The detection of micrometastases in the peripheral blood and bone marrow of patients with breast cancer using immunohistochemistry and reverse transcriptase polymerase chain reaction for keratin 19

Should Positive Cytology Revealed by Intraoperative Lavage Preclude Radical Resection in Resectable Pancreatic Cancer?: A Systemic Review and Meta-analysis

OBJECTIVES

The aims of this review were to determine whether positive peritoneal lavage cytology (CY+) precludes radical resection in pancreatic cancer and to propose prospections for future studies.

METHODS

MEDLINE, Embase, and Cochrane Central were searched for related articles. Dichotomous variables and survival outcomes were analyzed with the estimation of odds ratio and hazards ratio (HR), respectively.

RESULTS

A total of 4905 patients were included, of which 7.8% were CY+. Positive peritoneal lavage cytology was correlated with poor overall survival (univariate survival analysis [HR, 2.35; P < 0.00001]; multivariate analysis [HR, 1.62; P < 0.00001]), poor recurrence-free survival (univariate survival analysis [HR, 2.50; P < 0.00001]; multivariate analysis [HR, 1.84; P < 0.00001]), and higher initial peritoneal recurrence rate (odds ratio, 5.49; P < 0.00001).

CONCLUSIONS

Although CY+ predicts poor prognosis and a higher risk of peritoneal metastasis after curative resection, it is not sufficient to preclude curative resection based on the current evidence, and high-quality trials should be conducted to assess the prognostic impact of operation among resectable CY+ patients. In addition, more sensitive and accurate methods to detect peritoneal exfoliated tumor cells and more effective comprehensive treatment for resectable CY+ pancreatic cancer patients are clearly warranted.

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.

Synchronous Detection of Circulating Tumor Cells in Blood and Disseminated Tumor Cells in Bone Marrow Predicts Adverse Outcome in Early Breast Cancer

PURPOSE

We examined the prognostic impact of circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) detected at the time of surgery in 742 untreated patients with early breast cancer.

EXPERIMENTAL DESIGN

DTCs in bone marrow were enumerated using the EPCAM-based immunomagnetic enrichment and flow cytometry (IE/FC) assay. CTCs in blood were enumerated either by IE/FC or CellSearch. Median follow-up was 7.1 years for distant recurrence-free survival (DRFS) and 9.1 years for breast cancer-specific survival (BCSS) and overall survival (OS). Cox regressions were used to estimate hazard ratios for DRFS, BCSS, and OS in all patients, as well as in hormone receptor-positive (HR-positive, 87%) and HR-negative (13%) subsets.

RESULTS

In multivariate models, CTC positivity by IE/FC was significantly associated with reduced BCSS in both all (n = 288; P = 0.0138) and HR-positive patients (n = 249; P = 0.0454). CTC positivity by CellSearch was significantly associated with reduced DRFS in both all (n = 380; P = 0.0067) and HR-positive patients (n = 328; P = 0.0002). DTC status, by itself, was not prognostic; however, when combined with CTC status by IE/FC (n = 273), double positivity (CTC+/DTC+, 8%) was significantly associated with reduced DRFS (P = 0.0270), BCSS (P = 0.0205), and OS (P = 0.0168). In HR-positive patients, double positivity (9% of 235) was significantly associated with reduced DRFS (P = 0.0285), BCSS (P = 0.0357), and OS (P = 0.0092).

CONCLUSIONS

Detection of CTCs in patients with HR-positive early breast cancer was an independent prognostic factor for DRFS (using CellSearch) and BCSS (using IE/FC). Simultaneous detection of DTCs provided additional prognostic power for outcome, including OS.

Detection of Breast Cancer Cells in the Bone Marrow or Peripheral Blood: Methods and Prognostic Significance

Tumor cells can reach every anatomic district, organ and tissue through the peripheral blood circulation. Tumor cell shedding is considered an early event in the multi-phase process of metastasis, and the possibility of detecting tumor cells in the bloodstream and/or bone marrow before clinical evidence of distant metastases needs to be explored. The use of new sophisticated diagnostic and investigative techniques has boosted the study of tumor cell contamination of bone marrow and peripheral blood. Molecular techniques, such as reverse-transcriptase polymerase chain reaction, may be useful tools to reach this target, but, today, immunocytochemistry is still considered the gold standard to assess new techniques to detect isolated tumor cells in hematopoietic tissue. Little is known about the biology of isolated tumor cells in the peripheral blood or bone marrow. Two crucial points need to be evaluated: the identification of specific markers of breast cancer cells with clonogenic potential and their biologic properties, and the prognostic impact of the detection of isolated tumor cells in the bone marrow or peripheral blood stem cell collections.

A New Nested Primer Pair Improves the Specificity of Ck-19 Mrna Detection by Rt-Pcr in Occult Breast Cancer Cells

Reverse transcription polymerase chain reaction (RT-PCR) of cytokeratin-19 (CK-19) has been widely used to detect small numbers of circulating malignant epithelial cells in the bone marrow or the peripheral blood of patients with breast cancer. However, a high percentage of false positive results has been recorded and conflicting reports question the clinical relevance of this technical approach. We demonstrate that the use of a new nested primer pair for CK-19 RT-PCR avoids false positive results without affecting the sensitivity of the assay. Our experiments were carried out using MCF-7 cells alone or mixed with peripheral blood mononuclear cells (PBMNC) of healthy donors. The results were also validated in a large series of healthy donors and in a preliminary study on a limited number of patients with breast cancer, thus suggesting that our assay is feasible for application in the clinical evaluation of occult malignant epithelial cells.

Detection of Cytokeratin 19 mRNA and CYFRA 21–1 (Cytokeratin 19 Fragments) in Blood of Tunisian Women with Breast Cancer

Cytokeratin 19 (CK19) is an acidic protein of 40 kDa that is part of the cytoskeleton of epithelial cells. It is highly expressed by all epithelial cells and represents a useful indicator of epithelial differentiation. The soluble fragment of CK19 (CYFRA 21–1) can be a useful circulating tumor marker and can be detected in the serum of cancer patients. The development of metastasis in patients with cancer of epithelial origin is due to the migration of tumor cells from the original tumor to distant organs. In order to detect micrometastasis in patients with breast cancer, we evaluated and compared CK19 gene expression using RT-PCR in blood samples collected from 80 healthy women and 80 patients with localized or metastatic breast cancer. The concentration of the soluble CK19 fragment CYFRA 21–1 was measured in serum of all study subjects by radioimmunoassay employing specific monoclonal antibodies. The relationship between the expression of this molecular marker and clinical stage, tumor differentiation and CK19 mRNA transcripts was investigated. We found that CK19 mRNA expression in blood (as a direct index of the presence of circulating tumor cells) was not correlated with CYFRA 21–1.

Serum IGF-1, IGFBP-3 levels and circulating tumor cells (CTCs) in early breast cancer patients

OBJECTIVE

Insulin-like growth factor (IGF)-axis is involved in human oncogenesis and metastasis development for various solid tumors including breast cancer. Aim of this study was to assess the association between IGF-1, IGF-binding protein-3 (IGFBP-3) serum levels and the presence of circulating tumor cells (CTCs) in the peripheral blood of women diagnosed with early breast cancer (EBC), before and after adjuvant chemotherapy.

DESIGN

171 patients with early-stage breast adenocarcinomas were retrospectively evaluated. Immunoradiometric (IRMA) assays were employed for the in-vitro determination of IGF-1 and IGFBP-3 serum levels in blood samples collected after surgical treatment and before initiation of adjuvant chemotherapy. CTCs' presence was assessed through detection of cytokeratin-19 (CK-19) mRNA transcripts using quantitative real time reverse transcription polymerase chain reaction (RT-PCR). IGF-1, IGFBP-3 serum levels were correlated with CTCs' presence before and after adjuvant chemotherapy as well as with tumor characteristics including tumor size, axillary lymph node status, oestrogen (ER)/progestorene (PR) and human epidermural growth factor receptor 2 (HER2) receptor status. Log-rank test was applied to investigate possible association between IGF-1, IGFBP-3 serum levels and disease-free interval (DFI) and overall survival (OS).

RESULTS

Before initiation of adjuvant therapy IGF-1, IGFBP-3 serum levels were moderately associated (Spearman's rho=0.361, p<0.001) with each other, while presenting significant differences across age groups (all p values<0.05). IGF-1 serum levels did not correlate with the presence of CTCs before initiation (p=0.558) or after completion (p=0.474) of adjuvant chemotherapy. Similarly, IGFBP-3 serum levels did not show significant association with detectable CTCs either before (p=0.487) or after (p=0.134) completion of adjuvant chemotherapy. There was no statistically significant association between the clinical outcome of patients in terms of DFI, OS and IGF-1(DFI: p=0.499; OS: p=0.220) or IGFBP-3 (DFI: p=0.900; OS: p=0.406) serum levels.

CONCLUSIONS

IGF-1 and IGFBP-3 serum levels before initiation of adjuvant chemotherapy are not indicative of CTCs' presence in the blood and do not correlate with clinical outcome of women with early-stage breast cancer.

Real-time Detection of Breast Cancer Cells Using Peptide-functionalized Microcantilever Arrays

Ligand-directed targeting and capturing of cancer cells is a new approach for detecting circulating tumor cells (CTCs). Ligands such as antibodies have been successfully used for capturing cancer cells and an antibody based system (CellSearch(®)) is currently used clinically to enumerate CTCs. Here we report the use of a peptide moiety in conjunction with a microcantilever array system to selectively detect CTCs resulting from cancer, specifically breast cancer. A sensing microcantilever, functionalized with a breast cancer specific peptide 18-4 (WxEAAYQrFL), showed significant deflection on cancer cell (MCF7 and MDA-MB-231) binding compared to when exposed to noncancerous (MCF10A and HUVEC) cells. The peptide-functionalized microcantilever allowed efficient capture and detection of cancer cells in MCF7 spiked human blood samples emulating CTCs in human blood. A detection limit of 50-100 cancer cells mL(-1) from blood samples was achieved with a capture yield of 80% from spiked whole blood samples. The results emphasize the potential of peptide 18-4 as a novel peptide for capturing and detecting cancer cells in conjunction with nanomechanical cantilever platform. The reported peptide-based cantilever platform represents a new analytical approach that can lead to an alternative to the various detection platforms and can be leveraged to further study CTCs.

Mucins and Cytokeratins as Serum Tumor Markers in Breast Cancer

Structural and functional characteristics of mucins and cytokeratins are shortly described. Thereafter, those commonly used in breast cancer as serum tumor markers are considered. First CA15.3, MCA, CA549, CA27.29 mucins and CYFRA21.1, TPA, TPS cytokeratins alone or in association have been examined in different stages and conditions. Then their usefulness in monitoring disease-free breast cancer patients is evaluated. The central role of the established cut-off and critical change, the "early" treatment of recurrent disease and the potential benefit in survival are other issues that have been highlighted and discussed. The successive sections and subsections deal with the monitoring of advanced disease. In them, the current recommendations and the principal findings on using the above mentioned mucins and cytokeratins have been reported. A computer program for interpreting consecutive measurements of serum tumor markers also has been illustrated. The final part of the chapter is devoted to mucins and cytokeratins as markers of circulating and disseminated tumor cells and their usefulness for prognosis.

Rapid translation of circulating tumor cell biomarkers into clinical practice: technology development, clinical needs and regulatory requirements

The great hope in circulating tumor cell (CTC) research lies in the use of these rare cells as an accessible "fluid biopsy" that would permit frequent, minimally invasive sampling of tumor cells for similar molecular assays that are performed on traditional biopsies. Given the rarity of CTCs in peripheral circulation, microscale methods show great promise and superiority to capture and analyze these cells from patients with solid tumors. Novel technologies that produce validated CTC biomarkers may finally provide medical oncologists the tools needed to provide precise, personalized medical care for patients with advanced cancer. However, few CTC technologies demonstrate both experimental and clinical evidence of an accurate, reliable and reproducible assay that also meets the regulatory requirements to enter routine clinical practice. Many opportunities exist to incorporate clinical needs and regulatory benchmarks into technology development to more quickly garner FDA approval to direct decisions on patient care. This review will address: 1) device development tailored to address predictive, prognostic and/or therapeutic needs across the multitude of malignancies and disease stages; 2) validation benchmarks for clinical assay development; 3) early establishment of standard operating procedures for sample acquisition and analysis; 4) demonstration of clinical utility; 5) clinical qualification of a novel biomarker; and 6) integration of a newly validated and qualified technology into routine clinical practice. Early understanding and incorporation of these regulatory requirements into assay development can simplify and speed the integration of these novel technologies into patient care. Meeting these benchmarks will lead to the true personalization of cancer therapies, directing initial and subsequent treatments for each individual based on initial tumor characteristics while monitoring for emerging mechanisms of resistance in these continually evolving tumors.

Clinical relevance of cancer stem cells in bone marrow of early breast cancer patients

BACKGROUND

Cancer stem cells (CSCs) are epithelial tumor cells that express CD44(+)CD24(-/lo). CSCs can be further divided into those that have aldehyde dehydrogenase (ALDH) activity (Aldefluor(+)) and those that do not. We hypothesized that if CSCs are responsible for tumor dissemination, their presence in bone marrow (BM) would be prognostic in early stages of breast cancer (EBC) patients.

PATIENTS AND METHODS

BM aspirates were collected at the time of surgery from 108 patients with EBC. BM was analyzed for CSCs and ALDH activity by flow cytometry. Overall survival and disease-free survival (DFS) were calculated from the date of diagnosis and analyzed with Kaplan-Meier survival plots. Cox multivariate proportional hazards model was also carried out.

RESULTS

Patients with CSCs in BM had a hazard ratio (HR) of 8.8 for DFS (P = 0.002); patients with Aldefluor(+) CSCs had a HR of 5.9 (P = 0.052) for DFS. All deceased patients (n = 7) had CSCs in BM. In multivariate analysis, the presence of CSCs in BM was a prognostic factor of DFS (HR = 15.8, P = 0.017).

CONCLUSIONS

The presence of BM metastasis is correlated with CSCs and these CSCs irrespective of ALDH activity are an independent adverse prognostic factor in EBC patients.

Progress in using circulating tumor cell information to improve metastatic breast cancer therapy

Circulating tumor cells (CTCs) were discovered nearly 150 years ago but have only recently been recognized as a feature of most solid tumors due to their extremely low concentration in the peripheral circulation. Several technologies have been developed to isolate and analyze CTCs, which can now be routinely accessed for clinical information. The most mature of these (the CELLSEARCH system) uses immunomagnetic selection of epithelial cell adhesion molecule to isolate CTCs for analysis. Studies using this system have demonstrated that categorization of patients into high and low CTC groups using a validated decision point is prognostic in patients with metastatic breast, colorectal, or prostate cancer. Initial attempts to use CTC counts to guide therapeutic decisions appeared to yield positive results and key concepts in clinical application of CTC information, including the CTC cutoff, predictive value in disease subtypes, and comparison to current evaluation methods, have been demonstrated. Clinical studies of the impact of CTC counts in routine clinical practice are ongoing; however, recent published evidence on the clinical use of CTCs in metastatic breast cancer continues to support these concepts, and experience in the community oncology setting also suggests that CTC enumeration can be useful for therapy management.

Detection of disseminated tumor cells in the bone marrow of breast cancer patients using multiplex gene expression measurements identifies new therapeutic targets in patients at high risk for the development of metastatic disease

Disseminated tumor cells (DTCs) detected in the bone marrow (BM) of breast cancer patients identify women at high risk of recurrence. DTCs are traditionally detected by immunocytochemical staining for cytokeratins or single gene expression measurements, which limit both specificity and sensitivity. We evaluated the Nanostring nCounter™ platform for multi-marker, gene expression-based detection and classification of DTCs in the BM of breast cancer patients. Candidate genes exhibiting tumor cell-specific expression were identified from microarray datasets and validated by qRT-PCR analysis in non-malignant human BM and identical samples spiked with predefined numbers of molecularly diverse breast tumor cell lines. Thirty-eight validated transcripts were designed for the nCounter™ platform and a subset of these transcripts was technically validated against qRT-PCR measurements using identical spiked BM controls. Bilateral iliac crest BM aspirates were collected and analyzed from twenty breast cancer patients, prior to neoadjuvant therapy, using the full 38-gene nCounter™ code set. Tumor cell-specific gene expression by nCounter™ was detected with a sensitivity of one cancer cell per 1 × 10(6) nucleated BM cells after optimization. Measurements were quantitative, log linear over a 20-fold range, and correlated with qRT-PCR measurements. Using the nCounter™ 38-gene panel, 6 of 8 patients (75 %) who developed metastatic disease had detectable expression of at least one transcript. Notably, three of these patients had detectable expression of ERBB2 in their BM, despite the fact that their corresponding primary tumors were HER2/ERBB2 negative and therefore did not receive trastuzumab therapy. Four of these patients also expressed the PTCH1 receptor, a newly recognized therapeutic target based on hedgehog signaling pathway inhibition. The presumptive detection and classification of DTCs in the BM of breast cancer patients, based on sensitive and quantitative multi-marker detection of gene expression using the nCounter™ platform, provide an opportunity to both predict early distant recurrence and, more importantly, identify opportunities for preventing the spread of disease based on the expression of unique, therapeutically actionable gene targets. This study demonstrates the application of a new technology for multiplexed gene expression-based detection of DTCs in the BM of breast cancer patients and identifies at least two therapeutically targetable genes that are frequently expressed in the BM of patients who develop metastatic disease.

Clinical implications of the detection of circulating tumor cells in breast cancer patients

The detection of disseminated tumor cells in bone marrow is a common phenomenon seen in 30-40% of primary breast cancer patients. The presence of disseminated tumor cells at diagnosis as well as the persistence of disseminated tumor cells is strongly associated with poor clinical outcome. Since bone marrow biopsies are not well tolerated by many patients, the evaluation of circulating tumor cells in the blood might become a desired alternative. Circulating tumor cells are routinely detected, depending on stage of the disease and methodology, in 10-80% of breast cancer patients. Recent studies have shown a prognostic potential of circulating tumor cells in both primary and metastatic settings. The evaluation of circulating tumor cells may become one of the crucial markers for prediction of survival and therapy monitoring, and its characterization might enable specific targeting of minimal residual, and metastatic disease.

Trastuzumab decreases the incidence of clinical relapses in patients with early breast cancer presenting chemotherapy-resistant CK-19mRNA-positive circulating tumor cells: results of a randomized phase II study

BACKGROUND

Since the detection of circulating tumor cells (CTCs) which express HER2 is an adverse prognostic factor in early breast cancer patients, we investigated the effect of trastuzumab on patients' clinical outcome.

PATIENTS AND METHODS

Seventy five women with HER2 (-) breast cancer and detectable CK19 mRNA-positive CTCs before and after adjuvant chemotherapy, were randomized to receive either trastuzumab (n=36) or observation (n=39). CK19 mRNA-positive CTCs were detected by RT-PCR and double stained CK(+)/HER2(+) cells by immunofluorescence. The primary endpoint was the 3-year disease-free survival rate.

RESULTS

Fifty-one (89%) of the 57 analyzed patients had HER2-expressing CTCs. After trastuzumab administration, 27 of 36 (75%) women became CK19 mRNA-negative compared to seven of 39 (17.9%) in the observation arm (p=0.001). After a median follow up time of 67.2 months, four (11%) and 15 (38%) relapses were observed in the trastuzumab and observation arm, respectively (p=0.008); subgroup analysis indicated that this effect was mainly confined to women with >3 involved axillary lymph nodes (p=0.004). The median DFS was also significantly higher for the trastuzumab-treated patients (p=0.008).

CONCLUSION

Administration of trastuzumab can eliminate chemotherapy-resistant CK19 mRNA-positive CTCs, reduce the risk of disease recurrence and prolong the DFS.

CTCs in primary breast cancer (II)

CTCs can be detected by real-time RT-PCR for CK19 mRNA in the blood of early breast cancer patients before the start and after the completion of adjuvant chemotherapy and during adjuvant hormonal therapy and the follow-up. Patients with CK19 mRNA-positive cells both before and after chemotherapy have the worst prognosis with shorter disease-free and overall survival. The same is true for patients who have detectable CK19 mRNA-positive cells despite adjuvant tamoxifen while persistent detection during the follow-up predicts for late disease relapse. Thus CTC monitoring offers the opportunity to evaluate the efficacy of adjuvant therapy and identify those patients who are more likely to benefit from secondary adjuvant treatments.

Circulating Tumor Cells in Early-Stage Breast Cancer

Disseminated tumor cells (DTC) are routinely detected in bone marrow (BM) in 30-40 % of primary breast cancer patients. Positive BM status at the time of diagnosis as well as DTC persistence after therapy are strong independent prognostic factors. Since repeated BM aspirations are not well tolerated, detection of single tumor cells in peripheral blood (circulating tumor cells; CTC) have become of interest in recent years. CTC are found in 10-80 % breast cancer patients. Variability can be explained by stage of the disease and detection method. Emerging data have shown CTC to be of prognostic relevance for both, patients with primary and metastatic disease. The assessment of CTC in blood may become an important biomarker for prognostication and therapy monitoring. Determination of their molecular characteristics will enable specific targeting of minimal residual as well as metastatic disease. This review summarizes recent research and future perspectives.

Circulating cancer cells

Circulating tumour cells (CTCs) can be detected in the blood of many patients with different types of early or advanced cancer using antibody-based assays or molecular methods. In many studies the detection and quantification of CTCs has been linked to unfavourable prognosis. CTC detection offers the opportunity for individualized risk assessment beyond that determined by TNM staging. However, discordant results have been reported when different methodologies for CTC detection were used. Therefore, well-standardized detection methods cross-validated between different laboratories are still needed. CTCs are a heterogeneous population of cells with biological characteristics often different from those of their respective primary tumour cells. Pilot studies have shown that phenotyping of CTCs could be used to predict response to targeted therapies. In the era of biological therapeutics, CTC characterization at different time points during the course of disease may provide useful predictive information for the selection of the most appropriate treatment. Therefore, in the future, CTC detection and characterization might become a valuable tool to refine prognosis and serve as a real-time tumour biopsy for individually tailored cancer therapy. Prospective randomized studies are warranted to evaluate the utility of assessing and monitoring CTCs and modifying accordingly treatment strategies in order to improve the clinical outcome of cancer patients.

Gene expression of somatostatin receptor subtypes SSTR2a, SSTR3 and SSTR5 in peripheral blood of neuroendocrine lung cancer affected patients

BACKGROUND

Somatostatin (SS) acts as a universal endocrine off-switch, and also inhibits the growth of neuroendocrine tumours through its specific receptors (SSTRs). Somatostatin receptors are G-protein-coupled receptors, which are encoded by five separate genes (SSTR1-5). Short peptide analogues demonstrate specific binding only for the subgroup consisting of SSTR2a, SSTR3 and SSTR5. Moreover, previous studies reported that expression of mRNA for SSTR2a correlated with therapeutic outcome in patients with carcinoid tumours treated with somatostatin analogs.

PURPOSE

To develop and apply a Real Time Quantitative PCR technique (RT-qPCR) to compare and contrast the mRNA levels of SSTR2a, SSTR3 and SSTR5 in Neuroendocrine Lung Cancer affected patients.

METHODS

Peripheral blood samples from 21 neuroendocrine lung cancer affected patients (14 SCLC, 6 LC and 1 LCNEC) subjected to scintigraphy with (111)In-DTPA-D-Phe(1)-octreotide (OctreoScan) and 24 healthy blood donors were investigated by RT-qPCR. mRNA levels for SSTR2a, SSTR3 and SSTR5 were measured in peripheral blood samples with a relative quantification method using plasmid dilutions as calibration curves and GAPDH as reference gene.

RESULTS

A statistically significant increase in target genes/GAPDH copy number ratio was found for SSTR2a (median 38; IQR 22-141) and SSTR5 (median 51; IQR 19-499) in neuroendocrine lung cancer affected patients as compared with samples from healthy blood donors (P ≤ 0.0003 and P ≤ 0.0005). Since low levels of expression were detected in the control group for all three genes, optimal cut-off values were assessed using ROC curve analyses and were equal to 9.05 for SSTR2a and 16.97 for SSTR5. These cut off values resulted in a sensitivity of 86% (95%IC 65-95) for both markers and a specificity of 83% (95%IC 64-93%) and 79% (95%IC 60-91%) for SSTR2a and SSTR5 respectively. Comparison between OctreoScan results and RT-qPCR analysis demonstrated agreement in 76% of the cases.

CONCLUSIONS

Our results suggest that SSTR2a and SSTR5 mRNAs are detectable in peripheral blood of neuroendocrine lung cancer affected patients using real-time quantitative PCR, with a good agreement with OctreoScan. The high sensitivity of this non-invasive molecular technique suggests that this method could represent a useful tool in the clinical management of neuroendocrine lung cancers.

Circulating tumor cells in breast cancer patients: an evolving role in patient prognosis and disease progression

In this paper, we examine the role of circulating tumor cells (CTCs) in breast cancer. CTCs are tumor cells present in the peripheral blood. They are found in many different carcinomas but are not present in patients with benign disease. Recent advances in theories regarding metastasis support the role of early release of tumor cells in the neoplastic process. Furthermore, it has been found that phenotypic variation exists between the primary tumor and CTCs. Of particular interest is the incongruency found between primary tumor and CTC HER2 status in both metastatic and early breast cancer. Overall, CTCs have been shown to be a poor prognostic marker in metastatic breast cancer. CTCs in early breast cancer are not as well studied, however, several studies suggest that the presence of CTCs in early breast cancer may also suggest a poorer prognosis. Studies are currently underway looking at the use of CTC level monitoring in order to guide changes in therapy.

Cytokeratin 19-positive circulating tumor cells in early breast cancer prognosis

In spite of the heterogeneity of breast cancer at the molecular level, circulating tumor cells (CTCs) may provide a novel prognostic marker. Approximately 20–40% of early breast cancer patients have detectable CTCs using reverse transcription PCR for CK19. The detection of CTCs before adjuvant chemotherapy or during tamoxifen administration has been demonstrated to be an independent adverse prognostic factor in women with early-stage breast cancer. The prognostic value of CTC detection is of great significance in subgroups of patients with estrogen receptor-negative and human EGF receptor 2-positive tumors. Prospective clinical trials are warranted in order to validate the use of CTCs as predictive and/or prognostic markers and assess their utility in individualizing therapy of patients with early breast cancer.

Molecular assessment of sentinel lymph node in breast cancer management

Sentinel lymph node biopsy (SLNB) is becoming accepted as standard of care for axillary staging in breast cancer. World Health Organization (WHO) re-classification of axillary metastases into macrometastases, micrometastases and individual tumour cells has highlighted the issues of sampling and further histological examination of the initially negative SLNB. Molecular detection of metastatic breast cancer cells in lymph nodes is now available as a commercial kit for intraoperative use and can resolve the sampling issue. Semiquantitative assessment of axillary lymph node tumour burden can now be made using two separate technologies (histology and reverse transcriptase-polymerase chain reaction). The clinical implications of low metastatic axillary lymph node tumour burden are not clear, and future trials need to include molecular data. The consequences of the availability of molecular assessment are reviewed.

Detection and characterization of circulating tumor cells in blood of primary breast cancer patients by RT-PCR and comparison to status of bone marrow disseminated cells

INTRODUCTION

The role of circulating tumor cells (CTCs) in blood of primary breast cancer patients is still under investigation. We evaluated the incidence of CTCs in blood, we evaluated the correlation between CTCs and disseminated tumor cells (DTCs) in the bone marrow (BM), and we characterized CTCs for the expression of HER2, the estrogen receptor (ER) and the progesterone receptor (PR).

METHODS

Blood of 431 patients with primary breast cancer were analyzed for EpCAM, MUC1 and HER2 transcripts with the AdnaTest BreastCancer (AdnaGen AG, Germany). Expression of the ER and PR was assessed in an additional RT-PCR. BM aspirates from 414 patients were analyzed for DTCs by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3.

RESULTS

DTCs were found in 107/414 patients (24%), CTCs were detected in 58/431 (13%) patients. DTCs were associated with PR status of the primary tumor (P = 0.04) and CTCs significantly correlated with nodal status (P = 0.04), ER (P = 0.05), and PR (P = 0.01). DTCs in the BM weakly correlated with CTCs (P = 0.05) in blood. Interestingly, the spread of CTCs was mostly found in triple-negative tumors (P = 0.01) and CTCs in general were mostly found to be triple-negative regardless of the ER, PR and HER2 status of the primary tumor.

CONCLUSIONS

(1) Due to the weak concordance between CTCs and DTCs the clinical relevance may be different. (2) The biology of the primary tumor seems to direct the spread of CTCs. (3) Since the expression profile between CTCs and the primary tumor differs, the consequence for the selection of adjuvant treatment has to be evaluated.

Detection of cytokeratin-19 mRNA-positive cells in the peripheral blood and bone marrow of patients with operable breast cancer

Background:

To compare detection rates and evaluate the clinical relevance of cytokeratin-19 (CK-19) mRNA-positive cells in the peripheral blood (circulating tumour cells, CTCs) and bone marrow (disseminated tumour cells; DTCs) of patients with early breast cancer.

Methods:

Paired samples of peripheral blood and bone marrow were obtained from 165 patients with stage I–II breast cancer before the initiation of adjuvant chemotherapy. In 84 patients, paired blood and bone marrow samples were also available after chemotherapy. The detection of CK-19 mRNA-positive CTCs and DTCs was assessed by real-time PCR.

Results:

CK-19 mRNA-positive CTCs and DTCs were detected in 55.2 and 57.6% of patients before chemotherapy, respectively. After chemotherapy, CTCs and DTCs were identified in 44 (52.4%) and 43 (51.2%) of the 84 patients, respectively. There was a 93.9% (McNemar; P=0.344) and 72.6% (McNemar; P=0.999) concordance between blood and bone marrow samples before and after chemotherapy, respectively. The detection of CK-19 mRNA-positive CTCs or DTCs before chemotherapy was associated with decreased overall survival (P=0.024 and P=0.015, respectively). In addition, their simultaneous detection was also associated with an increased incidence of disease-related death and decreased overall survival (P=0.016).

Conclusions:

The detection of CK-19 mRNA-positive CTCs using reverse transcription-PCR (RT–PCR) both before and after chemotherapy is correlated with the detection of CK-19 mRNA-positive DTCs in patients with early-stage breast cancer. The determination of the CTC status by RT–PCR conveys clinically relevant information that is not inferior to DTC status and, owing to the ease of sampling, warrants further evaluation as a tool for monitoring minimal residual disease.

Circulating tumor cells (CTCs): detection methods and their clinical relevance in breast cancer

The enumeration of circulating tumor cells has long been regarded as an attractive diagnostic tool, as circulating tumor cells are thought to reflect aggressiveness of the tumor and may assist in therapeutic decisions in patients with solid malignancies. However, implementation of this assay into clinical routine has been cumbersome, as a validated test was not available until recently. Circulating tumor cells are rare events which can be detected specifically only by using a combination of surface and intracellular markers, and only recently a number of technical advances have made their reliable detection possible. Most of these new techniques rely on a combination of an enrichment and a detection step. This review addresses the assays that have been described so far in the literature, including the enrichment and detection steps and the markers used in these assays. We have focused on breast cancer as most clinical studies on CTC detection so far have been done in these patients.

Diagnostic accuracy of small breast epithelial mucin mRNA as a marker for bone marrow micrometastasis in breast cancer: a pilot study

BACKGROUND

Detection of isolated tumour cells (ITC) in the blood or minimal deposits in distant organs such as bone marrow (BM) could be important to identify breast cancer patients at high risk of relapse or disease progression. PCR amplification of tissue or tumour selective mRNA is the most powerful analytical tool for detection of this micrometastasis. We have evaluated for the first time, the diagnostic accuracy of small breast epithelial mucin (SBEM) as a potential marker for BM micrometastasis in breast cancer.

METHODS

A nested RT-PCR assay for detection of SBEM mRNA was compared with immunocytochemistry (ICC) with anticytokeratin AE1/AE3 antibody in paired samples obtained from the BM of breast cancer patients. Associations of SBEM mRNA detection in BM and clinical and pathological parameters were evaluated. SBEM mRNA status and time to breast cancer progression were analysed using Kaplan-Meyer curves.

RESULTS

Fifty stages I-IV breast cancer female patients were prospectively included in our study. SBEM specific transcript was found in BM in 26% of the patients. Detection rate was similar to the percentage of patients with ITCs detected using ICC (24%). SBEM mRNA in BM aspirates were significantly associated with presence of clinically active disease, including locally advanced and metastatic patients (47%, P = 0.021) and tumours with positive hormonal receptors (36.7%, P = 0.035). In addition association with Her2/neu over-expression (44.4%, P = 0.051) and low proliferating tumours (36%, P = 0.067) were close to significant levels. When we analysed time to breast cancer progression adjusting for grade or hormone receptor status, presence of SBEM mRNA in BM defines distinct prognostic groups.

CONCLUSIONS

SBEM might represent a suitable marker for molecular detection of ITCs in BM in breast cancer patients. Analysis of prognostic value for SBEM mRNA-based assay should take into account the heterogeneity and different molecular subtypes of breast cancer.

Comparison of bone marrow, disseminated tumour cells and blood-circulating tumour cells in breast cancer patients after primary treatment

The purpose of this study was to determine whether primary breast cancer patients showed evidence of circulating tumour cells (CTCs) during follow-up as an alternative to monitoring disseminated bone marrow tumour cells (DTCs) by immunocytochemistry and reverse transcriptase (RT)–PCR for the detection of micrometastases. We planned to compare CTC and DTC frequency in low-risk and high-risk patients. We identified two cohorts of primary breast cancer patients who were at low (group II, T₁N₀, n=18) or high (group III, >3 nodes positive (with one exception, a patient with two positive nodes) n=33) risk of relapse who were being followed up after primary treatment. We tested each cohort for CTCs using the CellSearch system on 1–7 occasions and for DTCs by immunocytochemistry and RT–PCR on 1–2 occasions over a period of 2 years. We also examined patients with confirmed metastatic disease (group IV, n=12) and 21 control healthy volunteers for CTCs (group I). All group I samples were negative for CTCs. In contrast, 7 out of 18 (39%) group II primary patients and 23 out of 33 (70%) group III patients were positive for CTCs (P=0.042). If we count only samples with >1 cell as positive: 2 out of 18 (11%) group II patients were positive compared with 10 out of 33 (30%) in group III (P=0.174). In the case of DTCs, 1 out of 13 (8%) group II patients were positive compared with 19 out of 27 (70%) in group III (P<0.001). Only 10 out of 33 (30%) patients in group III showed no evidence of CTCs in all tests over the period of testing, compared with 11 out of 18 (61%) in group II (P=0.033). A significant proportion of poor prognosis primary breast cancer patients (group III) have evidence of CTCs on follow-up. Many also have evidence of DTCs, which are more often found in patients who were lymph node positive. As repeat sampling of peripheral blood is more acceptable to patients, the measurement of CTCs warrants further investigation because it enables blood samples to be taken more frequently, thus possibly enabling clinicians to have prior warning of impending overt metastatic disease.

Circulating tumor cells and bone marrow micrometastasis

Sensitive immunocytochemical and molecular assays allow the detection of single circulating tumor cells (CTC) in the peripheral blood and disseminated tumor cells (DTC) in the bone marrow as a common and easily accessible homing organ for cells released by epithelial tumors of various origins. The results obtained thus far have provided direct evidence that tumor cell dissemination starts already early during tumor development and progression. Tumor cells are frequently detected in the blood and bone marrow of cancer patients without clinical or even histopathologic signs of metastasis. The detection of DTC and CTC yields important prognostic information and might help to tailor systemic therapies to the individual needs of a cancer patient. In the present review, we provide a critical review of (a) the current methods used for detection of CTC/DTC and (b) data on the molecular characterization of CTC/DTC with a particular emphasis on tumor dormancy, cancer stem cell theory, and novel targets for biological therapies; and we pinpoint to (c) critical issues that need to be addressed to establish CTC/DTC measurements in clinical practice.

Review: Biological relevance of disseminated tumor cells in cancer patients

The prognosis of cancer patients is largely determined by the occurrence of distant metastases. In patients with primary tumors, this relapse is mainly due to clinically occult micrometastasis present in secondary organs at primary diagnosis but not detectable even with high resolution imaging procedures. Sensitive and specific immunocytochemical and molecular assays enable the detection and characterization of disseminated tumor cells (DTC) at the single cell level in bone marrow (BM) as the common homing site of DTC and circulating tumor cells (CTC) in peripheral blood. Because of the high variability of results in DTC and CTC detection, there is an urgent need for standardized methods. In this review, we will focus on BM and present currently available methods for the detection and characterization of DTC. Furthermore, we will discuss data on the biology of DTC and the clinical relevance of DTC detection. While the prognostic impact of DTC in BM has clearly been shown for primary breast cancer patients, less is known about the clinical relevance of DTC in patients with other carcinomas. Current findings suggest that DTC are capable to survive chemotherapy and persist in a dormant nonproliferating state over years. To what extent these DTC have stem cell properties is subject of ongoing investigations. Further characterization is required to understand the biology of DTC and to identify new targets for improved risk prevention and tailoring of therapy. Our review will focus on breast, colon, lung, and prostate cancer as the main tumor entities in Europe and the United States.

Comparative evaluation of an extensive histopathologic examination and a real-time reverse-transcription-polymerase chain reaction assay for mammaglobin and cytokeratin 19 on axillary sentinel lymph nodes of breast carcinoma patients

OBJECTIVE

To assess the accuracy of a commercially available real-time reverse-transcription-polymerase chain reaction assay for mammaglobin and cytokeratin 19 mRNAs [GeneSearch Breast Lymph Node (BLN) Assay, Veridex LLC, Warren, NJ] in the detection of axillary sentinel lymph nodes (SLNs) metastases in patients with breast carcinoma.

SUMMARY BACKGROUND DATA

Because of the lack of standardized and widely accepted protocols for a truly accurate histopathologic examination of SLN, the relative merits of alternative assays based on the identification of tumor specific mRNA markers deserve further assessment.

METHODS

: A prospective series of 293 consecutive SLNs from 293 patients was evaluated. The BLN assay results were compared with those of an extensive histopathologic examination of the entire SLNs performed on serial frozen sections cut at 40 to 50 microm intervals.

RESULTS

The BLN assay correctly identified 51 of 52 macrometastatic and 5 of 20 micrometastatic SLNs, with a sensitivity of 98.1% to detect metastases larger than 2 mm, 94.7% for metastases larger than 1 mm, and 77.8% for metastases larger than 0.2 mm. The overall concordance with histopathology was 90.8%, with specificity of 95.0%, positive predictive value of 83.6%, and negative predictive value of 92.9%. When the results were evaluated according to the occurrence of additional metastases to non-SLN in patients with histologically positive SLNs, the assay was positive in 33 (91.7%) of the 36 patients with additional metastases and in 22 (66.6%) of the 33 patients without further echelon involvement.

CONCLUSIONS

The sensitivity of the reverse-transcription -polymerase chain reaction assay is comparable to that of the histopathologic examination of the entire SLN by serial sectioning at 1.5 to 2 mm.

Conventional and new emerging prognostic factors in breast cancer: an update

This article reviews the conventional clinicopathological, as well as the principal new emerging prognostic factors of breast cancer and proposes a tumor marker utility grading system for their use. In spite of the many advances in molecular biology toward better defining the biological aggressiveness of the primary malignancy, the conventional node-negative status, tumor size and grade are still the strongest predictors of relapse-free survival and/or overall survival. Microvessel count and bone-marrow micrometastases, among the more recently studied clinicopathological prognostic factors, and amplification and/or p53 mutation and S-phase fraction among the biological ones must be considered investigational, although, with enough documentation recommending their usefulness. Estrogen and/or progesterone expression, c-erbB-2 amplification and/or mutation are the prognostic factors currently included in the principal clinical guidelines. They also enable probable forecast of the response to endocrine treatment or chemotherapy. In particular, c-erbB-2 is used to define the different risk categories of node-negative operated breast cancer patients. In recent years, microarray and quantitative reverse-transcription PCR technologies have enabled the study of multiple genetic alterations and computer algorithms have been developed for visual recognition of tumors that share so-called ‘signatures’. So far, different gene-expression patterns with different prognoses have been identified but methodological problems remain to be solved prior to routine use.

Isolation and molecular profiling of bone marrow micrometastases identifies TWIST1 as a marker of early tumor relapse in breast cancer patients

PURPOSE

Micrometastatic cells detected in the bone marrow have prognostic significance in breast cancer. These cells are heterogeneous and likely do not exhibit uniform biological behavior. To understand the molecular diversity of disseminated cancer cells that reside in bone marrow, we enriched this cell population and did global gene expression profiling in the context of a prospective clinical trial involving women with clinical stage II/III breast cancer undergoing neoadjuvant chemotherapy.

EXPERIMENTAL DESIGN

Enrichment of TACSTD1 (EpCAM)-expressing cells from bone marrow of breast cancer patients was achieved using immunomagnetic beads. Gene expression profiles were compared between enriched cell populations and whole bone marrow from 5 normal volunteers and 23 breast cancer patients after neoadjuvant chemotherapy treatment. Enriched cells from bone marrow samples of breast cancer patients before treatment or at 1 year follow-up were also analyzed (total of 87 data sets). The expression of transcripts specifically detected in enriched cell populations from breast cancer patients was correlated with 1-year clinical outcome using quantitative reverse transcription-PCR in an independent cohort of bone marrow samples.

RESULTS

Analysis of EpCAM-enriched bone marrow cells revealed specific expression of a subgroup of transcripts, including the metastasis regulator, TWIST1. Most transcripts identified, including TWIST1, were not expressed in enriched populations of bone marrow from normal volunteers, suggesting that this expression profile reflects a signature of breast cancer bone marrow micrometastases that persist after chemotherapy. In an independent set of bone marrow samples obtained before any treatment, TWIST1 expression correlated with early disease relapse.

CONCLUSIONS

Disseminated breast cancer cells present in bone marrow after chemotherapy possess unique transcriptional signatures. Genes whose expression is overrepresented in these cell populations, such as TWIST1, may prove to be excellent markers of early distant relapse in breast cancer patients.

Epithelial molecular markers in the peripheral blood of patients with colorectal cancer

Despite the modest improvements in patient survival from colorectal cancer in the last few decades, the overall five-year survival rate remains at 40 to 45 percent. Surgical resection is the mainstay of treatment for colorectal cancer; however, nearly one-half of all patients who undergo a potentially curative resection will relapse because of undetected micrometastasis. The fact that the overall survival rate remains poor strongly suggests that the dissemination of these cells occurs early in the disease process and emphasizes the need for finding feasible diagnostic methods with sufficient sensitivity and specificity. The most commonly used technique for the detection of nucleic acid material of disseminated tumor cells is the polymerase chain reaction. We critically review the literature on DNA and messenger ribonucleic acid molecular markers that have been used for the detection of circulating tumor cells in the peripheral blood of patients with colorectal cancer and other solid tumors as appropriate for comparison. The cytokeratins, particularly cytokeratin 19 and cytokeratin 20, are the most investigated prognostic markers, but even for these questions remain about their clinical value, and hence most recent studies are utilizing a combination of factors. There is an urgent need for standardized isolation and analysis techniques to be adopted thus allowing large-scale, appropriately controlled, multicenter trials to be undertaken on the most promising candidate markers.

Bone marrow cytokeratin 19 mRNA level is an independent predictor of relapse-free survival in operable breast cancer patients

PURPOSE

To study the prognostic significance of elevated cytokeratin 19 (CK19) mRNA levels in the bone marrow (BM) of operable breast cancer patients.

PATIENTS AND METHODS

From 1998 to 2000, BM was collected from 195 consecutive breast cancer patients immediately prior to surgery and from 34 healthy volunteers. The patients received surgical and adjuvant treatment according to national guidelines at the time. We analyzed the level of CK19 mRNA in the BM samples from patients and normal controls using a real-time RT-PCR assay. The associations with known prognostic factors and the impact of pathological CK19 mRNA levels on patients' prognosis were investigated.

RESULTS

Using the 99 percentile of the normal control group as a cut-off, 24 (12%) of the 195 patients and 1 (3%) of the 34 volunteers were diagnosed as CK19 mRNA positive. There was no correlation between CK19 BM status and the clinicopathological factors tested. During a median follow-up of 72 months, 7 (29%) of the 24 CK19 mRNA BM positive patients experienced systemic relapse compared to 20 (12%) of the 171 in the CK19 mRNA negative group. The patients with CK19 mRNA-positive BM had significantly shorter systemic recurrence-free survival (P=0.01) and overall recurrence-free survival (P=0.005). Multivariate Cox regression showed CK19 mRNA BM status to be an independent predictor of relapse.

CONCLUSION

Detection of CK19 mRNA in the BM of breast cancer patients by real-time RT-PCR is an independent predictor of relapse-free survival in operable breast cancer patients.

Combination of multiple mRNA markers (PTTG1, Survivin, UbcH10 and TK1) in the diagnosis of Taiwanese patients with breast cancer by membrane array

OBJECTIVE

Early detection is a prerequisite to the effective reduction of morbidity and mortality from breast cancer. The present study intended to employ a high-throughput membrane array to detect a panel of mRNA markers expressed by circulating tumor cells (CTCs) in the peripheral blood of female patients with breast cancer.

METHODS

Peripheral blood was sampled from 92 breast cancer patients and 100 normal persons. CTCs were detected by using a membrane array technique. The markers used included the pituitary tumor transforming gene 1, survivin, UbcH10 and thymidine kinase 1.

RESULTS

The results showed that the membrane array could positively detect 5 cancer cells per 1 ml of peripheral blood in breast cancer cell dilution experiments. For the panel of 4 mRNA markers, sensitivity and specificity were elevated up to 86 and 88%, respectively. Furthermore, it was found that the patients' clinicopathological characteristics tumor size (p = 0.006), histologic grade (p = 0.012), lymph node metastasis (p = 0.001) and TNM stage (p = 0.006) significantly correlated with the positive detection rate of the multimarker panel.

CONCLUSIONS

These findings demonstrated that our multimarker membrane array method could detect CTCs in the circulation of breast cancer patients with considerably high sensitivity and specificity.

The clinical significance of disseminated tumor cells in breast cancer

The presence of tumor cells in the bone marrow of primary breast cancer patients at surgery has been shown to be an independent prognostic indicator of relapse. Tumor cells have been detected either directly, using immunocytochemical staining, or indirectly, using reverse transcription-polymerase chain reaction (RT-PCR). Studies have been initiated to determine whether the presence of disseminated cells can be monitored during the therapy of patients with primary breast cancer, and thus potentially be used to predict relapse before overt metastases are detectable. Studies are also ongoing to improve methods of detection, such as immunobead enrichment followed by staining and real-time RT-PCR, and to find alternative markers for the disseminated cells. Studies of patients with overt metastases have shown that there is a large tumor load in the peripheral blood and that this predicts overall survival. This article reviews the published literature on studies carried out in both primary and metastatic breast cancer patients, the methodologies and markers used, and improvements in detection methodologies that are being investigated including real-time RT-PCR, novel markers, enrichment and automated image analysis.

Validity of Messenger RNA Expression Analyses of Human Saliva

PURPOSE

The origins of expression microarray and reverse transcription-PCR (RT-PCR) signals in human saliva were evaluated.

EXPERIMENTAL DESIGN

The "RNA" extracts from human saliva samples were treated with vehicle, DNase, or RNase. Two-step amplification and hybridization to Affymetrix 133A cDNA microarrays were then done. Confirmatory RT-PCR experiments used conventionally designed PCR primer pairs for the reference housekeeper transcripts encoding 36B4, beta-actin, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA sequences, which are known to be homologous to genomic DNA pseudogene sequences. Negative controls included the omission of reverse transcriptase ("no-RT") to detect any DNA-derived signal. Finally, an RNA-specific RT-PCR strategy eliminated confounding signals from contaminating genomic DNA.

RESULTS

Microarray experiments revealed that untreated, DNase-treated, and RNase-treated "RNA" extracts from saliva all yielded negligible overall signals. Specific microarray signals for 36B4, beta-actin, and GAPDH were low, and were unaffected by RNase. Real-time quantitative RT-PCR reactions using conventional, non-RNA-specific primers on saliva samples yielded PCR products for 36B4, beta-actin, and GAPDH; DNase-treated saliva samples did not yield a PCR product, and the "no-RT" and "+RT" conditions yielded similar amounts of PCR product. The RNA-specific RT-PCR strategy, across all conditions, yielded no PCR product from saliva.

CONCLUSIONS

The combination of (a) a minimal microarray signal, which was unaffected by RNase treatment, (b) the presence of a conventional RT-PCR housekeeper product in both RNase-treated and no-RT saliva samples, (c) the absence of a conventional RT-PCR housekeeper product in DNase-treated conditions, and (d) the absence of a RNA-specific RT-PCR product shows that any microarray or RT-PCR signal in the saliva must arise from genomic DNA, not RNA. Thus, saliva extracts do not support mRNA expression studies.

Prognostic Significance of Disseminated Tumor Cells as Detected by Quantitative Real-Time Reverse-Transcriptase Polymerase Chain Reaction in Patients with Breast Cancer

BACKGROUND

In this study we have validated the feasibility of detecting disseminated tumor cells (DTC) by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. Bone marrow samples from a large cohort of patients with breast cancer were analyzed for the presence of DTC by immunocytochemistry (ICC) or a molecular-based method.

PATIENTS AND METHODS

Bone marrow samples were collected from 170 patients with breast cancer with stage I-IV disease before the initiation of any local or systemic treatment. Staining for cytokeratin (CK)-positive cells was performed with the Epimet kit. Disseminated tumor cells were also quantified by measuring relative gene expression for CK19 and mammaglobin (MAM) using a quantitative RT-PCR detection method. The mean follow-up time was 30 months. Kaplan-Meier analysis was used for predicting overall survival.

RESULTS

Despite an excellent quantitative correlation and qualitative concordance between ICC and RT-PCR, survival analysis suggested an improved prognostic significance of DTC as detected by quantitative RT-PCR. Univariate survival analysis computed a relative risk of death of 2.87 for women with ICC-positive cells in the bone marrow, as compared with those without positive cells. The relative risk for women with RT-PCR-positive bone marrow was even higher: 3.5 (CK19) and 3.39 (MAM). In multivariate analysis, bone marrow CK19 was a stronger prognostic factor than bone marrow ICC.

CONCLUSION

Reverse-transcriptase polymerase chain reaction-detected DTC is shown to be prognostically significant in untreated patients with breast cancer. Furthermore, it seems to be a more sensitive method for detecting DTC in bone marrow samples when compared with ICC.

Real-time RT-PCR detection of disseminated tumour cells in bone marrow has superior prognostic significance in comparison with circulating tumour cells in patients with breast cancer

This study assessed the ability of real-time reverse transcription–polymerase chain reaction (RT–PCR) analysis to detect disseminated epithelial cells (DEC) in peripheral blood (PB) and bone marrow (BM) of patients with breast cancer (BC). Detection of DEC in BM is an obvious choice in BC, but blood sampling is more convenient. The aim of this study was to evaluate whether the detection of DEC in either PB or BM predicts overall survival (OS). Peripheral blood and BM samples were collected from 148 patients with primary (stage M0, n=116/78%) and metastatic (stage M+, n=32/21%) BC before the initiation of any local or systemic treatment. Peripheral blood of healthy volunteers and BM of patients with a nonmalignant breast lesion or a haematological malignancy served as the control group. Disseminated epithelial cells was detected by measuring relative gene expression (RGE) for cytokeratin-19 (CK-19) and mammaglobin (MAM), using a quantitative RT–PCR detection method. The mean follow-up time was 786 days (+/− 487). Kaplan–Meier analysis was used for predicting OS. By taking the 95 percentile of the RGE of CK-19 (BM: 26.3 and PB: 58.7) of the control group as cutoff, elevated CK-19 expression was detected in 42 (28%) BM samples and in 22 (15%) PB samples. Mammaglobin expression was elevated in 20% (both PB and BM) of the patients with BC. There was a 68% (CK-19) and 75% (MAM) concordance between PB and BM samples when classifying the results as either positive or negative. Patients with an elevated CK-19 or MAM expression in the BM had a worse prognosis than patients without elevated expression levels (OS: log-rank test, P=0.0045 (CK-19) and P=0.025 (MAM)). For PB survival analysis, no statistical significant difference was observed between patients with or without elevated CK-19 or MAM expression (OS: log-rank test, P=0.551 (CK-19) and P=0.329 (MAM)). Separate analyses of the M0 and M+ patients revealed a marked difference in OS according to the BM CK-19 or MAM status in the M+ patient group, but in the M0 group, only MAM expression was a prognostic marker for OS. Disseminated epithelial cells, measured as elevated CK-19 or MAM mRNA expression, could be detected in both PB and BM of patients with BC. Only the presence of DEC in BM was highly predictive for OS. The occurrence of DEC in the BM is probably less time-dependent and may act as a filter for circulating BC cells. The use of either larger volumes of PB or performing an enrichment step for circulating tumour in blood cells might improve these results.

Simultaneous detection of multiple mRNA markers CK19, CEA, c-Met, Her2/neu and hMAM with membrane array, an innovative technique with a great potential for breast cancer diagnosis

The objective of this study was mainly to develop and evaluate a membrane array-based method simultaneously detecting the expression levels of a multiple mRNA marker panel in the peripheral blood for used in complementary breast cancer diagnosis. The mRNA markers employed included cytokeratin 19 (CK-19), carcinoembryonic antigen (CEA), c-Met, Her2/neu, and mammaglobin (hMAM). The specimens of peripheral blood were collected from 80 healthy women and 102 female patients with breast cancer. The expression levels of molecular markers were evaluated by real-time Q-PCR and membrane array. Data obtained from real-time Q-PCR and membrane array were subjected to linear regression analysis, revealing that there was a high degree of correlation between the results of these two methods (r=0.979, P<0.0001). The result of membrane array assay with a combined panel of five mRNA markers was demonstrated to achieve sensitivity of 80.6%, and specificity of 83.8% for breast cancer detection, much higher than those of analysis of single marker. In addition, we demonstrated that the membrane array method could detect circulating cancer cells at a density as low as five cancer cells per 1 ml of blood. The analysis of correlation between the outcome of membrane array and clinicopathological characteristics indicated that overexpression of the multiple marker panel was significantly correlated with tumor size (P=0.030) and TNM stage (0.009). In conclusion, the detection of circulating cancer cells by means of membrane array simultaneously monitoring five mRNA markers could significantly enhance the sensitivity and specificity for cancer cell detection.