Relevance of disseminated tumour cells in blood and bone marrow of patients with solid epithelial tumours in perspective

LUNX mRNA-positive cells at different time points predict prognosis in patients with surgically resected nonsmall cell lung cancer

LUNX is a lung-specific gene whose messenger ribonucleic acid (mRNA) expression is strictly limited to normal lung tissue and nonsmall cell lung cancer (NSCLC) tissue. The aim of this study was to investigate whether the detection of LUNX mRNA-positive circulating tumor cells (CTC)s in peripheral blood at different time points is useful for predicting disease recurrence, disease-free survival (DFS), and overall survival (OS) in NSCLC patients undergoing surgery. Serial blood samples from 68 patients with stage I-IIIA NSCLC were examined by real-time quantitative polymerase chain reaction assay targeting LUNX mRNA before (T0) and after surgery (T1) and after the completion of adjuvant chemotherapy (T2). Results showed that LUNX mRNA-positive CTCs were detected in 40 of 68 NSCLC patients (58.8%) before surgery; the detection rates of LUNX mRNA-positive CTCs at T1 and T2 time points were 32.4% (22/68) and 33.3% (20/60), respectively. The detection of LUNX mRNA-positive CTC at 3 time points was associated with lymph node status and pathologic stage. During the follow-up period, patients with LUXN mRNA-positive CTC at 3 time points had a higher relapse rate and a shorter DFS and OS than those without. Multivariate analysis revealed that presence of LUNX mRNA-positive CTC at T1 and T2 time points was an independent unfavorable factor for DFS and OS. In conclusion, detection of LUNX mRNA-positive CTC after surgery and the completion of adjuvant chemotherapy in patients with stage I-IIIA NSCLC are highly predictive for DFS and OS. This technique could aid in the prediction of prognosis and design of tailored treatment.

Insights into cancer metastasis from a clinicopathologic perspective: Epithelial-Mesenchymal Transition is not a necessary step

Epithelial-mesenchymal transition (EMT) has been implicated as the critical event initiating cancer invasion and metastasis. After disseminating through the circulation, the malignant cells have been proposed to undergo subsequent mesenchymal-epithelial transition (MET) to form secondary tumors. However, strong evidence from human tumor specimens for this paradigm is lacking. In carcinomas, cancers derived from epithelial tissues, epithelial morphology and gene expression are always retained to some degree. While mesenchymal transdifferentiation may be involved in the pathogenesis of carcinosarcomas, even in these neoplasms, as well as in germ cell tumors capable of multilineage differentiation, the mesenchymal phenotype does not facilitate metastatic progression. Indeed, most cancers invade and travel through lymphatic and blood vessels via cohesive epithelial migration, rather than going through the EMT-MET sequence. EMT gene expression is also consistently associated with high histologic grade and while the transcription factors, Snail, Slug and Twist have traditionally been thought of as inducers of EMT, under certain conditions, they also mediate dedifferentiation and maintenance of the stem cell state. In various malignancies, including basal-like breast cancer and colorectal cancer, the genetically unstable, undifferentiated phenotype predicts early metastatic spread and poor prognosis. This article discusses some of the controversies surrounding differentiation and metastasis from a clinicopathologic perspective and presents evidence that the epithelial phenotype is maintained throughout the process of cancer metastasis.

Electrochemical and electrochemiluminescence determination of cancer cells based on aptamers and magnetic beads

The electrochemical and electrochemiluminescence (ECL) detection of cell lines of Burkitt's lymphoma (Ramos) by using magnetic beads as the separation tool and high-affinity DNA aptamers for signal recognition is reported. Au nanoparticles (NPs) bifunctionalized with aptamers and CdS NPs were used for electrochemical signal amplification. The anodic stripping voltammetry technology employed for the analysis of cadmium ions dissolved from CdS NPs on the aggregates provided a means to quantify the amount of the target cells. This electrochemical method could respond down to 67 cancer cells per mL with a linear calibration range from 1.0×10(2) to 1.0×10(5) cells mL(-1), which shows very high sensitivity. In addition, the assay was able to differentiate between target and control cells based on the aptamer used in the assay, indicating the wide applicability of the assay for diseased cell detection. ECL detection was also performed by functionalizing the signal DNA, which was complementary to the aptamer of the Ramos cells, with tris(2,2-bipyridyl) ruthenium. The ECL intensity of the signal DNA, replaced by the target cells from the ECL probes, directly reflected the quantity of the amount of the cells. With the use of the developed ECL probe, a limit of detection as low as 89 Ramos cells per mL could be achieved. The proposed methods based on electrochemical and ECL should have wide applications in the diagnosis of cancers due to their high sensitivity, simplicity, and low cost.

Aptamer-nanoparticle strip biosensor for sensitive detection of cancer cells

We report an aptamer-nanoparticle strip biosensor (ANSB) for the rapid, specific, sensitive, and low-cost detection of circulating cancer cells. Known for their high specificity and affinity, aptamers were first selected from live cells by the cell-SELEX (systematic evolution of ligands by exponential enrichment) process. When next combined with the unique optical properties of gold nanoparticles (Au-NPs), ANSBs were prepared on a lateral flow device. Ramos cells were used as a model target cell to demonstrate proof of principle. Under optimal conditions, the ANSB was capable of detecting a minimum of 4000 Ramos cells without instrumentation (visual judgment) and 800 Ramos cells with a portable strip reader within 15 min. Importantly, ANSB has successfully detected Ramos cells in human blood, thus providing a rapid, sensitive, and low-cost quantitative tool for the detection of circulating cancer cells. ANSB therefore shows great promise for in-field and point-of-care cancer diagnosis and therapy.

Positive bone marrow biopsy is associated with a decreased disease-free survival in patients with operable breast cancer

BACKGROUND

Bone marrow (BM) biopsy has been suggested as an independent prognostic factor in patients with breast cancer.

METHODS

Patients operated for breast cancer from June 2000 to April 2008 were enrolled in this protocol after signing an informed consent. After primary surgery, BM aspirate from the iliac crest was obtained and 5-10 cc of blood collected. Since 2002 a peripheral blood (PB) sample was also obtained. Both carcinoembryonic antigen (CEA) and Mammaglobin-specific nested reverse-transcription polymerase chain reaction (RT-PCR) were used to examine BM and PB samples. Physicians and patients were blinded to results.

RESULTS

Two hundred seventy-three patients underwent BM and/or PB test. The median age of the patients was 63 years (31-80 years), and the median tumor diameter was 1.5 cm (0.1-6 cm). BM aspirates were unsuccessful in nine patients, and RT-PCR was not technically feasible in 18 women, leaving 246 patients available for analysis of results and follow-up. Among them, 110 patients (45%) had either a BM or a PB test positive for CEA or Mammaglobin (Test+). At median follow-up of 60 months, 31 events (deaths or relapse) occurred (13%). Disease-free survival (DFS) was significantly lower in the Test+ group (BP and/or PB) (P<0.001). This effect was independent of nodal status. At 5 years, event-free survival for Node-/Test- patients was 46/49 (94%) and for Node+/Test+ patients was 21/33 (64%), while patients with only one status positive (Node-/Test+ or Node+/Test-) had an intermediate disease-free survival (35/43, 81%) (P=0.005). In a subgroup analysis, RT-PCR results for BM and Mammaglobin retained statistical significance on DFS (P<0.001), while those for PB and CEA did not.

CONCLUSIONS

This study confirms that RT-PCR of the BM is an independent prognostic factor for disease-free survival of breast cancer patients, and may improve their staging, allowing better strategies for therapy and follow-up.

DETECTION OF DISSEMINATED TUMOR CELLS IN PERIPHERAL BLOOD

Metastases are the major cause of cancer-related deaths in patients with solid epithelial malignancies, such as breast, colorectal and prostate carcinomas. Hematogenous spreading of tumor cells from a primary tumor can be considered as a crucial step in the metastasis cascade leading eventually to the formation of clinically manifest metastases. Consequently, as shown in recent studies, the detection of disseminated tumor cells in peripheral blood might be of clinical relevance with respect to individual patient prognosis and staging or monitoring of therapy. However, the rarity of disseminated tumor cells in peripheral blood renders the application of sensitive techniques mandatory for their detection. The emergence of highly sophisticated reverse transciptase-polymerase chain reaction (RT-PCR) assays, combining a preanalytical enrichment step with the assessment of multiple molecular tumor markers expressed in disseminated tumor cells, provides a powerful tool in detecting disseminated tumor cells with high sensitivity and specificity. This review will discuss currently used tumor markers as well as experimental means to enhance the sensitivity and specificity of RT-PCR assays to detect disseminated tumor cells in the peripheral blood of patients with breast, colorectal, and prostate cancers, and their clinical relevance assessed in recent studies.

Micronodular transformation as a novel mechanism of VEGF-A-induced metastasis

How and why tumors metastasize is still a matter of debate. The assumption is that mutations render tumor cells with a metastatic phenotype, enabling entrance in and transport through lymph or blood vessels. Distant outgrowth is thought to occur only in a suitable microenvironment (the seed and soil hypothesis). However, the anatomical location of most metastases in cancer patients suggests entrapment of tumor cells in the first microcapillary bed that is encountered. We here investigated how vascular endothelial growth factor-A (VEGF-A) attributes to the metastatic process. We describe here that VEGF-A enhances spontaneous metastasis by inducing intravasation of heterogeneous tumor cell clusters, surrounded by vessel wall elements, via an invasion-independent mechanism. These tumor clusters generate metastatic tissue embolisms in pulmonary arteries. Treatment of tumor-bearing mice with the antiangiogenic compound ZD6474 prevented the development of this metastatic phenotype. This work shows that tumors with high constitutive VEGF-A expression metastasize via the formation of tumor emboli and provides an alternative rationale for anti-VEGF-A therapy, namely to inhibit metastasis formation.

Assays for pharmacodynamic analysis of histone deacetylase inhibitors

Histone deacetylase inhibitors (HDACIs) are a promising new class of targeted anticancer drugs. The pharmacodynamic (PD) assessment of whether a drug has hit its target is critically important to the successful development of any molecular targeted therapy. In the case of HDACIs there are many issues to be considered in PD development and implementation. Although originally it was thought that measurement of core histone hyperacetylation in peripheral blood mononuclear cells might suffice as a PD marker, as the field is evolving it is becoming evident that other measures may be essential, and are likely to be tumour context specific. This paper provides an overview of the assays that have been performed thus far in HDACI clinical trials, with an analysis of relative strengths and weaknesses, and a delineation of the complexity of HDACI PD analysis. Consideration is given to where new approaches are needed and potential approaches for future monotherapy and combination therapy trials are suggested.

Loss of adhesion in the circulation converts amelanotic metastatic melanoma cells to melanotic by inhibition of AKT

Direct injection of murine K-1735 melanoma cells into the subcutis, lung, or brain of syngeneic mice produces amelanotic tumors, whereas intravenous injection into the lateral tail vein or internal carotid artery produces both amelanotic and melanotic foci in the lung and the brain respectively. We hypothesized that loss of adhesion in the circulation may contribute to the melanogenic phenotypes of cells. To test this, we used enforced suspension culture of K-1735 cells by consistent rotating culture of K-1735 cells. We found that the expression of the microphthalmia transcription factor (MITF) and melanin-stimulating hormone receptor (MSHR) were upregulated in cells growing in suspension and were accompanied by inhibitions of AKT and ERK, which were reversed in cells upon regrowth as an adherent monolayer. Inhibition of the AKT pathway was responsible for MITF induction by suspension culture. Stable expression of constitutively active AKT significantly repressed the melanogenesis of K-1735 cells injected via circulation. An amelanotic clone of K-1735 cells was resistant to suspension culture-induced MITF, although the inhibition of AKT pathway was intact. Collectively, these data suggest that the inhibition of AKT pathway due to loss of adhesion within the circulation renders a subpopulation of K-1735 cells to produce melanin.

Tumor cell detection in peripheral blood and bone marrow

PURPOSE OF REVIEW

Whether the occurrence of tumor cells in peripheral blood or bone marrow from patients with solid tumors is predictive for disease recurrence or of any other prognostic relevance remains unknown. This article reviews recently published results focusing on the various methods used, their correlations with clinical or biological parameters and their potential prognostic value.

RECENT FINDINGS

An increasing number of marker genes and different techniques, alone or in combinations, have been used for the detection of tumor cells in peripheral blood and bone marrow. Various results obtained are hardly comparable, most often due to the different methods in use. The frequency of circulating tumor cells in peripheral blood varied within a broad range and their clinical relevance appeared to be contradictory, at least in part. Disseminated tumor cells in bone marrow reached an independent prognostic value in breast cancer patients, but several investigations led to inconsistent correlations with clinical or prognostic criteria.

SUMMARY

Still many questions remain unanswered; hence, the detection of tumor cells in peripheral blood or bone marrow cannot yet be taken into account for therapeutic decisions.

Matrix metalloproteinase-13 expression is associated with bone marrow microinvolvement and prognosis in non-small cell lung cancer

Our previous study demonstrated that bone marrow microinvolvement (BMM) is an epiphenomenon of tumor progression rather than a prognostic factor in non-small cell lung cancer. We hypothesize that an increase in mesenchymal transition power in epithelial tumor cells by up-regulation of the matrix metalloproteinases (MMPs) may contribute to the existence of BMM and poorer prognosis. Hereby we conducted a prospective study of BMM and MMPs expression in a cohort of 57 non-small cell lung cancer patients. Bone aspirates were examined by immunohistochemical stains. Expressions of MMPs were checked by Human MMP primer set kit (Maxim Biotech, USA). Correlations between the MMPs expression and BMM, nodal metastasis, and prognosis were examined. Cox model analysis was used to identify independent prognostic factors. Though positive BMM was identified in 38 (66.7%) of the patients, none of the clinicopathological factors, including sex, age, cell types, tumor differentiation, nodal metastasis and TNM status of the tumor, was related to BMM by the tumor cells. Up-regulation was observed in a broad spectrum of MMPs with the exception of MMP-3. However, only MMP-13 expression correlated with the existence of BMM (p=0.006). Univariate analysis revealed MMP-3, MMP-7 and MMP-13 as negative prognostic factors. Cox model analysis revealed T-status, cell differentiation, and MMP-13 expression of the tumor as independent prognostic factors. The overall 5-year survival rate of the patients was 36.8%. The existence of BMM itself did not influence the prognosis (p=0.109), however, patients with positive MMP-13 expression (N=34) had a poorer 5-year survival rate of 26.5% (p=0.025). In summary, non-small cell lung cancer cells with MMP-13 expression, despite of BMM status, tend to shed and aggregate in the bone marrow, which is subsequently reflected in a poorer survival rate.

Critical evaluation of real-time reverse transcriptase-polymerase chain reaction for the quantitative detection of cytokeratin 20 mRNA in colorectal cancer patients

We evaluated the usefulness of cytokeratin 20 (CK20) mRNA expression in the quantitative detection of circulating tumor cells in the blood of patients with colorectal cancer (CRC). Blood samples from healthy volunteers (HVs; n = 37), patients with localized (n = 42) and metastatic colorectal cancer (n = 40), and patients with chronic inflammatory bowel disease (CID; n = 15) were examined. After immunomagnetic enrichment using microbeads against human epithelial antigen, total RNA was extracted, reverse transcribed, and analyzed by real-time reverse transcriptase-polymerase chain reaction using the LightCycler instrument. CK20 expression in peripheral blood was found in 46 of 82 (56%) patients with CRC, 8 of 37 (22%) HVs, and 9 of 15 (60%) patients with CID. Levels of CK20 mRNA were significantly higher in blood samples from CRC patients (median 681) than in blood samples from HVs (median 0) (P = 0.001), whereas no difference could be detected between patients with CRC and CID. Although the present technique could not distinguish CRC from CID, the method warrants further efforts to improve sample preparation and tumor cell enrichment, which may render real-time CK20 reverse transcriptase-polymerase chain reaction a feasible technique in identifying circulating tumor cells in peripheral blood of cancer patients.

Peritoneal carcinomatosis of colorectal origin: incidence and current treatment strategies

OBJECTIVE

To review the literature with regard to the incidence and prognostic significance of peritoneal seeding during surgery for primary colorectal cancer (CRC), the incidence of intraperitoneal recurrence of CRC, and the current treatment strategies of established PC of colorectal origin, with special focus on cytoreductive surgery and intraperitoneal chemotherapy (IPEC).

SUMMARY BACKGROUND DATA

Although hematogenous dissemination forms the greatest threat to patients with CRC, peritoneal carcinomatosis (PC), presumably arising from intraperitoneal seeding of cancer cells, is a relatively frequent event in patients with recurrent CRC.

METHODS

The PubMed and Medline literature databases were searched for pertinent publications regarding the incidence and prognostic significance of exfoliated tumor cells in the peritoneal cavity during curative surgery for primary CRC, the incidence of intraperitoneal recurrence of CRC, and the therapeutic results of systemic chemotherapy or cytoreductive surgery followed by IPEC.

RESULTS

The incidence of peritoneal seeding during potentially curative surgery for primary CRC, as reported in 12 patient series, varied widely, from 3% to 28%, which may be explained by differences in methods to detect tumor cells. PC is encountered in approximately 7% of patients at primary surgery, in approximately 4% to 19% of patients during follow-up after curative surgery, in up to 44% of patients with recurrent CRC who require relaparotomy, and in 40% to 80% of patients who succumb to CRC. The reported median survival after systemic 5-fluorouracil-based chemotherapy for PC varies from 5.2 to 12.6 months. Median survival after aggressive cytoreductive surgery followed by (hyperthermic) IPEC in selected patients, as reported in 16 patient series, tends to be better and varies from 12 to 32 months at the cost of morbidity and mortality rates of 14% to 55% and 0% to 19%, respectively. One randomized controlled trial has been published confirming the superiority of aggressive surgical cytoreduction and intraperitoneal chemotherapy over strictly palliative treatment.

CONCLUSIONS

Peritoneal seeding of cancer cells possibly leading to PC is a rather common phenomenon in patients with CRC. Cytoreductive surgery and adjuvant (hyperthermic) IPEC have been shown to be efficacious in selected patients and should therefore be considered in patients with resectable PC of colorectal origin.

Comparison of two methods for enumerating circulating tumor cells in carcinoma patients

BACKGROUND

Monitoring of circulating tumor cells (CTCs) in blood of carcinoma patients treated with novel compounds may be a measurement of treatment effectiveness. Before it can be used clinically, a reliably method is needed to enumerate CTCs. We compared two methods for CTC enumeration, OnkoQuick and the CellSearch system.

METHODS

We drew 22.5 ml of blood into three CellSave tubes from 15 healthy donors and 61 patients with metastatic carcinoma. After pooling, 15 ml was processed with OncoQuick and 7.5 ml with CellSearch.

RESULTS

With both methods no CTCs were found in healthy donors. At least one CTC was detected in 14 of 61 patients (23%) with OncoQuick and 33 of 61 patients (54%) with CellSearch (P < 0.0001). The number of CTCs detected was larger for CellSearch (mean 20 CTCs/7.5 ml of blood) than for OncoQuick (3 CTCs/7.5 ml; P < 0.0001).

CONCLUSION

The CellSearch system is a more accurate and sensitive method to enumerate CTCs. Further studies are warranted to evaluate CTC enumeration by the CellSearch system as a monitoring tool for the evaluation of the efficacy of novel anticancer agents.

Differential interaction of magnetic nanoparticles with tumor cells and peripheral blood cells

PURPOSE

The separation of tumor cells from healthy cells is a vital problem in oncology and hematology, especially from peripheral blood. Magnetic assisted cell sorting (MACS) is a possibility to fulfill these needs.

METHODS

Tumor cell lines and leukocytes from peripheral blood were incubated with carboxymethyl dextran-coated magnetic nanoparticles under various conditions and separated by MACS.

RESULTS

We studied the interaction of magnetic nanoparticles devoid of antibodies with healthy and tumor cells. The magnetic nanoparticles interact with tumor cells and leukocytes and are located predominantly within the cell cytoplasm. Incubation of cell culture cells with magnetic nanoparticles led to a labeling of these cells without reduced biological properties for at least 14 days. The interaction of the magnetic nanoparticles with cells depends on several factors. The ionic strength (osmolality) of the solvent plays an important role. We could show that an increase in osmolality led to a dramatic reduction of labeled leukocytes. Tumor cells, however, are mildly affected. This could be detected not only in pure cultures of tumor cells or leukocytes but also in mixed cell populations.

CONCLUSION

This observation gives us the opportunity to selectively label and separate tumor cells but not leukocytes from the peripheral blood.

Kallikreins as Markers of Disseminated Tumour Cells in Ovarian Cancer – A Pilot Study

BACKGROUND

Kallikreins are a family of secreted serine proteases, encoded by 15 genes which all localize in tandem on chromosome 19q13.4. Several members of this family have been previously associated with ovarian cancer. Kallikreins 6 (KLK6) and 10 (KLK10) are elevated in tumour cells, serum and ascites fluid of ovarian cancer patients and correlate with disease prognosis. Other kallikreins that have been related to ovarian cancer include KLK4, 5, 7, 8, 9, 11, 13, 14 and 15. We hypothesized that KLK6 and KLK10 can be utilized to monitor dissemination of ovarian cancer cells in blood and ascites fluid of ovarian cancer patients.

METHODS

RNA was isolated by immunomagnetic separation of cancer cells and was amplified by RT-PCR.

RESULTS

Screening for disseminated cancer cells in blood from 24 ovarian cancer patients, with RT-PCR for KLK6 mRNA, resulted in 75% positivity; however, this was not different from the positivity of normal controls. By utilizing KLK10 as a marker, the positivity of patients was 40% versus 20% of controls. Screening of ascites fluid of ovarian cancer patients revealed 90% positivity for KLK6 and KLK10 mRNA compared with 33% for other cancer types. Significant correlations were identified among mRNA of KLK4, 5, 6, 7, 8, 9, 10, 11, 13, 14 and 15 in cancer cells isolated from ascites fluid.

CONCLUSION

Kallikrein expression by ovarian cancer cells is not specific enough for detecting disseminated disease. Kallikrein expression may have some value for differentiating ovarian cancer from other types of cancer or from non-malignant diseases that lead to ascites accumulation.

MUC1 Mediates Transendothelial Migration in vitro by Ligating Endothelial Cell ICAM-1

MUC1 is a transmembrane glycoprotein expressed by normal breast epithelium and virtually all breast cancers. MUC1 is normally restricted to the apical surface of epithelia and loss of this polarized distribution in breast carcinomas is associated with lymph node metastasis. Our previous work found that MUC1 can bind intercellular adhesion molecule-1 (ICAM-1), mediating adhesion of breast cancer cells to a simulated blood vessel wall, and also triggering a calcium-based signal in the MUC1-bearing cells. It is possible that the depolarized membrane distribution of MUC1 in breast carcinomas may facilitate interactions with stromal/endothelial ICAM-1 leading to adhesion and subsequent migration through the vessel wall. In the current study, we provide evidence that ICAM-1 can influence the migration of cells that express endogenous or transfected MUC1. Migration across a gelatin-coated Transwell membrane could be increased in a step-wise manner by the sequential addition of ICAM-1-expressing cells (endothelial cells and fibroblasts), and ICAM-1-inducing inflammatory cytokines (tumour necrosis factor-alpha and interleukin-1 beta). Antibodies against MUC1 or ICAM-1, but not a control antibody, could abrogate migratory increases. Cells that did not express MUC1 were unresponsive to ICAM-1. Our current findings build on our earlier work, by suggesting that the end result of the MUC1/ICAM-1-mediated cell-cell adhesion and calcium-based signal is migration. This has implications for the exit of circulating tumour cells from the vasculature, as well as tumour cell migration through fibroblast-containing stroma underlying the endothelial wall.

Rationnels de la chirurgie oncologique au sein d’un traitement multimodal des cancers

The permanent dissemination of circulating cancer cells from infiltrative cancers renders the notion of localized cancer obsolete. This raises the question of the role of treatments such as surgery which are localized in time and space. Moreover, it is now proven that surgery increases the number of circulating cancers cells and produces transient immunodepression which promotes cancer cell implantation. In addition, the healing process stimulates growth factors, which also act on tumor growth. In spite of these deleterious effects, oncological surgery remains an important tool in the anti-cancer armamentarium. Optimal cytoreductive surgery facilitates the effect of adjuvant treatments by eliminating the vascular sanctuaries present in the center of any large tumor and by its effect as a striking-force very localized in time and space. Oncological surgery must evolve as an integrative part of our improving understanding of tumor biology, taking into account recent developments in functional imaging, genomics and proteomics. Modalities and timing must be reconsidered for oncological surgery to play its proper role as one of the many components contributing to multimodal cancer treatments. New modalities will undoubtedly be necessary with the development of future technologies.

Detection of disseminated tumour cells in the liver of cancer patients

AIMS

The liver is a common site of metastasis from a variety of solid malignancies. This is due to disseminated tumour cells (DTC) that have spread prior to or during surgery from the primary carcinoma. This article gives a short overview of the data published on the detection of DTC in the liver and describes the commonly used detection methods and respective markers.

METHODS

A literature survey was performed in public medical databases comprising the last 15 years with focus on DTC detection in liver tissue of cancer patients.

KEY FINDINGS

Although the liver is a preferred site of metastasis, only a few studies have analysed the DTC incidence in inconspicuous liver tissue. The available reports include only patients with pancreatic and colorectal carcinomas. In patients with pancreatic cancer the DTC incidence varied from 5 to 76%. No follow-up data has been reported so far. In patients with colorectal carcinoma hepatic DTC were found in 5-69% of cases. A negative prognostic influence of hepatic DTC was reported in all but one studies with follow-up information.

CONCLUSIONS

The detection of DTC in the liver can contribute to identify patients with increased risk who could benefit from an intensified follow-up or new treatment strategies.

The use of a panel of monoclonal antibodies to enrich circulating breast cancer cells facilitates their detection

OBJECTIVE

Metastatic relapse due to early dissemination of tumor cells is associated with poor prognosis for epithelial cancer. The molecular characterization of these single cells or cell clusters that have evaded the tumor is indispensable in order to evaluate their biological behavior and metastatic potential. In this study, we established a sensitive immunomagnetic method to isolate rare cancer cells from peripheral blood based on their expression of epithelial- or tumor-cell-specific markers.

METHODS

Low numbers of cells of breast cancer cell lines - ZR-75-1, MCF-7, HBL-100 - were spiked into peripheral blood specimens of healthy volunteers. Enrichment of tumor cells was performed using either pre-coupled HEA and/or ErbB2 microbeads or a mixture of three monoclonal antibodies against HEA, ErbB2 and EGFR.

RESULTS

The recovery rate of spiked tumor cells correlated with the expression of the corresponding antigens. ZR-75-1 cells high expressing all three genes could be isolated to 60-71%. MCF-7 cells, which hardly express EGFR, showed a significant better recovery by using two specific antibodies in combination (50-68%) than one pre-coupled bead alone (31-42%). HBL-100 cells little expressing HEA could not be isolated with HEA microbeads and only to 27% in combination with ErbB2 beads -in contrast the use of an antibody cocktail achieved 38%.

CONCLUSION

As tumor and epithelial specific cell marker antigens are expressed differently in disseminated tumor cells, the immunomagnetic enrichment from peripheral blood is most robust and reliable when using a combination of specific antibodies compared to single antibodies.

Staging of colorectal cancer: past, present, and future

Since the inception of staging for colorectal cancer (CRC), anatomic extent of disease has provided a solid foundation for predicting prognosis and guiding treatment in patients with CRC. However, the rapid advances in biologic and genetic technology have provided many new possibilities for enhancing the predictive power of the staging system. In this article, we will briefly discuss the history of CRC staging, identify the current parameters for American Joint Committee on Cancer staging including recent changes, and offer guidelines for future staging modifications. Although anatomic parameters have served us well for many years, their continued use as sole contributors to CRC staging is questionable. Staging in the future is likely to be a complicated combination of anatomic and biologic markers used together in mathematic modeling to group patients into prognostic risk groups, which can be used to guide tailored therapy.

Molecular detection of clinical colorectal cancer metastasis: how should multiple markers be put to use?

BACKGROUND AND AIMS

Up to 45% of colorectal cancer (CRC) patients will develop local recurrence or metastasis following curative resection. The latter is due to cells shed from the primary carcinoma prior to or during surgery. The aim of this study was to contribute toward a "rational"-approach for detecting these disseminated tumor cells (DTC) using a combination of independent markers and detection methods.

PATIENTS/METHODS

Liver, lymph node, and bone marrow samples from 246 CRC patients were screened for DTC using three markers: mutated K-ras was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and cytokeratin 20 (CK20) and guanylylcyclase C (GCC), indicating circulating epithelial cells, were tracked by nested reverse-transcription (RT) PCR.

RESULTS

The rate of positive findings of the individual markers (CK20: 88%; GCC: 88%; K-ras: 67%) and their combinations (88-50%) was significantly higher in biopsies from liver metastases than in liver samples from patients without evident distant metastasis (M0; p<0.03). The detection rate of individual markers (except GCC) was also significantly elevated in inconspicuous liver tissue adjacent to metastasis compared with specimens from M0 patients. When using the concomitant detection of all three markers as criterion for DTC in the liver of M0 patients, however, no patient was DTC-positive. Therefore, the concomitant presence of the two CEC markers (CK20 plus GCC) and/or the presence of mutated K-ras were preferred for a combined evaluation, which resulted in a 24% detection rate for biopsies from both liver lobes. This translates into 39% of M0 patients with at least one positive liver biopsy.

CONCLUSION

Our results suggest that the concomitant detection of CK20 plus GCC and/or the presence of mutated K-ras are a rational approach for tracking CEC/DTC in CRC patients.

Preclinical studies on detection of circulating melanoma cells in patients: telomerase as a recognition marker of malignancy

Preclinical studies based on a "simulation design", were performed with cultured melanoma cells prelabeled with 51Cr, added to normal blood and subjected to separation and recognition steps. Mononuclear cells (MNC) were isolated on ficollhypaque gradient, and melanoma cells were separated from lymphocytes using anti-CD45 immunomagnetic beads. Malignant cells were then recognized by measuring telomerase activity (TRAP and TRAP-ELISA assays). It was found that: (a)recovery of prelabeled cells present in MNC did not exceed 75%; (b) further recovery of prelabeled cells after separation from lymphocytes did not exceed 68%. Therefore, the overall recovery of prelabeled cells did not exceed 48%; (c) the entire procedure was able to reliably detect as few as 30 malignant cells added to normal blood, providing a telomerase signal significantly higher than that found in absence of melanoma cells. These results furnish the technical bases for developing a tumor detection assay in the blood of melanoma patients.