***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: BACKGROUND & AIMS Few data have been published on the performance of colorectal cancer ( CRC ) screens that use multiple rounds of the fecal immunochemical test ( FIT ) . We evaluated outcomes of 4 screening rounds in over 7 years in an Italian population -based program . METHODS We conducted a prospect i ve cohort study of 2959 average-risk subjects , aged 50 - 74 years , who were invited for the first screening round in 2001 . We assessed the participation rate , the yield of advanced adenomas and CRC detected in the screening examinations , and we collected information about interval CRCs , with a follow-up period of 8.5 years . RESULTS Participation in each round varied from 56 % to 63 % ; 48.1 % of eligible subjects attended all 4 invitations . The positive predictive value of the FIT for advanced neoplasia ( CRC or advanced adenoma ) was 40 % at the first round , and approximately 33 % in the subsequent rounds . This decrease was attributable mainly to a decrease in the detection of CRC , although a high rate of advanced adenomas ( range , 0.8%-1.7 % ) was observed over all rounds . To find one advanced neoplasia in the study period the number of people that needed to be screened was 28 , and the number of tests needed was 74 . CONCLUSIONS About 60 % of invited individuals participated in every single round of FIT screening for CRC , but less than 50 % attended all 4 tests . A high detection rate of advanced adenomas in all rounds indicates that FIT screening could have a higher impact on incidence of CRC than the guaiac fecal occult blood test Purpose Fecal immunochemical tests ( FITs ) have been developed to address analytical problems inherent in the older guaiac-based fecal occult blood tests ( g-FOBTs ) . Our aim was to compare the performance characteristics of one g-FOBT ( Hemoccult II ) and two FITs ( the Hemoccult ICT and MagStream HemSp ) relative to colonoscopy for the detection of colorectal cancer and significant precursor lesions . We also examined whether a 1-day collection strategy would negatively impact test diagnostic performance . Methods We used a prospect i ve observational cohort design in a Canadian population eligible for screening . All participants received colonoscopy after performing the occult blood tests . Results One thous and seventy-five individuals were enrolled ( mean age 56.3 years , 53.8 % females ) . Using colonoscopy as the gold st and ard , the sensitivity for screen-relevant neoplasm was determined for Hemoccult II ( 7.2 , 95 % CI : 1.1–13.4 ) , Hemoccult ICT ( 23.2 % : 13.2–33.1 ) , and MagStream HemSp using 67 μg/gram stool as the cut-off ( 23.2 % : 13.2–33.1 ) . The Magstream HemSp , using a cut-off threshold of 30 μg/gram stool , had the lowest specificity at 87.6 % ( 85.4–89.6 ) , while the Hemoccult II had the highest at 98.8 % ( 98.1–99.5 ) . Single-day stool testing reduced the false-positive rates of all tests without significantly reducing the sensitivity . Conclusion We found that FITs have a significantly increased sensitivity but reduced specificity for screen-relevant neoplasm compared to g-FOBT using colonoscopy as the gold st and ard . Optimal threshold levels for hemoglobin detection depend on the desired trade off between sensitivity and false-positive rate . Single-day testing with an FIT may be an option to enhance population compliance with screening BACKGROUND In r and omized trials , fecal occult-blood testing reduces mortality from colorectal cancer . However , the duration of the benefit is unknown , as are the effects specific to age and sex . METHODS In the Minnesota Colon Cancer Control Study , 46,551 participants , 50 to 80 years of age , were r and omly assigned to usual care ( control ) or to annual or biennial screening with fecal occult-blood testing . Screening was performed from 1976 through 1982 and from 1986 through 1992 . We used the National Death Index to obtain up date d information on the vital status of participants and to determine causes of death through 2008 . RESULTS Through 30 years of follow-up , 33,020 participants ( 70.9 % ) died . A total of 732 deaths were attributed to colorectal cancer : 200 of the 11,072 deaths ( 1.8 % ) in the annual-screening group , 237 of the 11,004 deaths ( 2.2 % ) in the biennial-screening group , and 295 of the 10,944 deaths ( 2.7 % ) in the control group . Screening reduced colorectal-cancer mortality ( relative risk with annual screening , 0.68 ; 95 % confidence interval [ CI ] , 0.56 to 0.82 ; relative risk with biennial screening , 0.78 ; 95 % CI , 0.65 to 0.93 ) through 30 years of follow-up . No reduction was observed in all-cause mortality ( relative risk with annual screening , 1.00 ; 95 % CI , 0.99 to 1.01 ; relative risk with biennial screening , 0.99 ; 95 % CI , 0.98 to 1.01 ) . The reduction in colorectal-cancer mortality was larger for men than for women in the biennial-screening group ( P=0.04 for interaction ) . CONCLUSIONS The effect of screening with fecal occult-blood testing on colorectal-cancer mortality persists after 30 years but does not influence all-cause mortality . The sustained reduction in colorectal-cancer mortality supports the effect of polypectomy . ( Funded by the Veterans Affairs Merit Review Award Program and others . ) Context Several immunochemical fecal occult blood tests ( FOBTs ) that use different antibodies against human blood components are available . Contribution This study compared characteristics of 6 qualitative immunochemical FOBTs and 1 guaiac-based FOBT to identify adenomas among adults who attended screening colonoscopy .  The FOBTs had widely varying performance characteristics . Sensitivity and specificity for detecting advanced adenomas ranged from 25 % to 72 % and 70 % to 97 % , respectively , for the immunochemical tests and were 9 % and 96 % , respectively , for the guaiac test . Caution One-day stool sample s were used , and stool was frozen before testing . Implication Qualitative immunochemical FOBTs have varying performance characteristics for detecting precancerous colorectal lesions . The Editors Colorectal cancer ( CRC ) is the third most common cancer in the world ( 1 ) , with about 1 million new cases and more than 500000 deaths per year . Because most cases of CRC are sporadic and develop from removable precancerous lesions ( adenomas ) and curable early- stage cancer ( 2 ) , screening for CRC has high potential for reducing morbidity and mortality . R and omized , controlled trials have demonstrated reduced mortality with guaiac-based fecal occult blood testing ( FOBT ) followed by colonoscopy or sigmoidoscopy if the FOBT result is positive ( 3 ) . However , guaiac-based FOBT , which detects the pseudoperoxidase activity of heme or hemoglobin , has important limitations . It is not specific for human hemoglobin , and false-positive and false-negative results can result from certain compounds or medications in foods ( for example , red meat or vitamin C ) ( 4 ) that should be avoided during the days before testing . Another important limitation is the low diagnostic performance for precursors to CRC . An advantage of guaiac-based FOBT is the simple analysis , which can easily be done at the physician 's office , even though reliable interpretation of test results requires training ( 5 , 6 ) . Immunochemical FOBTs that use specific antibodies against human blood components overcome the problem of diet or medication restriction . Unlike quantitative immunochemical FOBTs , qualitative immunochemical FOBTs that mostly use immunochromatographic technology also allow simple , office-based analysis . However , there are differences among qualitative immunochemical FOBTs . For example , the antibodies used and the different detection limits may influence the diagnostic performance , especially with respect to detection of precursor lesions . We aim ed to determine and compare performance characteristics of different qualitative immunochemical FOBTs for the detection of colorectal adenomas in a large sample of women and men undergoing screening colonoscopy .  Methods Study Design and Sample The analyses were part of the BliTz study ( Begleitende Evaluierung innovativer Testverfahren zur Darmkrebsfrherkennung ) , an ongoing screening study conducted in cooperation with 20 gastroenterology practice s in southwestern Germany since January 2006 that aims to comparatively evaluate new tests for early detection of CRC . The study includes participants undergoing screening colonoscopya procedure that the German health care system has offered since October 2002 to average-risk persons 55 years or older . In Germany , preliminary consultation for any type of cancer screening is mostly done by general practitioners . For screening colonoscopy , patients are referred to the gastroenterologist only when the decision to have colonoscopy is made . All participants had a preliminary consultation with a gastroenterologist to receive detailed information and advice about screening colonoscopy . They were informed about and invited to participate in the study at that time . After we received written informed consent , we asked patients scheduled for screening colonoscopy to provide a stool sample before bowel preparation . Physicians who did colonoscopy and histologic examination were blinded to FOBT results . After colonoscopy , we collected reports on colonoscopic and histologic findings and extracted information in a st and ardized manner while blinded to the results of stool testing . We did not query patients about adverse events of testing ( such as psychological distress ) . The ethics committee of the University of Heidelberg , Heidelberg , Germany , approved the study . We included patients who provided stool sample s for qualitative immunochemical FOBTs until 13 December 2007 . The Figure shows the numbers of all potentially eligible patients . Figure . Study flow diagram . FOBadv = FOB advanced ( ulti med , Ahrensburg , Germany ) ; FOBplus = Bionexia FOBplus ( DIMA , Gttingen , Germany ) ; Hb/Hp C = Bionexia Hb/Hp Complex ( DIMA ) ; HO = HemOccult ( Beckman Coulter , Krefeld , Germany ) ; immoCare = immoCARE-C ( CAREdiagnostica , Voerde , Germany ) ; PreventID CC = PreventID CC ( Preventis , Bensheim , Germany ) ; QuickVue = QuickVue iFOB ( Quidel , San Diego , California ) . * The exclusion of 44 patients overall was due to missing or noninterpretable test cards . Of 1785 patients undergoing screening colonoscopy who agreed to participate , 111 were excluded because of visible rectal bleeding or preceding positive FOBT result . We excluded 13 patients because of inflammatory bowel disease . These patients usually receive close colonoscopic surveillance and would not be regarded as the target population for primary FOBT screening . We excluded 117 patients because they had undergone colonoscopy in the past 5 years and thus would not be eligible for primary FOBT screening  ( if the previous colonoscopy result was positive , they are recommended for colonoscopic surveillance ; if the result was negative , they are at very low risk for colorectal neoplasia ) . We further excluded participants whose stool sample s were collected after colonoscopy only ( and thus violated the study protocol [ n= 65 ] ) , those with inadequate bowel preparation before colonoscopy ( n= 79 ) , and those with incomplete colonoscopy ( that is , the cecum was not reached , [ n= 22 ] ) . We excluded patients who received a histologically confirmed diagnosis of CRC ( this subgroup comprised only 11 participants by the end of 2007 and would not allow meaningfully precise performance estimates for this end point ) . Sensitivity with respect to CRC will be analyzed separately after continued recruitment of a much larger number of screening participants . We excluded 10 participants with nondefined polyps ( no histologic reports were available ) because we could not definitively determine the presence or absence of advanced adenomas in this group . Finally , we excluded participants with pseudopolyps ( n= 38 ) because these patients probably have had ulcerative colitis or undocumented inflammatory bowel disease . Stool Sample Collection Participants undergoing screening colonoscopy  typically present at the gastroenterology practice for preliminary consultation about 1 week before colonoscopy . At that time , eligible patients received a study package that contained 1 test card for guaiac-based FOBT ( HemOccult , Beckman Coulter , Krefeld , Germany ) , a small container ( 60 mL ) for stool collection , a collection tissue for avoiding contact of the stool with toilet water , and detailed instructions for stool collection . Stool sample s were collected at home with no specific recommendations for diet or medicine restrictions . Patients received detailed instructions for sampling : Collect 1 bowel movement by using the collection tissue ; apply stool with a spatula ( provided in the study package ) on 2 windows of 1 HemOccult test card and store the test card at room temperature ; and fill at least half of the small container with stool by using plastic spoons ( provided in the study package ) , and store a plastic bag with the container in the freezer or , if not possible , 
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For gFOBT , we found no site-specific difference ( proximally vs distally located ) of pooled sensitivities observed in the colorectal cancer ( CRC ) , advanced adenomas , and advanced neoplasms groups .
Summary receiver operating characteristic curve analyses showed similar patterns for both types of FOBT regarding the diagnostic accuracy for detecting colorectal neoplasms according to the anatomical sites of the colorectum .
Conclusion iFOBT had higher sensitivity for detecting advanced adenomas and advanced neoplasia located in the distal colon/rectum than that for those in the proximal colon