RT-PCR-based detection of occult disseminated tumor cells in peripheral blood and bone marrow of patients with solid tumors. An overview

Circulating Biomarkers in the Management of Breast Cancer

Circulating biomarkers have become a promising modality in the management of many cancers. Similarly, in breast cancer, circulatory biomarkers are useful, non-invasive methods in the diagnosis, prognostication, and evaluation of response to treatment. Invasive surgical biopsies can be potentially replaced by “liquid biopsy,” which involves analysing circulatory biomarkers that may reveal features of primary and metastatic disease. Therefore, providing an insight into the cancer biology can be utilised to monitor treatment response, treatment-induced adaptation and tumour and disease progression through non-invasive means. The objective of this review is to provide an overview of the current status of the circulating biomarkers highlighting their promising impact on the management of patients with breast cancer.

Detection of Circulating Tumor Cells in Resectable Pancreatic Ductal Adenocarcinoma: A Prospective Evaluation as a Prognostic Marker

Circulating tumor cells (CTCs) are useful biomarkers of many solid tumors, but are infrequently detected in early stage pancreatic ductal adenocarcinomas (PDACs). The first drainage of pancreatic venous blood flow come to portal vein and pass through the liver, and they finally go out for peripheral blood. We thought that comparing CTCs from portal vein and peripheral blood could enable us to understand the clinical meaning of CTCs from each different site in PDACs. Therefore, we aimed to determine 1) whether CTCs could be reliably identified in early stages (operable) of PDACs, 2) if there are any differences in the detected number of CTC in portal vein blood and peripheral blood, and 3) whether CTCs can be sensitive biomarkers for the prognosis of resectable PDAC patients. Newly diagnosed PDAC patients who underwent operation with curative intention between 2013 and 2015 were prospectively enrolled. Blood draws from portal and peripheral vein ran through the microfabricated porous filter, and anti-epithelial cell adhesion molecule (EpCAM) and anti-Plectin-1 antibodies were used for CTC identification. Baseline clinical characteristics, tumor characteristics, treatment, and clinical outcomes were assessed. The clinical stages of the 32 enrolled patients were as follows: IA/IB 1 (3.1%); IIA 9 (28.1%); IIB 17 (53.1%); III 5 (15.6%). Twenty-seven patients (84.4%) received R0 resection, while five patients (15.6%) received R1 resection. EpCAM+ CTCs were detected in 20 portal blood (62.5%) and 22 peripheral blood (68.8%). Plectin-1+ CTCs were identified in 14 portal blood (43.8%) and 16 peripheral blood (50%). Plectin-1-expressing CTCs were picked from CTC platform (microfabricated porous filter) and we could find out all KRAS mutation. Patients with detectable EpCAM+ CTC less than one in peripheral blood showed longer overall survival (OS) compared to patients with detectable CTCs more than one (35.5 months vs. 16.0 months). EpCAM and Plectin-1 successfully identified CTCs at the early stage of PDACs. Also, the number of CTCs could be a prognostic marker for survival in resectable PDACs.

Potential use of aptamers for diagnosis and treatment of pancreatic cancer

Pancreatic cancer (PC) is highly malignant with a low 5-year survival rate. PC currently does not have good early diagnostic markers and responses poorly to chemotherapeutic drugs. The search for better biomarkers and developing more effective chemotherapy are important ways to improve the healthcare of PC patients. Aptamers are single-stranded nucleic acids with high binding affinity and specificity to target molecules. Many aptamers against different forms of cancer including PC have been selected for both diagnostic and therapeutic use. Aptamers can work as ligands to distinguish tumour cells from normal cells. Using cells as selection targets, the obtained aptamers have been used to discover new cancer biomarkers after identification of the binding target. Aptamers have been shown to have antagonists effect on cancer cell proliferation, apoptosis, and metastasis. In addition, aptamers have been used as carriers to deliver therapeutic agents to selectively kill PC cells. This review summarises the potential use of aptamers in the diagnosis and treatment of PC.

Prostate stem cell antigen mRNA in blood is a predictor of survival after radical prostatectomy in patients with high-risk prostate cancer

Objectives

To investigate whether the preoperative detection of prostate stem cell antigen (PSCA) mRNA in blood has predictive value for biochemical recurrence, overall survival, and cancer-specific survival after radical prostatectomy in patients with high-risk prostate cancer.

Results

Median age was 67 years (interquartile range: 63-71), and median follow-up was 41 months (interquartile range: 25–65). PSCA mRNA was detected in 151 patients (51.1%). Biochemical recurrence was developed in 101 patients (34.2%), and all-cause mortality and prostate cancer-specific mortality occurred in 17 (5.7%) and 8 (2.7%) patients, respectively. Kaplan–Meier analysis revealed significant differences in biochemical recurrence, overall survival, and cancer-specific survival according to PSCA mRNA positivity. Cox regression hazards model analysis showed that PSCA mRNA positivity was an independent predictor of biochemical recurrence, overall survival, and cancer-specific survival.

Conclusions

PSCA mRNA in the peripheral blood was related to poor prognosis. Detection of PSCA mRNA by polymerase chain reaction in peripheral blood can be used to predict survival after radical prostatectomy in patients with high-risk prostate cancer. Future study with larger cohort and long-term follow-up is required to confirm this finding.

Materials and methods

A total of 295 patients with high-risk prostate cancer scheduled to undergo radical prostatectomy were prospectively enrolled from 2008 to 2016. Nested reverse transcription polymerase chain reaction was used to detect cells with PSCA mRNA in peripheral blood. The predicting ability of PSCA mRNA positivity for biochemical recurrence, overall survival, and cancer-specific survival after radical prostatectomy was evaluated.

Capturing Cancer: Emerging Microfluidic Technologies for the Capture and Characterization of Circulating Tumor Cells

Circulating tumor cells (CTCs) escape from primary or metastatic lesions and enter into circulation, carrying significant information of cancer progression and metastasis. Capture of CTCs from the bloodstream and the characterization of these cells hold great significance for the detection, characterization, and monitoring of cancer. Despite the urgent need from clinics, it remains a major challenge to capture and retain these rare cells from human blood with high specificity and yield. Recent exciting advances in micro/nanotechnology, microfluidics, and materials science have enable versatile, robust, and efficient cell isolation and processing through the development of new micro/nanoengineered devices and biomaterials. This review provides a summary of recent progress along this direction, with a focus on emerging methods for CTC capture and processing, and their application in cancer research. Furthermore, classical as well as emerging cellular characterization methods are reviewed to reveal the role of CTCs in cancer progression and metastasis, and hypotheses are proposed in regard to the potential emerging research directions most desired in CTC-related cancer research.

SELEX aptamer used as a probe to detect circulating tumor cells in peripheral blood of pancreatic cancer patients

Many studies have shown that the quantity and dynamics of circulating tumor cells (CTCs) in peripheral blood of patients afflicted with solid tumours have great relevance in therapeutic efficacy and prognosis. Different methods based on various strategies have been developed to isolate and identify CTCs, but their efficacy needs to be improved because of the rarity and complexity of CTCs. This study was designed to examine the possibility of using a SELEX aptamer (BC-15) as a probe to identify rare CTCs out of background nucleated cells. Aptamer BC-15 was selected from a random oligonucleotide library screened against human breast cancer tissue. Fluorescence staining showed that BC-15 had a high affinity for nuclei of human cancer cell lines of various origins as well as CTCs isolated from pancreatic cancer patients, whereas its binding capacity for non-tumor breast epithelial cells and leukocytes was almost undetectable. BC-15⁺/CD45^- cells in cancer patient blood were also found to be cytokeratins 18-positive and aneuploid by immunofluorescence staining and fluorescent in situ hybridization, respectively. Finally, the aptamer method was compared with the well-established anti-cytokeratin method using 15 pancreatic cancer patient blood samples, and enumeration indicated no difference between these two methods. Our study establishes a novel way to identify CTCs by using a synthetic aptamer probe. This new approach is comparable with the anti-cytokeratin-based CTC identification method.

Detection of Circulating Tumour Cells from Blood of Breast Cancer Patients via RT-qPCR

Breast cancer is still the most frequent cause of cancer-related death in women worldwide. Often death is not caused only by the primary tumour itself, but also by metastatic lesions. Today it is largely accepted, that these remote metastases arise out of cells, which detach from the primary tumour, enter circulation, settle down at secondary sites in the body and are called Circulating Tumour Cells (CTCs). The occurrence of such minimal residual diseases in the blood of breast cancer patients is mostly linked to a worse prognosis for therapy outcome and overall survival. Due to their very low frequency, the detection of CTCs is, still a technical challenge. RT-qPCR as a highly sensitive method could be an approach for CTC-detection from peripheral blood of breast cancer patients. This assumption is based on the fact that CTCs are of epithelial origin and therefore express a different gene panel than surrounding blood cells. For the technical approach it is necessary to identify appropriate marker genes and to correlate their gene expression levels to the number of tumour cells within a sample in an in vitro approach. After that, samples from adjuvant and metastatic patients can be analysed. This approach may lead to new concepts in diagnosis and treatment.

Isolation and characterization of circulating tumor cells in prostate cancer

Circulating tumor cells (CTCs) are tumor cells found in the peripheral blood that putatively originate from established sites of malignancy and likely have metastatic potential. Analysis of CTCs has demonstrated promise as a prognostic marker as well as a source of identifying potential targets for novel therapeutics. Isolation and characterization of these cells for study, however, remain challenging owing to their rarity in comparison with other cellular components of the peripheral blood. Several techniques that exploit the unique biochemical properties of CTCs have been developed to facilitate their isolation. Positive selection of CTCs has been achieved using microfluidic surfaces coated with antibodies against epithelial cell markers or tumor-specific antigens such as EpCAM or prostate-specific membrane antigen (PSMA). Following isolation, characterization of CTCs may help guide clinical decision making. For instance, molecular and genetic characterization may shed light on the development of chemotherapy resistance and mechanisms of metastasis without the need for a tissue biopsy. This paper will review novel isolation techniques to capture CTCs from patients with advanced prostate cancer, as well as efforts to characterize the CTCs. We will also review how these analyzes can assist in clinical decision making.

CONCLUSION

The study of CTCs provides insight into the molecular biology of tumors of prostate origin that will eventually guide the development of tailored therapeutics. These advances are predicated on high yield and accurate isolation techniques that exploit the unique biochemical features of these cells.

Staying alive: metabolic adaptations to quiescence

Quiescence is a state of reversible cell cycle arrest that can grant protection against many environmental insults. In some systems, cellular quiescence is associated with a low metabolic state characterized by a decrease in glucose uptake and glycolysis, reduced translation rates and activation of autophagy as a means to provide nutrients for survival. For cells in multiple different quiescence model systems, including Saccharomyces cerevisiae, mammalian lymphocytes and hematopoietic stem cells, the PI3Kinase/TOR signaling pathway helps to integrate information about nutrient availability with cell growth rates. Quiescence signals often inactivate the TOR kinase, resulting in reduced cell growth and biosynthesis. However, quiescence is not always associated with reduced metabolism; it is also possible to achieve a state of cellular quiescence in which glucose uptake, glycolysis and flux through central carbon metabolism are not reduced. In this review, we compare and contrast the metabolic changes that occur with quiescence in different model systems.

OSNA-based novel molecular testing for lymph node metastases in colorectal cancer patients: results from a multicenter clinical performance study in Japan

BACKGROUND

Lymph node (LN) metastasis in colorectal cancer (CRC) is a critical factor in making accurate prognoses and therapeutic decisions. This study evaluated the clinical performance of the one-step nucleic acid amplification (OSNA) assay in accurately diagnosing LN metastases in CRC patients through the specific detection of cytokeratin 19 mRNA levels in LNs.

METHODS

The OSNA assay was performed on 121 LNs dissected from early-stage CRC patients (pStage 0 or I) or from patients with benign colorectal disease (study 1). Separately, 385 LNs were dissected from 85 CRC patients (any stage); the OSNA assay was performed on half of each LN, and the results were compared with histopathological examination in 2-mm intervals of the other LN half (study 2).

RESULTS

In study 1, all 121 histopathologically negative LNs were also negative by the OSNA assay (concordance rate for metastasis negative: 1.0, 95% confidence interval [95% CI]: 0.976-1.0). In study 2, the concordance rate between the OSNA assay and the 2-mm-interval histopathological examination was 0.971 (95% CI: 0.950-0.984), with a sensitivity of 0.952 (95% CI: 0.881-0.987) and a specificity of 0.977 (95% CI: 0.953-0.991).

CONCLUSIONS

The OSNA assay provided a judgment performance equivalent to a 2-mm-interval histopathological examination, a more detailed assay than the common pathological examination. Therefore, the OSNA assay is considered a new molecular examination method for the diagnosis of LN metastases in CRC patients in clinical settings.

Prostate specific membrane antigen mRNA in blood as a potential predictor of biochemical recurrence after radical prostatectomy

We investigated whether the detection of prostate specific membrane antigen (PSMA) in blood preoperatively has predictive value for biochemical recurrence (BCR) after radical prostatectomy in patients with prostate cancer. All 134 patients scheduled to receive radical prostatectomy for prostate cancer were prospectively enrolled. The authors used nested reverse transcriptase-polymerase chain reaction (RT-PCR) assay to detect PSMA mRNA-bearing cells in peripheral blood, and analyzed the ability of PSMA mRNA positivity to predict BCR after surgery. PSMA-mRNA was detected in 24 (17.9%) patients by RT-PCR. Over a median follow-up of 20 months (range, 3 to 46 months), BCR developed in 15 patients (11.2%) and median time to BCR was 7 months (range, 3 to 25 months). Kaplan-Meier analysis revealed a significant difference between those positive or negative for PSMA in terms of recurrence-free actuarial probability (log rank P=0.0039). Multivariate analysis showed that positivity for PSMA mRNA (HR: 3.697, 95% CI 1.285-10.634, P=0.015) and a biopsy Gleason score of >or=7 (HR: 4.500, 95% CI 1.419-14.274, P=0.011) were independent preoperative predictors of BCR. The presence of PSMA mRNA in peripheral blood can be used to predict BCR after radical prostatectomy.

Marker expression in circulating cancer cells of pancreatic cancer patients

BACKGROUND

By the time patients are diagnosed with pancreatic cancer, circulating cancer cells probably exist. Therefore, the detection of pancreatic cancer cells in the peripheral circulation could be used to diagnose early pancreatic cancer, which would otherwise not be detected by current imaging methods.

METHODS

The expression levels of h-TERT, CK20, CEA, and C-MET were detected in a model of circulating micrometastasis in pancreatic cancer that were enriched using immune-magnetic separation of the circulating cancer cells. The sensitivity and specificity of the measurements were evaluated. The expression of the above genes was measured in the circulating cancer cells of pancreatic cancer patients. We compared their expression rate in pancreatic cancer patients at different stages to screen for the indicator with highest sensitivity and specificity for the detection of circulating pancreatic cancer cells.

RESULTS

Immuno-magnetic nanoparticles combined with RT-PCR enabled the detection of one tumor cell per 1×10(7) peripheral blood mononuclear cells. The positive expression rates of C-MET, h-TERT, CK20, and CEA in the pancreatic cancer group were 80% (20/25), 100% (25/25), 84% (21/25), and 80% (20/25), respectively, while in the benign disease control group the rates were 0% (0/15), 0% (0/15), 6.77% (1/15), and 0% (0/15), respectively. There was a significant difference in the positive expression rate between the two groups (P<0.05). The specificity of h-TERT, CEA, and C-MET was higher than that of CK20. The positive expression rate of the four genes was not related to gender, age, tumor size, CA 19-9, or CEA serum levels (P>0.05). However, the positive expression of C-MET, CK20, and CEA closely correlated with tumor stage (P<0.05). Immuno-magnetic nanoparticles combined with RT-PCR were specific and sensitive for the detection of circulating cancer cells.

CONCLUSIONS

The positive expression of C-MET, h-TERT, CK20, and CEA in the circulation of pancreatic patients could be used as an indicator for circulating cancer cells. The combined detection of the four genes improved the specificity and sensitivity to 100%, which may be attributable to the use of immuno-magnetic separation and enrichment of the circulating pancreatic cancer cells. Our results suggest the clinical utility of this approach.

Gene expression of circulating tumour cells in breast cancer patients

Background

The diagnostic tools to predict the prognosis in patients suffering from breast cancer (BC) need further improvements. New technological achievements like the gene profiling of circulating tumour cells (CTC) could help identify new prognostic markers in the clinical setting. Furthermore, gene expression patterns of CTC might provide important informations on the mechanisms of tumour cell metastasation.

Materials and methods

We performed realtime-PCR and multiplex-PCR analyses following immunomagnetic separation of CTC. Peripheral blood (PB) samples of 63 patients with breast cancer of various stages were analyzed and compared to a control group of 14 healthy individuals. After reverse-transcription, we performed multiplex PCR using primers for the genes ga733.3, muc-1 and c-erbB2. Mammaglobin1, spdef and c-erbB2 were analyzed applying realtime-PCR.

Results

ga733.2 overexpression was found in 12.7% of breast cancer cases, muc-1 in 15.9%, mgb1 in 9.1% and spdef in 12.1%. In this study, c-erbB2 did not show any significant correlation to BC, possibly due to a highly ambient expression. Besides single gene analyses, gene profiles were additionally evaluated. Highly significant correlations to BC were found in single gene analyses of ga733.2 and muc-1 and in gene profile analyses of ga733.3*muc-1 and GA7 ga733.3*muc-1*mgb1*spdef.

Conclusion

Our study reveals that the single genes ga733.3, muc-1 and the gene profiles ga733.3*muc-1 and ga733.3*3muc-1*mgb1*spdef can serve as markers for the detection of CTC in BC. The multigene analyses found highly positive levels in BC patients. Our study indicates that not single gene analyses but subtle patterns of multiple genes lead to rising accuracy and low loss of specificity in detection of breast cancer cases.

Cancer dormancy: lessons from a B cell lymphoma and adenocarcinoma of the prostate

Cancer dormancy delineates a situation in which residual tumor cells persist in a patient with no apparent clinical symptoms. Although the precise mechanisms underlying cancer dormancy have not been explained, experimental models have provided some insights into the factors that might be involved in the induction and maintenance of a tumor dormant state. The authors of the present chapter studied a murine B cell lymphoma that can be made dormant when interacting with antibodies directed against the idiotype on its immunoglobulin Ig receptor. This experimental model of antibody-induced dormancy enabled the isolation and characterization of dormant lymphoma cells. The results indicated that anti-Ig antibodies activate growth-inhibiting signals that induced cycle arrest and apoptosis. This process appeared to be balanced by the growth of the tumor cells such that the tumor did not expand. In contrast, antibodies against HER-2expressed on prostate adenocarcinoma (PAC) cells were not growth inhibitory. However, an immunotoxin (IT) prepared by conjugating HER-2 to the A-chain of ricin (RTA) was internalized by PAC cells, followed by induction of cycle arrest and apoptotic death. Infusion of HER-2-specific IT into PAC-bearing immunodeficient mice did not eradicate the tumor but retained it dormant over an extended period of time. Hence, certain aspects of signaling receptors expressed on cancer can be manipulated by antibodies to induce and maintain a tumor dormant state.

Circulating tumor cells: a useful predictor of treatment efficacy in metastatic breast cancer

PURPOSE

Five or more circulating tumor cells (CTCs) per 7.5 mL of blood predicts for poorer progression-free survival (PFS) in patients with metastatic breast cancer (MBC). We conducted a prospective study to demonstrate that CTC results correlate strongly with radiographic disease progression at the time of and in advance of imaging.

PATIENTS AND METHODS

Serial CTC levels were obtained in patients starting a new treatment regimen for progressive, radiographically measurable MBC. Peripheral blood was collected for CTC enumeration at baseline and at 3- to 4-week intervals. Clinical outcomes were based on radiographic studies performed in 9- to 12-week intervals.

RESULTS

Sixty-eight patients were evaluable for the CTC-imaging correlations, and 74 patients were evaluable for the PFS analysis. Median follow-up was 13.3 months. A statistically significant correlation was demonstrated between CTC levels and radiographic disease progression in patients receiving chemotherapy or endocrine therapy. This correlation applied to CTC results obtained at the time of imaging (odds ratio [OR], 6.3), 3 to 5 weeks before imaging (OR, 3.1), and 7 to 9 weeks before imaging (OR, 4.9). Results from analyses stratified by type of therapy remained statistically significant. Shorter PFS was observed for patients with five or more CTCs at 3 to 5 weeks and at 7 to 9 weeks after the start of treatment.

CONCLUSION

We provide, to our knowledge, the first evidence of a strong correlation between CTC results and radiographic disease progression in patients receiving chemotherapy or endocrine therapy for MBC. These findings support the role of CTC enumeration as an adjunct to standard methods of monitoring disease status in MBC.

The urokinase receptor (u-PAR)--a link between tumor cell dormancy and minimal residual disease in bone marrow?

Minimal residual disease (MRD) is hypothesized to be the major cause of tumor recurrence and metastasis even years and decades after primary cancer diagnosis and curative solid tumor resection. In these patients disseminated tumor cells reflecting MRD can be detected in the bone marrow years after treatment. It is to be assumed that genetic determinants and a complex interplay between the disseminated tumor cells and their microenvironment in the bone marrow are responsible for tumor cell dormancy and the final reactivation towards metastasis. The urokinase receptor (u-PAR), a critical regulator of invasion, intravasation, and metastasis, is found to be a key player in regulating the shift between single cell tumor dormancy and proliferation. This has mainly been attributed to a regulation by u-PAR of integrins, and the ability of the latter to propagate signals from fibronectin through the EGF-receptor, ERK, and p38 signaling. Interestingly, u-PAR is found in disseminated tumor cells in the bone marrow of solid cancer patients, and is associated with the expansion of these cells and clinical prognosis. Here we summarize and discuss findings on disseminated tumor cells in the bone marrow, MRD and the role of u-PAR in tumor biology, especially focusing on its specific role in providing a switch between tumor cell proliferation and dormancy. Finally, we discuss the hypothesis that u-PAR might be an essential molecule in bone marrow disseminated tumor cells for long-term survival during dormancy, and/or reactivation of their proliferation years after primary treatment.

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.

Reverse transcriptase-polymerase chain reaction and immunohistochemical studies for detection of prostate stem cell antigen expression in prostate cancer: potential value in molecular staging of prostate cancer

OBJECTIVES

To determine whether detection of prostate stem cell antigen (PSCA) expression has potential for molecular staging in prostate cancer (PCa), we examined the relationship between established prognostic factors, biochemical recurrence (BCR) and PSCA expression.

METHODS

This study was comprised of 66 patients who underwent radical prostatectomy for the treatment of PCa. We employed reverse transcriptase-polymerase chain reaction (RT-PCR) to detect PSCA mRNA-bearing cells in peripheral blood, and used immunohistochemical (IHC) techniques to identify PSCA protein expression in microarrayed tissue.

RESULTS

PSCA-mRNA was detected in the peripheral blood of nine (13.6%) patients by RT-PCR. Whereas 3.2% of patients with low-grade disease were PSCA positive, 22.9% of patients with high-grade disease were PSCA positive (P = 0.030). There was also a significant relationship of RT-PCR PSCA positivity to whether or not the tumor was confined to the prostate. Whereas only 6.8% of patients with prostate-confined disease were RT-PCR PSCA positive, 27.3% of extraprostatic diseases were RT-PCR PSCA positive (P = 0.022). IHC studies of tumor tissue microarrays demonstrated that PSCA expression intensity was related to both extraprostatic extension (P = 0.014) and positive surgical margin (P = 0.053). Whereas 23.8% of prostate-confined diseases were high intensity, 54.5% of extraprostatic diseases were high intensity. BCR developed in seven patients (10.6%) during the follow-up period (median, 16.2 months; range, 9-25 months). Prognostic factors increasing the risk of BCR included: seminal vesicle invasion (P = 0.004), extraprostatic disease (P = 0.019), lymphovascular emboli (P = 0.036) and RT-PCR PSCA positivity (P = 0.004) in univariate analysis.

CONCLUSIONS

We were able to detect PSCA mRNA-bearing cells in peripheral blood by RT-PCR, and also identify PSCA protein expression in tumors by IHC analysis of tissue microarrays. RT-PCR PSCA positivity in peripheral blood may be a potential modality for molecular staging of PCa.

Isolated tumour cells in blood and E-cadherin expression in oesophageal squamous cell cancer

BACKGROUND

Patients with oesophageal squamous cell carcinoma have a high rate of recurrence, even after curative resection. The aim of this study was to examine the correlation between the presence of isolated tumour cells (ITCs) in the blood and recurrence, and between the presence of ITCs and E-cadherin expression in the primary tumour in these patients.

METHODS

Blood samples obtained immediately before and after resection in 125 patients with oesophageal squamous cell carcinoma were examined by real-time reverse transcription-polymerase chain reaction using carcinoembryonic antigen mRNA. Blood samples from 28 healthy volunteers and 42 patients with benign diseases were used as controls.

RESULTS

Seventy-seven patients (61.6 per cent) were ITC positive. ITC positivity correlated significantly with tumour depth, lymph node metastasis, stage, lymphatic invasion and venous invasion. Multivariable analysis revealed that tumour depth and ITC positivity were independent factors for a shortened haematogenous disease-free interval. A significant correlation was found between ITC positivity and reduced E-cadherin expression in the primary tumour (P < 0.001). ITC-positive patients with preserved E-cadherin expression had a longer disease-free interval (P = 0.016), haematogenous disease-free interval (P = 0.020) and overall survival (P = 0.004) than those with reduced E-cadherin expression.

CONCLUSION

Examination of ITCs in the blood is useful for predicting haematogenous recurrence in patients with oesophageal squamous cell carcinoma.

Recent advances in the detection of bone marrow micrometastases: A promising area for research or just another false hope? A review of the literature

The presence of early disseminated tumor cells (DTC), otherwise termed micrometastases or minimal residual disease, in the bone marrow (BM), or other secondary compartments, such as the blood and the lymph nodes, is the main reason for recurrence of patients with early stage epithelial cancers after "curative" resection of the primary tumor. There is increasing evidence, that the detection of DTC in BM aspirates may provide additional and independent prognostic information and aid in the stratification of these patients for adjuvant clinical treatment. However, the clinical relevance of micrometastases has not yet been firmly established. In addition, the molecular events and interactions that prevail in early metastatic disease and determine the formation or not of overt metastases remain poorly understood. The methods currently used for the detection of micrometastatic cells include extremely sensitive immunocytochemical and molecular assays, often in conjunction with enrichment techniques for the purification of tumor cells and additional increase of their sensitivity. Nevertheless, the specificity of these methods is mostly inadequate. After the impressive advances of molecular cytogenetics, a highly accurate and global assessment of the genetic status of tumors is now possible. Therefore, the greatest challenge of our time is the application of these novel technologies for the clarification of the key molecular events that initiate metastatic spread. This will further enable us to identify the highly specific and sensitive diagnostic and prognostic markers as well as the therapeutic targets which are so urgently needed.

Combination analysis of a whole lymph node by one-step nucleic acid amplification and histology for intraoperative detection of micrometastasis

OBJECTIVE

The aim was to develop a more efficient molecular detection system than histological examination (HE) for lymph node (LN) metastasis.

METHODS

Cytokeratin (CK) 19 mRNA copy numbers of 5 colon carcinoma cell lines (Lovo, DLD1, WiDr, Colo201 and Colo320) were calculated and compared by one-step nucleic acid amplification (OSNA) and conventional real-time reverse-transcription polymerase chain reaction (RT-PCR). Then, 91 LN submitted for HE from 6 patients with advanced colorectal adenocarcinoma and 64 LN submitted for frozen diagnosis from 47 patients with different malignancies were examined by OSNA and HE.

RESULTS

CK19 mRNA copy numbers of all but Colo320 cells detected by OSNA were within double of those detected by RT-PCR. The least cell count of Lovo cells detected at one reaction (2 microl) by OSNA was calculated as 0.8 cells. Carcinoma metastasis showing either HE+ or OSNA+ was detected in 7.9% of the LN from advanced colorectal adenocarcinomas and in 30.0% of the LN for frozen diagnosis from different malignancies; HE-/OSNA+ metastasis was detected in 4.8 and 4.0%, respectively. OSNA analysis of 1 LN could be completed within 40 min.

CONCLUSION

A combined analysis of LN by HE and OSNA could increase the sensitivity for detecting micrometastasis during surgery.

Specific detection of cytokeratin 20-positive cells in blood of colorectal and breast cancer patients by a high sensitivity real-time reverse transcriptase-polymerase chain reaction method

A real-time reverse transcriptase-polymerase chain reaction (RT-PCR) method for detection of cytokeratin 20-positive cells in blood characterized by two novel features was developed and tested on 99 patients with colorectal cancer, 110 with breast cancer, and 150 healthy subjects. To optimize the specificity and sensitivity of the method, two novel features were used. First, a primer overlapping two adjacent exons was generated to inhibit nonspecific amplification both in healthy donors and cancer patients; second, a non-end-point first-round amplification was used to increase sensitivity. The number of first-round cycles was chosen to reach the highest level of sensitivity while conserving quantitative characteristics. PCR efficiency increased from 88.9% in single-round RT-PCR to 99.0% in nested real-time RT-PCR. To establish sensitivity and specificity of the method, HT29 cells were serially diluted with normal blood. Detection limit improved from 100 HT29 cells (single-round RT-PCR) to 1 to 10 cells (nested real-time RT-PCR) per 3 ml of whole blood. None of the healthy subjects was positive, whereas 22 and 29% of all colorectal and breast cancer patients, respectively, had cytokeratin 20 cell equivalents in blood. The association between cytokeratin 20 cell equivalents and metastasis was statistically significant for breast (P = 0.026) but not colorectal cancer patients (P = 0.361). Negativity of all 150 healthy controls examined confers diagnostic potential to the method.

Quantitative PSA mRNA determination in blood: a biochemical tool for scoring localized prostate cancer

OBJECTIVES

Our aim was to verify whether the quantitative determination of PSA mRNA in circulating cells is helpful in diagnosing and scoring localized prostate cancer (PC).

DESIGN AND METHODS

The study included 145 patients with benign prostatic hyperplasia (BPH), 138 with localized PC and 28 healthy controls (CS). PSA cDNA was amplified by real-time PCR from circulating mononuclear cells. Serum total and free PSA were determined. Prostate cancers were histologically scored according to the Gleason criteria.

RESULTS

The most sensitive index of PC was tPSA (70%), and the most specific was f/t PSA (80%). High PSA mRNA was found more frequently in PC patients with poorly differentiated (23.1%) than in those with well (4.5%) or moderately (4.3%) differentiated tumors.

CONCLUSIONS

tPSA and f/t PSA are the best available tools for discriminating between localized PC and BPH. The quantitative assessment of PSA mRNA in blood might be helpful in the biochemical grading of prostate cancer.

Assessment of anti-metastatic drug efficacy via localization and quantification of ex vivo murine bone tumor load using high-throughput MRI T1 parametric analysis

MRI methods show great utility for assessing the growth of tumors metastasized to bone in clinical studies. However, preclinical MRI methods in rodents do not translate well to high-throughput studies of bone tumors, especially for early-stage tumors typically examined in pharmaceutical discovery efforts. To overcome these limitations, an ex vivo MR T1 parametric mapping method has been developed to measure metastasized bone tumor load in murine long bones. This method has been used to assess the therapeutic efficacy of SU11248, a multi-targeted inhibitor with demonstrated anti-tumor activity and reduction of bone loss, in a murine model of metastasized breast tumor cells. The results show precise localizations of relative tumor loads within the bones and reveal significant differences between SU11248-treated and untreated animal groups. The procedures were optimized for simultaneous, high-throughput parallel image acquisition of MRI data for 30 samples and included an automated segmentation method for image processing. The merits of this T1 parametric mapping method are compared with clinical T1-weighted MRI methods, histopathology and bioluminescence imaging of the same murine bone tumor model.

Circulating tumor cells in patients with breast cancer dormancy

PURPOSE

The purpose of this study was to test the hypothesis that circulating tumor cells (CTCs) are present in patients many years after mastectomy without evidence of disease and that these CTCs are shed from persisting tumor in patients with breast cancer dormancy.

EXPERIMENTAL DESIGN

We searched for CTCs in 36 dormancy candidate patients and 26 age-matched controls using stringent criteria for cytomorphology, immunophenotype, and aneusomy.

RESULTS

Thirteen of 36 dormancy candidates, 7 to 22 years after mastectomy and without evidence of clinical disease, had CTCs, usually on more than one occasion. Only 1 of 26 controls had a possible CTC (no aneusomy). The statistical difference of these two distributions was significant (exact P = 0.0043). The CTCs in patients whose primary breast cancer was just removed had a half-life measured in 1 to 2.4 hours.

CONCLUSIONS

The CTCs that are dying must be replenished every few hours by replicating tumor cells somewhere in the tissues. Hence, there appears to be a balance between tumor replication and cell death for as long as 22 years in dormancy candidates. We conclude that this is one mechanism underlying tumor dormancy.

Quantification of colorectal cancer micrometastases in lymph nodes by nested and real-time reverse transcriptase-PCR analysis for carcinoembryonic antigen

PURPOSE

Reverse-transcriptase PCR (RT-PCR) assays for carcinoembryonic antigen (CEA) have been described to identify lymph node micrometastases. These assays are not quantitative and can be confounded by false-positive results. The purpose of this study was to determine whether quantification of CEA in lymph nodes could more readily identify clinically relevant groups.

EXPERIMENTAL DESIGN

Specimens included 400 lymph nodes from 64 patients undergoing colon resections. Specimens were tested by immunohistochemistry and by RT-PCR using nested primers for CEA. Specimens from 59 patients that were positive by nested RT-PCR were further quantified by detection of CEA mRNA fluorescence increase at a threshold PCR cycle.

RESULTS

CEA was detected by nested RT-PCR analysis in 4 of 34 (12%) nodes of nonneoplastic disease, 2 of 13 (15%) nodes from T(1)N(0) patients, 32 of 81 (40%) nodes of T(2)N(0) patients, 49 of 109 (45%) nodes from T(3)N0 patients, and 92 of 163 (56%) nodes from T(1-4)N(1-2) patients. The overall presence of any RT-PCR-detectable CEA in nodes did not differentiate patient groups. Immunohistochemistry was positive in nodes from 7% of T(3)N(0) patients and 100% of T(1-3)N(1-2) patients. CEA quantification revealed that 0 of 7 patients with nonneoplastic disease and 2 of 17 (12%) patients with stage I T(1-2)N(0) cancers had one or more lymph nodes with >/=1.0 x 10(2) CEA transcripts per sample. In contrast, 4 of 13 (31%) patients with stage II T(3)N(0) cancer and 10 of 22 (45%) stage III patients with known metastases had lymph nodes with >/=1.0 x 10(2) CEA transcripts.

CONCLUSIONS

These data suggest that quantification of CEA levels in lymph nodes may more accurately identify patients at risk for cancer recurrence than does routine nested RT-PCR or immunohistochemistry.

Real-time RT-PCR correlates with immunocytochemistry for the detection of disseminated epithelial cells in bone marrow aspirates of patients with breast cancer

Real-time reverse transcriptase–polymerase chain reaction (RT–PCR) is a technique with the potential of improving the quantification of disseminated epithelial cells (DEC) in haematological tissues due to its exquisite sensitivity. This sensitivity may lead to false positivity. Immunocytochemistry (ICC) is regarded as the standard methodology to diagnose DEC. In this study, detection with ICC was compared with quantitative real-time RT–PCR for CK-19 and mammaglobin (hMAM) mRNA in bone marrow (BM) of patients with metastatic breast cancer (MBC). Bone marrow was aspirated from 14 control patients and from 29 patients with MBC. Mononuclear cells (MNC) were isolated. Immunostaining was carried out with the Epimet kit. Quantitative PCR was performed on the ABI Prism 7700. The CK-19 and hMAM mRNA quantities were normalised against β-Actin and calculated relative to a calibrator sample (relative gene expression). All controls were negative by ICC and for hMAM expression measured by RT–PCR, whereas the median RGE value for CK-19 was 0.57. For the MBC patients, the median RGE for hMAM was 0 and 10 out of 25 (40%) tested positive. Median RGE for CK-19 was 2.9 and 20 out of 25 (80%) tested positive. With ICC, the median value was 1 stained cell per sample, and 15 out of 24 (62%) samples were positive. A correlation was observed between CK-19 and hMAM expression (r=0.7; P=0.0003), and between hMAM expression and ICC (r=0.6; P=0.003). CK-19 expression and ICC (r=0.9; P<0.0001) showed the strongest correlation. Reverse transcriptase–polymerase chain reaction for CK-19 resulted in a higher number of positive BM samples of patients with MBC than ICC. Since an excellent correlation is observed between ICC and RT–PCR, and RT–PCR is probably more sensitive with the advantage of being less observer dependent and thus also more easy to automate, we consider our quantitative real-time RT–PCR method as validated for the detection of DEC in the bone marrow of breast cancer patients.

NB. Mammaglobin as a novel breast cancer biomarker: multigene reverse transcription-PCR assay and sandwich ELISA

BACKGROUND

The aim of this study was to examine the potential usefulness of a mammaglobin multigene reverse transcription-PCR (RT-PCR) assay and a mammaglobin sandwich ELISA as diagnostic tools in breast cancer.

METHODS

We studied peripheral blood samples from 147 untreated Senegalese women with biopsy-confirmed breast cancer and gathered patient information regarding demographic, and clinical staging of disease. The samples were tested for mammaglobin and three breast cancer-associated gene transcripts by a multigene real-time RT-PCR assay and for serum mammaglobin protein by a sandwich ELISA assay.

RESULTS

In 77% of the breast cancer blood samples, a positive signal was obtained in the multigene RT-PCR assay detecting mammaglobin and three complementary transcribed genes. Fifty samples from healthy female donors tested negative. Significant correlations were found between mammaglobin protein in serum, presence of mammaglobin mRNA-expressing cells in blood, stage of disease, and tumor size. Circulating mammaglobin protein was detected in 68% of the breast cancer sera, and was increased in 38% in comparison with a mixed control population. The RT-PCR assay and the ELISA for mammaglobin produced a combined sensitivity of 84% and specificity of 97%.

CONCLUSION

The ELISA and RT-PCR for mammaglobin and mammaglobin-producing cells could be valuable tools for diagnosis and prognosis of breast cancer.

Prognostic Value of Combined “Triple”-Reverse Transcription-PCR Analysis for Prostate-Specific Antigen, Human Kallikrein 2, and Prostate-Specific Membrane Antigen mRNA in Peripheral Blood and Lymph Nodes of Prostate Cancer Patients

PURPOSE

We present the largest study of both peripheral blood and lymph node samples examining the utility of reverse transcription-polymerase chain reaction (RT-PCR) for established molecular markers as a diagnostic tool in the molecular staging of prostate cancer patients undergoing radical prostatectomy.

EXPERIMENTAL DESIGN

Peripheral blood from 358 patients was obtained before radical prostatectomy. Corresponding obturatory lymph node samples were collected from 153 of these patients. Nested RT-PCR for prostate-specific antigen (PSA), human kallikrein 2 (hK2), and prostate-specific membrane antigen (PSMA) were performed on cDNA from peripheral blood. The lymph node cDNA was analyzed for PSA und hK2 expression.

RESULTS

RT-PCR in peripheral blood was positive in 124 (34.6%) of 358 samples for PSA, 215 (60.1%) of 358 for PSMA, and 97 (27.1%) of 358 for hK2. Comparison of positive RT-PCR rates of pT(2) and pT(3) tumors in corresponding peripheral blood for PSA, PSMA, and hK2 were 31.9 and 40.0%, 58.8 and 62.5%, and 26.9 and 27.5%, respectively. Histopathologically, cancer-free lymph node samples were positive in RT-PCR for PSA and hK2 in 70 (49.6%) of 141 and 89 (63.2%) of 141 of cases. All histologically positive lymph node samples (n = 12, pN+) were positive for PSA RT-PCR. PSA RT-PCR alone, as well as combined PSA/PSMA RT-PCR evaluation, in peripheral blood showed a significant association with grading. PSA RT-PCR lymph node-negative samples were significantly less likely positive in their corresponding peripheral blood RT-PCR sample.

CONCLUSIONS

Although the preoperative PSA RT-PCR in peripheral blood correlated with the grading of prostate cancer, no combination of RT-PCR results using "triple" markers (PSA, hK2, PSMA) in peripheral blood and/or lymph nodes yielded additional preoperative staging information.

The detection of circulating breast cancer cells in blood

At present, sampling of the lymph nodes or bone marrow for the detection of regions of metastatic disease in patients with breast cancer can only be undertaken at the time of initial diagnosis and surgery. However, the sampling of these tissues and the methods used are inaccurate, time consuming, and cannot be used for easy routine screening to determine disease recurrence and response to treatment. Because of the problems encountered with current methods and tissues sampled at the time of breast cancer diagnosis, this review discusses the urgent requirement for and potential development of a quick, simple, and accurate diagnostic test utilising the haematogenous system, a source of circulating tumour cells in patients with breast cancer, and highly sensitive molecular biological techniques, such as reverse transcription polymerase chain reaction. In addition, this review also highlights potential problems that may be encountered and should be avoided when devising such a test.

The quantification of angiogenesis in relation to metastasis in oral cancer: a review

Tumours need vessels to grow into clinically significant dimensions, and to metastasize. Varying results have been reported for the relation between angiogenic activity in oral carcinomas, and the occurrence of metastasis. Quantification of microvessels in tissue sections is mostly used to assess angiogenesis, but appears subject to biases as reflected in contradicting reports. Especially the choice of immunohistochemical staining technique appears pivotal. Although microvessel density measurements (MVD) appear promising for other tumour types, in oral carcinomas no unambiguous relation could be established. Furthermore, MVD assessment appears more elaborate than expected. New, more time efficient techniques may replace MVD as we know it.

Quantitative real-time RT-PCR for detection of disseminated tumor cells in peripheral blood of patients with colorectal cancer using different mRNA markers

The detection of disseminated tumor cells in peripheral blood from colorectal cancer patients by RT-PCR could be an attractive method for selecting patients for adjuvant therapy. We here report on real-time RT-PCR assays (LightCycler) to quantitate potential mRNA markers. We investigated specimens from colon carcinoma and normal colon mucosa tissues, cell lines, blood samples from 129 patients with colorectal cancer (all stages) and 58 reference blood samples (healthy donors, persons suffering from inflammatory bowel or infectious diseases). The expression profile in tissues showed high values for CEA and CK20, whereas in cell lines ProtM was predominant. All markers were detected in reference and patient blood samples (ProtM, 22, 17%; CEA, 84, 86%; CK20, 85, 88%). After quantitative analysis, the definition of cutoff values for each marker and the combination of markers, 13% of patients were judged to have elevated marker concentrations in their blood, from which only 6 had values significantly differing from cutoff value. There were no differences between stages of disease. In the case of 19 patients, investigated prior to and 1 week after surgery, 2 samples revealed a significant postoperative increase in CEA or CK20 mRNA concentration. In spite of high expression levels in tissues and cell lines, we were not able to differentiate satisfyingly mRNA markers originating from tumor cells and those from illegitimate transcription in hematopoetic cells in blood. We conclude that either copy numbers of analyzed markers in circulating tumor cells are not sufficient for detection or, more probably, peripheral blood is not a suitable compartment for detection of tumor cells in colorectal cancer.

Diagnostic potential of circulating nucleic acids for oncology

Approximately a decade ago, the PCR-based detection of extracellular, tumor-derived circulating nucleic acids in the plasma and serum of cancer patients was introduced as a noninvasive tool for cancer detection. Although the test criteria, sensitivity and specificity, compare favorably with conventional diagnostic measures, until now the methodical ponderousness of circulating nucleic acids in plasma and serum analysis prevented it from becoming a clinical routine application. However, with rapid technical improvement towards automated high-throughput platforms, it is expected that the next 5 years will see circulating nucleic acids in plasma and serum analysis integrated into the initial diagnosis and follow-up monitoring of cancer patients. The hope is that the use of circulating nucleic acids in plasma and serum as a molecular tumor marker and potential profiling tool will finally translate into a longer survival and better quality of life for cancer patients.

DNA methylation, a biomarker for colorectal cancer: implications for screening and pathological utility

Currently up to one-third of colorectal cancer patients present with locally advanced or metastatic disease that precludes a surgical cure. Performance limitations and low uptake of current screening tools have fueled research to develop minimally invasive approaches that can detect early-stage neoplasms. The observation that altered DNA can be amplified from the stool or circulation has stimulated research on its use as a biomarker of occult neoplasia. De novo methylation of CpG islands 5' to certain tumor suppressor genes has been associated with epigenetic silencing. At certain loci this phenomenon is specific for neoplastic populations, and it is frequently detected at early stages in colorectal tumorigenesis. Accordingly, hypermethylation events have been proposed by researchers as ideal targets for the basis of a screening panel to detect peripheral tumor DNA. This critique reviews research findings on the use of epigenetic biomarkers in screening for occult neoplasia. In addition, the authors consider the pathological utility of epigenetic testing in refining tumor staging and predicting disease recurrence.

Altered fractionation and combined radio-chemotherapy approaches: pioneering new opportunities in head and neck oncology

Squamous cell carcinoma of the head and neck (HNSCC) are increasingly treated by multimodality approaches combining surgery, radiotherapy and chemotherapy. Randomised controlled trials have demonstrated major improvements in loco-regional tumour control from altered fractionation radiotherapy, accelerated fractionation and hyperfractionation, as compared with conventional fractionation. This experience is summarised, and the limit as to how far these modifications can be taken is discussed. It is emphasised that radiation fractionation will need to be optimised separately in multimodality strategies. Combined chemotherapy and radiotherapy has also been shown in phase III trials to produce an improved survival and an improved disease control. Chemotherapy may be given as neoadjuvant, concurrent or adjuvant treatment and the biological rationales for each of these, and the data supporting them, are reviewed. Although, large meta-analyses have shown concurrent chemoradiation to be the most effective, there is still a strong rationale for trying to develop neoadjuvant and adjuvant schedules. New, more active drugs may be important in this context. As therapy is becoming more intense, a careful recording and reporting of treatment-related morbidity is a crucial element in estimating the therapeutic gain from competing therapeutic management strategies. Development of non-cytostatic drugs and individualization of therapy using molecular prognostic markers are exciting areas of research with a great potential for improving therapy in the next decade and these are briefly discussed. Finally, a number of avenues for further research are identified.

Detection of tumor specific gene expression in bone marrow and peripheral blood from patients with small cell lung carcinoma

BACKGROUND

Small cell lung carcinoma (SCLC) has the propensity to grow rapidly and metastasize extensively. Detection of micro-dissemination of SCLC may have clinical relevance. For its detection, tumor-specific gene expressions were examined in peripheral blood and bone marrow aspirate from patients with SCLC.

METHODS

Expression of prepro-gastrin-releasing peptide (preproGRP), neuromedin B receptor (NMB-R) and gastrin-releasing peptide receptor (GRP-R) were examined by reverse transcriptase polymerase chain reaction (RT-PCR) in peripheral blood and bone marrow aspirate from 40 untreated patients with SCLC. Control samples consisted of peripheral blood samples from 5 patients with nonsmall cell lung cancer (NSCLC) and 20 healthy volunteers.

RESULTS

Positive rates of preproGRP, NMB-R, and GRP-R in bone marrow aspirate of patients with SCLC were 23% (9/40), 8% (3/40), and 10% (4/40), respectively. Those rates in peripheral blood were 11% (4/38), 5% (2/38), and 29% (11/38), respectively. Although GRP-R expression was detected in patients with NSCLC and in healthy volunteers, preproGRP and NMB-R expressions were not detected in patients with NSCLC and in healthy volunteers. All three gene expressions in bone marrow were more frequently observed in patients with bone marrow metastasis, accessed by biopsy, than in patients without. PreproGRP gene expression in bone marrow was also more frequent in patients with bone metastasis, accessed by bone scintigram, than in patients without, and was related to poorer survival.

CONCLUSIONS

Micro-dissemination of SCLC was detectable by RT-PCR of preproGRP and NMB-R, both specific for SCLC. These gene expressions in bone marrow may be related to disease extent and prognosis.

Targeting lethal minimal residual disease in small cell lung cancer

In the last three decades, treatment for small cell lung cancer has improved with advances in chemotherapy and radiotherapy. Almost all patients respond initially to standard chemotherapy, and some patients with limited stage disease are cured with the combination of chemotherapy and thoracic irradiation. Nonetheless, the majority of patients will experience lethal relapse from chemotherapy-resistant micrometastatic disease, and this has resulted in poor long-term survival for most patients. Addressing the problem of relapse requires unique approaches to eliminating minimal residual disease. This review will focus on the detection of minimal residual disease as well as strategies with which to treat it, including matrix metalloproteinase inhibitors, tyrosine kinase inhibitors, and vaccine therapy.

Minimal residual disease in gastric cancer: evidence of an independent prognostic relevance of urokinase receptor expression by disseminated tumor cells in the bone marrow

PURPOSE

To study the invasion-related molecule urokinase-type plasminogen activator receptor (u-PAR) expressed by disseminated tumor cells as a biologic predictor of poor survival in a large prospective series of patients with gastric cancer.

PATIENTS AND METHODS

In 156 gastric cancer patients (prospective series), disseminated tumor cells in the bone marrow and the u-PAR expressed by these tumor cells were determined by cytokeratin (CK) 18 immunocytochemistry and u-PAR/CK18 double immunocytochemistry.

RESULTS

In contrast to the mere detection of disseminated tumor cells at primary surgery, the additional evidence of u-PAR on these cells correlated significantly with pathologic T stage (P =.0474) and the expression of u-PAR (P =.0093) and plasminogen-activator inhibitor 1 (P =.0145) in the primary tumor (immunohistochemistry, chi(2)). Kaplan-Meier analysis revealed no association with prognosis for the mere detection of disseminated tumor cells. In contrast, a significant association was seen between detection of u-PAR on these cells and shorter disease-free (P <.0001) and overall survival (P <.0001). Multivariate analysis revealed that u-PAR on disseminated tumor cells at the time of primary surgery is an independent prognostic factor for disease-free (95% confidence interval [CI], 1.72 to 3.21; P =.024) and overall survival (P =.0049; relative risk, 2.89; 95% CI, 1.92 to 4.30).

CONCLUSION

This is the first large study to show that u-PAR, detected on disseminated tumor cells in the bone marrow, is an independent prognostic parameter in gastric cancer, in contrast to the mere detection of minimal residual disease (MRD). u-PAR may be a promising marker to define a critical subpopulation of disseminated tumor cells and a target to eliminate MRD. Molecular phenotyping of MRD is critical for defining its individual clinical relevance.

Identification of an invasive, N-cadherin-expressing epithelial cell type in endometriosis using a new cell culture model

Studies of molecular, cellular, and pathophysiological parameters in endometriosis are primarily hampered by a lack of in vitro model systems, such as endometriotic cell lines. To overcome this we successfully established cell lines from peritoneal endometriotic biopsies and characterized them at the molecular and cellular level. Two types of cells could be transformed: one exhibiting stromal cell features (cytokeratin/E-cadherin-negative), the other epithelial-like (cytokeratin-positive/E-cadherin-negative, invasive in vitro). Using a Matrigel assay the epithelial-like cell lines proved as invasive as metastatic carcinoma cells, possibly through the influence of N-cadherin implicated as a path-finding cadherin allowing cellular invasion and migration in both normal and pathophysiological processes. Our results support the idea that endometriosis, although not neoplastic, shares features with malignant cells and that metastasis in endometriosis may include mechanisms proposed for micrometastasis in cancer. Thus our cell lines will not only be useful tools for analyzing molecular and cellular events relating to endometriosis, but may also represent a paradigm for invasion and metastasis in general.

Detection and clinical significance of occult tumour cells in colorectal cancer

BACKGROUND

A variety of techniques have been employed for the detection of occult tumour cells in the blood, bone marrow and lymph nodes of patients with colorectal cancer. This review examines the methods used, results obtained and the clinical significance of studies in this field.

METHODS

A Medline literature search was performed using the terms colorectal cancer, minimal residual disease, micrometastasis, polymerase chain reaction, reverse transcriptase polymerase chain reaction and immunocytochemistry; further references were obtained from key articles.

RESULTS

Immunocytochemical examination of bone marrow is the benchmark for detecting clinically significant occult disease. Larger standardized studies are required to confirm the prognostic significance of molecular assays for the detection of tumour cells in blood and bone marrow. The prognostic significance of lymph node tumour cells detected by either immunohistochemical or molecular methods awaits further affirmation.

CONCLUSION

Standardization of terminology and techniques used, combined with large prospective clinical studies, is required if detection of occult residual disease is to become a prognostic marker for recurrence in colorectal cancer.

Pathological serosa and node-based classification accurately predicts gastric cancer recurrence risk and outcome, and determines potential and limitation of a Japanese-style extensive surgery for Western patients: a prospective with quality control 10-year follow-up study

UICC classification accurately predicts overall survival but not recurrence-risk. We report here data of overall and first site-specific recurrence following curative surgery useful for the development of recurrence-oriented preventive target therapies. Patients who underwent resection for gastric cancer were stratified according to curability of surgery [curative (R0) vs non-curative resection], extent of surgery [limited (D1) vs extended (D2) node dissection] and pathological nodal/serosal status. The intent-to-treat principle, log-rank test and Cox regression analysis were used for statistical analysis of time-to-event (recurrence, death) endpoints. Curative resection only produced a chance of cure whereas survival was very poor following non-curative resection (P < 0.0001). For D2 R0 subgroup of patients, a pathological serosa and a node state-based classification into three groups, proved to be of clinical implication. Risk of recurrence after a median follow-up of 92 months was low among patients with both serosa and node-negative cancer (first group; 11%), moderate among those with either serosa or node-positive cancer (second group; 53%) and very high among those with both serosa and node-positive cancer (third group; 83%). In multivariate analysis, the relative risks of recurrence and death from gastric cancer among patients in the second and third groups, as compared to those in the first, were 7.07 (95% CI, 2.36-21.17; P = 0.0002) and 16.19 (95% CI, 5.76-45.54; P < 0.0001) respectively. First site-specific recurrence analysis revealed: low rate of loco-regional recurrence alone (12%), serosa state determinant factor of the site-recurrence (peritoneal for serosa-positive and haematogenous for serosa-negative cancers) and dramatic increase of all types of recurrence by the presence of nodal metastases. Our findings demonstrate that a pathological serosa- and node-based classification is very simple and predicts accurately site-specific recurrence-risks. Furthermore they reveal that risk of recurrence following curative D2 surgery alone is low for serosa- and node-negative cancers, but very high in serosa- and node-positive cancers suggesting the need for new therapeutic strategies in this subgroup of patients.