanwhile the values between adenocarcinoma and squamous carcinoma were significantly different (4.9110±1.0315 vs. 4.1891±0.4126,t=2.364,P=0.028). The values of CK19 mRNA in PB between PV-first group and PA-first group during perioperative period were significant different