Detection of circulating tumor cells (CTCs) in patients with lung carcinoma by real-time fluorescent quantitative-PCR approach before and after chemotherapy

Abstract

Circulating tumour cells (CTCs) are referred to the tumour cells that disseminated from the primary tumour and survive in circulating during the pro-ceeding of tumour growth. As surgical treatment evolves and local control has improved, the failure of cancer treatment has largely remained the re-sult of systemic metastasis. Selection of patients most likely to benefit from adjuvant strategies remains problematic. In order to develop a new standard of curative effect, this study was de-signed to track the number of CTCs in patients with lung cancer during chemotherapy. Methods: Samples of peripheral blood was taken from each lung cancer patients (n=32) on the day before chemotherapy as well as the third week after the chemotherapy cycle. The samples were subjected to real-time fluorescent quantitative reverse-tran- scriptase polymerase chain reaction (fqRT-PCR). Meanwhile the tumour size was determined by chest X-ray or computed tomograghy. Results Compared to that of pre-chemotherapy, the ex-pression level of cytokeratin (CK) 19 in the pa-tients significantly declined after chemotherapy (t=4.659,P=0.000). The level of CK19 mRNA in pa-tients with small cell lung cancer (SCLC) was higher than that of patients with non-small cell lung cancer (NSCLC) (t=1.944, P=0.061). The de-crease of CK19 mRNA level correlated well with the type during the treatment. Relatively the de-crease of SCLC is more obvious (t=6.073,P=0.000). The variation of CK19 mRNA level before and after chemotherapy was positively related to the dis-parity of tumour burden (r=0.593). There was also a significant association between the type (NSCLC vs. SCLC) and the change of tumour size (t=3.686, P=0.001).The positive rate before chemotherapy Supported by grant from the Natural Science Foundation in China (No.30972961). was 71.9% (23/32), while that after chemotherapy was 37.5% (12/32), indicating that 11 patients con- verted into negative after chemotherapy. Of the 16 patients which were in Ⅳ-stage, 11 cases were po- sitive (11/16,68.8%). Surprisingly, of the remaining 16 patients which were Ⅱ/Ⅲ stage, 12 cases were regarded as positive according to the criteria (12/6,75%). Conclusions: The real-time flu- ores-cent quantitative-PCR approach is useful for mea- suring the relative number of CTCs in a patients’ peripheral blood to monitor the effectiveness of treatment, and for designing more comprehensive and reasonable therapeutic regimes at earlier dates for patients. The treatment response can be immediately assessed by serial quantitation of CTCs after chemotherapy, and therefore this method highlights an alternative approach to rapidly access the patient’s response to treatment.