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Cell-free nucleic acids as biomarkers in cancer patients

Key Points

  • Increased levels of circulating nucleic acids (DNA, mRNA and microRNA (miRNA)) in the blood reflect pathological processes, including malignant and benign lesions, inflammatory diseases, stroke, trauma and sepsis. During these processes nucleic acids are shed into the blood by apoptotic and necrotic cells.

  • In cancer patients, circulating DNA carries tumour-related genetic and epigenetic alterations that are relevant to cancer development, progression and resistance to therapy. These alterations include loss of heterozygosity (LOH) and mutations of tumour suppressor genes (such as TP53) and oncogenes (such as KRAS and BRAF).

  • Additional genetic alterations that are detectable on circulating DNA and used as biomarkers in cancer include the integrity of non-coding genomic DNA repeat sequences (such as ALU and LINE1). Although still in their infancy, DNA integrity assays have the potential to become a universal blood biomarker for multiple cancers.

  • Epigenetic alterations in genes (such as glutathione S-transferase P1 (GSTP1 and septin 9 (SEPT9)) and adenomatous polyposis coli (APC)) that are relevant to tumorigenesis and the progression of solid tumours have been detected on circulating DNA in cancer patients, and their potential clinical utility is indicated by the launch of commercial tests for cancer screening.

  • The detection of circulating nucleosomes in blood indicates that cell-free DNA (cfDNA) retains at least some features of the nuclear chromatin during the process of DNA release. Initial clinical studies have indicated that monitoring the abundance of nucleosomes has potential utility for monitoring the efficacy of therapy in cancer patients.

  • Dying tumour cells also discharge miRNAs, which circulate stably in the blood. The pivotal functions of miRNAs in cancer development and progression may explain the promising results of pilot studies on cancer patients using miRNA blood tests for tumour detection and prognosis.

  • The cellular source of tumour-derived circulating nucleic acids is still subject to debate. After complete removal of the primary tumour the detection of cfDNA may signal the presence of micrometastatic cells in distant organs, such as the bone marrow, which pose a risk of relapse.

  • Metastatic and primary tumours from the same patient can vary at the genomic, epigenomic and transcriptomic levels. Minimally invasive blood analyses of cell-free nucleic acid allow repetitive real-time monitoring of these events and will, therefore, gain clinical utility in the determination of prognosis and treatment efficacy.

Abstract

DNA, mRNA and microRNA are released and circulate in the blood of cancer patients. Changes in the levels of circulating nucleic acids have been associated with tumour burden and malignant progression. In the past decade a wealth of information indicating the potential use of circulating nucleic acids for cancer screening, prognosis and monitoring of the efficacy of anticancer therapies has emerged. In this Review, we discuss these findings with a specific focus on the clinical utility of cell-free nucleic acids as blood biomarkers.

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Figure 1: Cell-free nucleic acids in the blood.

References

  1. Mandel, P. & Métais, P. Les acides nucléiques du plasma sanguin chez l'homme. C. R. Acad. Sci. Paris 142, 241–243 (1948).

    CAS  Google Scholar 

  2. Sorenson, G. D. et al. Soluble normal and mutated DNA sequences from single-copy genes in human blood. Cancer Epidemiol. Biomarkers Prev. 3, 67–71 (1994).

    CAS  PubMed  Google Scholar 

  3. Vasioukhin, V. et al. Point mutations of the N-ras gene in the blood plasma DNA of patients with myelodysplastic syndrome or acute myelogenous leukaemia. Br. J. Haematol. 86, 774–779 (1994).

    Article  CAS  PubMed  Google Scholar 

  4. Nawroz, H., Koch, W., Anker, P., Stroun, M. & Sidransky, D. Microsatellite alterations in serum DNA of head and neck cancer patients. Nature Med. 2, 1035–1037 (1996).

    Article  CAS  PubMed  Google Scholar 

  5. Kaiser, J. Medicine. Keeping tabs on tumor DNA. Science 327, 1074 (2010).

    Article  PubMed  Google Scholar 

  6. Swaminathan, R. & Butt, A. N. Circulating nucleic acids in plasma and serum: recent developments. Ann. N. Y Acad. Sci. 1075, 1–9 (2006). This review discusses the origin and biological importance of circulating nucleic acids in fetal medicine, oncology and other human-related diseases.

    Article  CAS  PubMed  Google Scholar 

  7. Fleischhacker, M. & Schmidt, B. Circulating nucleic acids (CNAs) and cancer-a survey. Biochim. Biophys. Acta 1775, 181–232 (2007).

    CAS  PubMed  Google Scholar 

  8. Choi, J. J., Reich, C. F. 3rd, & Pisetsky, D. S. The role of macrophages in the in vitro generation of extracellular DNA from apoptotic and necrotic cells. Immunology 115, 55–62 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  9. Stroun, M. et al. The origin and mechanism of circulating DNA. Ann. N. Y Acad. Sci. 906, 161–168 (2000).

    Article  CAS  PubMed  Google Scholar 

  10. Gahan, P. B. & Swaminathan, R. Circulating nucleic acids in plasma and serum. Recent developments. Ann. N. Y Acad. Sci. 1137, 1–6 (2008).

    Article  CAS  PubMed  Google Scholar 

  11. Diehl, F. et al. Detection and quantification of mutations in the plasma of patients with colorectal tumors. Proc. Natl Acad. Sci. USA 102, 16368–16373 (2005).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  12. Jahr, S. et al. DNA fragments in the blood plasma of cancer patients: quantitations and evidence for their origin from apoptotic and necrotic cells. Cancer Res. 61, 1659–1665 (2001).

    CAS  PubMed  Google Scholar 

  13. Schwarzenbach, H. et al. Cell-free tumor DNA in blood plasma as a marker for circulating tumor cells in prostate cancer. Clin. Cancer Res. 15, 1032–1038 (2009). A relationship between the occurrence of CTCs and circulating tumour-associated DNA in blood is described for the first time in patients with prostate cancer.

    Article  CAS  PubMed  Google Scholar 

  14. Schwarzenbach, H. et al. Detection of tumor-specific DNA in blood and bone marrow plasma from patients with prostate cancer. Int. J. Cancer 120, 1465–1471 (2007).

    Article  CAS  PubMed  Google Scholar 

  15. Bendich, A., Wilczok, T. & Borenfreund, E. Circulating DNA as a possible factor in oncogenesis. Science 148, 374–376 (1965).

    Article  CAS  PubMed  Google Scholar 

  16. Emlen, W. & Mannik, M. Effect of DNA size and strandedness on the in vivo clearance and organ localization of DNA. Clin. Exp. Immunol. 56, 185–192 (1984).

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Wimberger, P. et al. Impact of platinum-based chemotherapy on circulating nucleic acid levels, protease activities in blood and disseminated tumor cells in bone marrow of ovarian cancer patients. Int. J. Cancer 128, 2572–2580 (2010). This is the first study indicating the potential value of circulating nucleosomes in monitoring the effects of chemotherapy in ovarian cancer.

    Article  PubMed  CAS  Google Scholar 

  18. Boddy, J. L., Gal, S., Malone, P. R., Harris, A. L. & Wainscoat, J. S. Prospective study of quantitation of plasma DNA levels in the diagnosis of malignant versus benign prostate disease. Clin. Cancer Res. 11, 1394–1399 (2005).

    Article  CAS  PubMed  Google Scholar 

  19. Kamat, A. A. et al. Plasma cell-free DNA in ovarian cancer: an independent prognostic biomarker. Cancer 116, 1918–1925 (2010).

    Article  CAS  PubMed  Google Scholar 

  20. Allen, D. et al. Role of cell-free plasma DNA as a diagnostic marker for prostate cancer. Ann. N. Y Acad. Sci. 1022, 76–80 (2004).

    Article  CAS  PubMed  Google Scholar 

  21. Schwarzenbach, H., Stoehlmacher, J., Pantel, K. & Goekkurt, E. Detection and monitoring of cell-free DNA in blood of patients with colorectal cancer. Ann. N. Y Acad. Sci. 1137, 190–196 (2008).

    Article  CAS  PubMed  Google Scholar 

  22. Chun, F. K. et al. Circulating tumour-associated plasma DNA represents an independent and informative predictor of prostate cancer. BJU Int. 98, 544–548 (2006).

    Article  CAS  PubMed  Google Scholar 

  23. Sunami, E., Vu, A. T., Nguyen, S. L., Giuliano, A. E. & Hoon, D. S. Quantification of LINE1 in circulating DNA as a molecular biomarker of breast cancer. Ann. N. Y Acad. Sci. 1137, 171–174 (2008).

    Article  CAS  PubMed  Google Scholar 

  24. Gormally, E. et al. Amount of DNA in plasma and cancer risk: a prospective study. Int. J. Cancer 111, 746–749 (2004).

    Article  CAS  PubMed  Google Scholar 

  25. Catarino, R. et al. Quantification of free circulating tumor DNA as a diagnostic marker for breast cancer. DNA Cell Biol. 27, 415–421 (2008).

    Article  CAS  PubMed  Google Scholar 

  26. Mehra, N. et al. Circulating mitochondrial nucleic acids have prognostic value for survival in patients with advanced prostate cancer. Clin. Cancer Res. 13, 421–426 (2007).

    Article  CAS  PubMed  Google Scholar 

  27. Ellinger, J., Albers, P., Muller, S. C., von Ruecker, A. & Bastian, P. J. Circulating mitochondrial DNA in the serum of patients with testicular germ cell cancer as a novel noninvasive diagnostic biomarker. BJU Int. 104, 48–52 (2009).

    Article  CAS  PubMed  Google Scholar 

  28. Chiu, R. W. et al. Quantitative analysis of circulating mitochondrial DNA in plasma. Clin. Chem. 49, 719–726 (2003). This is one of the first studies describing the technical approach and detection of mitochondria circulating DNA in plasma.

    Article  CAS  PubMed  Google Scholar 

  29. Tangkijvanich, P. et al. Serum LINE-1 hypomethylation as a potential prognostic marker for hepatocellular carcinoma. Clin. Chim. Acta 379, 127–133 (2007).

    Article  CAS  PubMed  Google Scholar 

  30. Umetani, N. et al. Prediction of breast tumor progression by integrity of free circulating DNA in serum. J. Clin. Oncol. 24, 4270–4276 (2006). First major study demonstrating a direct PCR assay for detecting ALU cfNA in patients with breast cancer. The study demonstrates that an ALU DNA integrity assay can be sensitive to detect early stage metastasis to regional tumour-draining lymph nodes.

    Article  CAS  PubMed  Google Scholar 

  31. Umetani, N. et al. Increased integrity of free circulating DNA in sera of patients with colorectal or periampullary cancer: direct quantitative PCR for ALU repeats. Clin. Chem. 52, 1062–1069 (2006).

    Article  CAS  PubMed  Google Scholar 

  32. Schulz, W. A., Steinhoff, C. & Florl, A. R. Methylation of endogenous human retroelements in health and disease. Curr. Top. Microbiol. Immunol. 310, 211–250 (2006).

    CAS  PubMed  Google Scholar 

  33. Schwarzenbach, H. et al. Comparative evaluation of cell-free tumor DNA in blood and disseminated tumor cells in bone marrow of patients with primary breast cancer. Breast Cancer Res. 11, R71 (2009). First study indicating that tumour cfDNA may stem at least partly from DTCs in bone marrow.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  34. Silva, J. M. et al. Tumor DNA in plasma at diagnosis of breast cancer patients is a valuable predictor of disease-free survival. Clin. Cancer Res. 8, 3761–3766 (2002).

    CAS  PubMed  Google Scholar 

  35. Taback, B. et al. Detection of tumor-specific genetic alterations in bone marrow from early-stage breast cancer patients. Cancer Res. 63, 1884–1887 (2003).

    CAS  PubMed  Google Scholar 

  36. Bruhn, N. et al. Detection of microsatellite alterations in the DNA isolated from tumor cells and from plasma DNA of patients with lung cancer. Ann. N. Y Acad. Sci. 906, 72–82 (2000).

    Article  CAS  PubMed  Google Scholar 

  37. Sozzi, G. et al. Analysis of circulating tumor DNA in plasma at diagnosis and during follow-up of lung cancer patients. Cancer Res. 61, 4675–4678 (2001).

    CAS  PubMed  Google Scholar 

  38. Sunami, E. et al. Multimarker circulating DNA assay for assessing blood of prostate cancer patients. Clin. Chem. 55, 559–567 (2009).

    Article  CAS  PubMed  Google Scholar 

  39. Coulet, F. et al. Detection of plasma tumor DNA in head and neck squamous cell carcinoma by microsatellite typing and p53 mutation analysis. Cancer Res. 60, 707–711 (2000).

    CAS  PubMed  Google Scholar 

  40. Hibi, K. et al. Molecular detection of genetic alterations in the serum of colorectal cancer patients. Cancer Res. 58, 1405–1407 (1998).

    CAS  PubMed  Google Scholar 

  41. Kopreski, M. S. et al. Detection of mutant K-ras DNA in plasma or serum of patients with colorectal cancer. Br. J. Cancer 76, 1293–1299 (1997).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  42. Schulte-Hermann, R. et al. Role of active cell death (apoptosis) in multi-stage carcinogenesis. Toxicol. Lett. 82–83, 143–148 (1995).

    Article  PubMed  Google Scholar 

  43. De Roock, W., Biesmans, B., De Schutter, J. & Tejpar, S. Clinical biomarkers in oncology: focus on colorectal cancer. Mol. Diagn. Ther. 13, 103–114 (2009).

    Article  CAS  PubMed  Google Scholar 

  44. Downward, J. Targeting RAS signalling pathways in cancer therapy. Nature Rev. Cancer 3, 11–22 (2003).

    Article  CAS  Google Scholar 

  45. Levine, A. J. & Oren, M. The first 30 years of p53: growing ever more complex. Nature Rev. Cancer 9, 749–758 (2009).

    Article  CAS  Google Scholar 

  46. Castells, A. et al. K-ras mutations in DNA extracted from the plasma of patients with pancreatic carcinoma: diagnostic utility and prognostic significance. J. Clin. Oncol. 17, 578–584 (1999).

    Article  CAS  PubMed  Google Scholar 

  47. Ryan, B. M. et al. A prospective study of circulating mutant KRAS2 in the serum of patients with colorectal neoplasia: strong prognostic indicator in postoperative follow up. Gut 52, 101–108 (2003).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  48. Wang, S. et al. Potential clinical significance of a plasma-based KRAS mutation analysis in patients with advanced non-small cell lung cancer. Clin. Cancer Res. 16, 1324–1330 (2010).

    Article  CAS  PubMed  Google Scholar 

  49. Shinozaki, M. et al. Utility of circulating B-RAF DNA mutation in serum for monitoring melanoma patients receiving biochemotherapy. Clin. Cancer Res. 13, 2068–2074 (2007). This is the first major study to demonstrate circulating BRAF DNA mutation in patients with different stages of melanoma, and that cfDNA mutation detection has clinical utility for monitoring patient responses before and after therapy.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. Flaherty, K. T. et al. Inhibition of mutated, activated BRAF in metastatic melanoma. N. Engl. J. Med. 363, 809–819 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  51. Kefford, R. et al. Phase I/II study of GSK2118436, a selective inhibitor of oncogenic mutant BRAF kinase, in patients with metastatic melanoma and other solid tumors. J. Clin. Oncol. 28, 8503 (2010).

    Article  Google Scholar 

  52. Ciardiello, F. & Tortora, G. EGFR antagonists in cancer treatment. N. Engl. J. Med. 358, 1160–1174 (2008).

    Article  CAS  PubMed  Google Scholar 

  53. Kimura, H. et al. EGFR mutation status in tumour-derived DNA from pleural effusion fluid is a practical basis for predicting the response to gefitinib. Br. J. Cancer 95, 1390–1395 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  54. Kobayashi, S. et al. EGFR mutation and resistance of non-small-cell lung cancer to gefitinib. N. Engl. J. Med. 352, 786–792 (2005).

    Article  CAS  PubMed  Google Scholar 

  55. Bennett, E. A. et al. Active Alu retrotransposons in the human genome. Genome Res. 18, 1875–1883 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  56. Wolff, E. M. et al. Hypomethylation of a LINE-1 promoter activates an alternate transcript of the MET oncogene in bladders with cancer. PLoS Genet. 6, e1000917 (2010).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  57. Chan, K. C., Leung, S. F., Yeung, S. W., Chan, A. T. & Lo, Y. M. Persistent aberrations in circulating DNA integrity after radiotherapy are associated with poor prognosis in nasopharyngeal carcinoma patients. Clin. Cancer Res. 14, 4141–4145 (2008).

    Article  CAS  PubMed  Google Scholar 

  58. Ellinger, J. et al. Cell-free circulating DNA: diagnostic value in patients with testicular germ cell cancer. J. Urol. 181, 363–371 (2009).

    Article  CAS  PubMed  Google Scholar 

  59. Salani, R. et al. Measurement of cyclin E genomic copy number and strand length in cell-free DNA distinguish malignant versus benign effusions. Clin. Cancer Res. 13, 5805–5809 (2007).

    Article  CAS  PubMed  Google Scholar 

  60. Klose, R. J. & Bird, A. P. Genomic DNA methylation: the mark and its mediators. Trends Biochem. Sci. 31, 89–97 (2006).

    Article  CAS  PubMed  Google Scholar 

  61. Kristensen, L. S. & Hansen, L. L. PCR-based methods for detecting single-locus DNA methylation biomarkers in cancer diagnostics, prognostics, and response to treatment. Clin. Chem. 55, 1471–1483 (2009).

    Article  CAS  PubMed  Google Scholar 

  62. Ellinger, J. et al. CpG island hypermethylation in cell-free serum DNA identifies patients with localized prostate cancer. Prostate 68, 42–49 (2008).

    Article  CAS  PubMed  Google Scholar 

  63. Taback, B., Saha, S. & Hoon, D. S. Comparative analysis of mesenteric and peripheral blood circulating tumor DNA in colorectal cancer patients. Ann. N. Y Acad. Sci. 1075, 197–203 (2006).

    Article  CAS  PubMed  Google Scholar 

  64. Lane, A. A. & Chabner, B. A. Histone deacetylase inhibitors in cancer therapy. J. Clin. Oncol. 27, 5459–5468 (2009).

    Article  CAS  PubMed  Google Scholar 

  65. Cameron, E. E., Bachman, K. E., Myohanen, S., Herman, J. G. & Baylin, S. B. Synergy of demethylation and histone deacetylase inhibition in the re-expression of genes silenced in cancer. Nature Genet. 21, 103–107 (1999).

    Article  CAS  PubMed  Google Scholar 

  66. Laktionov, P. P. et al. Cell-surface-bound nucleic acids: free and cell-surface-bound nucleic acids in blood of healthy donors and breast cancer patients. Ann. N. Y Acad. Sci. 1022, 221–227 (2004).

    Article  CAS  PubMed  Google Scholar 

  67. Stollar, B. D. & Stephenson, F. Apoptosis and nucleosomes. Lupus 11, 787–789 (2002).

    Article  CAS  PubMed  Google Scholar 

  68. Ward, T. H. et al. Biomarkers of apoptosis. Br. J. Cancer 99, 841–846 (2008).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  69. Holdenrieder, S. et al. Nucleosomes in serum of patients with benign and malignant diseases. Int. J. Cancer 95, 114–120 (2001).

    Article  CAS  PubMed  Google Scholar 

  70. Roth, C. et al. Apoptosis-related deregulation of proteolytic activities and high serum levels of circulating nucleosomes and DNA in blood correlate with breast cancer progression. BMC Cancer 11, 4 (2010).

    Article  CAS  Google Scholar 

  71. Holdenrieder, S. et al. Clinical relevance of circulating nucleosomes in cancer. Ann. N. Y Acad. Sci. 1137, 180–189 (2008).

    Article  CAS  PubMed  Google Scholar 

  72. Lo, Y. M. et al. Molecular prognostication of nasopharyngeal carcinoma by quantitative analysis of circulating Epstein-Barr virus DNA. Cancer Res. 60, 6878–6881 (2000).

    CAS  PubMed  Google Scholar 

  73. Kim, B. K. et al. Persistent hepatitis B viral replication affects recurrence of hepatocellular carcinoma after curative resection. Liver Int. 28, 393–401 (2008).

    Article  CAS  PubMed  Google Scholar 

  74. Illades-Aguiar, B. et al. Prevalence and distribution of human papillomavirus types in cervical cancer, squamous intraepithelial lesions, and with no intraepithelial lesions in women from Southern Mexico. Gynecol. Oncol. 117, 291–296 (2010).

    Article  CAS  PubMed  Google Scholar 

  75. Yu, K. H. et al. Quantitative analysis of cell-free Epstein-Barr virus DNA in plasma of patients with nonnasopharyngeal head and neck carcinomas. Clin. Cancer Res. 10, 1726–1732 (2004).

    Article  CAS  PubMed  Google Scholar 

  76. Chan, A. T. et al. Plasma Epstein-Barr virus DNA and residual disease after radiotherapy for undifferentiated nasopharyngeal carcinoma. J. Natl Cancer Inst. 94, 1614–1619 (2002).

    Article  CAS  PubMed  Google Scholar 

  77. Leung, S. F. et al. Plasma Epstein-Barr viral deoxyribonucleic acid quantitation complements tumor-node-metastasis staging prognostication in nasopharyngeal carcinoma. J. Clin. Oncol. 24, 5414–5418 (2006). This study describes the use of plasma EBV in nasopharyngeal carcinoma (NPC) prognostication and monitoring during therapy. Pretherapy circulating EBV DNA level was shown to be an independent prognostic factor in NPC.

    Article  CAS  PubMed  Google Scholar 

  78. Lin, J. C. et al. Quantification of plasma Epstein-Barr virus DNA in patients with advanced nasopharyngeal carcinoma. N. Engl. J. Med. 350, 2461–2470 (2004).

    Article  CAS  PubMed  Google Scholar 

  79. Lo, Y. M. et al. Quantitative analysis of cell-free Epstein-Barr virus DNA in plasma of patients with nasopharyngeal carcinoma. Cancer Res. 59, 1188–1191 (1999). This study describes detection of circulating EBV DNA in patients with NPC and provides evidence that this approach can be used for the monitoring and early detection of NPC.

    CAS  PubMed  Google Scholar 

  80. Lo, Y. M. et al. Plasma cell-free Epstein-Barr virus DNA quantitation in patients with nasopharyngeal carcinoma. Correlation with clinical staging. Ann. N. Y Acad. Sci. 906, 99–101 (2000).

    Article  CAS  PubMed  Google Scholar 

  81. Ji, M. F. et al. Detection of Stage I nasopharyngeal carcinoma by serologic screening and clinical examination. Chin. J. Cancer 30, 120–123 (2011).

    Article  PubMed  PubMed Central  Google Scholar 

  82. Garcia-Olmo, D. C., Ruiz-Piqueras, R. & Garcia-Olmo, D. Circulating nucleic acids in plasma and serum (CNAPS) and its relation to stem cells and cancer metastasis: state of the issue. Histol. Histopathol. 19, 575–583 (2004).

    CAS  PubMed  Google Scholar 

  83. Garcia-Olmo, D. C. et al. Cell-free nucleic acids circulating in the plasma of colorectal cancer patients induce the oncogenic transformation of susceptible cultured cells. Cancer Res. 70, 560–567 (2010).

    Article  CAS  PubMed  Google Scholar 

  84. Sturgeon, C. M. & Diamandis, E. P. Use of tumor markers in clinical practice: quality requirements. Clin. Physiol. Biochem. 1–37 (2008).

  85. Bustin, S. A. et al. The MIQE guidelines: minimum information for publication of quantitative real-time PCR experiments. Clin. Chem. 55, 611–622 (2009).

    Article  CAS  PubMed  Google Scholar 

  86. Orozco, A. F. & Lewis, D. E. Flow cytometric analysis of circulating microparticles in plasma. Cytometry A 77, 502–514 (2010).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  87. Cocucci, E., Racchetti, G. & Meldolesi, J. Shedding microvesicles: artefacts no more. Trends Cell Biol. 19, 43–51 (2009).

    Article  CAS  PubMed  Google Scholar 

  88. O'Driscoll, L. et al. Feasibility and relevance of global expression profiling of gene transcripts in serum from breast cancer patients using whole genome microarrays and quantitative RT-PCR. Cancer Genomics Proteomics 5, 94–104 (2008).

    PubMed  Google Scholar 

  89. Barzon, L., Boscaro, M., Pacenti, M., Taccaliti, A. & Palu, G. Evaluation of circulating thyroid-specific transcripts as markers of thyroid cancer relapse. Int. J. Cancer 110, 914–920 (2004).

    Article  CAS  PubMed  Google Scholar 

  90. Lombardi, C. P. et al. Circulating thyroglobulin mRNA does not predict early and midterm recurrences in patients undergoing thyroidectomy for cancer. Am. J. Surg. 196, 326–332 (2008).

    Article  CAS  PubMed  Google Scholar 

  91. Garcia, V. et al. Free circulating mRNA in plasma from breast cancer patients and clinical outcome. Cancer Lett. 263, 312–320 (2008).

    Article  CAS  PubMed  Google Scholar 

  92. Wong, B. C. et al. Reduced plasma RNA integrity in nasopharyngeal carcinoma patients. Clin. Cancer Res. 12, 2512–2516 (2006).

    Article  CAS  PubMed  Google Scholar 

  93. Miura, N. et al. Clinical usefulness of serum telomerase reverse transcriptase (hTERT) mRNA and epidermal growth factor receptor (EGFR) mRNA as a novel tumor marker for lung cancer. Cancer Sci. 97, 1366–1373 (2006).

    Article  CAS  PubMed  Google Scholar 

  94. Kosaka, N., Iguchi, H. & Ochiya, T. Circulating microRNA in body fluid: a new potential biomarker for cancer diagnosis and prognosis. Cancer Sci. 101, 2087–2092 (2010).

    Article  CAS  PubMed  Google Scholar 

  95. Mitchell, P. S. et al. Circulating microRNAs as stable blood-based markers for cancer detection. Proc. Natl Acad. Sci. USA 105, 10513–10518 (2008). This is the first major study describing the detection of circulating miRNAs in both plasma and serum, and their use in assessing patients with prostate cancer.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  96. Schaefer, A. et al. Suitable reference genes for relative quantification of miRNA expression in prostate cancer. Exp. Mol. Med. 42, 749–758 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  97. Mestdagh, P. et al. A novel and universal method for microRNA RT-qPCR data normalization. Genome Biol. 10, R64 (2009).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  98. Heneghan, H. M., Miller, N., Lowery, A. J., Sweeney, K. J. & Kerin, M. J. MicroRNAs as novel biomarkers for breast cancer. J. Oncol. 2009, 950201 (2009).

    CAS  PubMed  Google Scholar 

  99. Lawrie, C. H. et al. Detection of elevated levels of tumour-associated microRNAs in serum of patients with diffuse large B-cell lymphoma. Br. J. Haematol. 141, 672–675 (2008). The presence of miRNAs in serum was first described for cancer patients in this paper.

    Article  PubMed  Google Scholar 

  100. Roth, C., Kasimir-Bauer, S., Heubner, M., Pantel, K. & Schwarzenbach, H. Circulating Nucleic Acids in Plasma and Serum. 63–71 (Springer, 2011).

    Google Scholar 

  101. Roth, C. et al. Circulating microRNAs as blood-based markers for patients with primary and metastatic breast cancer. Breast Cancer Res. 12, R90 (2010).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  102. Ng, E. K. et al. Differential expression of microRNAs in plasma of patients with colorectal cancer: a potential marker for colorectal cancer screening. Gut 58, 1375–1381 (2009).

    Article  CAS  PubMed  Google Scholar 

  103. Asaga, S. et al. Direct serum assay for microRNA-21 concentrations in early and advanced breast cancer. Clin. Chem. 57, 84–91 (2011). This study demonstrates the development of a direct blood PCR assay for detection of circulating miR-21 and its ability to assess early stage breast cancer in serum.

    Article  CAS  PubMed  Google Scholar 

  104. Hu, Z. et al. Serum microRNA signatures identified in a genome-wide serum microRNA expression profiling predict survival of non-small-cell lung cancer. J. Clin. Oncol. 28, 1721–1726 (2010). This article describes the first major study on the use of a panel of circulating miRNAs in serum to predict overall survival outcome in NSCLC.

    Article  PubMed  Google Scholar 

  105. Lu, J. et al. MicroRNA expression profiles classify human cancers. Nature 435, 834–838 (2005).

    Article  CAS  PubMed  Google Scholar 

  106. Yamamoto, Y. et al. MicroRNA-500 as a potential diagnostic marker for hepatocellular carcinoma. Biomarkers 14, 529–538 (2009).

    Article  CAS  PubMed  Google Scholar 

  107. Pantel, K. & Alix-Panabieres, C. Circulating tumour cells in cancer patients: challenges and perspectives. Trends Mol. Med. 16, 398–406 (2010).

    Article  PubMed  Google Scholar 

  108. Pantel, K., Brakenhoff, R. H. & Brandt, B. Detection, clinical relevance and specific biological properties of disseminating tumour cells. Nature Rev. Cancer 8, 329–340 (2008).

    Article  CAS  Google Scholar 

  109. Schwarzenbach, H. & Pantel, K. Methods of Cancer Diagnosis, Therapy and Prognosis. 481–497 (Springer, USA, 2008).

    Google Scholar 

  110. Nawroz-Danish, H. et al. Microsatellite analysis of serum DNA in patients with head and neck cancer. Int. J. Cancer 111, 96–100 (2004).

    Article  CAS  PubMed  Google Scholar 

  111. Koyanagi, K. et al. Association of circulating tumor cells with serum tumor-related methylated DNA in peripheral blood of melanoma patients. Cancer Res. 66, 6111–6117 (2006). This study indicates that a combined assessment of methylated cfDNA and CTCs in blood may be a useful determinant of disease status and efficacy of systemic therapy of metastatic melanoma.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  112. Matuschek, C. et al. Methylated APC and GSTP1 genes in serum DNA correlate with the presence of circulating blood tumor cells and are associated with a more aggressive and advanced breast cancer disease. Eur. J. Med. Res. 15, 277–286 (2010).

    CAS  PubMed  PubMed Central  Google Scholar 

  113. Pinzani, P. et al. Tyrosinase mRNA levels in the blood of uveal melanoma patients: correlation with the number of circulating tumor cells and tumor progression. Melanoma Res. 20, 303–310 (2010).

    Article  CAS  PubMed  Google Scholar 

  114. Van der Auwera, I. et al. The presence of circulating total DNA and methylated genes is associated with circulating tumour cells in blood from breast cancer patients. Br. J. Cancer 100, 1277–1286 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  115. Mori, T. et al. Predictive utility of circulating methylated DNA in serum of melanoma patients receiving biochemotherapy. J. Clin. Oncol. 23, 9351–9358 (2005). This was the first study to demonstrate that hypermethylation of cfDNA in patients with melanoma relates to tumour progression and response to therapy, and that a panel of methylated tumour-related cfDNA can be of prognostic value before therapy.

    Article  CAS  PubMed  Google Scholar 

  116. Diehl, F. et al. Circulating mutant DNA to assess tumor dynamics. Nature Med. 14, 985–990 (2008). This article describes a new highly sensitive approach to quantify cfDNA which was applied to monitor chemotherapy.

    Article  CAS  PubMed  Google Scholar 

  117. Esteller, M. & Herman, J. G. Cancer as an epigenetic disease: DNA methylation and chromatin alterations in human tumours. J. Pathol. 196, 1–7 (2002).

    Article  CAS  PubMed  Google Scholar 

  118. Hendrich, B. & Tweedie, S. The methyl-CpG binding domain and the evolving role of DNA methylation in animals. Trends Genet. 19, 269–277 (2003).

    Article  CAS  PubMed  Google Scholar 

  119. Zheng, Y. G., Wu, J., Chen, Z. & Goodman, M. Chemical regulation of epigenetic modifications: opportunities for new cancer therapy. Med. Res. Rev. 28, 645–687 (2008).

    Article  CAS  PubMed  Google Scholar 

  120. Cedar, H. & Bergman, Y. Linking DNA methylation and histone modification: patterns and paradigms. Nature Rev. Genet. 10, 295–304 (2009).

    Article  CAS  PubMed  Google Scholar 

  121. Croce, C. M. Causes and consequences of microRNA dysregulation in cancer. Nature Rev. Genet. 10, 704–714 (2009).

    Article  CAS  PubMed  Google Scholar 

  122. Bartel, D. P. MicroRNAs: target recognition and regulatory functions. Cell 136, 215–233 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  123. Ellinger, J. et al. Apoptotic DNA fragments in serum of patients with muscle invasive bladder cancer: a prognostic entity. Cancer Lett. 264, 274–280 (2008).

    Article  CAS  PubMed  Google Scholar 

  124. Valenzuela, M. T. et al. Assessing the use of p16INK4α promoter gene methylation in serum for detection of bladder cancer. Eur. Urol. 42, 622–628; discussion 628–30 (2002).

    Article  CAS  PubMed  Google Scholar 

  125. Utting, M., Werner, W., Dahse, R., Schubert, J. & Junker, K. Microsatellite analysis of free tumor DNA in urine, serum, and plasma of patients: a minimally invasive method for the detection of bladder cancer. Clin. Cancer Res. 8, 35–40 (2002).

    CAS  PubMed  Google Scholar 

  126. Fiegl, H. et al. Circulating tumor-specific DNA: a marker for monitoring efficacy of adjuvant therapy in cancer patients. Cancer Res. 65, 1141–1145 (2005).

    Article  CAS  PubMed  Google Scholar 

  127. Rykova, E. Y. et al. Extracellular DNA in breast cancer: cell-surface-bound, tumor-derived extracellular DNA in blood of patients with breast cancer and nonmalignant tumors. Ann. N. Y Acad. Sci. 1022, 217–220 (2004).

    Article  CAS  PubMed  Google Scholar 

  128. Sharma, G. et al. CpG hypomethylation of MDR1 gene in tumor and serum of invasive ductal breast carcinoma patients. Clin. Biochem. 43, 373–379 (2010).

    Article  CAS  PubMed  Google Scholar 

  129. Sharma, G. et al. Clinical significance of promoter hypermethylation of DNA repair genes in tumor and serum DNA in invasive ductal breast carcinoma patients. Life Sci. 87, 83–91 (2010).

    Article  CAS  PubMed  Google Scholar 

  130. Skvortsova, T. E. et al. Cell-free and cell-bound circulating DNA in breast tumours: DNA quantification and analysis of tumour-related gene methylation. Br. J. Cancer 94, 1492–1495 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  131. Deligezer, U. et al. Effect of adjuvant chemotherapy on integrity of free serum DNA in patients with breast cancer. Ann. N. Y Acad. Sci. 1137, 175–179 (2008).

    Article  CAS  PubMed  Google Scholar 

  132. Kohler, C. et al. Levels of plasma circulating cell free nuclear and mitochondrial DNA as potential biomarkers for breast tumors. Mol. Cancer 8, 105 (2009).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  133. Ren, C. C. et al. Methylation status of the fragile histidine triad and E-cadherin genes in plasma of cervical cancer patients. Int. J. Gynecol. Cancer 16, 1862–1867 (2006).

    Article  CAS  PubMed  Google Scholar 

  134. Widschwendter, A. et al. DNA methylation in serum and tumors of cervical cancer patients. Clin. Cancer Res. 10, 565–571 (2004).

    Article  CAS  PubMed  Google Scholar 

  135. Pornthanakasem, W. et al. Human papillomavirus DNA in plasma of patients with cervical cancer. BMC Cancer 1, 2 (2001).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  136. Lecomte, T. et al. Detection of free-circulating tumor-associated DNA in plasma of colorectal cancer patients and its association with prognosis. Int. J. Cancer 100, 542–548 (2002).

    Article  CAS  PubMed  Google Scholar 

  137. Lefebure, B. et al. Prognostic value of circulating mutant DNA in unresectable metastatic colorectal cancer. Ann. Surg. 251, 275–280 (2010).

    Article  PubMed  Google Scholar 

  138. Trevisiol, C. et al. Prognostic value of circulating KRAS2 gene mutations in colorectal cancer with distant metastases. Int. J. Biol. Markers 21, 223–228 (2006).

    Article  CAS  PubMed  Google Scholar 

  139. Wang, J. Y. et al. Molecular detection of APC, K- ras, and p53 mutations in the serum of colorectal cancer patients as circulating biomarkers. World J. Surg. 28, 721–726 (2004).

    PubMed  Google Scholar 

  140. deVos, T. et al. Circulating methylated SEPT9 DNA in plasma is a biomarker for colorectal cancer. Clin. Chem. 55, 1337–1346 (2009).

    Article  CAS  PubMed  Google Scholar 

  141. Grutzmann, R. et al. Sensitive detection of colorectal cancer in peripheral blood by septin 9 DNA methylation assay. PLoS ONE 3, e3759 (2008). This was the first study that demonstarated the clinical use of methylated cfDNA as a specific plasma biomarker for screening colorectal cancer.

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  142. He, Q. et al. Development of a multiplex MethyLight assay for the detection of multigene methylation in human colorectal cancer. Cancer Genet. Cytogenet. 202, 1–10 (2010).

    Article  CAS  PubMed  Google Scholar 

  143. Tanzer, M. et al. Performance of epigenetic markers SEPT9 and ALX4 in plasma for detection of colorectal precancerous lesions. PLoS ONE 5, e9061 (2010).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  144. Chan, K. C. et al. Quantitative analysis of circulating methylated DNA as a biomarker for hepatocellular carcinoma. Clin. Chem. 54, 1528–1536 (2008).

    Article  CAS  PubMed  Google Scholar 

  145. Wang, J., Qin, Y., Li, B., Sun, Z. & Yang, B. Detection of aberrant promoter methylation of GSTP1 in the tumor and serum of Chinese human primary hepatocellular carcinoma patients. Clin. Biochem. 39, 344–348 (2006).

    Article  CAS  PubMed  Google Scholar 

  146. Wong, I. H., Lo, Y. M., Yeo, W., Lau, W. Y. & Johnson, P. J. Frequent p15 promoter methylation in tumor and peripheral blood from hepatocellular carcinoma patients. Clin. Cancer Res. 6, 3516–3521 (2000).

    CAS  PubMed  Google Scholar 

  147. Ren, N. et al. The prognostic value of circulating plasma DNA level and its allelic imbalance on chromosome 8p in patients with hepatocellular carcinoma. J. Cancer Res. Clin. Oncol. 132, 399–407 (2006).

    Article  CAS  PubMed  Google Scholar 

  148. Szymanska, K. et al. Ser-249TP53 mutation in tumour and plasma DNA of hepatocellular carcinoma patients from a high incidence area in the Gambia, West Africa. Int. J. Cancer 110, 374–379 (2004).

    Article  CAS  PubMed  Google Scholar 

  149. Kirk, G. D. et al. 249ser TP53 mutation in plasma DNA, hepatitis B viral infection, and risk of hepatocellular carcinoma. Oncogene 24, 5858–5867 (2005).

    Article  CAS  PubMed  Google Scholar 

  150. Su, Y. W., Huang, Y. W., Chen, S. H. & Tzen, C. Y. Quantitative analysis of plasma HBV DNA for early evaluation of the response to transcatheter arterial embolization for HBV-related hepatocellular carcinoma. World J. Gastroenterol. 11, 6193–6196 (2005).

    Article  PubMed  PubMed Central  Google Scholar 

  151. Gautschi, O. et al. Origin and prognostic value of circulating KRAS mutations in lung cancer patients. Cancer Lett. 254, 265–273 (2007).

    Article  CAS  PubMed  Google Scholar 

  152. Jian, G. et al. Prediction of epidermal growth factor receptor mutations in the plasma/pleural effusion to efficacy of gefitinib treatment in advanced non-small cell lung cancer. J. Cancer Res. Clin. Oncol. 136, 1341–1347 (2010).

    Article  PubMed  CAS  Google Scholar 

  153. An, Q. et al. Detection of p16 hypermethylation in circulating plasma DNA of non-small cell lung cancer patients. Cancer Lett. 188, 109–114 (2002).

    Article  CAS  PubMed  Google Scholar 

  154. Bearzatto, A. et al. p16INK4A Hypermethylation detected by fluorescent methylation-specific PCR in plasmas from non-small cell lung cancer. Clin. Cancer Res. 8, 3782–3787 (2002).

    CAS  PubMed  Google Scholar 

  155. Liu, Y. et al. Hypermethylation of p16INK4α in Chinese lung cancer patients: biological and clinical implications. Carcinogenesis 24, 1897–1901 (2003).

    Article  CAS  PubMed  Google Scholar 

  156. Ng, C. S. et al. Tumor p16M is a possible marker of advanced stage in non-small cell lung cancer. J. Surg. Oncol. 79, 101–106 (2002).

    Article  PubMed  Google Scholar 

  157. Ramirez, J. L. et al. 14-3-3sigma methylation in pretreatment serum circulating DNA of cisplatin-plus-gemcitabine-treated advanced non-small-cell lung cancer patients predicts survival: The Spanish Lung Cancer Group. J. Clin. Oncol. 23, 9105–9112 (2005).

    Article  CAS  PubMed  Google Scholar 

  158. Hosny, G., Farahat, N. & Hainaut, P. TP53 mutations in circulating free DNA from Egyptian patients with non-Hodgkin's lymphoma. Cancer Lett. 275, 234–239 (2009).

    Article  CAS  PubMed  Google Scholar 

  159. Au, W. Y., Pang, A., Choy, C., Chim., C. S. & Kwong, Y. L. Quantification of circulating Epstein-Barr virus (EBV) DNA in the diagnosis and monitoring of natural killer cell and EBV-positive lymphomas in immunocompetent patients. Blood 104, 243–249 (2004).

    Article  CAS  PubMed  Google Scholar 

  160. Lei, K. I., Chan, L. Y., Chan, W. Y., Johnson, P. J. & Lo, Y. M. Diagnostic and prognostic implications of circulating cell-free Epstein-Barr virus DNA in natural killer/T-cell lymphoma. Clin. Cancer Res. 8, 29–34 (2002).

    CAS  PubMed  Google Scholar 

  161. Machado, A. S. et al. Circulating cell-free and Epstein-Barr virus DNA in pediatric B-non-Hodgkin lymphomas. Leuk. Lymphoma 51, 1020–1027 (2010).

    Article  CAS  PubMed  Google Scholar 

  162. Deligezer, U., Yaman, F., Erten, N. & Dalay, N. Frequent copresence of methylated DNA and fragmented nucleosomal DNA in plasma of lymphoma patients. Clin. Chim. Acta 335, 89–94 (2003).

    Article  CAS  PubMed  Google Scholar 

  163. Board, R. E. et al. Detection of BRAF mutations in the tumour and serum of patients enrolled in the AZD6244 (ARRY-142886) advanced melanoma phase II study. Br. J. Cancer 101, 1724–1730 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  164. Pinzani, P. et al. Allele specific Taqman-based real-time PCR assay to quantify circulating BRAFV600E mutated DNA in plasma of melanoma patients. Clin. Chim. Acta 411, 1319–1324 (2010).

    Article  CAS  PubMed  Google Scholar 

  165. Fujimoto, A., O'Day, S. J., Taback, B., Elashoff, D. & Hoon, D. S. Allelic imbalance on 12q22–23 in serum circulating DNA of melanoma patients predicts disease outcome. Cancer Res. 64, 4085–4088 (2004).

    Article  CAS  PubMed  Google Scholar 

  166. Fujiwara, Y. et al. Plasma DNA microsatellites as tumor-specific markers and indicators of tumor progression in melanoma patients. Cancer Res. 59, 1567–1571 (1999).

    CAS  PubMed  Google Scholar 

  167. Taback, B. et al. Prognostic significance of circulating microsatellite markers in the plasma of melanoma patients. Cancer Res. 61, 5723–5726 (2001).

    CAS  PubMed  Google Scholar 

  168. Taback, B. et al. Circulating DNA microsatellites: molecular determinants of response to biochemotherapy in patients with metastatic melanoma. J. Natl Cancer Inst. 96, 152–156 (2004).

    Article  CAS  PubMed  Google Scholar 

  169. Melnikov, A., Scholtens, D., Godwin, A. & Levenson, V. Differential methylation profile of ovarian cancer in tissues and plasma. J. Mol. Diagn. 11, 60–65 (2009).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  170. Muller, H. M. et al. Analysis of methylated genes in peritoneal fluids of ovarian cancer patients: a new prognostic tool. Clin. Chem. 50, 2171–2173 (2004).

    Article  PubMed  CAS  Google Scholar 

  171. Swisher, E. M. et al. Tumor-specific p53 sequences in blood and peritoneal fluid of women with epithelial ovarian cancer. Am. J. Obstet. Gynecol. 193, 662–667 (2005).

    Article  CAS  PubMed  Google Scholar 

  172. Zachariah, R. R. et al. Levels of circulating cell-free nuclear and mitochondrial DNA in benign and malignant ovarian tumors. Obstet. Gynecol. 112, 843–850 (2008).

    Article  CAS  PubMed  Google Scholar 

  173. Liggett, T. et al. Differential methylation of cell-free circulating DNA among patients with pancreatic cancer versus chronic pancreatitis. Cancer 116, 1674–1680 (2010).

    Article  CAS  PubMed  Google Scholar 

  174. Melnikov, A. A., Scholtens, D., Talamonti, M. S., Bentrem, D. J. & Levenson, V. V. Methylation profile of circulating plasma DNA in patients with pancreatic cancer. J. Surg. Oncol. 99, 119–122 (2009).

    Article  PubMed  Google Scholar 

  175. Bastian, P. J. et al. Preoperative serum DNA GSTP1 CpG island hypermethylation and the risk of early prostate-specific antigen recurrence following radical prostatectomy. Clin. Cancer Res. 11, 4037–4043 (2005).

    Article  CAS  PubMed  Google Scholar 

  176. Bryzgunova, O. E., Morozkin, E. S., Yarmoschuk, S. V., Vlassov, V. V. & Laktionov, P. P. Methylation-specific sequencing of GSTP1 gene promoter in circulating/extracellular DNA from blood and urine of healthy donors and prostate cancer patients. Ann. N. Y Acad. Sci. 1137, 222–225 (2008).

    Article  CAS  PubMed  Google Scholar 

  177. Goessl, C., Muller, M., Heicappell, R., Krause, H. & Miller, K. DNA-based detection of prostate cancer in blood, urine, and ejaculates. Ann. N. Y Acad. Sci. 945, 51–58 (2001).

    Article  CAS  PubMed  Google Scholar 

  178. Jeronimo, C. et al. Quantitative GSTP1 hypermethylation in bodily fluids of patients with prostate cancer. Urology 60, 1131–1135 (2002).

    Article  PubMed  Google Scholar 

  179. Roupret, M. et al. Promoter hypermethylation in circulating blood cells identifies prostate cancer progression. Int. J. Cancer 122, 952–956 (2008).

    Article  CAS  PubMed  Google Scholar 

  180. Ellinger, J. et al. Noncancerous PTGS2 DNA fragments of apoptotic origin in sera of prostate cancer patients qualify as diagnostic and prognostic indicators. Int. J. Cancer 122, 138–143 (2008).

    Article  CAS  PubMed  Google Scholar 

  181. Ellinger, J., Muller, S. C., Wernert, N., von Ruecker, A. & Bastian, P. J. Mitochondrial DNA in serum of patients with prostate cancer: a predictor of biochemical recurrence after prostatectomy. BJU Int. 102, 628–632 (2008).

    Article  PubMed  Google Scholar 

  182. Jemal, A. et al. Global cancer statistics. CA Cancer J. Clin. 61, 69–90 (2011).

    Article  PubMed  Google Scholar 

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Acknowledgements

Funding was provided by Deutsche Forschungsgemeinschaft, Deutsche Krebshilfe, BMBF, Erich und Gertrud Roggenbuck-Stiftung, and the Sheldon and Miriam Adelson Foundation (to D.S.B.H.), the Melanoma Research Alliance (to D.S.B.H.), KOMEN BCTR0707528, CBCRP 16IB-0076 (to D.S.B.H.), and the US National Institutes of Health NCI R33, PO1 CA29605 and CA12582 (to D.S.B.H.).

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microRNAs

Small non-coding RNA molecules that modulate the activity of specific mRNA molecules by binding and inhibiting their translation into polypeptides.

Quantitative real-time clamp PCR assay

A technique that uses a peptide nucleic acid clamp and locked nucleic acid probes, which are DNA synthetic analogues that hybridize to complementary DNA and are highly sensitive and specific for recognizing single base pair mismatches.

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Schwarzenbach, H., Hoon, D. & Pantel, K. Cell-free nucleic acids as biomarkers in cancer patients. Nat Rev Cancer 11, 426–437 (2011). https://doi.org/10.1038/nrc3066

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