Detecting carcinoma cells in peripheral blood of patients with hepatocellular carcinoma by immunomagnetic beads and rt-PCR

Circulating Tumor Cells as a Promising Tool for Early Detection of Hepatocellular Carcinoma

Liver cancer is a significant contributor to the cancer burden, and its incidence rates have recently increased in almost all countries. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and is the second leading cause of cancer-related deaths worldwide. Because of the late diagnosis and lack of efficient therapeutic modality for advanced stages of HCC, the death rate continues to increase by ~2-3% per year. Circulating tumor cells (CTCs) are promising tools for early diagnosis, precise prognosis, and follow-up of therapeutic responses. They can be considered to be an innovative biomarker for the early detection of tumors and targeted molecular therapy. In this review, we briefly discuss the novel materials and technologies applied for the practical isolation and detection of CTCs in HCC. Also, the clinical value of CTC detection in HCC is highlighted.

Liquid Biopsy in Hepatocellular Carcinoma: The Significance of Circulating Tumor Cells in Diagnosis, Prognosis, and Treatment Monitoring

Hepatocellular carcinoma (HCC) is an aggressive malignancy with poor outcomes when diagnosed at an advanced stage. Current curative treatments are most effective in early-stage HCC, highlighting the importance of early diagnosis and intervention. However, existing diagnostic methods, such as radiological imaging, alpha-fetoprotein (AFP) testing, and biopsy, have limitations that hinder early diagnosis. AFP elevation is absent in a significant portion of tumors, and imaging may have low sensitivity for smaller tumors or in the presence of cirrhosis. Additionally, as our understanding of the molecular pathogenesis of HCC grows, there is an increasing need for molecular information about the tumors. Biopsy, although informative, is invasive and may not always be feasible depending on tumor location. In this context, liquid biopsy technology has emerged as a promising approach for early diagnosis, enabling molecular characterization and genetic profiling of tumors. This technique involves analyzing circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), or tumor-derived exosomes. CTCs are cancer cells shed from the primary tumor or metastatic sites and circulate in the bloodstream. Their presence not only allows for early detection but also provides insights into tumor metastasis and recurrence. By detecting CTCs in peripheral blood, real-time tumor-related information at the DNA, RNA, and protein levels can be obtained. This article provides an overview of CTCs and explores their clinical significance for early detection, prognosis, treatment selection, and monitoring treatment response in HCC, citing relevant literature.

Liquid Biopsy in Hepatocellular Carcinoma: Where Are We Now?

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related death worldwide. Diagnostic, prognostic, and predictive biomarkers are urgently needed in order to improve patient survival. Indeed, the most widely used biomarkers, such as alpha-fetoprotein (AFP), have limited accuracy as both diagnostic and prognostic tests. Liver biopsy provides an insight on the biology of the tumor, but it is an invasive procedure, not routinely used, and not representative of the whole neoplasia due to the demonstrated intra-tumoral heterogeneity. In recent years, liquid biopsy, defined as the molecular analysis of cancer by-products, released by the tumor in the bloodstream, emerged as an appealing source of new biomarkers. Several studies focused on evaluating extracellular vesicles, circulating tumor cells, cell-free DNA and non-coding RNA as novel reliable biomarkers. In this review, we aimed to provide a comprehensive overview on the most relevant available evidence on novel circulating biomarkers for early diagnosis, prognostic stratification, and therapeutic monitoring. Liquid biopsy seems to be a very promising instrument and, in the near future, some of these new non-invasive tools will probably change the clinical management of HCC patients.

Utility of Liquid Biopsy Analysis in Detection of Hepatocellular Carcinoma, Determination of Prognosis, and Disease Monitoring: A Systematic Review

BACKGROUND & AIMS

Liquid biopsies, or blood samples, can be analyzed to detect circulating tumor cells (CTCs), cell-free DNA (cfDNA), and extracellular vesicles, which might identify patients with hepatocellular carcinoma (HCC) or help determine their prognoses. We performed a systematic review of studies of analyses of liquid biopsies from patients with HCC and their comparisons with other biomarkers.

METHODS

We performed a systematic review of original studies published before December 1, 2019. We included studies that compared liquid biopsies alone and in combination with other biomarkers for the detection of HCC, performed multivariate analyses of the accuracy of liquid biopsy analysis in determining patient prognoses, or evaluated the utility of liquid biopsy analysis in monitoring treatment response.

RESULTS

Our final analysis included 112 studies: 67 on detection, 46 on determining prognosis, and 25 on treatment monitoring or selection. Ten studies evaluated assays that characterized cfDNA for detection of HCC in combination with measurement of α-fetoprotein (AFP)-these studies found that the combined measurement of cfDNA and AFP more accurately identified patients with HCC than measurement of AFP alone. Six studies evaluated assays for extracellular vesicles and 2 studies evaluated assays for CTC in detection of HCC, with and without other biomarkers-most of these studies found that detection of CTCs or extracellular vesicles with AFP more accurately identified patients with HCC than measurement of AFP alone. Detection of CTCs before surgery was associated with HCC recurrence after resection in 13 of 14 studies; cfDNA and extracellular vesicles have been studied less frequently as prognostic factors. Changes in CTC numbers before vs after treatment more accurately identify patients with HCC recurrence than pretreatment counts alone, and measurements of cfDNA can identify patients with disease recurrence or progression before changes can be detected by imaging. We found little evidence that analyses of liquid biopsies can aid in the selection of treatment for HCC. Quality assessment showed risk of bias in studies of HCC detection and determination of prognosis.

CONCLUSIONS

In a systematic review of 112 studies of the accuracy of liquid biopsy analysis, we found that assays for CTCs and cfDNA might aid in determining patient prognoses and monitoring HCC, and assays for cfDNA might aid in HCC detection, but there is a risk of bias in these studies. Studies must be standardized before we can assess the clinical utility of liquid biopsy analysis in the detection and management of patients with HCC.

Diagnostic performance of blood-based liquid biopsies in hepatocellular carcinoma: A protocol for systematic review and meta-analysis

BACKGROUND

Hepatocellular carcinoma (HCC) is an aggressive cancer associated with poor prognosis. Early diagnosis is crucial to improve its prognosis. Blood-based liquid biopsies are promising methods in detecting HCC. However, their accuracies have not been systematically assessed, so it is essential to conduct a meta-analysis to evaluate the diagnostic performance of blood-based liquid biopsies in detecting HCC.

METHODS

We will search PubMed, EMBASE, Cochrane Library, Web of Science, Medline, China National Knowledge Infrastructure(CNKI) for the relevant studies that assessed the diagnostic performance of blood-based liquid biopsies including circulating tumor cells(CTCs), circulating tumor DNA(ctDNA), and exosomes(EVs) in HCC patients from inception to September 2020. Two researchers will independently extract the data and use Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) to evaluate the quality of included literature. We will also conduct the pool diagnostic value, heterogeneity across studies and reporting bias. All the statistical analysis will be conducted by Stata V.15.0 and Meta-disc V.1.4.

RESULTS

This review will evaluate the pooled diagnostic value of blood-based liquid biopsies in HCC.

CONCLUSION

This review will summarize the current published evidence of blood-based liquid biopsies in diagnosing HCC, which may provide a great opportunity for promotion and application of them.

OPEN SCIENCE FRAMEWORK(OSF) REGISTRATION NUMBER

September 3, 2020. https://osf.io/9n4yz.

Circulating tumor DNA/circulating tumor cells and the applicability in different causes induced hepatocellular carcinoma

In 2015, liquid biopsy was rated one of the top 10 breakthrough technologies of the year by MIT Technology Review. Liquid biopsy is a type of in vitro diagnostic method involving a noninvasive blood test. It is also a breakthrough technology used to detect tumors and cancers and assist in therapeutic strategies. The most widely used markers are circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). Primary carcinoma of the liver is a malignancy of hepatocytes or intrahepatic biliary epithelial cells. The most common type of liver cancer is hepatocellular carcinoma (HCC), the causes of which mainly include infection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV), alcohol abuse, aflatoxicosis, and nonalcoholic fatty liver disease/ nonalcoholic steatohepatitis. As there are few typical clinical characteristics during the early stage of the disease, early diagnosis of HCC is very challenging. However, CTCs and ctDNA carry tumor-specific information. Therefore, the detection and analysis of CTCs and ctDNA can provide evidence for the early diagnosis of HCC and guide treatment. Furthermore, several studies have indicated that different inducers of HCC cause different DNA mutations, and accordingly, detection of specific mutations in ctDNA will facilitate the determination of the HCC type and help physicians provide distinctive therapies.

Clinical effects of miR-101 on prognosis of hepatocellular carcinoma and carcinogenic mechanism of anti-miR-101

The aim of this study was to verify whether anti-miR-101 participates in the treatment of hepatocellular carcinoma (HCC) as a small-molecule antitumor agent, and to explore the effect on phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Patients who received consecutive hepatectomies were followed-up, and miR-101 expressions in their tumor and paracancerous tissues were detected. Correlation between miR-101 expression and clinical pathological factors and prognosis was studied. High‑throughput sequencing was used to detect the genetic and microRNA (miRNA) levels of tumor tissues. Expression of anti-miR-101 in different HCC cell lines was determined, and those of desired genes and proteins were detected by qRT-PCR and western blotting to obtain the target gene. miR-101 was significantly upregulated in HCC patients compared with that in paracancerous tissues. High miR-101 expression, vascular invasion, tumor size ≥7 cm and late pathological stage were the risk factors of recurrence-free survival rate. High miR-101 expression was the independent prognostic factor of total and recurrence-free survival rates. CXCL12, IL6R, FOXO3 and PTEN were screened as desired genes, and only PTEN was expressed significantly differently in three cell lines. miR-101 could bind 3'-UTR of WT-PTEN with reduced fluorescent intensity, suggesting that PTEN was the target gene. SMMC-7721, HepG2 and Huh7 were eligible cell lines for miR-101 studies. miR-101 was an applicable molecular marker of HCC. Anti-miR-101 regulated the transcription of PTEN and may promote cell proliferation, differentiation and apoptosis by regulating downstream genes with PTEN. The regulatory effects of anti-miR-101 on PTEN provide valuable evidence for finding novel miRNA drugs.

Circulating Tumor Cell Isolation and Analysis

Isolation and analysis of cancer cells from body fluids have significant implications in diagnosis and therapeutic treatment of cancers. Circulating tumor cells (CTCs) are cancer cells circulating in the peripheral blood or spreading iatrogenically into blood vessels, which is an early step in the cascade of events leading to cancer metastasis. Therefore, CTCs can be used for diagnosing for therapeutic treatment, prognosing a given anticancer intervention, and estimating the risk of metastatic relapse. However, isolation of CTCs is a significant technological challenge due to their rarity and low recovery rate using traditional purification techniques. Recently microfluidic devices represent a promising platform for isolating cancer cells with high efficiency in processing complex cellular fluids, with simplicity, sensitivity, and throughput. This review summarizes recent methods of CTC isolation and analysis, as well as their applications in clinical studies.

Circulating Tumor Cells in Gastrointestinal Cancer: Current Practices and Future Directions

GI cancers are the leading cause of cancer-related death worldwide primarily due to a combination of late presentation and aggressive biology. The lack of adequate biomarkers for screening, diagnosis, staging, and prognosis confounds clinical decision-making and delays potentially effective therapies. Circulating tumor cells (CTCs) are a new biomarker with particular promise in GI cancers, potentially offering clinicians and researchers real-time access to tumor tissue in a reliable, safe, and cost-effective manner. Preliminary studies have investigated the potential clinical utility of CTCs for all GI cancer types with promising results. Furthermore, advances in single cell analytics have been successfully applied to CTCs, allowing for exciting new clinical and research applications. In this chapter, we will review the current state of CTC research in GI cancers as well as the potential future applications that are currently being developed.

IGFBP1 in epithelial circulating tumor cells as a potential response marker to selective internal radiation therapy in hepatocellular carcinoma

BACKGROUND

Local ablative techniques such as selective internal radiation therapy (SIRT) have become the mainstay of treating hepatocellular carcinoma (HCC) in the bridging-to-transplant and palliative setting. We recently demonstrated that epithelial circulating tumor cells (CTCs) correlate to an unfavorable outcome. We wanted to scrutinize whether molecular markers detected in this specific CTC subgroup may also have clinical implications.

MATERIALS & METHODS

Mononuclear cells and CTCs were isolated from peripheral blood samples using density gradient centrifugation followed by depletion of hematopoietic and enrichment of epithelial (EpCAM(+)) cells employing immunomagnetic beads. The mRNA expression of candidate markers was correlated with response to SIRT in 25 patients using quantitative real-time reverse-transcription PCR.

RESULTS

IGFBP1 mRNA expression levels were significantly correlated with time to progression in a Kaplan-Meier log rank test (p = 0.04; 0 vs 4 months) and receiver operating characteristic analysis demonstrated a potential use to predict patients with shortened time to progression (area under the curve: 0.8; 95% CI: 0.44-0.98; p = 0.03).

CONCLUSION

The EpCAM fraction of CTCs may be useful to detect novel molecular markers to individualize treatment decision in patients with HCC.

Upregulation of circulating cytokeratin 20, urokinase plasminogen activator and C-reactive protein is associated with poor prognosis in gastric cancer

Gastric cancer is one of the most common types of cancer, with a high mortality rate. The aim of this study was to investigate the role of several key molecules, including cytokeratin (CK) 19 and CK20, urokinase plasminogen activator (uPA), C-reactive protein (CRP) and matrix metalloproteinase (MMP)-9, which are involved in cancer invasion and metastasis, in order to determine whether they may be considered as novel prognostic factors for gastric cancer. Peripheral blood was collected from 165 patients with gastric adenocarcinoma who underwent curative surgical resection at Zhejiang Cancer Hospital (Hangzhou, China) between 2010 and 2011. The mRNA levels of CK19, CK20, uPA and MMP-9 were detected by reverse transcription-quantitative polymerase chain reaction. The protein expression of CRP was measured by immunoturbidimetry. The Students t-test was used in the univariate analyses and the Kaplan-Meier method was used to analyze the survival curves. The relative mRNA expression of CK19 and MMP-9 was not found to be significantly associated with gender, age or cancer stage, whereas that of CK20 and uPA was associated with gastric cancer stage: The low-expression group was associated with early-stage and the high-expression group with more advanced-stage disease (P<0.05). The CRP protein level was associated with gender and cancer stage: The low-expression group was predominantly associated with male gender and early-stage disease, whereas the high-expression group was associated with female gender and advanced-stage disease (P<0.05). The expression of CK19, CK20, uPA and CRP, but not MMP-9, was negatively associated with overall survival (OS): The OS rate in the high-expression groups was significantly lower compared with that in the low-expression groups (P<0.05). In conclusion, the upregulation of CK20, uPA and CRP was found to be a negative prognostic factor for gastric cancer.

An ensemble of aptamers and antibodies for multivalent capture of cancer cells

We developed an optimized ensemble of aptamers and antibodies that functions as a multivalent adhesive domain for the capture and isolation of cancer cells. When incorporated into a microfluidic device, the ensemble showed not only high capture efficiency, but also superior capture selectivity at a high shear stress (or high flow rate).

Role of circulating tumor cells and cancer stem cells in hepatocellular carcinoma

Circulating tumor cells (CTC) and cancer stem cells (CSC) have been proposed as tools for detection and characterization of disease and individualization of therapy in patients with many solid tumors. Several automated and semi-automated techniques for identification and isolation of these cells from blood have been proposed and reviewed mostly focusing on their feasibility. In this mini review we summarize the recent relevant literature on this topic and discuss the clinical usability of measuring CTC and CSC in peripheral blood in patients with hepatocellular carcinoma (HCC). Besides literature, the basis for this evaluation was the authors' experience with treating HCC and research experience on CSC and CTC. Few original reports and reviews have been published focusing on CTC and CSC in HCC. Though HCC is one of the five most common malignancies worldwide only recently these cells have come into focus for detection and characterization of this disease that is characterized by high plasticity and malignancy. A focused and prospective validation of the clinical usability of detecting these cells in HCC is still needed, but results seem promising that they may add great benefit for early detection and individualization of therapy.

Individual profiling of circulating tumor cell composition and therapeutic outcome in patients with hepatocellular carcinoma

BACKGROUND AND AIMS

Circulating tumor cells (CTCs) have been proposed as a monitoring tool in patients with solid tumors. So far, automated approaches are challenged by the cellular heterogeneity of CTC, especially the epithelial-mesenchymal transition. Recently, Yu and colleagues showed that shifts in these cell populations correlated with response and progression, respectively, to chemotherapy in patients with breast cancer. In this study, we assessed which non-hematopoietic cell types were identifiable in the peripheral blood of hepatocellular carcinoma (HCC) patients and whether their distribution during treatment courses is associated with clinical characteristics.

METHODS

Subsequent to few enrichment steps, cell suspensions were spun onto glass slides and further characterized using multi-immunofluorescence staining. All non-hematopoietic cells were counted and individual cell profiles were analyzed per patient and treatment.

RESULTS

We detected a remarkable variation of cells with epithelial, mesenchymal, liver-specific, and mixed characteristics and different size ranges. The distribution of these subgroups varied significantly between different patient groups and was associated with therapeutic outcome. Kaplan-Meier log-rank test showed that a change in the ratio of epithelial to mesenchymal cells was associated with longer median time to progression (1 vs 15 months; P = .03; hazard ratio = 0.18; 95% confidence interval = 0.01-2.75).

CONCLUSIONS

Our data suggest that different CTC populations are identifiable in peripheral blood of HCC patients and, for the first time in HCC, that these individual cell type profiles may have distinct clinical implications. The further characterization and analysis of patients in this ongoing study seems to be warranted.

Capturing circulating tumor cells of hepatocellular carcinoma

Early metastases of hepatocellular carcinoma (HCC) may be detected by the isolation of circulating tumor cells (CTCs) in the bloodstream. During the course of therapeutic attempts, monitoring CTC changes in patients with HCC is helpful for the efficacy assessment. Nevertheless, the markers used for the detection, such as α-feto protein, asialoglycoprotein receptor or epithelial cell adhesion molecule, CD133 or CD90, are not specific for HCC CTCs. In spite of these limitations, a timely determination of the existence of CTCs will be beneficial for the monitoring of distant metastases, the evaluation of therapeutic attempts, and the prediction of prognosis.

Microribonucleic acids and gastric cancer

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Microribonucleic acids (miR) are a recently-described class of genes encoding small non-coding RNA molecules, which primarily act by downregulating the translation of target mRNA. It has become apparent that miR are also key factors in cancer, playing both oncogenic and tumor-suppressing roles in gastric cancer. Recent studies have shown that a substantial number of miR show differential expression in gastric cancer tissues, and they are turning out to be just like any other regulatory gene. In this connection, miR dysregulation are reported to be associated with incidence, early diagnosis and prognosis of gastric cancer. Therefore, investigation of the biological aspects of miR dysregulation might help us better understand the pathogenesis of gastric cancer and promote the development of miR-directed therapeutics against this deadly disease. The aim of the present review was to describe the mechanisms of several known miR, summarize recent studies on oncogenic miR (e.g. miR-21, miR-106a and miR-17), tumor suppressor miR (e.g. miR-101, miR-181, miR-449, miR-486, let-7a) and controversial roles of miR (e.g. miR-107, miR-126) for gastric cancer. In addition, their potential clinical applications and prospects in gastric cancer, such as biomarkers and clinical therapy tools, are also briefly discussed.

Microribonucleic acids and gastric cancer

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Microribonucleic acids (miR) are a recently-described class of genes encoding small non-coding RNA molecules, which primarily act by downregulating the translation of target mRNA. It has become apparent that miR are also key factors in cancer, playing both oncogenic and tumor-suppressing roles in gastric cancer. Recent studies have shown that a substantial number of miR show differential expression in gastric cancer tissues, and they are turning out to be just like any other regulatory gene. In this connection, miR dysregulation are reported to be associated with incidence, early diagnosis and prognosis of gastric cancer. Therefore, investigation of the biological aspects of miR dysregulation might help us better understand the pathogenesis of gastric cancer and promote the development of miR-directed therapeutics against this deadly disease. The aim of the present review was to describe the mechanisms of several known miR, summarize recent studies on oncogenic miR (e.g. miR-21, miR-106a and miR-17), tumor suppressor miR (e.g. miR-101, miR-181, miR-449, miR-486, let-7a) and controversial roles of miR (e.g. miR-107, miR-126) for gastric cancer. In addition, their potential clinical applications and prospects in gastric cancer, such as biomarkers and clinical therapy tools, are also briefly discussed.

Expression and prognostic significance of CEACAM6, ITGB1, and CYR61 in peripheral blood of patients with gastric cancer

BACKGROUND

We examined CEACAM6, ITGB1, and cyr61 concentrations from patients with gastric cancers (GCs) to assess their clinical application for diagnosing and monitoring diseases.

METHODS

Real-time reverse transcription-polymerase chain reaction was used to detect the expressions of CEA, CEACAM6, ITGB1, IGF1R, CK20, cyr61, and S100A4 in peripheral blood karyocyte from 82 patients with GC, 24 patients with recurrence, and 37 healthy volunteers. Receiver operating characteristics (ROC) curves were constructed.

RESULTS

There were significant association between these CEACAM6, ITGB1, and cyr61 and TNM Stages and distant metastasis. The AUC of CEACAM6 was 0.884 ± 0.044 (P = 0.0001), the AUC of cyr61 was 0.833 ± 0.047 (P = 0.0001), and the AUC of ITGB1 was 0.838 ± 0.042 (P = 0.0001) by differentiating preoperative GC patients from healthy volunteers from ROC curve analysis. The AUC of CEACAM6 was 0.761 ± 0.066 (P = 0.001), the AUC of CYR61 was 0.762 ± 0.063 (P = 0.001), and the AUC of ITGB1 was 0.824 ± 0.051 (P = 0.0001), by differentiating recurrence of GC from healthy volunteers from ROC curve analysis.

CONCLUSION

The method of detecting the expression of CEACAM6, ITGB1, and CYR61 in peripheral blood of GC patients was more sensitive than CEA, IGF1R, CK20, and S100A4 for the early diagnosis of metastasis and recurrence.

Isolation of circulating tumor cells in patients with hepatocellular carcinoma using a novel cell separation strategy

PURPOSE

To establish a sensitive and specific isolation and enumeration system for circulating tumor cells (CTC) in patients with hepatocellular carcinoma (HCC).

EXPERIMENTAL DESIGN

HCC cells were bound by biotinylated asialofetuin, a ligand of asialoglycoprotein receptor, and subsequently magnetically labeled by antibiotin antibody-coated magnetic beads, followed by magnetic separation. Isolated HCC cells were identified by immunofluorescence staining using Hep Par 1 antibody. The system was used to detect CTCs in 5 mL blood. Blood samples spiked with Hep3B cells (ranging from 10 to 810 cells) were used to determine recovery and sensitivity. Prevalence of CTCs was examined in samples from HCC patients, healthy volunteers, and patients with benign liver diseases or non-HCC cancers. CTC samples were also analyzed by FISH.

RESULTS

The average recovery was 61% or more at each spiking level. No healthy, benign liver disease or non-HCC cancer subjects had CTCs detected. CTCs were identified in 69 of 85 (81%) HCC patients, with an average of 19 ± 24 CTCs per 5 mL. Both the positivity rate and the number of CTCs were significantly correlated with tumor size, portal vein tumor thrombus, differentiation status, and the disease extent as classified by the TNM (tumor-node-metastasis) classification and the Milan criteria. HER-2 gene amplification and TP53 gene deletion were detected in CTCs.

CONCLUSION

Our system provides a new tool allowing for highly sensitive and specific detection and genetic analysis of CTCs in HCC patients. It is likely clinically useful in diagnosis and monitoring of HCC and may have a role in clinical decision making.

Detection of circulating tumor cells in peripheral blood from patients with gastric cancer using microRNA as a marker

Recently, the detection of occult cancer cells in peripheral blood has received a great deal of attention regarding the prediction of postoperative cancer recurrence and for novel strategies of adjuvant therapy. The aim of this study was to establish a new molecular diagnostic method of detecting circulating tumor cells. Gastric cancer SGC-7901 cells in 2 ml blood from healthy volunteers were serially diluted. Additional peripheral blood samples were collected from 90 patients and 27 healthy volunteers. Real-time reverse transcription-polymerase chain reaction was used to detect the levels of microRNA-106a (miR-106a) and microRNA-17 (miR-17). Receiver operating characteristics (ROC) curves were constructed. In recovery experiments, a significant correlation between the number of cancer cells and the levels of both miR-106a (r = -0.906, p = 0.037) and miR-17 (r = -0.912, p = 0.031) was found. In preoperative and postoperative patient groups, miR-106a and miR-17 levels were significantly higher than those in controls. The areas under the ROC curve for miR-106a, miR-17, and combination were 0.684 (p = 0.0066), 0.743 (p = 0.0001), and 0.741 (p = 0.0002), respectively. Our results indicate that the detection of miRNA in peripheral blood may be a novel tool for monitoring circulating tumor cells in patients with gastric cancers.