Heterogeneous tumor clones as an explanation of discordance between plasma DNA and tumor DNA alterations

Metabolomics-Based Discovery of Molecular Signatures for Triple Negative Breast Cancer in Asian Female Population

Triple negative breast cancer (TNBC) is a devastating cancer disease characterized by its poor prognosis, distinct metastatic patterns, and aggressive biological behavior. Research indicates that the prevalence and presentation of TNBC varies among races, with Asian TNBC patients more commonly presenting with large invasive tumors, high node positivity, and high histologic grade. In this work, we applied ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS)-based metabolomics to discover metabolic signatures in Asian female TNBC patients. Serum samples from 31 TNBC patients and 31 healthy controls (CN) were involved in this study. A total of 2860 metabolic features were detected in the serum samples. Among them, 77 metabolites, whose levels were significantly different between TNBC with CN, were confirmed. Using multivariate statistical analysis, literature mining, metabolic network and pathway analysis, we performed an in-depth study of the metabolic alterations in the Asian TNBC population. In addition, we discovered a panel of metabolic signatures that are highly correlated with the 5-year survival rate of the TNBC patients. This metabolomic study provides a better understanding of the metabolic details of TNBC in the Asian population.

Sox17 promoter methylation in plasma DNA is associated with poor survival and can be used as a prognostic factor in breast cancer

Aberrant DNA methylation that leads to the inactivation of tumor suppressor genes is known to play an important role in the development and progression of breast cancer. Methylation status of cancer-related genes is considered to be a promising biomarker for the early diagnosis and prognosis of tumors. This study investigated the methylation status of the Sox17 gene in breast cancer tissue and its corresponding plasma DNA to evaluate the association of methylation levels with clinicopathological parameters and prognosis.The methylation status of the Sox17 gene promoter was evaluated with methylation-specific polymerase chain reaction (MSP) in 155 paired breast cancer tissue and plasma samples and in 60 paired normal breast tissue and plasma samples. Association of Sox17 methylation status with clinicopathological parameters was analyzed by χ tests. Overall and disease-free survival (DFS) curves were calculated using Kaplan-Meier analysis, and the differences between curves were analyzed by log-rank tests.The frequency of Sox17 gene methylation was 72.9% (113/155) in breast cancer tissues and 58.1% (90/155) in plasma DNA. Sox17 gene methylation was not found in normal breast tissues or in their paired plasma DNA. There was a significant correlation of Sox17 methylation between corresponding tumor tissues and paired plasma DNA (r = 0.688, P < 0.001). Aberrant Sox17 methylation in cancer tissues and in plasma DNA was significantly associated with the tumor node metastasis stage (P = 0.035 and P = 0.001, respectively) and with lymph node metastasis (P < 0.001 and P = 0.001, respectively). Kaplan-Meier survival curves showed that aberrant Sox17 promoter methylation in cancer tissues and plasma DNA was associated with poor DFS (P < 0.005) and overall survival (OS) (P < 0.005). Multivariate analysis showed that Sox17 methylation in plasma DNA was an independent prognostic factor in breast cancer for both DFS (P = 0.020; hazard ratio [HR] = 2.142; 95% confidence interval [CI]: 1.128-4.067) and for OS (P = 0.001; HR = 4.737; 95% CI: 2.088-10.747).Sox17 gene promoter methylation may play an important role in breast cancer progression and could be used as a prognostic biomarker to identify patients at risk of developing metastasis or recurrence after mastectomy.

Clinical significance of serum circulating insulin-like growth factor-1 (IGF-1) mRNA in hepatocellular carcinoma

The principal aim of our study was to investigate the usefulness of serum protein and circulating mRNA of insulin-like growth factor-1 (IGF-1) as a diagnostic and prognostic tool in hepatocellular carcinoma (HCC). Fifty-four HCC patients and age- and sex-matched 20 healthy controls were enrolled into this study. Pretreatment serum IGF-1 and IGF-1 mRNA were determined by the solid-phase sandwich ELISA and quantitative RT-PCR method, respectively. The median age at diagnosis was 60 years, range 36-77 years; where majority of group were male (n = 48, 88.8%). All patients had cirrhotic history. Forty-six percent (n = 25) of patients had Child-Pugh score A, 30% (n = 16) had score B or C. All of the patients were treated with local therapies and none of them received sorafenib. The baseline serum IGF-1 mRNA levels were significantly higher in HCC patients than in the control group (p = 0.04), whereas no significant difference was observed for IGF-1 protein levels between the two group (p = 0.18). Patients with history of HBV infection, who were not treated, and who received multiple palliative treatment for HCC had higher serum IGF-1 mRNA levels (p = 0.03, 0.03, and 0.05, respectively). Poor performance status (p < 0.001), viral etiology of cirrhosis (p = 0.03), larger tumor size (p = 0.01), lower serum hemoglobin levels (p = 0.03), and not be treated for HCC (p = 0.001) related to worse survival. However, neither serum IGF-1 nor serum IGF-1 mRNA had significantly adverse effect on survival (p = 0.53 and 0.42, respectively).

Circulating nucleic acids in plasma and serum (CNAPS): applications in oncology

The presence of small amounts of circulating nucleic acids in plasma and serum (CNAPS) is not a new finding. The verification that such amounts are significantly increased in cancer patients, and that CNAPS might carry a variety of genetic and epigenetic alterations related to cancer development and progression, has aroused great interest in the scientific community in the last decades. Such alterations potentially reflect changes that occur during carcinogenesis, and include DNA mutations, loss of heterozygosity, viral genomic integration, disruption of microRNA, hypermethylation of tumor suppressor genes, and changes in the mitochondrial DNA. These findings have led to many efforts toward the implementation of new clinical biomarkers based on CNAPS analysis. In the present article, we review the main findings related to the utility of CNAPS analysis for early diagnosis, prognosis, and monitoring of cancer, most of which appear promising. However, due to the lack of harmonization of laboratory techniques, the heterogeneity of disease progression, and the small number of recruited patients in most of those studies, there has been a poor translation of basic research into clinical practice. In addition, many aspects remain unknown, such as the release mechanisms of cell-free nucleic acids, their biological function, and the way by which they circulate in the bloodstream. It is therefore expected that in the coming years, an improved understanding of the relationship between CNAPS and the molecular biology of cancer will lead to better diagnosis, management, and treatment.

Diagnostic and prognostic value of plasma and tissue ubiquitin-like, containing PHD and RING finger domains 1 in breast cancer patients

Ubiquitin-like, containing PHD and RING finger domains 1 (UHRF1) has been reported to play an important role in breast carcinogenesis. This work investigated the correlation of UHRF1 DNA level in plasma with clinical characteristics of breast cancer and its clinical significance in breast cancer diagnosis. The expression of UHRF1 in primary breast cancer tissue was examined by Western blot. The UHRF1 DNA levels in plasma and UHRF1 mRNA expression in tissues were determined by accurate real-time quantitative PCR. The associations of UHRF1 levels with clinical variables were evaluated using standard statistical methods. The UHRF1 DNA in plasma of 229 breast cancer patients showed higher expression than healthy controls, which showed high specificity up to 76.2% at a sensitivity of 79.2%, and was significantly associated with c-erbB2 positive status, cancer stage and lymph node metastasis. High UHRF1 DNA level in plasma was significantly associated with short progression-free survival. The UHRF1 DNA level in plasma is highly correlative with breast cancer and its status and stage, and may be a potential independent diagnostic and prognostic factor for both breast cancer and the survival of breast cancer patients.

Circulating free tumor DNA and colorectal cancer

Cancer is characterized by multiple somatic genetic and epigenetic alterations that could be useful as molecular markers for detecting tumor DNA in different bodily fluids. In patients with various diseases as well as in healthy subjects, circulating plasma and serum carry small amounts of non-cell-bound DNA. In this free circulating DNA, tumor-associated molecular alterations can be detected in patients who have cancer. In many instances, the alterations identified are the same as those found in the primary tumor tissue, thereby suggesting tumor origin from a fraction of the circulating free DNA. In fact, various types of DNA alterations described in colorectal cancer have been detected in the circulating free DNA of patients with colorectal cancer. These alterations include KRAS2, APC and TP53 mutations, DNA hypermethylation, microsatellite instability (MSI) and loss of heterozygosity (LOH). Also, advances in polymerase chain reaction (PCR)-based technology now allow the detection and quantification of extremely small amounts of tumor-derived circulating free DNA in colorectal cancer patients. The present report summarizes the literature available so far on the mechanisms of circulating free DNA, and on the studies aimed at assessing the clinical and biological significance of tumor-derived circulating free DNA in colorectal cancer patients. Thus, tumor-derived circulating free DNA could serve as a marker for the diagnosis, prognosis and early detection of recurrence, thereby significantly improving the monitoring of colorectal cancer patients.

Plasma-based detection of clonality in lymphoid malignancies

OBJECTIVES

Plasma has been found to be enriched with tumor-specific DNA, RNA, and protein in patients with hematologic disease. We assessed the utility of plasma as a DNA source for detection of genetic abnormalities in patients with suspected B- or T-cell lymphoproliferative disorders.

METHODS

DNA was extracted from paired peripheral blood (PB) cells and plasma for polymerase chain reaction (PCR)-based detection of immunoglobulin heavy chain (IgH) and T-cell receptor gamma chain (TCR-gamma) rearrangements, and B-cell leukemia/lymphoma (BCL)-1/IgH and BCL-2/IgH translocations.

RESULTS

Concordance between plasma and PB cell analysis was 100% for IgH (n = 57), TCR-gamma (n = 57), and BCL-1/IgH (n = 37) rearrangements, and 94% (60/64) for BCL-2/IgH; four of 11 plasma samples positive for BCL-2/IgH tested negative in paired cells. No plasma or PB cell samples from 195 healthy donors showed genetic abnormalities.

CONCLUSIONS

These findings indicate that plasma is a reliable sample type for detection of abnormalities associated with B- and T-cell lymphoproliferative disorders, providing sensitivity equal to or greater than that of PB cells.

Levels of VEGF-A mRNA in plasma from patients with colorectal carcinoma as possible surrogate marker of angiogenesis

PURPOSE

The regulator of angiogenesis most extensively studied is VEGF. VEGF mRNA in plasma from patients with colorectal cancer was analyzed as a possible surrogate marker of tumor angiogenesis.

METHODS

VEGF mRNA was measured by quantitative PCR in plasma, tumors and circulating tumor cells from colorectal cancer patients. Circulating VEGF protein was analyzed by ELISA. Microvessel density was determined.

RESULTS

Levels of VEGF mRNA and protein in plasma were higher in patients than in controls. VEGF mRNA was overexpressed in tumors with respect to normal tissues. Levels of VEGF protein were associated with VEGF mRNA in plasma, but no associations with tumor samples were found. A trend to statistical significance was shown between high VEGF mRNA and vascular invasion. MVD was not related to VEGF mRNA in plasma.

CONCLUSIONS

Thus, VEGF mRNA could be a marker similar to VEGF protein in plasma.

Free circulating mRNA in plasma from breast cancer patients and clinical outcome

We studied by real-time PCR cyclin D1 and thymidylate synthase (TS) mRNA in plasma as possible markers of clinical outcome in breast cancer. We observed poor outcome in patients with presence of cyclin D1 mRNA in good-prognosis groups, such as negative vascular invasion. Presence of both markers was associated with non-response to treatment after relapse. In patients treated with tamoxifen, a trend to significant relation between poor outcome and cyclin D1 mRNA was found. Cyclin D1 mRNA in plasma could identify patients with poor overall survival in good-prognosis groups and patients non-responsive to tamoxifen.

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.

Thymidylate synthase messenger RNA expression in plasma from patients with colon cancer: prognostic potential

PURPOSE

Thymidylate synthase (TS), a critical target in fluorouracil-based chemotherapy, is a prognostic marker in colon carcinomas and a predictor of response to treatment. Tumor RNA has been detected in plasma from cancer patients and is associated with poor prognosis. This is the first study to examine extracellular TS mRNA in plasma from patients with colon carcinoma, and its possible relation with TS promoter enhancer region (TSER) polymorphism.

EXPERIMENTAL DESIGN

TS expression was measured in plasma from 88 patients and 26 controls, and in a tumor subgroup of this series by quantitative PCR. Genotyping for TSER polymorphism was done in 60 patients. Clinicopathologic variables were correlated with these molecular changes.

RESULTS

TS mRNA was detected in plasma in 47% of patients, showing significant differences from healthy controls. Patients with TS mRNA in plasma had higher levels of TS in tumor tissue than patients without. The presence of TS mRNA was associated with lymph node metastases and more advanced stages. Polymorphism TSER 3/3 was found in 38% of cases, and was significantly correlated with high amounts of TS mRNA in plasma.

CONCLUSIONS

Our results suggest that TS mRNA in plasma originated from tumors, it may indicate poor prognosis and might help to classify tumors in Dukes' stages B and C. The TSER genotype may influence TS mRNA expression in plasma.

Whole genome amplification of plasma-circulating DNA enables expanded screening for allelic imbalance in plasma

Apoptotic and necrotic tumor cells release DNA into plasma, providing an accessible tumor biomarker. Tumor-released plasma-circulating DNA can be screened for tumor-specific genetic changes, including mutation, methylation, or allelic imbalance. However, technical problems relating to the quantity and quality of DNA collected from plasma hinder downstream genetic screening and reduce biomarker detection sensitivity. Here, we present a new methodology, blunt-end ligation-mediated whole genome amplification (BL-WGA), that efficiently amplifies small apoptotic fragments (<200 bp) as well as intermediate and large necrotic fragments (>5 kb) and enables reliable high-throughput analysis of plasma-circulating DNA. In a single-tube reaction, purified double-stranded DNA was blunted with T4 DNA polymerase, self-ligated or cross-ligated with T4 DNA ligase and amplified via random primer-initiated multiple displacement amplification. Using plasma DNA from breast cancer patients and normal controls, we demonstrate that BL-WGA amplified the plasma-circulating genome by approximately 1000-fold. Of 25 informative polymorphic sites screened via polymerase chain reaction-denaturating high-performance liquid chromatography, 24 (95%) were correctly determined by BL-WGA to be allelic retention or imbalance compared to 44% by multiple displacement amplification. By enabling target magnification and application of high-throughput genome analysis, BL-WGA improves sensitivity for detection of circulating tumor-specific biomarkers from bodily fluids or for recovery of nucleic acids from suboptimally stored specimens.

Detection of Cell-Free DNA in Bronchial Lavage Fluid Supernatants of Patients with Lung Cancer

Recently, it was shown that it is possible to isolate free circulating DNA from plasma/serum of patients with benign and malignant diseases. In addition, several groups were able to detect tumor-associated alterations in these nucleic acids. We wondered whether any nucleic acids are detectable in cell-free bronchial lavage supernatants, which until now have been discarded after cell harvest. Additionally, we wanted to find out if it is possible to detect tumor-associated alterations in these DNA molecules. DNA was isolated from cell-free lavage supernatants from 30 lung cancer patients, and the DNA was examined for microsatellite alterations. Intact DNA could be isolated from all cell-free bronchial lavage supernatants. Microsatellite alterations were found in lavage supernatants of 12 of 30 patients and in lavage cells of 6 of 30 patients. Altogether, alterations were found in 14 of 30 patients. Thus, we could demonstrate for the first time that it is possible to isolate intact DNA from cell-free bronchial lavage supernatants. Their quantity and quality are sufficient for further amplification via polymerase chain reaction. Altogether, tumor-associated changes were detected in the DNA of 47% of the patients that were analyzed.

Detection of cell-free nucleic acids in bronchial lavage fluid supernatants from patients with lung cancer

The aim of this study was to determine whether nucleic acids are detectable in cell-free bronchial lavage supernatants, and whether it is possible to find alterations in this DNA and RNA of genes known to be present in lung tumour cells. DNA was isolated from cell-free lavage supernatants from 30 and RNA from 25 lung cancer patients. The DNA was examined for microsatellite alterations (MA) and the RNA analysed for the expression of seven tumour-associated genes. Intact DNA and mRNA could be isolated from all cell-free bronchial lavage supernatants. MA were found in lavage supernatants of 12/30 patients and in lavage cells of 6/30 patients. Altogether alterations were found in 14/30 patients. Analyses of tumour-associated gene expression showed positive results, with at least one marker in the lavage supernatants of all 25 patients. Thus, we could demonstrate, for the first time, that it is possible to isolate intact DNA and RNA from cell-free bronchial lavage supernatants. Their quantity and quality is sufficient for further amplification by polymerase chain reaction (PCR)/reverse transcriptase (RT)-PCR. Altogether, tumour-associated changes were detected in DNA samples from 47% of the patients and in RNA samples from all of the patients analysed.

Loss of heterozygosity in serial plasma DNA samples during follow-up of women with breast cancer

We evaluated the potential utility of occult circulating tumor DNA as a molecular marker of disease in subjects previously diagnosed with breast cancer. Using 24 microsatellite markers located at sites of frequent loss of heterozygosity (LOH) or allele imbalance in breast cancer, we analyzed DNA from 16 primary tumors (Stage IIA or more advanced) and 30 longitudinally collected plasma specimens. Clinical data at the time of plasma collection were obtained. All 16 tumors were characterized by an individual pattern of LOH. LOH was detected in 12 of 30 (40%) plasma samples, taken from 8 of 14 (57%) subjects. However, the number of LOH in plasma was small (n = 15), and the mean proportion of LOH was much lower than in the tumors (0.05 vs. 0.52). Although infrequent, 12 of 15 (80%) plasma LOH were concordant with abnormalities in the paired tumors, and the mean percent LOH was higher than in normal plasmas, suggesting that they were authentic tumor-derived abnormalities. We found, despite this, no association, between plasma LOH and tumor stage or clinical status at time of blood collection (i.e., LOH was as common in subjects with no evident disease as in those with evident disease). In addition, detection of LOH was not consistent between serial samples from 5 of 11 subjects (45%), despite stable clinical conditions. No association with clinical outcome was evident, although the sample size was small. Microsatellite instability in plasma was infrequent, nonconcordant with paired tumor and inconsistent in serial samples. This pilot study suggests that identifying tumor-specific LOH in the plasma of breast cancer subjects may not be useful for detecting occult metastases or for monitoring disease. Other detection techniques may be more promising, but circulating tumor DNA may not be a sufficiently accurate reflection of breast cancer clinical status or tumor activity.

Intratumoral Heterogeneity in Microsatellite Alterations in BRCA1 and PTEN Regions in Sporadic Colorectal Cancer

BACKGROUND

Chromosome regions 17q21 (BRCA1) and 10q23 (PTEN) have been found deleted in colorectal cancer.

METHODS

We studied the frequency of loss of heterozygosity (LOH) in these 2 regions in 214 patients with only 1 sample per tumor and in 100 patients with several samples per tumor. Three microsatellite markers of each region were used for the LOH test. The polymerase chain reaction product was electrophoresed in 8% polyacrylamide gels, and band intensity was shown by silver staining.

RESULTS

The proportions of LOH in the two regions were 38.4% for 17q21 and 30.8% for 10q23 in the group of 214 and were 47.7% for 17q21 and 34.7% for 10q23 in the group of 100. We found a high correlation between the LOH in both regions (P <.001), where 81% of LOH in 10q23 region was matched by concomitant LOH in 17q21. In the group of tumors with several samples (group of 100), 39% and 68% did not present LOH in the 17q21 and 10q23 regions, respectively, in all of their tumor samples. However, in the 20 patients with LOH in both regions in the group of 100 (several samples per tumor), all samples with LOH in 10q23 also had LOH in 17q21, whereas not all samples with LOH in 17q21 had LOH in 10q23.

CONCLUSIONS

These results show that colorectal cancer is highly heterogeneous, at least for these tumors markers, and suggest a sequential acquisition pattern of these anomalies during tumor growth, in which changes in 17q21 could occur before those in 10q23.

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.

Plasma DNA microsatellite panel as sensitive and tumor-specific marker in lung cancer patients

The majority of lung cancer patients have tumor-derived genetic alterations in circulating plasma DNA that could be exploited as a diagnostic tool. We used fluorescent microsatellite analysis to detect alterations in plasma and tumor DNA in 34 patients who underwent bronchoscopy for lung cancer, including 11 small cell lung cancer (SCLC) and 23 nonsmall cell lung cancer (NSCLC) (12 adenocarcinomas, 11 squamous cell carcinomas) and 20 controls. Allelotyping was performed with a selected panel of 12 microsatellites from 9 chromosomal regions 3p21, 3p24, 5q, 9p, 9q, 13q, 17p, 17q and 20q. Plasma DNA allelic imbalance (AI) was found in 88% (30 of 34 patients), with a similar sensitivity in SCLC and NSCLC. In the 24 paired available tumor tissues, 83% (20 of 24) presented at least 1 AI. Among these patients, 85% (17 of 20) presented also at least 1 AI in paired plasma DNA, but the location of the allelic alterations in paired plasma and tumor DNA could differ, suggesting the presence of heterogeneous tumor clones. None of the 20 controls displayed plasma or bronchial DNA alteration. A reduced panel of six markers (at 3p, 5q, 9p, 9q) showed a sensitivity of 85%. Moreover, a different panel of microsatellites at 3p and 17p13 in SCLC and at 5q, 9p, 9q and 20q in NSCLC patients could be specifically used. Analysis of plasma DNA using this targeted panel could be a valuable noninvasive test and a useful tool to monitor disease progression without assessing the tumor.

Genetic heterogeneity in lung and colorectal carcinoma as revealed by microsatellite analysis in plasma or tumor tissue DNA

BACKGROUND

Determination of tumor clonality has implications for molecular characterization and the optimal treatment of cancer. Allelotyping allows detection of the two alleles, maternal and paternal, and provides additional information regarding clonal genetic defects. The presence of allelic imbalances (AI) in tumors is a general event, but is not necessary at the same allele (alternative AI). The authors' goal was to determine whether the presence of alternative AI (AA) was a marker of heterogeneity and prognosis.

METHODS

To further analyze the heterogeneity of lung tumors, tumor DNA released in the plasma was compared with primary tumor DNA from 24 lung carcinoma patients. The comparison was performed by allelotyping using 12 microsatellites targeting 9 chromosomal regions, taking in each case leukocyte DNA as reference. To extend and confirm these observations, 26 primary colorectal carcinomas with paired synchronous liver metastasis were analyzed using an enlarged panel of 33 microsatellites.

RESULTS

AA were observed in 40% (20 of 50) of all patients, in 25% (6 of 24) of lung carcinoma patients but at a higher level, and in 54% (14 of 26) of colorectal carcinoma patients. They affected different chromosome localizations and each tumor stage. In both types of cancer, patients with AA had a higher AI mean frequency in their primary tumor.

CONCLUSIONS

Detection of AA is an original marker of heterogeneous tumors, demonstrating that independent events occurred on specific genetic sites required for cancer progression.

Detecting lung cancer in plasma with the use of multiple genetic markers

Recent studies have demonstrated the possibility to detect genetic changes in plasma DNA of cancer patients. The goal of this study was to validate a panel of molecular markers for lung cancer detection in plasma DNA. Three markers, p53, FHIT and microsatellite alterations at loci on chromosome 3, were used to detect mutations in tumor and plasma DNA of 64 stage I-III non small cell lung cancer patients. p53 mutations were studied by direct sequencing of exons 5 through 8 in tumor DNA and by plaque hybridization assay and sequencing in plasma DNA. Allelic losses were evaluated by fluorescent PCR in tumor and plasma DNA. p53 genomic mutations were detected in 26 (40.6%) of 64 tumor DNA samples and the identical mutation was identified in plasma of 19 (73.1%) of them. Microsatellite alterations at FHIT and 3p loci were observed in 40 (62.5%) tumors and in 23 (35.9%) plasma samples. Of the 40 patients showing microsatellite alterations in tumors, 19 (47.5%) displayed the same change in plasma DNA. At least 1 of the 3 genetic markers (p53, FHIT and 3p) was altered in plasma of 51.6% of all patients and 60.7% of stage I patients. Moreover, genetic markers in plasma identified 29 of 45 (64.4%) of all stages and 15 of 22 (68.2%) of stage I patients whose tumors had an alteration. These results provide the proof of principle that plasma DNA alterations are tumor-specific in most cases and support blood testing as a noninvasive strategy for early detection.