Progress and Challenges in Colorectal Cancer Screening and Surveillance
2010; Elsevier BV; Volume: 138; Issue: 6 Linguagem: Inglês
10.1053/j.gastro.2010.02.006
ISSN1528-0012
Autores Tópico(s)Gastric Cancer Management and Outcomes
ResumoColorectal cancer is a leading cause of cancer death throughout the world. There is evidence that screening of average-risk individuals can result in mortality reduction with early cancer detection and cancer prevention by detection and removal of cancer precursor lesions. The optimal form of screening is not clear. Fecal screening tests can be performed at home at low initial cost, but current versions lack high sensitivity for cancer precursor lesions, and tests need to be repeated at regular intervals. Adherence to repeat testing for negative tests and referral for colonoscopy for positive tests are important elements of program effectiveness. Structural examinations of the colon are more invasive and may result in detection of both early cancer and cancer precursor lesions. Every screening program has advantages and limitations, but each program ultimately depends on quality and patient adherence. Colorectal cancer is a leading cause of cancer death throughout the world. There is evidence that screening of average-risk individuals can result in mortality reduction with early cancer detection and cancer prevention by detection and removal of cancer precursor lesions. The optimal form of screening is not clear. Fecal screening tests can be performed at home at low initial cost, but current versions lack high sensitivity for cancer precursor lesions, and tests need to be repeated at regular intervals. Adherence to repeat testing for negative tests and referral for colonoscopy for positive tests are important elements of program effectiveness. Structural examinations of the colon are more invasive and may result in detection of both early cancer and cancer precursor lesions. Every screening program has advantages and limitations, but each program ultimately depends on quality and patient adherence. Colorectal cancer (CRC) is the second leading cause of cancer death in North America1Jemal A. Siegel R. Ward E. et al.Cancer statistics 2008.CA Cancer J Clin. 2008; 58: 71-96Crossref PubMed Scopus (10213) Google Scholar and western Europe. The lifetime risk of CRC is 5%–6% in Western countries.1Jemal A. Siegel R. Ward E. et al.Cancer statistics 2008.CA Cancer J Clin. 2008; 58: 71-96Crossref PubMed Scopus (10213) Google Scholar In the United States, there was a decline in mortality from 1980 to 1990 of nearly 7% in men and 12% in women.1Jemal A. Siegel R. Ward E. et al.Cancer statistics 2008.CA Cancer J Clin. 2008; 58: 71-96Crossref PubMed Scopus (10213) Google Scholar However, since 1990 there has been a more dramatic decline in mortality (Figure 1), and a decline in incidence since 1985 (Figure 2). Because life expectancy and obesity have increased during this same time period, we might have expected cancer rates to increase. Coincident with these trends, CRC screening has increased among individuals age 50 years and older (Figure 2). Although it is tempting to attribute the reduction in CRC incidence and mortality to screening, there are other variables that might have contributed to this effect. In the 1970s and 1980s, many women received hormone-replacement therapy during the onset of menopause, which might protect against CRC.2Chlebowski R.T. Wactawski-Wende J. Ritenbaugh C. et al.Women's Health Initiative InvestigatorsEstrogen plus progestin and colorectal cancer in postmenopausal women.N Engl J Med. 2004; 350: 991-1004Crossref PubMed Scopus (553) Google Scholar During this same period, there was increased use of aspirin for cardiovascular disease and over-the-counter nonsteroidal anti-inflammatory drugs for musculoskeletal problems, a class of drugs that reduces the risk of colon polyps and CRC.3Rostom A. Dube C. Lewin G. et al.U.S. Preventive Services Task ForceNonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors for primary prevention of colorectal cancer: a systemic review prepared for the U.S. Preventive Services Task Force.Ann Intern Med. 2007; 146: 376-389Crossref PubMed Scopus (282) Google Scholar Therefore, any analysis of CRC incidence trends is complicated because of concurrent historical events, and the reduction in incidence and mortality cannot be attributed solely to increased screening activity.Figure 1Death rates from CRC per 100,000 population.1Jemal A. Siegel R. Ward E. et al.Cancer statistics 2008.CA Cancer J Clin. 2008; 58: 71-96Crossref PubMed Scopus (10213) Google ScholarView Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 2CRC incidence rates per 100,000 and rates of CRC screening in individuals older than age 50.1Jemal A. Siegel R. Ward E. et al.Cancer statistics 2008.CA Cancer J Clin. 2008; 58: 71-96Crossref PubMed Scopus (10213) Google ScholarView Large Image Figure ViewerDownload Hi-res image Download (PPT) This discussion focuses on screening of average-risk individuals. A total of 20%–25% of individuals with CRC have familial or other risk factors and are not considered average risk. Individuals with a first-degree relative who has been diagnosed with CRC before age 50 should be considered to be at risk for hereditary syndromes, which are discussed in other sections of this issue of Gastroenterology. People with one or more first-degree relatives with CRC who were diagnosed before age 60 but do not have a known hereditary syndrome have an increased risk of CRC based on their family history of disease.4Winawer S. Fletcher R. Rex D. et al.Colorectal cancer screening and surveillance: clinical guidelines and rationale—update based on new evidence.Gastroenterology. 2003; 124: 544-560Abstract Full Text PDF PubMed Scopus (1985) Google Scholar These individuals should be offered screening with colonoscopy at age 40, or 10 years before the age of diagnosis in the index family member (whichever comes first). Average-risk individuals account for 70%–75% of patients with CRC. Screening of average-risk populations provides opportunities for early cancer detection and prevention by detection and removal of cancer precursors and has been recommended by the US Preventive Services Task Force (USPSTF) since 1995. Guidelines from several organizations were updated in 2008 (Table 1).5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google Scholar, 6U.S. Preventive Services Task ForceScreening for colorectal cancer: U.S. Preventive Services Task Force Recommendation Statement.Ann Intern Med. 2008; 149: 627-637Crossref PubMed Scopus (1229) Google Scholar, 7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google Scholar, 8Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1175) Google Scholar The type of evidence and reported efficacy of the different screening programs are summarized in Table 2. There are important differences among the guidelines. The guideline of the American Cancer Society, Multi-Society Task Force on CRC, and the American College of Radiology (ACS-MSTF-ACR) was a consensus document, based on a systematic review of the literature by experts in methodology who were not gastroenterologists; where evidence was lacking, the information gaps and the consensus of experts were noted5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google Scholar (Dr Lieberman participated as Chair of the MSTF-CRC). This guideline distinguished 2 categories of screening tests: stool-based tests, which primarily detect early cancer, and structural colon tests, which detect early cancer and cancer precursor lesions. The ACS-MSTF-ACR believed that there was sufficient evidence to express a preference for strategies that would result in CRC prevention and early cancer detection.5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google Scholar The USPSTF guideline observed strict rules of evidence, and made recommendations based on evidence tables and decision modeling.6U.S. Preventive Services Task ForceScreening for colorectal cancer: U.S. Preventive Services Task Force Recommendation Statement.Ann Intern Med. 2008; 149: 627-637Crossref PubMed Scopus (1229) Google Scholar, 7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google Scholar The key difference is that the USPSTF believed that evidence was insufficient to recommend computed tomography colonography (CTC) and stool DNA. The American College of Gastroenterology endorsed the concept of 2 categories of tests and went further than other guidelines in expressing a preference for a single test in each of the 2 categories.8Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1175) Google ScholarTable 1The CRC Screening Guidelines for the United States in 2008Screening testACS-MSTF-ACR5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google ScholarUSPSTF6U.S. Preventive Services Task ForceScreening for colorectal cancer: U.S. Preventive Services Task Force Recommendation Statement.Ann Intern Med. 2008; 149: 627-637Crossref PubMed Scopus (1229) Google Scholar, 7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google ScholarACG8Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1175) Google ScholarRecommended intervalgFOBTYes, requires >50% sensitivity for CRCYesYes, high-sensitivity test onlyAnnuallyFITYes, requires >50% sensitivity for CRCYesYes, preferred as cancer detection testAnnuallyStool DNAYes, requires >50% sensitivity for CRCNo, insufficient evidenceYes, every 3 yUncertainFlexible sigmoidoscopyYes, requires insertion to 40 cm or splenic flexureYes, with FOBT every 3 yYes, every 5–10 y5 yBarium enemaYes, but only if other tests are not availableNot recommendedNot recommended5 yCTCYes, with referral to colonoscopy if polyps ≥6 mm are seenNo, insufficient evidenceYes5 yColonoscopyYesYesYes, preferred10 yACG, American College of Gastroenterology. Open table in a new tab Table 2Types of CRC Screening Tests and Efficacy in Clinical TrialsAdapted from Lieberman DA. Screening for colorectal cancer. N Engl J Med 2009;361:1179–1187.Screening testEvidenceMortality reductionIncidence reductionOne-time sensitivity for CRCOne-time sensitivity for advanced adenomaStool-based tests gFOBT-standard9Lieberman D.A. Weiss D.G. VA Cooperative Study #380 GroupOne-time screening for colorectal cancer with combined fecal occult-blood test and examination of the distal colon.N Engl J Med. 2001; 345: 555-560Crossref PubMed Scopus (530) Google Scholar, 13Allison J.E. Sakoda L.C. Levin T.R. et al.Screening for colorectal neoplasms with new fecal occult blood tests: update on performance characteristics.J Natl Cancer Inst. 2007; 99: 1-9Crossref Scopus (317) Google Scholar, 14Imperiale T.F. Ransohoff D.E. Itzkowitz S.H. et al.Colorectal Cancer Study GroupFecal DNA vs. fecal occult blood for colorectal cancer screening in an average-risk population.N Engl J Med. 2004; 351: 2704-2714Crossref PubMed Scopus (699) Google Scholar, 15Ahlquist D.A. Sargent D.J. Loprinzi C.L. et al.Stool DNA and occult blood testing for screen detection of colorectal neoplasia.Ann Intern Med. 2008; 149: 441-450Crossref PubMed Scopus (239) Google Scholar, 16Mandel J.S. Bond J.H. Church T.R. et al.Reducing mortality from colorectal cancer by screening for fecal occult blood.N Engl J Med. 1993; 328: 1365-1371Crossref PubMed Scopus (2917) Google ScholarRCTs15%–33%18%13%–50%11%–24% gFOBT-SENSA7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google Scholar, 13Allison J.E. Sakoda L.C. Levin T.R. et al.Screening for colorectal neoplasms with new fecal occult blood tests: update on performance characteristics.J Natl Cancer Inst. 2007; 99: 1-9Crossref Scopus (317) Google ScholarCross-sectional——50%–75%20%–25% FIT7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google ScholarCross-sectional——60%–85%20%–50% Stool DNA-old14Imperiale T.F. Ransohoff D.E. Itzkowitz S.H. et al.Colorectal Cancer Study GroupFecal DNA vs. fecal occult blood for colorectal cancer screening in an average-risk population.N Engl J Med. 2004; 351: 2704-2714Crossref PubMed Scopus (699) Google ScholarCross-sectional——51%18% Stool DNA-new15Ahlquist D.A. Sargent D.J. Loprinzi C.L. et al.Stool DNA and occult blood testing for screen detection of colorectal neoplasia.Ann Intern Med. 2008; 149: 441-450Crossref PubMed Scopus (239) Google ScholarCohort——80%+40%Structural examinations of colon CTC27Rockey D.C. Paulson E. Niedzwiecki D. et al.Analysis of air contrast barium enema, computed tomographic colonography and colonoscopy: prospective comparison.Lancet. 2005; 365: 305-311Abstract Full Text Full Text PDF PubMed Scopus (455) Google Scholar, 28Pickhardt P.J. Choie R. Hwang I. et al.Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults.N Engl J Med. 2003; 349: 2191-2200Crossref PubMed Scopus (1726) Google Scholar, 29Cotton P.B. Durkalski V.L. Pineau B.C. et al.Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasms.JAMA. 2004; 291: 1713-1719Crossref PubMed Scopus (592) Google Scholar, 30Johnson C.D. Chen M.-H. Toledano A.Y. et al.Accuracy of CT colonography for detection of large adenomas and cancers.N Engl J Med. 2008; 359: 1207-1217Crossref PubMed Scopus (875) Google ScholarCross-sectional——>90%90% Sigmoidoscopy41Selby J.V. Friedman G.D. Quesenberry Jr, C.P. et al.A case-control study of screening sigmoidoscopy and mortality from colorectal cancer.N Engl J Med. 1992; 326: 653-657Crossref PubMed Scopus (1573) Google Scholar, 42Lieberman D.A. Weiss D.G. Bond J.H. et al.VACSP Group # 380Use of colonoscopy to screen asymptomatic adults for colorectal cancer.N Engl J Med. 2000; 343: 162-168Crossref PubMed Scopus (1615) Google Scholar, 43Imperiale T.F. Wagner D.R. Lin C.Y. et al.Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings.N Engl J Med. 2000; 343: 169-174Crossref PubMed Scopus (924) Google ScholarCase-control RCT60% distal colon—>95% distal colon30%–70% Colonoscopy27Rockey D.C. Paulson E. Niedzwiecki D. et al.Analysis of air contrast barium enema, computed tomographic colonography and colonoscopy: prospective comparison.Lancet. 2005; 365: 305-311Abstract Full Text Full Text PDF PubMed Scopus (455) Google Scholar, 28Pickhardt P.J. Choie R. Hwang I. et al.Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults.N Engl J Med. 2003; 349: 2191-2200Crossref PubMed Scopus (1726) Google Scholar, 29Cotton P.B. Durkalski V.L. Pineau B.C. et al.Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasms.JAMA. 2004; 291: 1713-1719Crossref PubMed Scopus (592) Google Scholar, 30Johnson C.D. Chen M.-H. Toledano A.Y. et al.Accuracy of CT colonography for detection of large adenomas and cancers.N Engl J Med. 2008; 359: 1207-1217Crossref PubMed Scopus (875) Google Scholar, 42Lieberman D.A. Weiss D.G. Bond J.H. et al.VACSP Group # 380Use of colonoscopy to screen asymptomatic adults for colorectal cancer.N Engl J Med. 2000; 343: 162-168Crossref PubMed Scopus (1615) Google Scholar, 43Imperiale T.F. Wagner D.R. Lin C.Y. et al.Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings.N Engl J Med. 2000; 343: 169-174Crossref PubMed Scopus (924) Google Scholar, 44Schoenfeld P. Cash B. Flood A. et al.Colonoscopic screening of average-risk women for colorectal neoplasia.N Engl J Med. 2005; 352: 2061-2068Crossref PubMed Scopus (424) Google Scholar, 47Regula J. Rupinski M. Kraszewska E. et al.Colonoscopy in colorectal-cancer screening for detection of advanced neoplasia.N Engl J Med. 2006; 355: 1863-1872Crossref PubMed Scopus (707) Google Scholar, 48Kahi C.J. Imperiale T.F. Juliar B.E. et al.Effect of screening colonoscopy on colorectal cancer incidence and mortality.Clin Gastroenterol Hepatol. 2009; 7: 770-775Abstract Full Text Full Text PDF PubMed Scopus (308) Google Scholar, 49Muller A.D. Sonnenberg A. Prevention of colorectal cancer by flexible endoscopy and polypectomy: a case-control study of 32,702 veterans.Ann Intern Med. 1995; 123: 904-910Crossref PubMed Scopus (562) Google Scholar, 50Singh H. Turner D. Xue L. et al.Risk of developing colorectal cancer following a negative colonoscopy examination Evidence for a 10-year interval between colonoscopies.JAMA. 2006; 295: 2366-2373Crossref PubMed Scopus (365) Google Scholar, 51Baxter N.N. Goldwasser M.A. Paszat L.F. et al.Association of colonoscopy and death from colorectal cancer: a population-based, case-control study.Ann Intern Med. 2009; 150: 1-8Crossref PubMed Scopus (1065) Google ScholarCase-control cohort31%53%–72%95%88%–98%RCT, randomized controlled trial. Open table in a new tab ACG, American College of Gastroenterology. RCT, randomized controlled trial. This report reviews some of the progress and continued challenges associated with these tests. It should be noted that the performance of all screening programs in clinical practice is uncertain because most data come from clinical trials, which may be subject to bias. Studies of programs that are operator-dependent (colonoscopy, sigmoidoscopy, CTC) may have expertise bias, and results may not necessarily be generalizable. Clinical studies of programs that are highly dependent on adherence to repeat testing (fecal testing) may introduce bias by having study nurses remind patients to complete testing, which may not occur in a typical primary care practice. The performance (sensitivity, specificity, adherence) of new CRC screening technologies ideally should be evaluated in cohorts for whom screening is recommended. Fecal screening tests can be performed at home. These include tests that detect fecal occult blood (fecal occult blood test [FOBT]) or specific DNA in stool that may be associated with colon neoplasia. Colonoscopy is recommended for patients with positive tests, who have an increased risk of CRC and adenomatous polyps.5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google Scholar, 6U.S. Preventive Services Task ForceScreening for colorectal cancer: U.S. Preventive Services Task Force Recommendation Statement.Ann Intern Med. 2008; 149: 627-637Crossref PubMed Scopus (1229) Google Scholar, 7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google Scholar, 8Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1175) Google Scholar The standard guaiac FOBT (gFOBT) detects peroxidase activity of heme and is not specific for human blood. The test is based on the principle that significant colon neoplasia may bleed intermittently. There is better detection of cancer and large polyps with 2 or 3 stool samples obtained on separate days compared with one sample.7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google Scholar, 9Lieberman D.A. Weiss D.G. VA Cooperative Study #380 GroupOne-time screening for colorectal cancer with combined fecal occult-blood test and examination of the distal colon.N Engl J Med. 2001; 345: 555-560Crossref PubMed Scopus (530) Google Scholar Because the guaiac test is not specific for human blood, false-positive tests may occur if patients consume red meat or peroxidase-containing foods, and false-negative tests may occur when consuming vitamin C. Although some physicians recommend avoiding these items for 3 days before gFOBT, compliance with these recommendations is unknown.10Ransohoff D.F. Lang C.A. Screening for colorectal cancer with the fecal occult blood test: a background paper American College of Physicians.Ann Intern Med. 1997; 126: 811-822Crossref PubMed Scopus (169) Google Scholar There is little evidence that the predictive value is impacted by the use of nonsteroidal anti-inflammatory drugs11Kahi C.J. Imperiale T.F. Do aspirin and nonsteroidal anti-inflammatory drugs cause false-positive fecal occult blood test results? A prospective study in a cohort of veterans.Am J Med. 2004; 117: 837-841Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar or anticoagulants.12Bini E.J. Rajapaksa R.C. Weinsehl E.H. Positive predictive value of fecal occult blood testing in persons taking warfarin.Am J Gastroenterol. 2005; 100: 1586-1592Crossref PubMed Scopus (33) Google Scholar Current guidelines do not recommend stopping these medications for testing. Individuals with a positive test result have a 3- to 4-fold increased risk of cancer compared with those with a negative test result.4Winawer S. Fletcher R. Rex D. et al.Colorectal cancer screening and surveillance: clinical guidelines and rationale—update based on new evidence.Gastroenterology. 2003; 124: 544-560Abstract Full Text PDF PubMed Scopus (1985) Google Scholar Colonoscopy should be offered to patients with positive test results.5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google Scholar, 6U.S. Preventive Services Task ForceScreening for colorectal cancer: U.S. Preventive Services Task Force Recommendation Statement.Ann Intern Med. 2008; 149: 627-637Crossref PubMed Scopus (1229) Google Scholar, 7Whitlock E.P. Lin J.S. Liles E. et al.Screening for colorectal cancer: a targeted, updated systematic review for the U.S. Preventive Services Task Force.Ann Intern Med. 2008; 149: 638-658Crossref PubMed Scopus (617) Google Scholar, 8Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1175) Google Scholar When the test is performed only once (with 3 stool samples), it is not very sensitive for neoplasia, detecting 13%–50% of patients with cancer and 11%–24% of patients with advanced adenomas (defined as tubular adenoma ≥10 mm, adenoma with villous histology, or high-grade dysplasia).9Lieberman D.A. Weiss D.G. VA Cooperative Study #380 GroupOne-time screening for colorectal cancer with combined fecal occult-blood test and examination of the distal colon.N Engl J Med. 2001; 345: 555-560Crossref PubMed Scopus (530) Google Scholar, 13Allison J.E. Sakoda L.C. Levin T.R. et al.Screening for colorectal neoplasms with new fecal occult blood tests: update on performance characteristics.J Natl Cancer Inst. 2007; 99: 1-9Crossref Scopus (317) Google Scholar, 14Imperiale T.F. Ransohoff D.E. Itzkowitz S.H. et al.Colorectal Cancer Study GroupFecal DNA vs. fecal occult blood for colorectal cancer screening in an average-risk population.N Engl J Med. 2004; 351: 2704-2714Crossref PubMed Scopus (699) Google Scholar, 15Ahlquist D.A. Sargent D.J. Loprinzi C.L. et al.Stool DNA and occult blood testing for screen detection of colorectal neoplasia.Ann Intern Med. 2008; 149: 441-450Crossref PubMed Scopus (239) Google Scholar Effectiveness depends on a program of annual repeat testing if tests are negative. In randomized controlled trials, subjects who were screened had cancers that were detected at an early and more curable stage than unscreened patients (controls). There were study differences in screening interval (annual or biennial) and method (nonrehydrated or rehydrated with water), but all showed a significant reduction in CRC mortality (by 15% to 33%) over 10–13 years of follow-up evaluation.16Mandel J.S. Bond J.H. Church T.R. et al.Reducing mortality from colorectal cancer by screening for fecal occult blood.N Engl J Med. 1993; 328: 1365-1371Crossref PubMed Scopus (2917) Google Scholar, 17Hardcastle J.D. Chamberlain J. Robinson M.H.E. et al.Randomised, controlled trial of faecal occult blood. screening for colorectal cancer.Lancet. 1996; 148: 1472-1477Abstract Full Text Full Text PDF Scopus (2434) Google Scholar, 18Kronborg O. Fenger C. Olsen J. et al.Randomised study of screening for colorectal cancer with faecal occult blood test.Lancet. 1996; 148: 14667-14671Google Scholar, 19Kewenter J. Brevinge H. Engaras B. et al.Results of screening, rescreening, and follow-up in a prospective randomized study for detection of colorectal cancer by fecal occult blood testing Results for 68,308 subjects.Scand J Gastroenterol. 1994; 29: 468-473Crossref PubMed Scopus (259) Google Scholar In one study, CRC incidence was reduced by 17%–20% after 18 years of follow-up evaluation, compared with controls.20Mandel J.S. Church T.R. Bond J.H. et al.The effect of fecal occult-blood screening on the incidence of colorectal cancer.N Engl J Med. 2000; 343: 1603-1607Crossref PubMed Scopus (1242) Google Scholar Fecal testing for occult blood can be performed at home with a relatively low up-front cost. Effectiveness depends on completion of colonoscopy for those with positive test results and repeat annual testing for those with negative test results. Levels of adherence in clinical practice are uncertain. Standard gFOBT is no longer recommended in 2 of the US guidelines because one-time testing for cancer has low levels of sensitivity.5Levin B. Lieberman D.A. McFarland B. et al.Screening and surveillance for early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.Gastroenterology. 2008; 134: 1570-1595Abstract Full Text Full Text PDF PubMed Scopus (1704) Google Scholar, 8Rex D.K. Johnson D.A. Anderson J.C. et al.American College of Gastroenterology guidelines for colorectal cancer screening 2008.Am J Gastroenterol. 2009; 104: 739-750Crossref PubMed Scopus (1175) Google Scholar The USPSTF model suggested that a sensitive gFOBT (SENSA, Beckman Coulter, Inc, Brea, CA) may be superior to standard gFOBT.6U.S. Preventive Services Task ForceScreening for colorectal cancer: U.S. Preventive Services Task Force Recommendation Statement.Ann Intern Med. 2008; 149: 627-637Crossref PubMed Scopus (1229) Google Scholar The fecal immunochemical test (FIT) is a newer occult blood test that uses antibodies specific to human hemoglobin, albumin, or other blood components; is more specific for human blood; and less prone to false-positive tests related to diet than gFOBT. These tes
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