The prognostic role of circulating tumor cells (CTCs) detected by RT-PCR in breast cancer: a meta-analysis of published literature

Association Between Obesity and Circulating Tumor Cells in Early Breast Cancer Patients

BACKGROUND

Obesity and the presence of circulating tumor cells (CTCs) before and/or after chemotherapy are associated with poor outcome in breast cancer (BC) patients. The activation of oncogenic pathways in fatty tissue leads to cell proliferation, suggesting a possible link between obesity and CTCs.

MATERIALS AND METHODS

In the phase III SUCCESS A trial, 3754 patients with early BC were randomized to 3 cycles of fluorouracil, epirubicin and cyclophosphamide followed by 3 cycles of docetaxel with or without gemcitabine. Data of 1088 patients with CTC assessments (CellSearch-System; Menarini Silicon Biosystems, Italy) and body mass index (BMI) measurements both before and after chemotherapy were available. Patients were classified according to the WHO's international definitions as underweight, normal weight, overweight, or obese, and according to their weight-change during chemotherapy into a weight-loss group (> 5% decrease), stable-weight group (≤ 5% weight-change) or weight-gain group (>5% increase). Associations between CTC positivity and, BMI or weight-change group were analyzed using frequency-table methods.

RESULTS

At study entry, 47.4% patients were underweight or normal weight, 33.6% were overweight and 18.9% were obese. Before and after chemotherapy, CTCs were detected in 20.1% and 22.6% of patients, respectively. There was no association between CTC positivity and BMI before (P = 0.104) or after (P = 0.051) chemotherapy. Furthermore, there was no association between weight-change group and CTC status before/after chemotherapy (P = 0.332).

CONCLUSIONS

According to our analysis, the risk factors obesity and prevalence of CTCs are not associated and may represent independent prognostic factors.

Multifunctional Gold Nano-Cytosensor With Quick Capture, Electrochemical Detection, and Non-Invasive Release of Circulating Tumor Cells for Early Cancer Treatment

Circulating tumor cells (CTCs) are metastatic tumor cells that shed into the blood from solid primary tumors, and their existence significantly increases the risk of metastasis and recurrence. The timely discovery and detection of CTCs are of considerable importance for the early diagnosis and treatment of metastasis. However, the low number of CTCs hinders their detection. In the present study, an ultrasensitive electrochemical cytosensor for specific capture, quantitative detection, and noninvasive release of EpCAM-positive tumor cells was developed. The biosensor was manufactured using gold nanoparticles (AuNPs) to modify the electrode. Three types of AuNPs with controllable sizes and conjugated with a targeting molecule of monoclonal anti-EpCAM antibody were used in this study. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) of the cytosensors were performed to evaluate the cell capture efficiency and performance. The captured 4T1 cells by the AuNPs hindered electron transport efficiency, resulting in increased EIS responses. The cell capture response recorded using EIS or DPV indicated that the optimal AuNPs size should be 17 nm. The cell capture response changed linearly with the concentration range from 8.0 × 10 to 1 × 10⁷ cells/mL, and the limit of detection was 50 cells/mL. After these measurements, glycine-HCl (Gly-HCl) was used as an antibody eluent to destroy the binding between antigen and antibody to release the captured tumor cells without compromising their viability for further clinical research. This protocol realizes rapid detection of CTCs with good stability, acceptable assay precision, significant fabrication reproducibility with a relative standard deviation of 2.09%, and good recovery of cells. Our results indicate that the proposed biosensor is promising for the early monitoring of CTCs and may help customize personalized treatment options.

Detection of Minimal Residual Disease in the Peripheral Blood of Breast Cancer Patients, with a Multi Marker (MGB-1, MGB-2, CK-19 and NY-BR-1) Assay

Purpose

Minimal residual disease (MRD) refers to micrometastases that are undetectable by conventional means and is a potential source of disease relapse. This study aimed to detect the presence of breast cancer (BC) biomarkers (MGB-1, MGB-2, CK-19, NY-BR-1) using real-time polymerase chain reaction (RT-PCR) in peripheral blood mononuclear cells (PBMC) of BC patients and the impact of a positive assay on clinical outcome.

Patients and Methods

Patients in the analysis included females >18 years of age with biopsy-proven carcinoma of the breast. A 10 mL sample of venous blood was obtained from 10 healthy controls and 25 breast cancer patients. Comparisons of peripheral blood markers were made with clinicopathological variables.

Results

High-quality RNA was extracted from all samples with a mean RNA concentration of 224.8±155.3 ng/µL. Each of the molecular markers examined was highly expressed in the primary breast tumors (n = 3, positive controls) with none of the markers detected in healthy negative controls. The NY-BR-1 marker was expressed in one (4%) patient with metastatic disease with no MGB-1 and MGB-2 detected in any sample derived from the study patients. The CK-19 marker was detected in 16 (64%) of the BC cases. No correlation was found between CK-19 expression and tumor stage (P = 0.07) or nodal status (P = 0.32). No correlation was identified in the BC patients between CK-19 expression and receptor status in the BC primary tumor.

Conclusion

This study showed high expression of all 4 markers NY-BR-1, MGB-1, MGB-2 and CK-19 in the PBMCs derived from breast cancer patients. CK-19 was detected in 64% of the stage I–III cases operated with curative intent, the only recurrent events occurring in the CK-19-positive cases. Our data confirm the need to enhance techniques for detection of MRD, which may better predict patients at risk for relapse.

Expression of DOG1 in peripheral blood cells of patients with gastrointestinal stromal tumor

BACKGROUND AND STUDY AIMS

The diagnosis and surveillance of gastrointestinal stromal tumor (GIST) rely on pathology and immunochemistry (IHC), making it complicated and invasive. Noninvasive and convenient biomarkers of this disease need to be explored. The high specificity and sensitivity of IHC in detecting GIST 1 (DOG1) in biopsy indicate that it is also expressed in circulating tumor cells of the blood and may be an ideal biomarker for GIST. This aimed to detect the expression of DOG1 in peripheral blood cells (PBCs) and determine the relationship between DOG1 expression and clinical factors.

PATIENTS AND METHODS

A total of 45 patients with GIST and 46 healthy controls (HCs) were recruited from the Second Affiliated Hospital of Nanchang University between December 2015 and June 2018. PBCs were isolated from peripheral venous blood by density gradient centrifugation. RNA was extracted from PBCs, and DOG1 mRNA was detected by quantitative reverse transcription polymerase chain reaction. DOG1 mRNA expression between GIST and HC was compared, and the relationship between clinical factors and DOG1 was also analyzed.

RESULTS

DOG1 mRNA expression in PBCs was significantly higher in patients with GIST than that in HCs (3.326 [1.942-5.328] versus 0.744 [0.269-1.087], p < 0.01). The specificity and sensitivity were 88.9% and 89.1%, respectively (AUC = 0.912). Tumor diameter and risk of aggressive behavior were correlated with DOG1 expression, and other clinical factors (sex, age, location, number of phase-splitting cells, Ki-67 index, metastatic status) did not show any relationship with DOG1 expression. However, clinical factors, including tumor diameter and risk grade, were not independent factors in DOG1 expression when multivariate analysis was conducted.

CONCLUSION

DOG1 expressions were significantly higher in patients with GIST than that in HCs. Tumor diameter and risk classification correlated with DOG1 expression but were not independent factors. DOG1 in PBCs is a promising noninvasive biomarker for GIST.

Detection of circulating tumor cells in patients with laryngeal cancer using ScreenCell: Comparative pre- and post-operative analysis and association with prognosis

The presence of circulating tumor cells (CTCs) in the blood of patients with metastatic breast, colorectal and prostate cancer have been widely investigated; however, few studies have examined CTCs in patients with laryngeal cancer. The present pilot study aimed to detect pre- and postoperative CTCs in the blood of patients with laryngeal cancer and evaluate the association with prognosis. Eight patients with laryngeal squamous cell carcinoma (LSCC) at stage III were included in the present study and underwent total or subtotal laryngectomy and radical bilateral neck lymph node dissection. Blood samples were collected from all patients before and after surgery at different time-points. The following processing steps were followed; preoperative blood sampling, surgery, postoperative blood sampling at 3, 6 and 12 month follow-ups, and prognostic association analysis. CTCs were retained on ScreenCell filters for cytological characterization. The presence of CTCs was associated with a less favorable prognosis, whereas a decrease of CTCs in the postoperative sampling was observed in patients who exhibited an improved therapeutic response. The results of the present pilot study revealed a possible association between the presence of CTCs and a less favorable prognosis in patients with LSCC; therefore, these preliminary findings may encourage further research into the incorporation of a liquid biopsy in the management of LSCC, as this may help identify patients with occult metastatic disease earlier and in a non-invasive manner. In addition, this approach may represent novel independent prognostic factor for use in the clinical evaluation of patients with LSCC.

A microfluidic system based on the monoclonal antibody BCMab1 specifically captures circulating tumor cells from bladder cancer patients

Circulating bladder tumor cells provide significant information for cancer diagnosis, tumor staging and personalized cancer therapy. Previous studies have reported various methods for capturing circulating tumor cells; however, capturing circulating tumor cells remain a challenge. Here, we present a microfluidic chip with high specificity and capture yields that we refer to as a bladder cancer diagnosis chip. We show that this chip can be used to effectively capture circulating bladder cancer cells based on antibody-BCMab1, a monoclonal antibody that binds to aberrantly glycosylated integrin a3b1. This capture platform is composed of a polydimethylsiloxane (PDMS) chip, whose microchannels are functionalized with biotinylated BCMab1. To change the direction of flow to increase cell-substrate contact, we also introduced a herringbone or chevron channel pattern into the chip. Using this system, we were able to capture bladder cancer cells with high specificity. The capture rates of the bladder cancer diagnosis chip were evaluated at different flow rates and cell concentrations. We found that 90% of the cancer cells were successfully captured at flow rates of 10 μL/min and at various cell concentrations. This highly specific microfluidic chip is a novel tool for bladder cancer diagnosis and offers an opportunity for personalized treatment.

The Prognostic Value of Circulating Tumor Cells in Primary Breast Cancer Prior to any Systematic Therapy: A Systematic Review

BACKGROUND

Numerous studies have defined the outstanding role of circulating tumor cells (CTC) in the management of cancer, particularly the ones in association with primary tumor metastases.

OBJECTIVE

The overall aim of the present study was to investigate whether CTCs may serve as a clinical prognostic marker for survival in primary breast cancer.

METHODS

Articles Published from June 2011 to July 2017 in PubMed, EMBase, and Cochrane library databases were thoroughly screened for selecting the ones meeting the inclusion criteria.

RESULT

Studies applying CellSearch® method demonstrated the risk ratios (RR) of 2.51 (95% CI: 1.78- 3.54), 3.98 (95% CI: 2.28- 6.95), 5.59 (95% CI: 3.29- 9.51), and 3.38 (95% CI: 1.88- 6.06) for death rate and relapse rates of 2.48 (95% CI: 1.89 - 3.26), 3.62 (95% CI: 2.37 - 5.51), 4.45 (95% CI: 2.94 - 6.73), and 2.88 (95 % CI: 1.99 - 4.17) at four CTC positive cut points (≥ 1, ≥ 2, ≥ 3, and ≥ 5 CTCs/7.5 ml). Two studies applying the AdnaTest® also documented increased death (RR: 1.38, 95 % CI: 0.42- 4.49) and relapse rates (RR: 2.97, 95 % CI: 1.23 - 7.18)).

CONCLUSION

Results of this meta-analysis allude CTCs as potent prognostic markers in primary breast cancers prior to any systemic therapy especially when it is studied via CellSearch® administration, considering that the more the CTCs, the greater the death and relapse rates.

Detection of human mammaglobin mRNA in breast cancer cells among Vietnamese women

Background

Detecting circulating tumor cells (CTCs) is a promising approach for evaluating the progression of occult metastases as well as the efficacy of treatment therapies among patients with breast cancer. A real-time reverse transcriptase polymerase chain reaction (RT-PCR) technique has been proposed for detecting CTCs due to its high sensitivity. In this study, we aimed to validate the RT-PCR technique for human mammaglobin (hMAM) mRNA detection among Vietnamese women with breast cancer.

Patients and methods

Peripheral blood samples and breast cancer tissues from 43 patients suffering from breast cancer and 21 patients with fibroids were obtained. Real-time RT-PCR and gene sequencing techniques were employed to detect hMAM gene in CTCs of breast cancer cell lines and cancer tissues.

Results

hMAM mRNA transcription was detected in 36 out of 43 (83.7%) breast cancer tissues and in blood of 23 out of 43 (53.5%) breast cancer patients, while it was detected in only 9.5% out of tissues and 0% of the blood of fibrosis patients. hMAM mRNA in the peripheral blood of breast cancer patients increased with tumor size, stage of cancer and distant metastasis (P<0.05). No difference in the expression of hMAM mRNA was found in breast cancer tissue regarding age, distant metastasis, lymph node, stages of cancer and histopathology (P>0.05).

Conclusion

The study highlighted the expression of hMAM mRNA in breast cancer cells and tissues. This reveals the overall picture of the replication of hMAM mRNA in breast cancer, suggesting the role of hMAM mRNA in breast cancer molecular pathology.

[Effects of minimally invasive versus open esophagectomy on circulating tumor cells in patients with esophageal cancer]

OBJECTIVE

To investigate the effects of minimally invasive esophagectomy (MIE) and open esophagectomy (OE) on the level of circulating tumor cells (CTCs) in patients with esophageal cancer (EC).

METHODS

A total of 73 patients with EC undergoing MIE (n=38) or OE (n=35) in our department between October, 2015 and October, 2017 were enrolled, with 10 patients with benign esophagus disease and 10 healthy volunteers as controls. The levels of CTCs in the peripheral blood of the participants were detected using CanPatrol^TM technique and analyzed for their association with the operation methods and perioperative complications.

RESULTS

CTCs were detected in 60.3% (44/73) of the EC patients but in none of the control subjects. CTC level after the surgery was significantly higher than that during the surgery, and CTC level during the surgery was significantly higher than that before surgery (P<0.001). The preoperative and intra-operative CTC levels were not significantly different between MIE and OE groups (P>0.05), but the postoperative CTC level was significantly lower in MIE group than in OE group, and postoperative increment of CTC level (from the preoperative level) was significantly lower in MIE group than in OE group (P<0.001). The total incidence of postoperative complications was significantly lower in MIE group than in OE group (28.9% vs 54.3%, P=0.023), and in both groups, CTC levels in patients with complications were significantly higher than those in patients without complications (P=0.001 and P=0.005 in MIE and OE groups, respectively).

CONCLUSION

MIE may help to reduce the number of peripheral blood CTCs early after the operation, and dynamic monitoring CTCs level assists in evaluation of the prognosis of EC patients. CTC level may serve as an indicator for monitoring the prognosis of EC.

Circulating tumor cells predict survival benefit from chemotherapy in patients with lung cancer

Background

This meta-analysis was to explore the clinical significance of circulating tumor cells (CTCs) in predicting the tumor response to chemotherapy and prognosis of patients with lung cancer.

Methods

We searched PubMed, Embase, Cochrane Database, Web of Science and reference lists of relevant articles. Our meta-analysis was performed by Stata software, version 12.0, with a random effects model. Risk ratio (RR), hazard ratio (HR) and 95% confidence intervals (CI) were used as effect measures.

Results

8 studies, including 453 patients, were eligible for analyses. We showed that the disease control rate (DCR) in CTCs-negative patients was significantly higher than CTCs-positive patients at baseline (RR = 2.56, 95%CI [1.36, 4.82], p < 0.05) and during chemotherapy (RR = 9.08, CI [3.44, 23.98], p < 0.001). Patients who converted form CTC-negative to positive or persistently positive during chemotherapy had a worse disease progression than those with CTC-positive to negative or persistently negative (RR = 8.52, CI [1.66, 43.83], p < 0.05). Detection of CTCs at baseline and during chemotherapy also indicated poor overall survival (OS) (baseline: HR = 3.43, CI [2.21, 5.33], p<0.001; during chemotherapy: HR = 3.16, CI [2.23, 4.48], p < 0.001) and progression-free survival (PFS) (baseline: HR = 3.16, 95%CI [2.23, 4.48], p < 0.001; during chemotherapy: HR = 3.78, CI [2.33, 6.13], p < 0.001).

Conclusions

Detection of CTCs in peripheral blood indicates poor tumor response to chemotherapy and poor prognosis in patients with lung cancer.

CK19, CK20, EGFR and HER2 Status of Circulating Tumor Cells in Patients with Breast Cancer

Aims and background

The major cause of death in breast cancer patients is metastasis. Various biomarkers have been used for the early detection of circulating tumor cells in the peripheral blood of breast cancer patients. The aims of the current study were to analyze circulating tumor cells in the blood of breast cancer patients by investigating EGFR, CK19, CK20 and HER2 expression profiles and to evaluate their prognostic importance.

Methods

CK19, CK20 and EGFR gene expression profiles were evaluated in the blood samples of 84 female patients with primary invasive ductal breast cancer and 20 healthy female volunteers using SYBR green-based real-time qPCR assays. HER2 expression analyses were conducted in 46 patients who had an HER2-positive primary tumor and in 30 healthy women to determine the cutoff level of positivity.

Results

The positive rates of CK20, EGFR, CK19 and HER2 mRNA expression in the peripheral blood were 28.57% (24/84), 20.23% (17/84), 5.95% (5/84) and 2.17% (1/46), respectively. The high positive ratio of CK20 mRNA expression in the peripheral blood of breast cancer was identified for the first time in the current study. Significant differences were identified in CK20 expression status and several clinical parameters related with aggressiveness of tumors using a binary logistic regression analysis. Higher CK20-positive levels were observed in patients who had lymph node metastasis and advanced-grade primary tumors, which were estrogen receptor-negative. We have demonstrated that CK20 may be a novel biomarker that is useful to identify circulating tumor cells and predict breast cancer progression.

Conclusions

The results suggest that the investigation of CK20 mRNA with other biomarkers in the peripheral blood of breast cancer patients may be useful to monitor the presence of disseminated tumor cells in the blood circulation and to predict the prognosis of breast cancer.

Geometrically enhanced sensor surfaces for the selective capture of cell-like particles in a laminar flow field

Medical wires inserted into the blood stream of patients offer an attractive perspective to capture rare cells such as circulating tumor cells in vivo. A major challenge in such systems is to achieve an efficient interaction of the desired cells with the sensing surface and avoid those cells that simply flow by the wire without any contact while floating in a laminar flow field at some small distance to the sensor surface. We describe a new strategy to increase the interaction of cells or cell-like particles to such wire-shaped sensor surfaces both from an experimental and a theoretical point of view. For model experiments, we use cell-like particles that are flowing past the profile wire in a blood-like liquid stream. In the fluid dynamics simulations, this sensor is inserted into small capillaries. The influence of geometry and orientation of the wire with respect to the surrounding capillary onto the capture behavior is studied. Parameters, such as wire diameter, profile shape, wire torsion, and orientation of it with respect to the liquid stream, induce in some cases quite strong crossflows. These crossflows enhance the contact probability compared to a straight line wire of the same length by factors of up to about 80. A general model connecting the wire geometry with the crossflow intensity and the particle capture behavior is developed. Particle capture experiments demonstrate that the identified geometric factors can improve the capture of cell-like particles in laminar fluid flows and enhance the performance of such cell sensors.

Circulating and disseminated tumor cells in pancreatic cancer and their role in patient prognosis: a systematic review and meta-analysis

Background

Disseminated tumor cells (DTCs) and circulating tumor cells (CTCs) have been postulated to seed metastases and contribute to poorer patient outcomes in many types of solid cancer. To date, no systematic reviews have examined the role of both DTCs and CTCs in pancreatic cancer. We aimed to determine the prognostic value of DTCs/CTCs in pancreatic cancer using a systematic review and meta-analysis.

Materials and Methods

A comprehensive literature search identified studies examining DTCs and CTCs in the bone marrow and blood of pancreatic cancer patients at diagnosis with follow-up to determine disease-free/progression-free survival (DFS/PFS) and overall survival (OS). Statistical analyses were performed to determine the hazard ratio (HR) of DTCs/CTCs on DFS/PFS and OS.

Results

The literature search identified 16 articles meeting the inclusion criteria. The meta-analysis demonstrated statistically significant HR differences in DFS/PFS (HR = 1.93, 95% CI 1.19–3.11, P = 0.007) and OS (HR = 1.84, 95% CI 1.37–2.45, P =< 0.0001), indicating patients with detectable DTCs/CTCs at diagnosis have worse prognoses. Subgroup analyses suggested CTCs in the peripheral blood (HR =2.03) were more indicative of poor OS prognosis than DTCs in the bone marrow (HR = 1.91), although the difference between these was not statistically significant. Positivity of the CellSearch detection method for DTC/CTC had the highest correlation with decreased OS (HR = 2.79) while immunodetection (HR = 1.91) and RT-PCR (HR = 1.25) were less effective in determining prognosis.

Conclusion

The detection of DTCs/CTCs at diagnosis is associated with poorer DFS/PFS and OS in pancreatic cancer.

Detection of Circulating Tumor Cells in Breast Cancer Patients Using Cytokeratin-19 Real-Time RT-PCR

PURPOSE

The roles of circulating tumor cells (CTCs) as predictive and prognostic factors, as well as key mediators in the metastatic cascade, have been investigated. This study aimed to validate a method to quantify CTCs in peripheral blood using a real-time reverse transcriptase polymerase chain reaction (RT-PCR) assay for cytokeratin (CK)-19 and to evaluate the utility of this assay in detecting CTCs in breast cancer patients.

MATERIALS AND METHODS

Real-time monitoring PCR of fluorescently labeled specific hybridization probes for CK-19 mRNA was established. Peripheral blood samples from 30 healthy donors, 69 patients with early breast cancer, 47 patients with locally advanced breast cancer, and 126 patients with metastatic breast cancer were prospectively obtained and analyzed for CTC detection.

RESULTS

CK-19 mRNA was not detectable in healthy subjects using the real-time RT-PCR method. The detection rates of CK-19 mRNA in breast cancer patients were 47.8% for early breast cancer (33/69), 46.8% for locally advanced breast cancer (22/47), and 61.1% for metastatic breast cancer (77/129). The detection rate of CK-19-positive CTCs in metastatic disease was slightly higher than early or locally advanced breast cancer; however, the detection rate according to disease burden was not statistically different (p=0.097). The detection rate was higher in patients with pleural metastasis (p=0.045). CTC detection was associated with poor survival (p=0.014).

CONCLUSION

A highly specific and sensitive CK-19 mRNA-based method to detect CTCs in peripheral blood in breast cancer patients can be used in further prospective studies to evaluate the predictive and prognostic importance of CTCs.

Prognostic value of circulating tumor cells in metastatic breast cancer: a systemic review and meta-analysis

OBJECTIVE

Metastatic breast cancer (MBC) remains the main cause of cancer-related death, and the clinical significance and prognostic role of circulating tumor cells (CTCs) in metastatic breast cancer are still controversial. Here, we conducted a meta-analysis to clarify the correlation between CTCs and the clinicopathological features and prognosis of MBC.

METHODS

We performed a comprehensive search of Pubmed and the ISI Web of Science through December 2014. Only articles that focused on MBC patients and detected CTCs using the CellSearch system were included. The associations between CTCs and survival rate and clinicopathological parameters, including molecular pattern, metastatic region and treatment response, were evaluated.

RESULTS

This meta-analysis included 24 studies (3701 MBC patients), 13 prospective studies and 11 retrospective studies. We found that CTCs were more frequently detected with HER2 + primary tumors (pooled RR = 0.73, 95 % CI = 0.63-0.84). Additionally, higher CTC numbers indicated a worse treatment response (RR = 0.56, 95 % CI = 0.40-0.79), poorer PFS (RR = 0.64, 95 % CI = 0.56-0.73) and poorer OS (RR = 0.69, 95 % CI = 0.64-0.75) in MBC patients.

CONCLUSION

Based on these results, we propose that HER2 positivity could be a significant risk factor for the presence of CTCs. Additionally, CTCs have a significant prognostic value for MBC patients. Therefore, CTCs should be continually monitored to guide the treatment of MBC patients, especially those with HER2 + primary tumors.

CXCR4-SDF-1 interaction potentially mediates trafficking of circulating tumor cells in primary breast cancer

Background

Cytokines are involved in cancer invasion and metastasis. Circulating tumor cells (CTCs) play key role in tumor dissemination and are an independent survival predictor in breast cancer patients. The aim of this study was to assess correlation between CTCs and plasma cytokines in primary breast cancer (PBC) patients.

Methods

This study included 147 chemotherapy naïve PBC patients. Peripheral blood mononuclear cells (PBMC) were depleted of hematopoetic cells using RossetteSep™ negative selection kit. RNA extracted from CD45-depleted PBMC was interrogated for expression of EMT (Twist1, Snail1, Slug, Zeb1) and epithelial (Ck19) gene transcripts by qRT-PCR. The concentrations of 51 plasma cytokines were measured using multiplex bead arrays.

Results

CTCs were detected in 25.2 % patients. CTCs exhibiting only epithelial markers (CTC_EP) and only EMT markers (CTC_EMT) were present evenly in 11.6 % patients, while CTCs co-expressing both markers were detected in 2.0 % patients. Patients with presence of CTC_EP in peripheral blood had significantly elevated levels of plasma IFN-α2, IL-3, MCP-3, β-NGF, SCF, SCGF-β, TNF-β and SDF-1 compared to patients without CTC_EP. CTC_EP exhibited overexpression of SDF-1 receptor and CXCR4, but not other corresponding cytokine receptor, and in multivariate analysis SDF-1 was independently associated with CTC_EP. There was an inverse correlation between CTC_EMT and plasma cytokines CTACK, β-NGF and TRAIL, while presence of either subtype of CTCs was associated with increased level of TGF-β2.

Conclusion

Using cytokine profiling, we identified cytokines associated with CTCs subpopulations in peripheral blood of PBC. Our data suggest that CXCR4-SDF-1 axis is involved in mobilization and trafficking of epithelial CTCs.

Gene expression profiling and DNA methylation analyses of CTCs

A variety of molecular assays have been developed for CTCs detection and molecular characterization. Molecular assays are based on the nucleic acid analysis in CTCs and are based on total RNA isolation and subsequent mRNA quantification of specific genes, or isolation of genomic DNA that can be for DNA methylation studies and mutation analysis. This review is mainly focused on gene expression and methylation studies in CTCs in various types of cancer.

Simultaneous detection of circulating immunological parameters and tumor biomarkers in early stage breast cancer patients during adjuvant chemotherapy

BACKGROUND

Chemotherapy-induced immune suppression has mainly been studied in patients with advanced cancer, but the influence of chemotherapy on the immune system in early stage cancer patients has so far not been studied systematically. The aim of the present study was to monitor the immune system during anthracycline- and taxane-based adjuvant chemotherapy in early stage breast cancer patients, to assess the impact of circulating tumor cells on selected immune parameters and to reveal putative angiogenic effects of circulating endothelial cells.

METHODS

Peripheral blood samples from 20 early stage breast cancer patients were analyzed using a flow cytometric multi-color of antibodies to enumerate lymphocyte and dendritic cell subsets, as well as endothelial and tumor cells. An enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of various serological factors.

RESULTS

During chemotherapy, all immunological parameters and angiogenesis surrogate biomarkers showed significant decreases. The numbers of circulating tumor cells showed significant inverse correlations with the numbers of T helper cells, a lymphocyte subset directly related to effective anti-tumor responses. Reduced T helper cell numbers may contribute to systemic immunosuppression and, as such, the activation of dormant tumor cells.

CONCLUSIONS

From our results we conclude that adjuvant chemotherapy suppresses immune function in early stage breast cancer patients. In addition, we conclude that the presence of circulating tumor cells, defined as pan-cytokeratin(+), CD326(+), CD45(-) cells, may serve as an important indicator of a patient's immune status. Further investigations are needed to firmly define circulating tumor cells as a predictor for the success of breast cancer adjuvant chemotherapy.

Circulating tumour cells predict survival in gastric cancer patients: a meta-analysis

AIM OF THE STUDY

The prognostic value of the detection of circulating tumour cells (CTCs) in gastric cancer has been studied intensely in recent years. However, the application of different technologies led to inconsistent results between the studies. Here, we performed a meta-analysis of published studies to summarise the evidence.

MATERIAL AND METHODS

Medline and ISI Web of Knowledge were searched up to March 2013 using "circulating tumor cells" and "gastric cancer" as search terms. Hazard ratio (HR) with 95% confidence intervals (CIs) for prognostic outcomes and clinical characteristics were extracted from each study. Pooled hazard ratios (HR) and odds ratios (OR) were calculated using random or fixed-effects models.

RESULTS

Twelve studies enrolling 774 patients were included. The combined HR estimate for overall survival (OS), disease-free survival (DFS), and progression-free survival (PFS) were 1.41 (95% CI: 1.28-1.62), 2.99 (95% CI: 2.01-4.45) and 1.64 (95% CI: 1.02-2.62), respectively. Subgroup analysis concerning detection methods and sampling time showed that results of RT-PCR for the OS group and RT-PCR for the DFS group suggest a prognostic significance of CTC detection (pooled HR [95% CI]: 1.45 [1.28-1.65], I(2) = 38%, p = 0.13; 2.99 [2.01-4.45], I(2) = 0%, p = 0.32). In addition, results of the baseline CTC detection group also indicated a significant prognostic value to predict OS and DFS (pooled HR [95% CI]: 1.47 [1.19-1.82], I(2) = 38%, p = 0.14; 2.99 [2.01-4.45], I(2) = 0%, p = 0.32). We simultaneously found that the detection of CTCs correlated with pathological stage (pooled OR [95% CI]: 2.95 [1.65-5.28], I(2) = 56%, p = 0.03), lymph node status (pooled OR [95% CI]: 2.26 [1.50-3.41], I(2) = 37%, p = 0.09), the depth of invasion (pooled OR [95% CI]: 3.21 [1.38-7.43], I(2) = 72%, p = 0.002), and distant metastasis (pooled OR [95% CI]: 2.68 [1.25-5.73], I(2) = 43%, p = 0.15).

CONCLUSIONS

Detection of CTCs is associated with poorer prognosis in gastric cancer patients.

Relationship between circulating tumor cells and epithelial to mesenchymal transition in early breast cancer

BACKGROUND

Circulating tumor cells (CTCs) play a crucial role in tumor dissemination and are an independent survival predictor in breast cancer (BC) patients. Epithelial to mesenchymal transition (EMT) is involved in cancer invasion and metastasis. The aim of this study was to assess correlation between CTCs and expression of EMT transcription factors TWIST1 and SLUG in breast tumor tissue.

METHODS

This study included 102 early BC patients treated by primary surgery. Peripheral blood mononuclear cells (PBMC) were depleted of hematopoietic cells using RossetteSep™ negative selection kit. RNA extracted from CD45-depleted PBMC was interrogated for expression of EMT (TWIST1, SNAIL1, SLUG, FOXC2 and ZEB1) and epithelial (KRT19) gene transcripts by qRT-PCR. Expression of TWIST1 and SLUG in surgical specimens was evaluated by immunohistochemistry and quantified by multiplicative score.

RESULTS

CTCs were detected in 24.5 % patients. CTCs exhibiting only epithelial markers were present in 8.8 % patients, whereas CTCs with only EMT markers were observed in 12.8 % of pts and CTCs co-expressing both markers were detected in 2.9 % pts. We observed lack of correlation between CTCs and expression of TWIST1 and SLUG in breast cancer cells or cancer associated stroma. Lack of correlation was observed for epithelial CTCs as well as for CTCs with EMT.

CONCLUSIONS

In this translational study, we showed a lack of association between CTCs and expression of EMT-inducing transcription factors, TWIST1 and SLUG, in breast tumor tissue. Despite the fact that EMT is involved in cancer invasion and metastasis our results suggest, that expression of EMT proteins in unselected tumor tissue is not surrogate marker of CTCs with either mesenchymal or epithelial features.

A novel preclinical method to quantitatively evaluate early-stage metastatic events at the murine blood-brain barrier

The observation that approximately 15% of women with disseminated breast cancer will develop symptomatic brain metastases combined with treatment guidelines discouraging single-agent chemotherapeutic strategies facilitates the desire for novel strategies aimed at outright brain metastasis prevention. Effective and robust preclinical methods to evaluate early-stage metastatic processes, brain metastases burden, and overall mean survival are lacking. Here, we develop a novel method to quantitate early metastatic events (arresting and extravasation) in addition to traditional end time-point parameters such as tumor burden and survival in an experimental mouse model of brain metastases of breast cancer. Using this method, a reduced number of viable brain-seeking metastatic cells (from 3,331 ± 263 cells/brain to 1,079 ± 495 cells/brain) were arrested in brain one week postinjection after TGFβ knockdown. Treatment with a TGFβ receptor inhibitor, galunisertib, reduced the number of arrested cells in brain to 808 ± 82 cells/brain. Furthermore, we observed a reduction in the percentage of extravasated cells (from 63% to 30%) compared with cells remaining intralumenal when TGFβ is knocked down or inhibited with galunisertib (40%). The observed reduction of extravasated metastatic cells in brain translated to smaller and fewer brain metastases and resulted in prolonged mean survival (from 36 days to 62 days). This method opens up potentially new avenues of metastases prevention research by providing critical data important to early brain metastasis of breast cancer events.

hsa-mir-499 rs3746444 gene polymorphism is associated with susceptibility to breast cancer in an Iranian population

AIM

Our study aimed to evaluate the possible association between four miRNA polymorphisms, hsa-miR-146a (rs2910164 G>C), hsa-miR-499 (rs3746444 T>C) and hsa-miRNA-196a2 (rs11614913 C>T and rs185070757 T>G), and susceptibility to breast cancer in an Iranian population.

MATERIALS & METHODS

In this case-control study we enrolled 236 patients with breast cancer and 203 healthy individuals. Tetra primer amplification refractory mutation system PCR was applied for genotyping the four miRNA SNPs.

RESULTS

Our study indicated that the hsa-mir-499 rs3746444 CC homozygote increased the risk of breast cancer in the dominant (odds ratio [OR]: 2.42; 95% CI: 1.43-4.09; p = 0.001; CC vs TT) and recessive (OR: 2.48; 95% CI: 1.49-4.13; p = 0.004; CC vs TT+TC) inheritance models tested. In addition, the rs3746444 C allele increased the risk of breast cancer (OR: 1.71; 95% CI: 1.27-2.29; p = 0.0004) in comparison with the T allele. However, distribution of the rs2910164 G>C, rs11614913 C>T and rs185070757 T>G genotypes was not statistically different between cases and controls (p > 0.05).

CONCLUSION

Our findings demonstrated that the hsa-mir-499 rs3746444 polymorphism is associated with higher risk of developing breast cancer in our population.

Matrix metalloproteinase 1 and circulating tumor cells in early breast cancer

Background

Matrix metalloproteinases (MMPs) are involved in cancer invasion and metastasis. Circulating tumor cells (CTCs) play role in tumor dissemination and are an independent survival predictor in breast cancer (BC) patients. The aim of this study was to assess correlation between CTCs and tumor MMP1 in BC.

Methods

Study included 149 primary BC patients treated by surgery from March 2012 to March 2013. Peripheral blood mononuclear cells (PBMC) were depleted of hematopoietic cells using RossetteSep^TM selection kit. RNA extracted from CD45-depleted PBMC was interrogated for expression of EMT (TWIST1, SNAIL1, SLUG, ZEB1) and epithelial (CK19) gene transcripts by qRT-PCR. Patient samples with higher epithelial and/or mesenchymal gene transcripts than those of healthy donors (n = 60) were considered as CTC positive. Expression of MMP1 in surgical specimens was evaluated by immunohistochemistry.

Results

CTCs were detected in 24.2% patients. CTCs exhibiting only epithelial markers were present in 8.7% patients, whereas CTCs with epithelial-mesenchymal transition (EMT) markers (CTC_EMT) were observed in 13.4% of patients and CTCs co-expressing both markers were detected in 2.0% patients. Patients with CTC_EMT in peripheral blood had significantly increased expression of MMP1 in tumor cells (p = 0.02) and tumor associated stroma (p = 0.05) than those of patients without CTC_EMT. In multivariate analysis, CTC_EMT and tumor grade were independently associated with MMP1 expression in cancer cells, while CTC_EMT and Ki67 were independently associated with MMP1 expression in cancer associated stroma.

Conclusion

Our data suggest link between MMP1 and CTCs with EMT phenotype and support role of MMPs and EMT in tumor dissemination.

Circulating Tumor Cells in Metastatic Breast Cancer: A Prognostic and Predictive Marker

The role of circulating tumor cells (CTCs) as a marker for disease progression in metastatic cancer is controversial. The current review will serve to summarize the evidence on CTCs as a marker of disease progression in patients with metastatic breast cancer. The immunohistochemistry(IHC)-based CellSearch^® is the only FDA-approved isolation technique for quantifying CTCs in patients with metastatic breast cancer. We searched PubMed and Web of Knowledge for clinical studies that assessed the prognostic and predictive value of CTCs using IHC-based isolation. The patient outcomes reported include median and Cox-proportional hazard ratios for overall-survival (OS) and progression-free-survival (PFS). All studies reported shorter OS for CTC-positive patients versus CTC-negative. A subset of the selected trials reported significant lower median PFS for CTC-positive patients. The reported trials support the utility of CTC enumeration for patient prognosis. But further studies are required to determine the utility of CTC enumeration for guiding patient therapy. There are three clinical trials ongoing to test this hypothesis. These studies, and others, will further establish the role of CTCs in clinical practice.

Mesenchymal phenotype of CTC-enriched blood fraction and lymph node metastasis formation potential

Introduction

Circulating tumor cells (CTCs) that present mesenchymal phenotypes can escape standard methods of isolation, thus limiting possibilities for their characterization. Whereas mesenchymal CTCs are considered to be more malignant than epithelial CTCs, factors responsible for this aggressiveness have not been thoroughly defined. This study analyzed the molecular profile related to metastasis formation potential of CTC-enriched blood fractions obtained by marker unbiased isolation from breast cancer patients without (N−) and with lymph nodes metastases (N+).

Materials and Methods

Blood samples drawn from 117 patients with early-stage breast cancer were enriched for CTCs using density gradient centrifugation and negative selection with anti-CD45 covered magnetic particles. In the resulting CTC-enriched blood fractions, expression of CK19, MGB1, VIM, TWIST1, SNAIL, SLUG, HER2, CXCR4 and uPAR was analyzed with qPCR. Results were correlated with patients' clinicopathological data.

Results

CTCs (defined as expression of either CK19, MGB1 or HER2) were detected in 41% (20/49) of N− and 69% (34/49) of N+ patients (P = 0.004). CTC-enriched blood fractions of N+ patients were more frequently VIM (P = 0.02), SNAIL (P = 0.059) and uPAR-positive (P = 0.03). Positive VIM, CXCR4 and uPAR status correlated with >3 lymph nodes involved (P = 0.003, P = 0.01 and P = 0.045, respectively). In the multivariate logistic regression MGB1 and VIM-positivity were independently related to lymph node involvement with corresponding overall risk of 3.2 and 4.2. Moreover, mesenchymal CTC-enriched blood fractions (CK19−/VIM+ and MGB1+ or HER2+) had 4.88 and 7.85-times elevated expression of CXCR4 and uPAR, respectively, compared with epithelial CTC-enriched blood fractions (CK19+/VIM− and MGB1+ or HER2+).

Conclusions

Tumors of N+ patients have superior CTC-seeding and metastatic potential compared with N- patients. These differences can be attributed to VIM, uPAR and CXCR4 expression, which endow tumor cells with particularly malignant phenotypes.

Carboxybetaine methacrylate-modified nylon surface for circulating tumor cell capture

Conventional in vitro circulating tumor cell (CTC) detection methods are always limited by blood sample volume because of the requirement of a large amount of blood. The aim of this study was to overcome the limitation by designing and making an in vivo CTC capture device. In this study, we designed and prepared a kind of proper material to serve the purpose of intervention. A method employing 3-aminopropyltriethoxysilane (γ-APS) as the coupling reagent to graft carboxybetaine methacrylate (CBMA) and to immobilize an anti-epithelial cell adhesion molecular (EpCAM) antibody on Nylon was developed. The results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy proved the successful graft of γ-APS and CBMA to Nylon. Furthermore, the predicted improvement in the biocompatibilities of our modified Nylon was confirmed by water contact angle measurement, bovine serum albumin adhesion, platelet adhesion, plasma recalcification time determination, and cytotoxicity tests. The tumor cells adhesion experiment revealed that Nylon with the antibody immobilized on it had an affinity for EpCAM positive tumor cells higher than that of pristine Nylon. Additionally, the capture ability of the CTCs was demonstrated in a nude mouse tumor model using the interventional device made of the modified Nylon wire. The positive results suggest that CBMA-grafted and anti-EpCAM antibody-immobilized Nylon is a promising new material for in vivo CTC capture devices.

Heterogeneity of mesenchymal markers expression-molecular profiles of cancer cells disseminated by lymphatic and hematogenous routes in breast cancer

Breast cancers can metastasize via hematogenous and lymphatic routes, however in some patients only one type of metastases are detected, suggesting a certain proclivity in metastatic patterns. Since epithelial-mesenchymal transition (EMT) plays an important role in cancer dissemination it would be worthwhile to find if a specific profile of EMT gene expression exists that is related to either lymphatic or hematogenous dissemination. Our study aimed at evaluating gene expression profile of EMT-related markers in primary tumors (PT) and correlated them with the pattern of metastatic spread. From 99 early breast cancer patients peripheral blood samples (N = 99), matched PT (N = 47) and lymph node metastases (LNM; N = 22) were collected. Expression of TWIST1, SNAI1, SNAI2 and VIM was analyzed in those samples. Additionally expression of CK19, MGB1 and HER2 was measured in CTCs-enriched blood fractions (CTCs-EBF). Results were correlated with each other and with clinico-pathological data of the patients. Results show that the mesenchymal phenotype of CTCs-EBF correlated with poor clinico-pathological characteristics of the patients. Additionally, PT shared more similarities with LNM than with CTCs-EBF. Nevertheless, LNM showed increased expression of EMT-related markers than PT; and EMT itself in PT did not seem to be necessary for lymphatic dissemination.

Molecular detection of peripheral blood breast cancer mRNA transcripts as a surrogate biomarker for circulating tumor cells

Circulating tumor cells (CTCs) are becoming a scientifically recognized indicator of primary tumors and/or metastasis. These cells can now be accurately detected and characterized as the result of technological advances. We analyzed the presence of CTCs in the peripheral blood of patients with metastatic breast cancer by real-time reverse-transcription PCR (RT-qPCR) using a panel of selected genes. The analysis of a single marker, without an EpCAM based enrichment approach, allowed the positive identification of 35% of the metastatic breast cancer patients. The analysis of five genes (SCGB2, TFF1, TFF3, Muc1, KRT20) performed in all the samples increased the detection to 61%. We describe a sensitive, reproducible and easy to implement approach to characterize CTC in patients with metastasic breast cancer.

Are morphological criteria sufficient for the identification of circulating tumor cells in renal cancer?

Background

Single circulating tumor cells (CTCs) or circulating tumor microemboli (CTMs) are potential biomarkers of renal cell cancer (RCC), however studies of CTCs/CTMs in RCC are limited. In this pilot study we aimed to evaluate a novel blood filtration technique suited for cytomorphological classification, immunocytochemical and molecular characterization of filtered, so called circulating non-hematologic cells (CNHCs) - putative CTCs/CTMs - in patients with RCC.

Methods

Blood of 40 patients with renal tumors was subjected to ScreenCell® filtration. CNHCs were classified according to cytomorphological criteria. Immunocytochemical analysis was performed with antibodies against CD45, CD31 and carbonic anhydrase IX (CAIX, a RCC marker). DNA of selected CNHCs and respective primary tumors was analysed by array-CGH.

Results

CNHC-clusters with malignant or uncertain malignant cytomorphological features - putative CTMs - were negative for CD45, positive for CD31, while only 6% were CAIX positive. Array-CGH revealed that 83% of malignant and uncertain malignant cells did represent with a balanced genome whereas 17% presented genomic DNA imbalances which did not match the aberrations of the primary tumors. Putative single CTCs were negative for CD45, 33% were positive for CD31 and 56% were positive for CAIX.

Conclusions

The majority of CNHC-clusters, putative CTMs, retrieved by ScreenCell® filtration may be of endothelial origin. Morphological criteria seem to be insufficient to distinguish malignant from non-malignant cells in renal cancer.

Essentials of circulating tumor cells for clinical research and practice

The major cause of death due to cancer is its metastatic deposit in numerous tissues and organs. The metastatic process requires the migration of malignant cells from primary sites to distant environments. Even for tumors initially spreading through lymphatic vessels, hematogenous transport is the most common metastatic pathway. The detachment of cancer cells from a primary tumor into the blood stream is called epithelial-mesenchymal transition (EMT). As these cells circulate further in the bloodstream they are known as circulating tumor cells (CTCs). The CTC population is highly resilient, enabling the cells to colonize a foreign microenvironment. Alternatively, cancer stem cells (CSCs) may arise from differentiated cancer cells through EMT and an embryonic transdifferentiation process. The presence of CTCs/CSCs in blood seems to be a determining factor of metastasis. This paper reviews various methods of clinical cancer detection as well as the biology and molecular characterization of CTCs/CSCs. Our goal was to summarize clinical studies which used CTC/CSCs for prognosis in patients with breast, colorectal, prostate, lung, ovarian, and bladder cancer.

The Prognostic Value of p16 Hypermethylation in Cancer: A Meta-Analysis

Background

The prognostic value of p16 promoter hypermethylation in cancers has been evaluated for several years while the results remain controversial. We thus performed a systematic review and meta-analysis of studies assessing the impact of p16 methylation on overall survival (OS) and disease-free survival (DFS) to clarify this issue.

Methods

We searched Pubmed, Embase and ISI web of knowledge to identify studies on the prognostic impact of p16 hypermethylation in cancers. A total of 6589 patients from 45 eligible studies were included in the analysis. Pooled hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated to estimate the effect using random-effects model.

Results

The analysis indicated that p16 hypermethylation had significant association with poor OS of non-small cell lung cancer (NSCLC) (HR 1.74, 95% CI: 1.36–2.22) and colorectal cancer (CRC) (HR 1.80; 95% CI 1.27–2.55). Moreover, the significant correlation was present between p16 hypermethylation and DFS of NSCLC (HR 2.04, 95% CI: 1.19–3.50) and head and neck cancer (HR 2.24, 95% CI: 1.35–3.73). Additionally, in the analysis of the studies following REMARK guidelines more rigorously, p16 hypermethylation had unfavorable impact on OS of NSCLC (HR 1.79, 95% CI: 1.35–2.39) and CRC (HR 1.96, 1.16–3.34), and on DFS of NSCLC (HR 2.12, 95% CI: 1.21–3.72) and head and neck cancer (HR 2.24, 95% CI: 1.35–3.73).

Conclusions

p16 hypermethylation might be a predictive factor of poor prognosis in some surgically treated cancers, particularly in NSCLC.

Meta-analysis of circulating tumor cells as a prognostic marker in lung cancer

INTRODUCTION

Recent studies have shown that circulating tumor cells (CTCs) play potential roles as diagnostic and prognostic biomarkers with various cancer types. The aim of this study was to comprehensively and quantitatively summarize the evidence for the use of CTCs to predict the survival outcome of lung cancer patients.

MATERIALS AND METHODS

Relevant literature was identified using Medline and EMBASE. Patients' clinical characteristics, overall survival (OS) and progression-free survival (PFS) together with CTC positive rates at different time points (before, during and after treatment) were extracted. A meta-analysis was performed to clarify the prognostic role of CTCs and the correlation between the CTC appearance and clinical characteristics.

RESULTS

A total of 12 articles containing survival outcomes and clinical characteristics and 15 articles containing only clinical characteristics were included for the global meta-analysis. The hazard ratio (HR) for OS predicted by pro-treatment CTCs was 2.61 [1.82, 3.74], while the HR for PFS was 2.37 [1.41, 3.99]. The HR for OS predicted by post-treatment CTCs was 4.19 [2.92, 6.00], while the HR for PFS was 4.97 [3.05, 8.11]. Subgroup analyses were conducted according to histological classification and detection method. Odds ratio (OR) showed the appearance of pro-treatment CTCs correlated with the lymph node status, distant metastasis, and TNM staging, while post-treatment CTCs correlated with TNM staging only.

CONCLUSION

Detection of CTCs in the peripheral blood indicates a poor prognosis in patients with lung cancer.

Prognostic value of circulating tumor cells in primary and metastatic breast cancer

In patients with breast cancer, there is evidence correlating the presence of circulating tumor cells (CTCs) with disease-free survival, progression-free survival and overall survival. The detection of CTCs may be useful in gaining a better understanding of the mechanisms of tumor growth and in the improvement of patient management. This review analyzes the prognostic and predictive relevance of CTCs through the principal published studies, cytometric techniques and nucleic acid-based approaches to detect CTCs, phenotypic expression of specific receptors, molecular pathways and genetic signatures for potential tailored therapies.

Meta-analysis of the prognostic value of circulating tumor cells in breast cancer

PURPOSE

The prognostic value of circulating tumor cells (CTC) detected in breast cancer patients is currently under debate. Different time points of blood collections and various CTC assays have been used in the past decades. Here, we conducted the first comprehensive meta-analysis of published literature on the prognostic relevance of CTC, including patients with early and advanced disease.

EXPERIMENTAL DESIGN

A comprehensive search for articles published between January 1990 and January 2012 was conducted; reviews of each study were conducted and data were extracted. The main outcomes analyzed were overall survival (OS) and disease-free survival (DFS) in early-stage breast cancer patients, as well as progression-free survival (PFS) and OS in metastatic breast cancer patients. Pooled hazard ratio (HR) and 95% confidence intervals (CIs) were calculated using the random and the fixed-effects models. Subgroup and sensitivity analyses were also conducted.

RESULTS

Forty-nine eligible studies enrolling 6,825 patients were identified. The presence of CTC was significantly associated with shorter survival in the total population. The prognostic value of CTC was significant in both early (DFS: HR, 2.86; 95% CI, 2.19-3.75; OS: HR, 2.78; 95% CI, 2.22-3.48) and metastatic breast cancer (PFS: HR, 1.78; 95% CI, 1.52-2.09; OS: HR, 2.33; 95% CI, 2.09-2.60). Further subgroup analyses showed that our results were stable irrespective of the CTC detection method and time point of blood withdrawal.

CONCLUSION

Our present meta-analysis indicates that the detection of CTC is a stable prognosticator in patients with early-stage and metastatic breast cancer. Further studies are required to explore the clinical utility of CTC in breast cancer.

Circulating tumors cells as biomarkers: progress toward biomarker qualification

Personalized cancer medicine requires the development of tumor-specific biomarkers to optimize selection of targeted therapies and to better assess response to therapy. Current efforts in several tumor types have shown that patients in whom circulating tumor cells (CTCs) are detected have an inferior prognosis relative to those in whom CTCs are not detected and that the elimination or decrease of CTCs following treatment is associated with improved clinical outcomes. Technological advances in the detection, isolation, capture, and characterization of CTCs from phlebotomy samples obtained in a routine clinical practice setting have enabled the evaluation of different CTC biomarkers. Unmet needs in cancer diagnosis and treatment where CTC biomarkers have been studied include determining prognosis, assessing the effects of treatment, and as a source of tumor for the biologic identification and characterization of determinants to predict sensitivity to one form of treatment versus another and to understand mechanisms of treatment resistance.At present, there is no single definition of a CTC and no single CTC "biomarker." Rather, multiple assays (tests) are in development for CTC biomarkers. However, before the role of any biomarker in medical decision making can be determined, it is essential that the assays used to measure the biomarker are analytically validated in a sequence of trials to generate the evidence to support the biomarker's use in the given context of use. It is against this background that this review focuses on the process of developing CTC biomarker assays, with the objective of outlining the necessary steps to qualify specific CTC tests for medical decision making in clinical practice or drug development. The potential for point-of-care tests is clear.

Epithelial mesenchymal transition: a new insight into the detection of circulating tumor cells

Many research groups reported on the relation between circulating tumor cells (CTCs) in peripheral blood and worse prognosis for metastatic cancer patients. These results are based on CTCs counting and did not take into account molecular characteristics of cells. To establish CTCs as a reliable and accurate biological marker, new technologies must be focused on CTC subpopulations: dedifferentiated circulating tumor cells (ddCTCs) arising from epithelial mesenchymal transition (EMT). To select and detect them, different methods have been proposed but none has still reached the goal. Technical progress and translational research are expected to establish CTCs as a real marker. Thus CTC evaluation profiling for each patient will lead to personalize followup and therapy.

High-definition imaging of circulating tumor cells and associated cellular events in non-small cell lung cancer patients: a longitudinal analysis

Sampling circulating tumor cells (CTCs) from peripheral blood is ideally accomplished using assays that detect high numbers of cells and preserve them for downstream characterization. We sought to evaluate a method using enrichment free fluorescent labeling of CTCs followed by automated digital microscopy in patients with non-small cell lung cancer. Twenty-eight patients with non-small cell lung cancer and hematogenously seeded metastasis were analyzed with multiple blood draws. We detected CTCs in 68% of analyzed samples and found a propensity for increased CTC detection as the disease progressed in individual patients. CTCs were present at a median concentration of 1.6 CTCs ml⁻¹ of analyzed blood in the patient population. Higher numbers of detected CTCs were associated with an unfavorable prognosis.

Diagnostic value of circulating tumor cell detection in bladder and urothelial cancer: systematic review and meta-analysis

Background

The diagnostic value and prognostic significance of circulating tumor cell (CTC) detection in patients with bladder cancer is controversial. We performed a meta-analysis to consolidate current evidence regarding the use of CTC detection assays to diagnose bladder and other urothelial cancers and the association of CTC positivity with advanced, remote disease.

Methods

Studies that investigated the presence of CTCs in the peripheral blood of patients with bladder cancer and/or urothelial cancer were identified and reviewed. Sensitivities, specificities, and positive (LR+) and negative likelihood ratios (LR-) of CTC detection in individual studies were calculated and meta-analyzed by random effects model. Overall odds ratio of CTC positivity in patients with advanced disease versus those with organ-confined cancer was also calculated.

Results

Overall sensitivity of CTC detection assays was 35.1% (95%CI, 32.4-38%); specificity, LR+, and LR- was 89.4% (95%CI, 87.2-91.3%), 3.77 (95%CI, 1.95-7.30) and 0.72 (95%CI, 0.64-0.81). CTC-positive patients were significantly more likely to have advanced (stage III-IV) disease compared with CTC-negative patients (OR, 5.05; 95%CI, 2.49-10.26).

Conclusions

CTC evaluation can confirm tumor diagnosis and identify patients with advanced bladder cancer. However, due to the low overall sensitivity, CTC detection assays should not be used as initial screening tests.