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Colorectal cancer screening: prospects for molecular stool analysis


Colorectal cancer is common. As many patients present with advanced disease, an effective screening test would have substantial clinical benefits. Recent progress in understanding the biology of colorectal cancer (and of cancer cells in general) has led to possible new approaches to screening. In particular, there are prospects of developing tests based on analysis of stool, which promise improved accuracy, safety, affordability and patient compliance.

Key Points

  • Colorectal cancer (CRC) is amenable to screening: it has a recognizable early stage and a defined natural history; surgical treatment of malignancy is effective; and pre-malignant lesions can be removed if detected. However, it is not yet clear whether screening should target early cancers or pre-malignant adenomas.

  • Current screening tests either detect the presence of blood in stool (faecal occult blood testing) or identify gross abnormalities (for example, flexible sigmoidoscopy and colonoscopy). All current tests are limited in patient acceptability and/or effectiveness.

  • There are prospects for new screening tests based on increased understanding of the biology and natural history of CRC. There is considerable interest in stool testing, which is non-invasive; does not require bowel preparation; potentially enables screening of the entire length of the colon and rectum; and produces specimens that are transportable.

  • One category of stool test involves detecting cells or cell contents in stool, for which colonocytes are likely to be a better target than blood. Biomarkers such as minichromosome maintenance proteins could indicate the presence of CRC cells in stool and/or facilitate the identification of such cells following colonocyte isolation.

  • An alternative approach involves testing for abnormal DNA in stool, using target genes identified as being abnormal in the colorectal adenoma–carcinoma sequence. Individual DNA tests generally have high specificity but low sensitivity, so multitarget DNA assays have been developed.

  • Large-scale evaluation of candidate tests, either singly or in combination, is now required. Of particular value would be randomized controlled trials showing a reduction in CRC incidence and/or mortality in the tested individuals.

  • An effective screening strategy would produce extra health-care provision costs, although these would be balanced by a reduced requirement to treat patients with established CRC. 'Halo effects' of an effective screening test would produce benefits for patients with symptomatic CRC as well as the screened population.

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  1. 1

    Parkin, D. M. Global cancer statistics in the year 2000. Lancet Oncol. 2, 533–543 (2001).

  2. 2

    Hayne, D. et al. Current trends in colorectal cancer: site, incidence, mortality and survival in England and Wales. Clin. Oncol. (R. Coll. Radiol.) 13, 448–452 (2001).

  3. 3

    Mamazza, J. & Gordon, P. H. The changing distribution of large intestinal cancer. Dis. Colon Rectum 25, 558–562 (1982).

  4. 4

    McCallion, K. et al. Flexible sigmoidoscopy and the changing distribution of colorectal cancer: implications for screening. Gut 48, 522–525 (2001).

  5. 5

    Cucino, C., Buchner, A. M. & Sonnenberg, A. Continued rightward shift of colorectal cancer Dis. Colon Rectum 45, 1035–1040 (2002).

  6. 6

    Cooper, G. S., Yuan, S., Landefeld, C. S., Johanson, J. F. & Rimm, A. A. A national population-based study of colorectal cancer and age: implications for screening in older Americans. Cancer 75, 775–781 (1995).

  7. 7

    Rabeneck, L., Davila, J. A. & El-Serag, H. B. Is there a true 'shift' to the right colon in the incidence of colorectal cancer? Am. J. Gastroenterol. 98, 1400–1409 (2003).

  8. 8

    Morson, B. C. Evolution of cancer of the colon and rectum. Cancer 34 (Suppl.), 845–849 (1974).

  9. 9

    Fearon, E. R. & Vogelstein, B. A genetic model for colorectal tumorigenesis. Cell 61, 759–767 (1990).

  10. 10

    Kinzler, K. W. & Vogelstein B. Lessons from hereditary colorectal cancer. Cell 87, 159–170 (1996).

  11. 11

    Kozuka, S., Nogaki, M., Ozeki, T. & Masumori, S. Premalignancy of the mucosal polyp in the large intestine: II. Estimation of the periods required for malignant transformation of mucosal polyps. Dis. Colon Rectum 18, 494–500 (1975).

  12. 12

    O'Brien, M. J. et al. The National Polyp Study. Patient and polyp characteristics associated with high-grade dysplasia in colorectal adenomas. Gastroenterology 98, 371–379 (1990).

  13. 13

    Kudo, S., Kashida, H. & Tamura, T. Early colorectal cancer: flat or depressed type. J. Gastroenterol. Hepatol. 15 (Suppl.), D66–D70 (2000).

  14. 14

    Umetani, N. et al. Involvement of APC and K-ras mutation in non-polypoid colorectal tumorigenesis. Br. J. Cancer 82, 9–15 (2000).

  15. 15

    Hirota, S. et al. p53 immunoreactive stain and early colorectal adenocarcinomas. Eur. J. Cancer 31A, 2220–2222 (1995).

  16. 16

    Wada, R. et al. Histopathological studies of superficial-type early colorectal carcinoma. Cancer 77, 44–50 (1996).

  17. 17

    Chung, D. C. & Rustgi, A. K. DNA mismatch repair and cancer. Gastroenterology 109, 1685–1699 (1995).

  18. 18

    Thibodeau, S. N., Bren, G. & Schaid, D. Microsatellite instability in cancer of the proximal colon. Science 260, 816–819 (1993).

  19. 19

    Frayling, I. M. Microsatellite instability. Gut 45, 1–4 (1999).

  20. 20

    Rhodes, J. M. Colorectal cancer screening in the UK: joint position statement by the British Society of Gastroenterology, the Royal College of Physicians, and the Association of Coloproctology of Great Britain and Ireland. Gut 46, 746–748 (2000).

  21. 21

    Baldwin, P., Laskey, R. & Coleman, N. Translational approaches to improve cervical screening. Nature Rev. Cancer 3, 217–226 (2003).

  22. 22

    Winawer, S. et al. Gastrointestinal Consortium Panel. Colorectal cancer screening and surveillance: clinical guidelines and rationale—update based on new evidence. Gastroenterology 124, 544–560 (2003).

  23. 23

    Newcomb, P. A., Norfleet, R. G., Storer, B. E., Surawicz, T. S. & Marcus, P. M. Screening sigmoidoscopy and colorectal cancer mortality. J. Natl Cancer Inst. 84, 1572–1575 (1992).

  24. 24

    Selby, J. V., Friedman, G. D., Quesenberry, C. P. Jr. & Weiss, N. S. A case-control study of screening sigmoidoscopy and mortality from colorectal cancer. N. Engl. J. Med. 326, 653–657 (1992).

  25. 25

    Muller, A. D. & Sonnenberg, A. Prevention of colorectal cancer by flexible sigmoidoscopy and polypectomy. A case-control study of 32,702 veterans. Ann. Intern. Med. 123, 904–910 (1995).

  26. 26

    Newcomb, P. A., Storer, B. E., Morimoto, L. M., Templeton, A. & Potter, J. D. Long-term efficacy of sigmoidoscopy in the reduction of colorectal cancer incidence. J. Natl Cancer Inst. 95, 622–625 (2003).

  27. 27

    Pickhardt, P. J. et al. Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. N. Engl. J. Med. 349, 2191–2200 (2003).

  28. 28

    Luboldt, W. et al. Computer-aided diagnosis in contrast-enhanced CT colonography: an approach based on contrast. Eur. Radiol. 12, 2236–2241 (2002).

  29. 29

    Ahlquist, D. A., McGill, D. B., Schwartz., S., Taylor, W. F. & Owen, R. A. Fecal blood levels in health and disease. N. Engl. J. Med. 312, 1422–1428 (1985).

  30. 30

    Young, G. P. & St. John, D. J. Selecting an occult blood test for use as a screening tool for large bowel cancer. Front. Gastrointest. Res. 18, 135–156 (1991).

  31. 31

    Macrae, F. A. & St. John, D. J. Relationship between patterns of bleeding and Haemoccult sensitivity in patients with colorectal cancers or adenomas. Gastroenterology 82, 891–898 (1982).

  32. 32

    Ahlquist, D. A. et al. Patterns of occult bleeding in asymptomatic colorectal cancer. Cancer 63, 1826–1830 (1989).

  33. 33

    Mandel, J. S. et al. Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study. N. Engl. J. Med. 328, 1365–1371 (1993). The first published randomized trial to show a reduction in mortality from CRC following FOBT screening.

  34. 34

    Mandel, J. S., Church, T. R., Ederer, F. & Bond, J. H. Colorectal cancer mortality: effectiveness of biennial screening for fecal occult blood. J. Natl Cancer Inst. 91, 434–437 (1999).

  35. 35

    Kronborg, O., Fenger, C., Olsen J., Jorgensen, O. D. & Sondergaard, O. Randomised study of screening for colorectal cancer with faecal-occult-blood test. Lancet 348, 1467–1471 (1996).

  36. 36

    Jorgensen, O. D., Kronborg, O. & Fenger, C. A randomised study of screening for colorectal cancer using faecal occult blood testing: results after 13 years and seven biennial screening rounds. Gut 50, 29–32 (2002).

  37. 37

    Hardcastle, J. D. et al. Randomised controlled trial of faecal-occult-blood screening for colorectal cancer. Lancet 348, 1472–1477 (1996).

  38. 38

    Mandel, J. S. et al. The effect of fecal occult-blood screening on the incidence of colorectal cancer. N. Engl. J. Med. 343, 1603–1607 (2000).

  39. 39

    Towler, B. P., Irwig, L., Glasziou, P., Weller, D. & Kewenter, J. Screening for colorectal cancer using the faecal occult blood test, Hemoccult. Cochrane Database Syst. Rev. 2, CD001216 (1998).

  40. 40

    Cole, S. R. & Young, G. P. Effect of dietary restriction on participation in faecal occult blood test screening for colorectal cancer. Med. J. Aust. 175, 195–198 (2001).

  41. 41

    Young, G. P. et al. Prescreening evaluation of a brush-based faecal immunochemical test for haemoglobin. J. Med. Screen. 10, 123–128 (2003).

  42. 42

    Cole, S. R., Young, G. P., Esterman, A., Cadd, B. & Morcom, J. A randomised trial of the impact of new faecal haemoglobin test technologies on population participation in screening for colorectal cancer. J. Med. Screen. 10, 117–122 (2003).

  43. 43

    Nakajima, M. et al. Prevention of advanced colorectal cancer by screening using the immunochemical faecal occult blood test: a case-control study. Br. J. Cancer 89, 23–28 (2003).

  44. 44

    Gilbert, J. A. et al. Fecal marker variability in colorectal cancer: calprotectin versus hemoglobin. Scand. J. Gastroenterol. 31, 1001–1005 (1996).

  45. 45

    Johne, B., Kronberg, O., Ton, H. I., Kristinsson, J. & Fuglerud, P. A new fecal calprotectin test for colorectal neoplasia. Scand. J. Gastroenterol. 3, 291–296 (2001).

  46. 46

    Limburg, P. J. et al. Prospective evaluation of fecal calprotectin as a screening biomarker for colorectal neoplasia. Am. J. Gastroenterol. 98, 2299–2305 (2003).

  47. 47

    Hoff, G. et al. Testing for calprotectin (PhiCal) in the Norwegian Colorectal Cancer Prevention trial on flexible sigmoidoscopy screening: comparison with an immunochemical test for occult blood (FlexSure OBT). Gut 53, 1329–1333 (2004).

  48. 48

    Moran, A., Radley, S., Neoptolemos, J., Jones, A. F. & Asquith, P. Detection of colorectal cancer by faecal α1-antitrypsin. Ann. Clin. Biochem. 30, 28–33 (1993).

  49. 49

    Nakayama, T., Yasuoka, H., Kishino, T., Ohguchi, H. & Takada M. ELISA for occult faecal albumin. Lancet I, 1368–1369 (1987).

  50. 50

    Miyoshi, H., Ohshiba, S., Asada, S., Hirata, I. & Uchida K. Immunological determination of fecal hemoglobin and transferring levels: a comparison with other fecal occult blood tests. Am. J. Gastroenterol. 87, 67–73 (1992).

  51. 51

    Dubrow, R., Kinm, C. S. & Eldred, A. K. Fecal lysozyme: an unreliable marker for colorectal cancer. Am. J. Gastroenterol. 87, 617–621 (1992).

  52. 52

    Ahlquist, D. A. & Shuber, A. P. Stool screening for colorectal cancer: evolution from occult blood to molecular markers. Clin. Chim. Acta 315, 157–168 (2002).

  53. 53

    Bader, G. & Papanicolaou, G. The application of cytology in the diagnosis of cancer of the rectum, sigmoid, and descending colon. Cancer 5, 307–314 (1952).

  54. 54

    Lipkin, M., Bell, B. & Sherlock, P. Cell proliferation kinetics in the gastrointestinal tract of man. I. Cell renewal in colon and rectum. J. Clin. Invest. 42, 767–776 (1963).

  55. 55

    Ahlquist, D. A., Harrington, J. J., Burgart, L. J. & Roche, P. C. Morphometric analysis of the 'mucocellular layer' overlying colorectal cancer and normal mucosa: relevance to exfoliation and stool screening. Hum. Pathol. 31, 51–57 (2000).

  56. 56

    Loktionov, A. et al. Quantitation of DNA from exfoliated colonocytes isolated from human stool surface as a novel noninvasive screening test for colorectal cancer. Clin. Cancer Res. 4, 337–342 (1998).

  57. 57

    Bandaletova, T., Bailey, N., Bingham, S. A. & Loktionov, A. Isolation of exfoliated colonocytes from human stool as a new technique for colonic cytology. APMIS 110, 239–246 (2002).

  58. 58

    Davies, R. J. et al. Analysis of minichromosome maintenance proteins as a novel method for detection of colorectal cancer in stool. Lancet 359, 1917–1919 (2002). In this paper, we demonstrated that markers of exfoliated cancer cells can accurately be detected in stool.

  59. 59

    Moldenhauer, G., Momburg, F., Moller, P., Schwartz, R. & Hammerling, G. J. Epithelium-specific surface glycoprotein of Mr 34,000 is a widely distributed human carcinoma marker. Br. J. Cancer 56, 714–721 (1987).

  60. 60

    Gonzalez, M. A., Tachibana, K. E., Laskey, R. A. & Coleman, N. Control of DNA replication and its potential clinical exploitation. Nature Rev. Cancer 5, 135–141 (2005).

  61. 61

    Ishibashi, K., Hirose, K., Kato, H., Ogawa, K. & Haga, S. Determining the telomerase activity of exfoliated cells in intestinal lavage solution to detect colorectal carcinoma. Anticancer Res. 19, 2831–2836 (1999).

  62. 62

    Luo, C., Zhao, D. & Qu, J. Telomerase activity in stool of patients with colorectal cancer. Zhonghua Wai Ke Za Zhi 39, 580–582 (2001).

  63. 63

    Yokoyama, S. et al. The potential role of fecal carbonic anhydrase II in screening for colorectal cancer. Am. Surg. 63, 243–246 (1997).

  64. 64

    Hardt, P. D. et al. Faecal tumour M2 pyruvate kinase: a new, sensitive screening tool for colorectal cancer. Br. J. Cancer 91, 980–984 (2004).

  65. 65

    Mizuno, M. et al. Testing of multiple samples increases the sensitivity of stool decay-accelerating factor test for detection of colorectal cancer. Am. J. Gastroenterol. 98, 2550–2555 (2003).

  66. 66

    Kim, Y. et al. Gastrointestinal tract cancer screening using fecal carcinoembryonic antigen. Ann. Clin. Lab. Sci. 33, 32–38 (2003).

  67. 67

    Machiels, B. et al. New protocol for DNA extraction of stool. Biotechniques 28, 286–290 (2000).

  68. 68

    Deuter, R., Pietsch, S., Hertel, S. & Muller, O. A method for preparation of fecal DNA suitable for PCR. Nucleic Acids Res. 23, 3800–3801 (1995).

  69. 69

    Andreyev, H. J., Norman, A. R., Cunningham, D., Oates, J. R. & Clarke, P. A. Kirsten ras mutations in patients with colorectal cancer: the multicenter 'RASCAL' study. J. Natl Cancer Inst. 90, 675–684 (1998).

  70. 70

    Sidransky, D. et al. Identification of ras oncogene mutations in the stool of patients with curable colorectal tumors. Science 256, 102–105 (1992). The first study to demonstrate that mutations can be detected in the stool of patients with CRC.

  71. 71

    Frattini, M., Balestra, D., Pilotti, S., Bertario, L., Pierotti, M. A. Tumor location and detection of k-ras mutations in stool from colorectal cancer patients. J. Natl Cancer Inst. 95, 72–73 (2003).

  72. 72

    Eguchi, S., Kohara, N., Komuta, K. & Kanematsu T. Mutations of the p53 gene in the stool of patients with resectable colorectal cancer. Cancer 77 (Suppl. 8), 1707–1710 (1996).

  73. 73

    Lu, X., Xu, T., Qian, J., Wen, X. & Wu, D. Detecting K-ras and p53 gene mutation from stool and pancreatic juice for diagnosis of early pancreatic cancer. Chin. Med. J. 115, 1632–1636 (2002).

  74. 74

    Powell, S. M. et al. APC mutations occur early during colorectal tumorigenesis. Nature 359, 235–237 (1992).

  75. 75

    Fearnhead, N. S., Britton, M. P. & Bodmer, W. F. The ABC of APC. Hum. Mol. Genet. 10, 721–733 (2001).

  76. 76

    Traverso, G. et al. Detection of APC mutations in fecal DNA from patients with colorectal tumors. N. Engl. J. Med. 346, 311–320 (2002).

  77. 77

    Boland, C. R. Molecular genetics of hereditary nonpolyposis colorectal cancer. Ann. NY Acad. Sci. 910, 50–59 (2000).

  78. 78

    Issa, J. P. CpG island methylator phenotype in cancer. Nature Rev. Cancer 4, 988–993 (2004).

  79. 79

    Traverso, G. et al. Detection of proximal colorectal cancers through analysis of faecal DNA. Lancet 359, 403–404 (2002). Demonstrated that proximal CRCs can be detected using stool DNA analysis.

  80. 80

    Bedi, A, et al. Inhibition of apoptosis during delopment of colorectal cancer. Cancer Res. 55, 1811–1816 (1995).

  81. 81

    Boynton, K. A., Summerhayes, I. C., Ahlquist, D. A. & Shuber, A. P. DNA integrity as a potential marker for stool-based detection of colorectal cancer. Clin. Chem. 49, 1058–1065 (2003).

  82. 82

    Ahlquist, D. A. et al. Novel use of hypermethylated DNA markers in stool for detection of colorectal cancer: a feasibility study. Gastroenterology 122, A40 (2002).

  83. 83

    Suzuki, H. et al. A genomic screen for genes upregulated by demethylation and histone deacetylase inhibition in human colorectal cancer. Nature Genet. 31, 141–149 (2002).

  84. 84

    Muller, H. M. et al. Methylation changes in faecal DNA: a marker for colorectal cancer screening? Lancet 363, 1283–1285 (2004).

  85. 85

    Brand, R. E., Ross, M. E. & Shuber, A. P. Reproducibility of a multitarget stool-based DNA assay for colorectal cancer detection. Am. J. Gastroenterol. 99, 1338–1341 (2004).

  86. 86

    Imperiale, T. F. et al. Fecal DNA versus fecal occult blood for colorectal-cancer screening in an average-risk population. N. Engl. J. Med. 351, 2704–2714 (2004). A detailed assessment of the performance of stool DNA testing in 2,507 average-risk asymptomatic individuals.

  87. 87

    Schoen, R. E. Interrupting the adenoma-carcinoma sequence: screening for adenomas and cancer, now and in the future. Semin. Gastrointest. Dis. 11, 219–228 (2000).

  88. 88

    Steele, R. J. C. et al. A demonstration pilot trial for colorectal cancer screening in the United Kingdom: a new concept in the introduction of healthcare strategies. J. Med. Screen. 8, 197–203 (2001).

  89. 89

    Dukes, C. E. The classification of cancer of the rectum. J. Pathol. Bacteriol. 35, 323–332 (1932).

  90. 90

    Whittaker, M. & Goligher, J. C. The prognosis after surgical treatment for carcinoma of the rectum. Br. J. Surg. 63, 384–388 (1976).

  91. 91

    Lieberman, D. A. & Weiss, D. G. One-time screening for colorectal cancer with combined fecal occult-blood testing and examination of the distal colon. N. Engl. J. Med. 345, 555–560 (2001).

  92. 92

    UK Flexible Sigmoidoscopy Screening Trial Investigators. Single flexible sigmoidoscopy screening to prevent colorectal cancer: baseline findings of a UK multicentre trial. Lancet 359, 1291–1299 (2002).

  93. 93

    Segnan, N. et al. Baseline findings of the Italian multicenter randomised controlled trial of 'once-only flexible sigmoidoscopy'—SCORE. J. Natl Cancer Inst. 94, 1763–1772 (2002).

  94. 94

    Citarda, F. et al. Efficacy in standard clinical practice of colonoscopic polypectomy in reducing colorectal cancer incidence. Gut 48, 812–815 (2001).

  95. 95

    Winawer, S. J. et al. Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. N. Engl. J. Med. 329, 1977–1981 (1993).

  96. 96

    Johnson, C. D. et al. Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps. Gastroenterology 125, 311–319 (2003).

  97. 97

    Kamar, M. et al. Actual colonic perforation in virtual colonoscopy: report of a case. Dis. Colon Rectum 47, 1242–1246 (2004).

  98. 98

    Coady-Fariborzian, L., Angel, L. P. & Procaccino, J. A. Perforated colon secondary to virtual colonoscopy: report of a case. Dis. Colon Rectum 47, 1247–1249 (2004).

  99. 99

    Fidler, J. L. et al. Detection of flat lesions in the colon with CT colonography. Abdom. Imaging 27, 292–300 (2002).

  100. 100

    Tagore, K. S. et al. Sensitivity and specificity of a stool DNA multitarget assay panel for the detection of advanced colorectal neoplasia. Clin. Colorectal Cancer 3, 47–53 (2003).

  101. 101

    Ahlquist, D. A. et al. Colorectal cancer screening by detection of altered human DNA in stool: feasibility of a multitarget assay panel. Gastroenterology 119, 1219–1227 (2000). The first study to report the use of a multitarget DNA assay for molecular stool screening.

  102. 102

    Rengucci, C. et al. Multiple detection of genetic alterations in tumors and stool. Clin. Cancer Res. 7, 590–593 (2001).

  103. 103

    Dong, S. M. et al. Detecting colorectal cancer in stool with the use of multiple genetic targets. J. Natl Cancer Inst. 93, 858–865 (2001).

  104. 104

    Koshiji, M., Yonekura, Y., Saito, T. & Yoshioka, K. Microsatellite analysis of fecal DNA for colorectal cancer detection. J. Surg. Oncol. 80, 34–40 (2002).

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Nicholas Coleman is entitled to a share of royalties received by Cancer Research Technology Ltd on sales of products related to the use of MCM detection in cancer diagnosis.

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A flexible fibre-optic instrument inserted through the anus, which enables direct visual examination of the lining of the rectum and distal colon.


The likelihood that a test is negative in the absence of disease.


A study in which patients who already have a certain condition are compared with people who do not.


A study in which patients who have a certain condition and/or receive a particular test or treatment are followed over time and compared with another group of patients who are not subject to the condition or intervention.


The likelihood that a test is positive in the presence of disease.


A diagnostic imaging technique that uses specialized X-ray equipment to obtain image data from different angles, followed by computer processing of the information to show a cross-section of tissues and organs.


Faecal occult blood test cards are impregnated with guaiac resin, obtained from the wood of Guaiacum officinale trees (which are native to central America and the Carribean). The cards are developed with a liquid hydrogen-peroxide solution that causes the guaiac to turn blue in the presence of the peroxidase-like enzymatic activity of haemoglobin.


A condition in which pouches of mucosa and submucosa protrude through the wall of the colon, with the risk of mucosal ulceration and haemorrhage.


An assay for immunological detection and quantitation of single or multiple antigens or antibodies in a biological sample.


Disease of the intestinal tract.


Prostaglandin inhibitors with anti-inflammatory and analgesic properties.


An adhesion molecule, also known as Ep-CAM, that is broadly expressed by (and specific to) normal and neoplastic epithelial cells.


An assay carried out in solution, rather than on a solid support.


A ribonucleoprotein enzyme complex that stabilizes the length of chromosome telomeric ends by adding hexameric nucleotide repeats.


A sensitive assay for measuring telomerase activity, in which telomerase products are generated and subsequently amplified by PCR.


An intrinsic cell membrane inhibitor of autologous complement attack.


An ELISA variant in which antigen is captured between two layers of antibodies.


An immunoglobulin supergene family glycoprotein that is normally only present during fetal development, but can be re-expressed by certain malignancies, including colorectal cancer.


A method for detecting single base changes in genes, based on differences in the secondary structure of single-stranded DNA molecules causing an alteration of mobility in non-denaturing gel electrophoresis.

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Figure 1: The site distribution of colorectal cancer in England and Wales between 1971 and 1994.
Figure 2: The colorectal adenoma–carcinoma sequence.