ABSTRACT
Background: Surgical treatment of early-stage non-small cell lung cancer (NSCLC) yields highest expectations for recovery. However, the frequency of further disease progression remains high since micro-metastatic disease may be undetected by conventional diagnostic methods. We test the presence and prognostic impact of circulating tumor cells (CTCs) in peripheral blood (PB), tumor-draining pulmonary blood (TDB) and bone marrow (BM) samples from NSCLC patients. Methods: The presence of circulating/disseminated tumor cells (CTCs/DTCs) was detected by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis in PB, TDB and BM samples before surgery in 119 stage IA-IIIA NSCLC patients (Clinical Trial NS10285). Results: NSCLC patients with the presence of carcinoembryonic antigen (CEA) mRNA-positive CTCs/DTCs in TDB and BM had significantly shorter cancer-specific survival (CSS) (P<0.013, resp. P<0.038). Patients with the presence of epithelial cellular adhesion molecule (EpCAM) mRNA-positive CTCs in TDB samples had significantly shorter CSS and disease-free survival (DFS) (P<0.031, resp. P<0.045). A multivariate analysis identified the presence of CEA mRNA-positive CTCs in the PB as an independent negative prognostic factor for DFS (P<0.005). No significant correlation of CTCs/DTCs presence and other prognostic factors was found. Conclusions: In NSCLC patients undergoing radical surgery, the presence of CEA and EpCAM mRNA-positive CTCs/DTCs is associated with poorer survival.
ABSTRACT
Circulating tumor cells (CTCs) are released from primary tumors and transported through the body via blood or lymphatic vessels before settling to form micrometastases under suitable conditions. Accordingly, several studies have identified CTCs as a negative prognostic factor for survival in many types of cancer. CTCs also reflect the current heterogeneity and genetic and biological state of tumors; so, their study can provide valuable insights into tumor progression, cell senescence, and cancer dormancy. Diverse methods with differing specificity, utility, costs, and sensitivity have been developed for isolating and characterizing CTCs. Additionally, novel techniques with the potential to overcome the limitations of existing ones are being developed. This primary literature review describes the current and emerging methods for enriching, detecting, isolating, and characterizing CTCs.
Subject(s)
Neoplastic Cells, Circulating , Humans , Neoplastic Cells, Circulating/pathology , Cell Separation/methodsABSTRACT
Background: Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related death with a 5-year survival of only 21%. Reliable prognostic and/or predictive biomarkers are needed to improve NSCLC patient stratification, particularly in curative disease stages. Since the endogenous cannabinoid system is involved in both carcinogenesis and anticancer immune defense, we hypothesized that tumor tissue expression of cannabinoid 1 and 2 receptors (CB1 and CB2) may affect survival. Methods: Tumor tissue samples collected from 100 NSCLC patients undergoing radical surgery were analyzed for CB1 and CB2 gene and protein expression using the quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC). The gene and protein expression data were correlated with disease stage, histology, tumor grading, application of chemotherapy, and survival. Additional paired tumor and normal tissue samples of 10 NSCLC patients were analyzed independently for comparative analysis of CB1 and CB2 gene expression. Results: Patients with tumors expressing the CB2 gene had significantly longer overall survival (OS) (P<0.001), cancer specific survival (CSS) (P=0.002), and disease-free survival (DFS) (P<0.001). They also presented with fewer lymph node metastases at the time of surgery (P=0.011). A multivariate analysis identified CB2 tumor tissue gene expression as a positive prognostic factor for CSS [hazard ratio (HR) =0.274; P=0.013] and DFS (HR =0.322; P=0.009), and increased CSS. High CB2 gene and protein expression were detected in 79.6% and 31.5% of the tested tumor tissue samples, respectively. Neither CB1 gene nor CB1 or CB2 protein expression affected survival. When comparing paired tumor and tumor-free lung tissue samples, we observed reduced CB1 (P=0.008) and CB1 (P=0.056) gene expression in tumor tissues. Conclusions: In NSCLC patients undergoing radical surgery, expression of the CB1 and CB2 receptor genes is significantly decreased in neoplastic versus tumor-free lung tissue. CB2 tumor tissue gene expression is strongly associated with longer survival (OS, CSS, DFS) and fewer lymph node metastases at the time of surgery. More studies are needed to evaluate its role as a biomarker in NSCLC and to investigate the potential use of CB2 modulators to treat or prevent lung cancers.
