Diagnosis of renal cancer by molecular urinalysis

Nanomaterials for Fluorescent Detection of Hemoglobin

Hemoglobin plays a vital role in a series of biological activities. Abnormal levels of hemoglobin in blood are associated with many clinical diseases. Therefore, development of simple and accurate methods for sensing hemoglobin is of considerable significance. The blowout advancement in nanotechnology has urged the use of different types of fluorescent nanomaterials for hemoglobin assay. The past decades have witnessed the rapid progress of fluorescent nanosensors for hemoglobin assay. In the review, the sensing principles of fluorescent nanomaterials for sensing hemoglobin were briefly discussed. The advances of fluorescent nanosensors for detection of hemoglobin were further highlighted. And the sensing performance of fluorescent nanosensors versus traditional detection approaches was compared. Finally, the challenges and future directions of fluorescent nanomaterials for detection of hemoglobin are discussed. The review will arouse much more attention to the construction of hemoglobin sensors and facilitate rapid development of fluorescent nanosensors of hemoglobin.

Circulating Cell-Free DNA in Renal Cell Carcinoma: The New Era of Precision Medicine

Simple Summary

Early diagnosis of renal cell carcinoma (RCC) is challenging and typically incidental. Currently, several therapeutic strategies are used for the treatment; however, no established predictive biomarker has been established yet, and the optimal treatment choice and sequence of use remain unclear. Moreover, the recurrence occurs in about one-third of patients after tumor resection. Although several prognostic classification systems have been proposed, most of them showed only limited potential in recurrence prediction. Therefore, identifying simple, reliable, and easily accessible biomarkers to anticipate the diagnosis, effectively evaluate the risk of relapse, and predict the response to the therapeutic regimens is an unmet clinical need. Circulating cell-free DNA (cfDNA), released from cancer cells into the bloodstream, was shown to be a non-invasive, viable, inexpensive method to diagnose and monitor several solid malignancies, designed as a potential blood RCC biomarker. This review aims to summarize the state of the art of the current genetic and epigenetic techniques of plasma and serum cfDNA detection and outline the potential application of liquid biopsy in RCC.

Abstract

Tumor biopsy is still the gold standard for diagnosing and prognosis renal cell carcinoma (RCC). However, its invasiveness, costs, and inability to accurately picture tumor heterogeneity represent major limitations to this procedure. Analysis of circulating cell-free DNA (cfDNA) is a non-invasive cost-effective technique that has the potential to ease cancer detection and prognosis. In particular, a growing body of evidence suggests that cfDNA could be a complementary tool to identify and prognosticate RCC while providing contemporary mutational profiling of the tumor. Further, recent research highlighted the role of cfDNA methylation profiling as a novel method for cancer detection and tissue-origin identification. This review synthesizes current knowledge on the diagnostic, prognostic, and predictive applications of cfDNA in RCC, with a specific focus on the potential role of cell-free methylated DNA (cfMeDNA).

Trans-Renal Cell-Free Tumor DNA for Urine-Based Liquid Biopsy of Cancer

Cancer biomarkers are a promising tool for cancer detection, personalization of therapy, and monitoring of treatment response or recurrence. “Liquid biopsy” commonly refers to minimally invasive or non-invasive sampling of a bodily fluid (i.e., blood, urine, saliva) for detection of cancer biomarkers such as circulating tumor cells or cell-free tumor DNA (ctDNA). These methods offer a means to collect frequent tumor assessments without needing surgical biopsies. Despite much progress with blood-based liquid biopsy approaches, there are limitations—including the limited amount of blood that can be drawn from a person and challenges with collecting blood samples at frequent intervals to capture ctDNA biomarker kinetics. These limitations are important because ctDNA is present at extremely low levels in plasma and there is evidence that measuring ctDNA biomarker kinetics over time can be useful for clinical prediction. Additionally, blood-based assays require access to trained phlebotomists and often a trip to a healthcare facility. In contrast, urine is a body fluid that can be self-collected from a patient’s home, at frequent intervals, and mailed to a laboratory for analysis. Multiple reports indicate that fragments of ctDNA pass from the bloodstream through the kidney’s glomerular filtration system into the urine, where they are known as trans-renal ctDNA (TR-ctDNA). Accumulating studies indicate that the limitations of blood based ctDNA approaches for cancer can be overcome by measuring TR-ctDNA. Here, we review current knowledge about TR-ctDNA in urine as a cancer biomarker approach, and discuss its clinical potential and open questions in this research field.

Fluorescence photobleaching of urine for improved signal to noise ratio of the Raman signal - An exploratory study

Urine analysis is an important clinical test routinely performed in pathology labs for disease diagnosis and prognosis. In recent years, near-infrared Raman spectroscopy has drawn considerable attention for urine analysis as it can provide rapid, reliable, and reagent-free analysis of urine samples. However, one important practical problem encountered in such Raman measurements is the orders of magnitude stronger spectral background preventing one to utilize the full dynamic range of the detector which is required for the measurement of Raman signal with good signal-to-noise ratio (SNR). We report here the results of an exploratory study carried out on human urine samples to show that the photobleaching, which is a major disadvantage during the fluorescence measurement, could be utilized for suppressing the measured background to improve the SNR of the Raman peaks. It was found that once the photobleaching reached its plateau, there were improvements by ~67% and ~47% in the SNR and the signal to background ratio (SBR), respectively, of the Raman signals as compared to the spectra measured at the start of acquisition. Further, the reduced background also allowed us to utilize the full dynamic range of the detector at increased integration time without saturating the detector indicating the possibility of obtaining an improved detection limit.

Assessment of somatic mutations in urine and plasma of Wilms tumor patients

Tumor DNA has been detected in body fluids of cancer patients. Somatic tumor mutations are being used as biomarkers in body fluids to monitor chemotherapy response as a minimally invasive tool. In this study, we evaluated the potential of tracking somatic mutations in free DNA of plasma and urine collected from Wilms tumor (WT) patients for monitoring treatment response. Wilms tumor is a pediatric renal tumor resulting from cell differentiation errors during nephrogenesis. Its mutational repertoire is not completely defined. Thus, for identifying somatic mutations from tumor tissue DNA, we screened matched tumor/leukocyte DNAs using either a panel containing 16 WT‐associated genes or whole‐exome sequencing (WES). The identified somatic tumor mutations were tracked in urine and plasma DNA collected before, during and after treatment. At least one somatic mutation was identified in five out of six WT tissue samples analyzed. Somatic mutations were detected in body fluids before treatment in all five patients (three patients in urine, three in plasma, and one in both body fluids). In all patients, a decrease of the variant allele fraction of somatic mutations was observed in body fluids during neoadjuvant chemotherapy. Interestingly, the persistence of somatic mutations in body fluids was in accordance with clinical parameters. For one patient who progressed to death, it persisted in high levels in serial body fluid samples during treatment. For three patients without disease progression, somatic mutations were not consistently detected in samples throughout monitoring. For one patient with bilateral disease, a somatic mutation was detected at low levels with no support of clinical manifestation. Our results demonstrated the potential of tracking somatic mutations in urine and plasma DNA as a minimally invasive tool for monitoring WT patients. Additional investigation is needed to check the clinical value of insistent somatic mutations in body fluids.

Biocatalytically Initiated Precipitation Atom Transfer Radical Polymerization (ATRP) as a Quantitative Method for Hemoglobin Detection in Biological Fluids

The hemoglobin content of blood is an important health indicator, and the presence of microscopic amounts of hemoglobin in places where it normally does not occur, e.g. in blood plasma or in urine, is a sign of diseases such as hemolytic anemia or urinary tract infections. Thus, methods to detect and quantify hemoglobin are important for clinical laboratories, blood banks, and for point-of-care diagnostics. The precipitation polymerization of N-isopropylacrylamide by hemoglobin-catalyzed atom transfer radical polymerization (ATRP) is used as an assay for hemoglobin quantification relying on the formation of turbidity as a simple optical read-out. Dose-response curves for pure hemoglobin and for hemoglobin in blood plasma, in urine, in erythrocytes, and in full blood are obtained. Turbidity formation increases with the concentration of hemoglobin. Concentrations of hemoglobin as low as 6.45 × 10^-3 mg mL^-1 in solution, 4.88 × 10^-1 mg mL^-1 in plasma, and 1.65 × 10^-1 mg mL^-1 in urine could be detected, which is below the clinically relevant concentrations in the respective body fluids. Total hemoglobin in full blood is also accurately determined. The reaction can be regarded as a polymerization-based signal amplification for the sensing of hemoglobin, as the analyte catalyzes the formation of radicals which add many monomer units into detectable polymer chains. While most established hemoglobin tests involve the use of highly toxic reagents such as potassium cyanide, the polymerization-based test uses simple and stable organic reagents. Thus, it is an environmentally friendlier alternative to established chemical assays for hemoglobin.

The pre-analytical phase of the liquid biopsy

The term 'liquid biopsy', introduced in 2013 in reference to the analysis of circulating tumour cells (CTCs) in cancer patients, was extended to cell-free nucleic acids (cfNAs) circulating in blood and other body fluids. CTCs and cfNAs are now considered diagnostic and prognostic markers, used as surrogate materials for the molecular characterisation of solid tumours, in particular for research on tumour-specific or actionable somatic mutations. Molecular characterisation of cfNAs and CTCs (especially at the single cell level) is technically challenging, requiring highly sensitive and specific methods and/or multi-step processes. The analysis of the liquid biopsy relies on a plethora of methods whose standardisation cannot be accomplished without disclosing criticisms related to the pre-analytical phase. Thus, pre-analytical factors potentially influencing downstream cellular and molecular analyses must be considered in order to translate the liquid biopsy approach into clinical practice. The present review summarises the most recent reports in this field, discussing the main pre-analytical aspects related to CTCs, cfNAs and exosomes in blood samples for liquid biopsy analysis. A short discussion on non-blood liquid biopsy samples is also included.

[Progress in Non-invasive Detection of EGFR Mutation in Non-small Cell Lung Cancer]

在过去的十年里，癌症患者的管理模式已经逐渐转向为基于分子突变检测的个体化模式。表皮生长因子受体（epidermal growth factor receptor, EGFR）基因突变是非小细胞肺癌（non-small cell lung cancer, NSCLC）的重要驱动因素，针对EGFR的靶向治疗和传统化疗相比，显示出显著的安全性和有效性。然而，并不是所有的EGFR突变患者都可接受EGFR靶向治疗，不同的突变类型往往预示着不同的临床结局，如敏感性突变EGFR 19-Del、L858R和耐药性突变20ins。此外，如今已经开发出第三代TKI药物Osimertinib（AZD9291）和Rociletinib（CO-1686）可使因EGFR T790M突变，导致初代TKI耐药的患者进一步获益。因此，治疗前了解患者EGFR突变状态，治疗过程中持续监测耐药基因EGFR T790M突变情况，对NSCLC患者靶向药物的管理有着重要的意义。最近几年来，“液体活检”技术得到快速的发展，让我们看到采用非侵入性方法以实时监测耐药性突变成为现实的可能。在本综述中，我们回顾了NSCLC中检测EGFR突变的多种非侵入性检测技术在不同液体样本的临床应用。

Non-blood circulating tumor DNA detection in cancer

Tumor DNA contains specific somatic alterations that are crucial for the diagnosis and treatment of cancer. Due to the spatial and temporal intra-tumor heterogeneity, multi-sampling is needed to adequately characterize the somatic alterations. Tissue biopsy, however, is limited by the restricted access to sample and the challenges to recapitulate the tumor clonal diversity. Non-blood circulating tumor DNA are tumor DNA fragments presents in non-blood body fluids, such as urine, saliva, sputum, stool, pleural fluid, and cerebrospinal fluid (CSF). Recent studies have demonstrated the presence of tumor DNA in these non-blood body fluids and their application to the diagnosis, screening, and monitoring of cancers. Non-blood circulating tumor DNA has an enormous potential for large-scale screening of local neoplasms because of its non-invasive nature, close proximity to the tumors, easiness and it is an economically viable option. It permits longitudinal assessments and allows sequential monitoring of response and progression. Enrichment of tumor DNA of local cancers in non-blood body fluids may help to archive a higher sensitivity than in plasma ctDNA. The direct contact of cancerous cells and body fluid may facilitate the detection of tumor DNA. Furthermore, normal DNA always dilutes the plasma ctDNA, which may be aggravated by inflammation and injury when very high amounts of normal DNA are released into the circulation. Altogether, our review indicate that non-blood circulating tumor DNA presents an option where the disease can be tracked in a simple and less-invasive manner, allowing for serial sampling informing of the tumor heterogeneity and response to treatment.

Integrating liquid biopsies into the management of cancer

During cancer progression and treatment, multiple subclonal populations of tumour cells compete with one another, with selective pressures leading to the emergence of predominant subclones that replicate and spread most proficiently, and are least susceptible to treatment. At present, the molecular landscapes of solid tumours are established using surgical or biopsy tissue samples. Tissue-based tumour profiles are, however, subject to sampling bias, provide only a snapshot of tumour heterogeneity, and cannot be obtained repeatedly. Genomic profiles of circulating cell-free tumour DNA (ctDNA) have been shown to closely match those of the corresponding tumours, with important implications for both molecular pathology and clinical oncology. Analyses of circulating nucleic acids, commonly referred to as 'liquid biopsies', can be used to monitor response to treatment, assess the emergence of drug resistance, and quantify minimal residual disease. In addition to blood, several other body fluids, such as urine, saliva, pleural effusions, and cerebrospinal fluid, can contain tumour-derived genetic information. The molecular profiles gathered from ctDNA can be further complemented with those obtained through analysis of circulating tumour cells (CTCs), as well as RNA, proteins, and lipids contained within vesicles, such as exosomes. In this Review, we examine how different forms of liquid biopsies can be exploited to guide patient care and should ultimately be integrated into clinical practice, focusing on liquid biopsy of ctDNA - arguably the most clinically advanced approach.

The potential use of urine cell free DNA as a marker for cancer

INTRODUCTION

Although the role of circulating cell free DNA in cancer has been widely demonstrated, less is known about the role of urine cell free DNA (UcfDNA). UcfDNA can serve as a 'liquid biopsy' for urological and non-urological tumors, as it carries information on DNA from cells exfoliated in urine and from circulation. Areas covered: We review the studies on UcfDNA as a source of biomarkers for cancer, focusing on the new techniques and the differences between urological and non-urological tumors. We searched Pubmed for articles published between 1998 and 2016 with the following key words and phrases: 'urine' and 'cell free DNA' or 'liquid biopsy' or 'cancer'. Expert commentary: Despite the few papers published on this topic, UcfDNA is an important component of 'liquid biopsy', a useful and non-invasive tool for cancer diagnosis, prognosis and treatment monitoring, containing a wide range of genetic information.

Generation of blood circulating DNA: the sources, peculiarities of circulation and structure

Extracellular nucleic acids (exNA) were described in blood of both healthy and illness people as early as in 1948, but staied overlooked until middle 60-th. Starting from the beginning of new millennium and mainly in the last 5 years exNA are intensively studied. Main attention is directed to investigation of exNA as the source of diagnostic material whereas the mechanisms of their generation, as well as mechanisms to providing long-term circulation of exNA in the bloodstream are not established unambiguously. According to some authors, the main source of circulating nucleic acids in blood are the processes of apoptosis and necrosis, while others refer to the possible nucleic acid secretion by healthy and tumor cells. Circulating DNA were found to be stable in the blood for a long time, escaping from the action of DNA hydrolyzing enzymes and are apparently packed in different supramolecular complexes. This review presents the opinions of various authors and evidence in favor of all the theories describingappearance of extracellular DNA, the features of the circulation and structure of the extracellular DNA and factors affecting the time of DNA circulation in blood

Mapping of microsatellite instability in endoscopic normal colon

Genomic instability in colorectal cancer (CRC) occurs as either microsatellite instability (MSI) or chromosomal instability. The present study was aimed at examining the MSI for the MLH1 and MSH2 genes in normal colon and polyps, if detected. Four segments of the colon were sampled in 102 subjects during colonoscopy. DNA samples were analyzed for the MSI status according to the Bethesda consensus panel. Family history of any type of cancer or for colon cancer was present in 44.8% and 9.4% of the individuals, respectively. Forty-eight percent of individuals were microsatellite stable for all five markers at all locations, 20% had low MSI status (MSI-L), and 32% had high MSI status (MSI-H). The frequencies of MSI markers differed significantly from each other (p=0.003). The most frequent positive marker was D17S250. This is the first study which revealed that MSI is present in endoscopically normal-looking colon of normal individuals and, more frequently, in individuals with family histories of CRC. The detection of very early-stage CRC is possible by MSI analysis of DNA mismatch repair genes in colon tissues. This study has revealed crucial information for the use of molecular tests in CRC screening, such as high frequencies of MSI in endoscopically normal colon, which might cause false positivity.

Clinical value of loss of heterozygosity in serum microsatellite DNA of patients with gastrointestinal stromal tumors

GOALS

To study the role of loss of heterozygosity (LOH) in serum microsatellite DNA of patients with gastrointestinal stromal tumors (GIST).

BACKGROUND

In GIST, tumor markers from peripheral blood are missing.

STUDY

Seventy-eight patients (59 GIST, 13 leiomyomas, 2 leiomyosarcomas, and 4 schwannomas) underwent resection at our institute between 1985 and 2006. Thirty-three preoperative sera (26 GIST and 7 non-GIST) and 62 postoperative sera (47 GIST and 15 non-GIST) were available and tested for alterations in 12 representative microsatellite loci on chromosomes 22, 17, 13, 9, and 3, using fluorescence-based automated capillary electrophoresis by ABI Prism. Survival was calculated with Kaplan-Meier plots.

RESULTS

Seventeen out of 26 GIST patients had a positive preoperative serum LOH score (> or =2 LOH, sensitivity 65.4%), and 6 out of 7 non-GIST patients had a negative score (< or =1 LOH, specificity 85.7%, P=0.030, Fisher exact test). Serum LOH in GIST were strongly correlated with Fletcher risk groups (P=0.016, chi test). All metastasized GIST (7/7) showed > or =2 LOH preoperatively. Postoperative sensitivity and specificity of LOH analysis for prediction of relapse in 47 GIST was 75.0% and 64.1%, respectively. After a median observation time of 51.3 months (95% confidence interval, 39.4-61.4), LOH in serum significantly predicted overall survival (P=0.007, log-rank test).

CONCLUSIONS

LOH serum analysis in GIST may play a role as a noninvasive, differential diagnostic, prognostic, and monitoring marker in the clinical routine.

Microsatellite analysis of voided-urine samples for surveillance of low-grade non-muscle-invasive urothelial carcinoma: feasibility and clinical utility in a prospective multicenter study (Cost-Effectiveness of Follow-Up of Urinary Bladder Cancer trial [CEFUB])

BACKGROUND

Microsatellite analysis (MA) of voided-urine samples has been promoted as an alternative for cystoscopy surveillance (UCS) of patients with low-grade non-muscle-invasive papillary urothelial carcinoma (UC).

OBJECTIVE

To assess the feasibility and clinical utility of MA on voided-urine samples in a routine setting to detect or predict bladder cancer recurrences.

DESIGN, SETTING, AND PARTICIPANTS

We evaluated 228 patients monitored by MA of voided-urine samples and synchronous UCS who participated in a longitudinal prospective study in 10 hospitals. Follow-up started after diagnosis of a primary or recurrent pTa, pT1, grade 1 or grade 2 papillary UC.

MEASUREMENTS

Clinico-pathological parameters and fibroblast growth factor receptor 3 (FGFR3) gene mutation status of the inclusion tumour were determined. MA outcome was analysed in 1012 urine samples during a mean follow-up of 41 mo. Poor DNA quality prevented MA in 19% (197/1012) of the samples, leaving 815 visits for a cross-sectional analysis of sensitivity and specificity. We determined the predictive value (PPV) in a longitudinal analysis for 458 series with persistent MA results. Factors influencing diagnostic quality of MA were investigated. Kaplan-Meier analysis was performed to relate MA results to recurrence.

RESULTS AND LIMITATIONS

Cross-sectional sensitivity and specificity of MA for detection of a recurrence were 58% (49/84) and 73% (531/731), respectively. One pT1 grade 3 UC was missed. In a longitudinal analysis, the 2-yr risk to develop a recurrence reached 83% if MA outcome was persistently positive and 22% when MA was persistently negative. PPV of MA was higher with wild-type FGFR3 gene status and smoking habits. All four upper urinary tract tumours detected were preceded by a positive MA test.

CONCLUSIONS

Consecutive positive MA results are a strong predictor for future recurrences, but sensitivity needs to be improved, for example, by patient selection and testing of additional genetic markers in urine samples.

Microsatellite DNA alterations of gastrointestinal stromal tumors are predictive for outcome

PURPOSE

In gastrointestinal stromal tumors (GIST), loss of heterozygosity (LOH) on chromosome 22 and its presumptive biological function has been described. The prognostic value of these and other DNA regions for patient survival remains unclear.

EXPERIMENTAL DESIGN

Sixty patients who underwent surgery at our institution between 1992 and 2003 for GIST were histopathologically reclassified by immunohistochemistry and the GIST consensus group criteria 2001. Twenty-one microsatellite loci on chromosomes 3, 9, 13, 17, 18, and 22 were screened for alterations in tumor and healthy DNA. Survival was calculated by Kaplan-Meier plots.

RESULTS

Eleven (18.3%) of 60 patients showed metastases at presentation. Thirteen (21.7%) of 60 were high-risk GISTs. LOH was found in all tumors. Twenty-eight (46.7%) of 60 showed more than two LOH in 21 microsatellite marker sites. The frequency of single marker LOH varied from 1.7% to 28.3% among tumors. Frequent LOH was found on chromosomes 22 and 17. The correlation of LOH positivity and the consensus scoring was significant (P=0.005, chi2 test). After a median observation time of 33.3 months (95% confidence interval, 23.9-42.6), overall survival was best for patients with tumors of very low, low, and intermediate risks with only 6 of 36 death events, whereas 14 of 24 high-risk and metastasized patients had died (P<0.001, log-rank test). Likewise, LOH significantly predicted survival (P=0.013) and the effect was particularly detrimental for LOH on chromosome 17 (P<0.001).

CONCLUSIONS

LOH is a useful phenomenon for the prognosis of GIST. Rather than chromosome 22 markers, chromosome 17 markers independently predict survival.

Analysis of microsatellite instability in stool DNA of patients with colorectal cancer using denaturing high performance liquid chromatography

AIM: To evaluate the usefulness of denaturing high performance liquid chromatography (DHPLC) for analyzing microsatellite instability (MSI) status in stool DNA of patients with colorectal cancer.

METHODS: A total of 80 cancer tissues from patients with primary sporadic colorectal tumor (proximal cancer: 27, distal cancer: 53) and matched stool (which were employed for comparison with the tissues) were analyzed for MSI status in BAT 26. DNA samples extracted from stool were evaluated by nested polymerase chain reaction (PCR) and DHPLC for MSI analysis.

RESULTS: Six cases (7.5%) of MSI were identified in BAT 26 from 80 cancer tissues. All the stool DNA samples from patients whose cancer tissue showed MSI also displayed MSI in BAT 26.

CONCLUSION: As MSI is one of the established fecal DNA markers to screen colorectal cancer, we propose to use DHPLC for the MSI analysis in fecal DNA.

Circulating nucleic acids (CNAs) and cancer--a survey

It has been known for decades that it is possible to detect small amounts of extracellular nucleic acids in plasma and serum of healthy and diseased human beings. The unequivocal proof that part of these circulating nucleic acids (CNAs) is of tumor origin, initiated a surge of studies which confirmed and extended the original observations. In the past few years many experiments showed that tumor-associated alterations can be detected at the DNA and RNA level. At the DNA level the detection of point mutations, microsatellite alterations, chromosomal alterations, i.e. inversion and deletion, and hypermethylation of promoter sequences were demonstrated. At the RNA level the overexpression of tumor-associated genes was shown. These observations laid the foundation for the development of assays for an early detection of cancer as well as for other clinical means.

The detection of oesophageal adenocarcinoma by serum microsatellite analysis

BACKGROUND AND AIMS

Organ-confined oesophageal cancer in an early stage can be cured in many patients, whereas more extensive lesions have a poor prognosis. We sought to develop a non-invasive test for cancer detection and evaluation of the prognosis of the patients by using a novel molecular approach.

MATERIAL AND METHODS

Matched normal-, tumour- and serum-samples were obtained from 32 patients with adenocarcinoma of the oesophagus. DNA was extracted and the samples were subjected to microsatellite analysis using 12 markers. Serum and normal samples from 10 healthy individuals served as controls.

RESULTS

Twenty-seven of the 32 patients (84.4%) with malignant tumours were found to have one or more microsatellite DNA alterations in their primary tumour. Twenty-six of the 32 patients (81.3%) had alterations in the serum by microsatellite analysis. Interestingly, all patients without lymphatic metastasis and three early carcinomas (pT1pN0) already displayed LOH alteration in the serum, while all serum DNA of samples from normal control subjects were negative. Survival was not significantly correlated with either LOH in the tumour or LOH in the serum.

CONCLUSION

These data suggest that microsatellite DNA analysis in serum specimens might provide a potentially valuable tool for early detection of oesophageal cancer. The evidence of circulating tumour DNA reflects the propensity of these tumours to spread to distant sites. Up to now the follow-up is still too short to draw further conclusions on the prognostic impact of this finding.

Detection of Tumor DNA in Plasma Using Whole Genome Amplification

Altered microsatellite DNA in the blood of cancer patients may provide a novel means for tumor detection. Such alterations are a major characteristic of many types of tumor especially those associated with head or neck cancer. Moreover, recent evidence suggests that senescent tumor cells release DNA into the circulation, which is subsequently carried by the blood and thus enriched in the serum and plasma. We tested 10 head and neck cancer patients (5 with malignant melanomas (MM) and 5 with adenoid cystic carcinomas (ACC)) by polymerase chain reaction (PCR)-based microsatellite analysis of DNA from white blood cells and paired plasma samples. Our goal was to amplify two microsatellite markers, D1S243 and D19S246, which sometimes show microsatellite alterations in head and neck cancer patients. However amplification of fragments from three loci in the plasma samples proved impossible, probably due to the small amounts of DNA isolated. We used multiple displacement amplification (MDA) to amplify genomic DNA from the plasma samples. Two microsatellite fragments were amplified from whole genome amplified DNA. Among 5 heterozygote samples, 3 showed the same pattern in DNA samples from both blood cells and plasma but 2 showed loss of heterozygosity (LOH). Although further study is necessary to confirm whether the LOH found in this study reflects alteration in circulating tumor cell DNA, application of whole genome amplification may allow DNA analysis from limited amounts of such DNA and provide a minimally invasive diagnostic procedure and useful aid in therapy.

Microsatellite analysis of pleural supernatants could increase sensitivity of pleural fluid cytology

Pleural effusions may result from various inflammatory, hemodynamic, or neoplastic conditions. A common diagnostic problem lies in distinguishing malignant from benign pleural effusions using routine cytological evaluation. We studied pleural fluid samples obtained from 14 patients with histologically confirmed malignancy and from 6 patients with benign pleural effusions using 12 microsatellite markers from 8 different chromosomal regions. Supernatants and cellular sediments of all 20 pleural fluid samples were analyzed. Routine cytological examination was 100% specific for malignancy but was only 57% sensitive. Microsatellite analyses of pleural fluid supernatants showed genetic alterations in tumor patients only. However, 50% of pleural effusions that were considered negative for malignancy by routine cytological analysis showed either loss of heterozygosity or microsatellite instability. The sensitivity of pleural fluid examination rose to 79% when routine cytological assessment was supplemented by molecular studies. Our data suggest that microsatellite analysis increases the sensitivity of cytological pleural fluid examination in assessing potential malignancy and that combining cytological and molecular methods may improve yield and certainty in diagnostically challenging cases.

Diagnostic developments involving cell-free (circulating) nucleic acids

BACKGROUND

The detection of circulating nucleic acids has long been explored for the non-invasive diagnosis of a variety of clinical conditions. In earlier studies, detection of circulating DNA has been investigated for the detection of various forms of cancer. Metastasis and recurrence in certain cancer types have been associated with the presence of high levels of tumor-derived DNA in the circulation. In the case of pregnancies, detection of fetal DNA in maternal plasma is a useful tool for detecting and monitoring certain fetal diseases and pregnancy-associated complications. Similarly, levels of circulating DNA have been reported to be elevated in acute medical emergencies, including trauma and stroke, and have been explored as indicators of clinical severity. Apart from circulating DNA, much attention and effort have been put into the study of circulating RNA over the last few years. This area started from the detection of tumor-derived RNA in the plasma of cancer patients. Soon after that, detection of circulating fetal RNA in maternal plasma was described. Plasma RNA detection appears to be a promising approach for the development of gender- and polymorphism-independent fetal markers for prenatal diagnosis and monitoring. This development also opens up the possibility of non-invasive prenatal gene expression profiling by maternal blood analysis. Besides circulating DNA and RNA in plasma and serum, cell-free DNA in other body fluids, such as urine, has been detected in patients with different clinical conditions. Regardless of the sources of cell-free DNA for clinical use, the amount is frequently scarce.

METHODS

Technical advancements in detecting free DNA have been made over the years.

CONCLUSIONS

It is likely that further developments in the field of circulating nucleic acids will provide us with new diagnostic and monitoring possibilities over the next few years.

Allelic loss of 14q32 in the pathogenesis of gastrointestinal and ampullary malignancies: mapping of the target region to a 17�cM interval

PURPOSE

The genetic basis for gastrointestinal and ampullary carcinomas remains uncertain. This study was performed to pinpoint novel chromosomal region involved in the tumorigenesis of gastrointestinal tract.

METHODS

We screened the allelic status on 16 chromosomal arms in a patient with synchronous ampullary carcinoma and gastric cancer, but who had no family history of familial cancer syndrome. The significance of the shared 14q deletion was examined on clinical cohorts of sporadic gastric (n=12) and ampullary (n=10) carcinoma, respectively. Then, high-density allelotype mapping was performed on 14q32 by using 23 microsatellite markers for the synchronous tumors.

RESULTS

The synchronous gastric and ampullary carcinomas had no frameshift mutations in the APC, MSH2, MSH3, and MSH6 genes. Among the microsatellite markers screened, only D14S267 showed identical loss in the synchronous tumors. The same allelic loss was also detected in one of ampullary carcinomas (10%) and two of gastric cancers (16.7%). Fine mapping of 14q determined a minimally deleted region between D14S65 and D14S1010 (17 centiMorgans) for the synchronous tumors.

CONCLUSIONS

This study illustrates a paradigm using molecular genetic approach in identifying chromosome 14q32 that may harbor a tumor suppressor gene involved in the pathogenesis of a subset of gastrointestinal and ampullary malignancies.

Quantitative detection of promoter hypermethylation of multiple genes in the tumor, urine, and serum DNA of patients with renal cancer

Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of human cancers and is a promising marker for cancer detection. We investigated the feasibility of detecting aberrant DNA methylation in the urine and serum samples of renal cancer patients. We examined the tumor and the matched urine and serum DNA for aberrant methylation of nine gene promoters (CDH1, APC, MGMT, RASSF1A, GSTP1, p16, RAR-beta2, and ARF) from 17 patients with primary kidney cancer by quantitative fluorogenic real-time PCR. An additional 9 urine samples (total, 26) and 1 serum sample (total, 18) also were tested from renal cancer patients. Urine from 91 patients without genitourinary cancer and serum from 30 age-matched noncancer individuals were used as controls. Promoter hypermethylation of at least two of the genes studied was detected in 16 (94%) of 17 primary tumors. Aberrant methylation in urine and serum DNA generally was accompanied by methylation in the matched tumor samples. Urine samples from 91 control subjects without evidence of genitourinary cancer revealed no methylation of the MGMT, GSTP1, p16, and ARF genes, whereas methylation of RAR-beta2, RASSF1A, CDH1, APC, and TIMP3 was detected at low levels in a few control subjects. Overall, 23 (88%) of 26 urine samples and 12 (67%) of 18 serum samples from cancer patients were methylation positive for at least one of the genes tested. By combination of urine or serum analysis of renal cancer patients, hypermethylation was detected in 16 of 17 patients (94% sensitivity) with high specificity. Our findings suggest that promoter hypermethylation in urine or serum can be detected in the majority of renal cancer patients. This noninvasive high-throughput approach needs to be evaluated in large studies to assess its value in the early detection and surveillance of renal cancer.

Human urine contains small, 150 to 250 nucleotide-sized, soluble DNA derived from the circulation and may be useful in the detection of colorectal cancer

Human urine has been shown to possess submicrogram per milliliter amounts of DNA. We show here that DNA isolated from human urine resolves into two size categories: the large species, greater than 1 kb, being predominantly cell associated and heterogeneous in size, and the smaller, between 150 to 250 bp, being mostly non-cell associated. We showed that the low molecular weight class of urine DNA is derived from the circulation, by comparing the mutated K-ras sequences present in DNA isolated from tumor, blood, and urine derived from an individual with a colorectal carcinoma (CRC) containing a mutation in codon 12 of the K-ras proto-oncogene. In the urine, mutated K-ras sequences were abundant in the low molecular weight species, but far less abundant in the large molecular weight-derived DNA. Finally, the possibility that detection of mutant K-ras sequences in DNA derived from the urine correlates with the occurrence of a diagnosis of CRC and polyps that contain mutant K-ras was explored in a blinded study. There was an 83% concurrence of mutated DNA detected in urine and its corresponding disease tissue from the same individuals, when paired urine and tissue sections from 20 subjects with either CRC or adenomatous polyps were analyzed for K-ras mutation. The possibility that the source of the trans renal DNA is apoptotic cells, and the potential use of this finding for cancer detection and monitoring is discussed.

Klatskin tumors and Klatskin mimicking lesions of the biliary tree

AIM

We report on the preoperative capability of imaging modalities and clinical assessment to differentiate between Klatskin tumors and Klatskin mimicking lesions of the biliary tree. Adenocarcinomas of the hepatic ducts (Klatskin tumors) mimic benign fibrosing cholangitis. Extensive resections carry a substantial risk but offer the only chance for cure in patients with a Klatskin tumor.

METHODS

Thirty-three consecutive patients who underwent resection for suspicion of a malignant tumor of the hepatic hilum were reviewed. All patients underwent preoperative ultrasonography, computed tomography, ERCP and angiography. The patients were divided into a group of true Klatskin tumors and a group of benign Klatskin mimicking lesions.

RESULTS

Twenty-seven of the resected specimens were malignant tumors, and six lesions showed only fibrosing cholangitis. Preoperative clinical presentation and imaging modalities were very similar between Klatskin tumors and fibrosing cholangitis.

CONCLUSIONS

Management of obstruction of the liver hilum is dictated by the suspicion of malignancy. Complete removal of the tumor remains the therapeutic aim but clinical presentation and imaging modalities cannot help to differentiate between Klatskin tumors and Klatskin mimicking lesions prior to surgery.

Chromosome aberrations in solid tumors

Chromosome aberrations in human solid tumors are hallmarks of gene deregulation and genome instability. This review summarizes current knowledge regarding aberrations, discusses their functional importance, suggests mechanisms by which aberrations may form during cancer progression and provides examples of clinical advances that have come from studies of chromosome aberrations.

The basic biology and immunobiology of renal cell carcinoma: considerations for the clinician

These are indeed exciting times in the study of RCC. No longer should the clinician view RCC as a single entity, nor should the researcher pose basic questions without considering the biologic diversity of this tumor. The success of novel targeted therapeutic strategies will depend on the systematic study of genetic and epigenetic events and their relationship to aberrant protein expression and function, and an understanding of the permissive microenvironment that allows the tumor to be sustained. These studies must be correlated in a rigorous fashion to clinical parameters and outcomes. Progress against this elusive tumor will require a continuous translational dialogue between laboratory and clinical investigators.

Molecular detection of von Hippel-Lindau gene mutations in urine and lymph node samples in patients with renal cell carcinoma: potential biomarkers for early diagnosis and postoperative metastatic status

PURPOSE

Organ confined renal cell carcinoma can be cured in the majority of patients, whereas more extensive lesions have a poor prognosis. Therefore, the development of a useful biomarker for early diagnosis as well as postoperative metastatic status would contribute to the appropriate therapy for renal cell carcinoma. To diagnose renal cell carcinoma preoperatively we developed a novel urinary test and detected occult lymph node micrometastasis using a molecular approach.

MATERIALS AND METHODS

Urine samples were obtained preoperatively from 27 patients with renal cell carcinoma and von Hippel-Lindau (VHL) gene mutations in the tumors, and were analyzed for VHL gene mutations using a nested single strand conformational polymorphism analysis. Lymph nodes without evidence of histological metastasis were obtained from 15 patients with renal cell carcinoma and VHL gene mutations, and analyzed for VHL gene mutations using mutation specific nested reverse transcription polymerase chain reaction method.

RESULTS

In urine samples 5 of 27 VHL gene mutations (18.5%) were found and each mutation pattern was the same as that detected in each renal cell carcinoma. One lymph node micrometastasis was found.

CONCLUSIONS

These data indicate the presence of detectable levels of tumor derived DNA in the urine of patients with renal cell carcinoma and suggest that nested single strand conformational polymorphism analysis of VHL gene of urine samples provides a possible tool for the early detection of renal cell carcinoma. Furthermore, mutation specific nested reverse transcription polymerase chain reaction is useful to detect occult lymph node micrometastasis and may predict patients at risk for local recurrence. These 2 combined approaches using VHL gene mutations may contribute to the total therapy for and prognosis of renal cell carcinoma.

[Molecular diagnostics in urologic oncology. Detection of nucleic acids in urine samples]

The goal of molecular diagnostics in oncology is the early diagnosis of malignant disease processes during initial work-up or as part of follow-up. Body fluids serve as the primary material for non-invasive diagnostic methods. Besides actual tumor cells, the examination of urine can yield evidence of secreted proteins or even free nucleic acids. In principle, all of the methods available for the detection of tumor markers in tissue or blood samples can be successfully applied to the examination of urine samples. However, molecular biological examination of urine samples is associated with important problems because the cells in such samples are exposed to significant degradation and regression effects and because certain components of the urine act to inhibit the polymerase chain reaction. The present overview discusses the respective strengths and weakness of the available technology as applied to the diagnosis of urologic malignancies. Experimental studies conducted to date have reported high sensitivities and specificities for molecular diagnostics using urine samples. It is important to note that not only carcinomas of the urinary bladder can be diagnosed from material obtained in urine samples: in fact, the method can be used to diagnose entities such as renal cell and prostate carcinomas and, due to renal filtration of DNA, even non-urologic malignancies. The diagnostic application of these methods, however, remains in an experimental stage and must still clear several hurdles before becoming available for routine clinical use.

Molecular diagnosis of primary liver cancer by microsatellite DNA analysis in the serum

Frequent loss of heterozygosity of microsatellites markers on specific chromosomal region have been reported in various types of primary human cancer. The same loss of heterozygosity has also been identified in the matched plasma/serum DNA. Using 109 microsatellite markers representing 24 chromosomal arms, we have examined the loss of heterozygosity in 21 cases of hepatocellular carcinoma, six of cholangiocarcinoma, and 27 cases of chronic hepatitis or cirrhosis. All cases of the hepatocellular carcinoma showed deletion from two to 10 chromosomal arms, while deletion of chromosomes from two to eight regions was detected in five of six cholangiocarcinoma patients. One or more loss of heterozygosity in the paired serum DNA could be detected in 16 of 25 (76.2%) hepatocellular carcinoma patients. In contrast, no alterations in serum DNA test could be found in cholangiocarcinoma patients. Five of seven (71.4%) hepatocellular carcinoma patients with alpha-fetoprotein levels less than 20 ng ml(-1) produced positive serum DNA test. The profiles of 19 microsatellite markers gave a 100% positive predictive value and an 80.8% negative predictive value for hepatocellular carcinoma. In conclusion, we have determined a profile of microsatellite markers appropriate for differential diagnosis of primary liver cancer. The discovery may permit a high-throughput screening of hepatocellular carcinoma at an early stage of disease.

The molecular biology of laryngeal cancer

Novel techniques have led to the discovery of many genes and gene products important in the development of HNSC and laryngeal cancer. Tumor suppressive genes and oncogenes have been identified, and many of their roles have been elucidated in a genetic progression model. As these molecular pathways become better understood, the information obtained will increasingly be used to guide patient therapy. Specifically, advances will probably be made in (1) molecular characterization of steps leading to laryngeal cancer; (2) molecular screening, staging, and surveillance; (3) molecularly based therapy, including gene transfer and small molecule therapy directed at specific molecular pathways involved in neoplasia; and (4) characterization of patients who are at high risk for laryngeal cancer. In the final analysis, however, smoking cessation for those at risk for head and neck cancer would have greater effect than all these efforts combined.

Circulating DNA: a new diagnostic gold mine?

The recent discovery that cell-free DNA can be shed into the bloodstream as a result of tumour cell death has generated great interest. Numerous studies have demonstrated tumour-specific alterations in DNA recovered from plasma or serum of patients with various malignancies, a finding that has potential for molecular diagnosis and prognosis. The implication is that tumour-derived nucleic acids of human or viral origin can be retrieved from blood by a minimally invasive procedure, and used as a surrogate tumour marker to monitor the course of the disease or aid in early diagnosis. The present review will describe the main areas of ongoing investigation, with particular emphasis on technical issues and available data of clinical relevance.

Mismatch repair genes and microsatellite instability as molecular markers for gynecological cancer detection

Due to major developments in genetics over the past decade, molecular biology tests are serving promising tools in early diagnosis and follow-up of cancer patients. Recent epidemiological studies revealed that the risk for each individual to develop cancer is closely linked to his/her own genetic potentialities. Some populations that are defective in DNA repair processes, for example in Xeroderma pigmentosum or in the Lynch syndrome, are particularly prone to cancer due to the accumulation of mutations within the genome. Such populations would benefit from the development of tests aimed at identifying people who are particularly at risk. Here, we review some data suggesting that the inactivation of mismatch repair is often found in endometrial cancer and we discuss molecular-based strategies that would help to identify the affected individuals in families with cases of glandular malignancies.

DNA alterations in body fluids as molecular tumor markers for urological malignancies

OBJECTIVES

DNA-based tumor markers are characterized by unique specificity rendering them an attractive target for molecular diagnosis of cancer in body fluids like blood serum/plasma and urine. Both cell-free tumor DNA circulating in plasma/serum and cellular tumor DNA are detectable by minimally invasive measures.

METHODS

Three main detection methods, microsatellite analysis, mutation analysis in genomic or mitochondrial DNA and gene promoter hypermethylation analysis are applied. Detection of gene promoter hypermethylation by methylation-specific PCR enables the best methodical sensitivity requiring a ratio of tumor DNA within normal DNA of less than 1:1000.

RESULTS/CONCLUSIONS

Tumor DNA derived from renal cell carcinoma, bladder cancer or prostate cancer is detectable in considerably more than 50% of plasma/serum samples and more than 70% of urine samples from these patients. Because the targeted DNA alterations are absent or very rare in controls, the specificity of DNA-based tumor detection methods reaches almost 100%. Although the methodology currently is experimental, automatization will make it easier and less expensive. This review is focused on the potential clinical value of DNA-based analysis of body fluids for the initial diagnosis and the follow-up of urologic cancer patients.

Microsatellite analysis of fecal DNA for colorectal cancer detection

BACKGROUND AND OBJECTIVES

The advent of noninvasive methods of testing for colorectal cancer that have a high level of specificity and sensitivity is eagerly awaited.

METHODS

Thirty patients with sporadic colorectal cancer and 11 patients with hereditary nonpolyposis colon cancer (HNPCC) enrolled in this study. We analyzed the loss of heterozygosity (LOH) in matched genomic DNA extracted from blood and surgical specimens (tumor and tumor-free colonic mucosa), and the corresponding oral rinse and stool specimens using seven microsatellite loci (APC, p53, DCC, hMLH1, D9S162, D9S171, and IFNA). To reduce the normal colonocyte DNA contamination of the stool samples, we compared three different methods for fecal genomic DNA extraction. As normal controls, we analyzed the LOH using the oral rinse and stool samples from 15 individuals without cancer.

RESULTS

The LOH determined from the oral rinse and the stool samples matched those determined from the blood and the neoplastic tissue. All patients with HNPCC had microsatellite alterations at hMLH-1 in tumor DNA and corresponding fecal DNA. There were significant differences in the frequency of p53-LOH and D9S171-LOH between the group with sporadic disease and those with HNSCC (P = 0.0031 and 0.0294, respectively). Two cases with D9S162-LOH were detected in individuals without cancer. For the patients with sporadic disease, using p53 and adenomatous polyposis coli (APC), the sensitivity of the fecal DNA analysis was 96.7% (95% CI, 83-100) with a specificity of 100%.

CONCLUSION

We demonstrate that LOH analysis using oral rinse and stool samples may be a suitable screening tool for colorectal cancer.

The changing natural history of renal cell carcinoma

PURPOSE

Our understanding of the natural history of renal cell carcinoma, the role of nephrectomy, the benefits of immunotherapy and the possibilities of new technologies are evolving and being integrated with advances in classification and staging. We reviewed the relevant literature to clarify these pertinent questions and provide a current review of the changes in the epidemiology, treatment and prognosis of patients with renal cell carcinoma.

MATERIALS AND METHODS

We comprehensively reviewed the peer reviewed literature on the current management of and results of treatment for renal cell carcinoma.

RESULTS

The incidence of and mortality from renal cell carcinoma have continuously increased during the last 50 years. Despite this increase in the number of new patients and consequently the number of deaths yearly the percent of those surviving for 5 years has notably improved. Factors related to improved survival include advances in renal imaging, earlier diagnosis, improved staging, better understanding of prognostic indicators, refinement in surgical technique and the introduction of immunotherapy approaches for advanced disease.

CONCLUSIONS

Currently patients with localized and metastatic renal cell carcinoma have had improvements in outlook and the therapeutic options available have expanded.

The changing natural history of renal cell carcinoma

PURPOSE

Our understanding of the natural history of renal cell carcinoma, the role of nephrectomy, the benefits of immunotherapy and the possibilities of new technologies are evolving and being integrated with advances in classification and staging. We reviewed the relevant literature to clarify these pertinent questions and provide a current review of the changes in the epidemiology, treatment and prognosis of patients with renal cell carcinoma.

MATERIALS AND METHODS

We comprehensively reviewed the peer reviewed literature on the current management of and results of treatment for renal cell carcinoma.

RESULTS

The incidence of and mortality from renal cell carcinoma have continuously increased during the last 50 years. Despite this increase in the number of new patients and consequently the number of deaths yearly the percent of those surviving for 5 years has notably improved. Factors related to improved survival include advances in renal imaging, earlier diagnosis, improved staging, better understanding of prognostic indicators, refinement in surgical technique and the introduction of immunotherapy approaches for advanced disease.

CONCLUSIONS

Currently patients with localized and metastatic renal cell carcinoma have had improvements in outlook and the therapeutic options available have expanded.

DNA-based detection of prostate cancer in urine after prostatic massage

OBJECTIVES

Promoter hypermethylation of the glutathione-S-transferase P1 (GSTP1) gene is a specific feature of prostate cancer. This epigenetic DNA alteration served as the target for molecular detection of prostate cancer cells in urine sediments after prostatic massage.

METHODS

Bisulfite treatment followed by methylation-specific polymerase chain reaction was used to detect GSTP1 promoter hypermethylation in DNA isolated from urine sediments obtained after prostatic massage of men with and without prostate cancer.

RESULTS

GSTP1 promoter hypermethylation was demonstrated in the sediments of 1 (2%) of 45 patients diagnosed with benign prostatic hyperplasia, 2 (29%) of 7 patients with prostatic intraepithelial neoplasia, 15 (68%) of 22 patients with early, intracapsular cancer, and 14 (78%) of 18 patients with locally advanced or systemic prostate cancer, resulting in a specificity of 98% and an overall sensitivity of 73% for the detection of prostate cancer.

CONCLUSIONS

Urinalysis for GSTP1 promoter hypermethylation constitutes a sensitive and highly specific DNA-based marker for molecular detection of prostate cancer, including early stages.

Microsatellite analysis--DNA test in urine competes with cystoscopy in follow-up of superficial bladder carcinoma: a phase II trial

BACKGROUND

It has been shown that microsatellite analysis (MA) is able to detect bladder carcinoma in urine. Relatively small groups of patients often with high stage and grade disease were investigated. However, greater than 85% of cystoscopies are performed for follow-up of superficial bladder carcinoma. The authors evaluated this DNA-based method in a group of consecutive patients in follow-up after transurethral resection of superficial disease.

METHODS

Matched blood and urine samples from 109 patients were obtained before cystoscopy and subjected to MA. The BTA stat test (Bard Diagnostic Sciences, Inc., Redmond, WA) and cytology were used for comparison.

RESULTS

Sixteen patients were excluded: the DNA was of insufficient quality for 7 patients and leukocyte abundance rendered the result of MA unreliable for 9 patients. For the remaining 93 patients, MA detected 18 of the 24 recurrent tumors. The six undetected tumors were small pTaG1 lesions for which immediate surgery was not necessary. Conversely, 5 of 9 patients with a positive MA and a negative cystoscopy had a tumor recurrence within 6 months after urine collection. In contrast, a recurrence occurred in only 7 of 60 patients who were negative in both MA and cystoscopy (P = 0.006). The MA (74%) appeared more sensitive than the BTA stat test (56%) or urine cytology (22%).

CONCLUSIONS

Microsatellite analysis is a DNA test in urine that reliably signals the presence of recurrent bladder carcinoma, sometimes even before cystoscopic evidence of the disease. This noninvasive diagnostic tool has the potential to replace cystoscopy in many cases. The authors' results warrant the need for randomized trials.

Loss of heterozygosity assay for molecular detection of cancer using energy-transfer primers and capillary array electrophoresis

Microsatellite DNA loci are useful markers for the detection of loss of heterozygosity (LOH) and microsatellite instability (MI) associated with primary cancers. To carry out large-scale studies of LOH and MI in cancer progression, high-throughput instrumentation and assays with high accuracy and sensitivity need to be validated. DNA was extracted from 26 renal tumor and paired lymphocyte samples and amplified with two-color energy-transfer (ET) fluorescent primers specific for loci associated with cancer-induced chromosomal changes. PCR amplicons were separated on the MegaBACE-1000 96 capillary array electrophoresis (CAE) instrument and analyzed with MegaBACE Genetic Profiler v.1.0 software. Ninety-six separations were achieved in parallel in 75 minutes. Loss of heterozygosity was easily detected in tumor samples as was the gain/loss of microsatellite core repeats. Allelic ratios were determined with a precision of +/- 10% or better. Prior analysis of these samples with slab gel electrophoresis and radioisotope labeling had not detected these changes with as much sensitivity or precision. This study establishes the validity of this assay and the MegaBACE instrument for large-scale, high-throughput studies of the molecular genetic changes associated with cancer.