***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: All 68,308 inhabitants of Göteborg born between 1918 and 1931 were r and omly divided into a test and a control group . The subjects in the test group were invited to perform Hemoccult II fecal occult blood testing  on 3 days and to repeat the test after 16 to 24 months . In the prevalence screening 21,347 ( 63 % ) performed the test , and in the rescreening 19,991 ( 60 % ) . Investigation of the 942 ( 4.4 % ) with positive tests in the prevalence screening showed 47 cancers and 129 subjects with adenomas > or = 1.0 cm . In the rescreening 5.1 % had a positive test , and 34 cancers and 122 subjects with adenomas ( > or = 1.0 cm ) were found among those . Cancer had also been diagnosed in 19 subjects in the interval between the two screening occasions and in 15 subjects among the non-responders . Forty-four cancers had been diagnosed in the control group during the same period . Cancers detected by screening were at a less advanced stage than in the control group . It is too early to show any effect of  screening  on mortality from colorectal cancer BACKGROUND Although tests for occult blood in the feces are widely used to screen for colorectal cancers , there is no conclusive evidence that they reduce mortality from this cause . We evaluated a fecal occult-blood test  in a r and omized trial and documented its effectiveness . METHODS We r and omly assigned 46,551 participants 50 to 80 years of age to screening for colorectal cancer once a year , to  screening every two years , or to a control group .  Participants who were screened su bmi tted six guaiac-impregnated paper slides with two smears from each of three consecutive stools . About 83 percent of the slides were rehydrated . Participants who tested positive underwent a diagnostic evaluation that included colonoscopy .  Vital status was ascertained for all study participants during 13 years of follow-up . A committee determined causes of death . A single pathologist determined the stage of each tissue specimen . Differences in mortality from colorectal cancer , the primary study end point , were monitored with the sequential log-rank statistic . RESULTS The 13-year cumulative mortality per 1000 from colorectal cancer was 5.88 in the annually screened group ( 95 percent confidence interval , 4.61 to 7.15 ) , 8.33 in the biennially screened group ( 95 percent confidence interval , 6.82 to 9.84 ) , and 8.83 in the control group ( 95 percent confidence interval , 7.26 to 10.40 ) . The rate in the annually screened group , but not in the biennially screened group , was significantly lower than that in the control group . Reduced mortality in the annually screened group was accompanied by improved survival in those with colorectal cancer and a shift to detection at an earlier stage of cancer . CONCLUSIONS Annual fecal occult-blood testing with rehydration of the sample s decreased the 13-year cumulative mortality from colorectal cancer by 33 percent BACKGROUND Flexible sigmoidoscopy ( FS ) has been recommended as a screening method to reduce mortality from colorectal cancer ( CRC ) . The present study evaluates the effect of adding FS to the fecal occult blood test Hemoccult-II ( H-II ) on diagnostic yield of colorectal neoplasia . METHODS A total of 10,978 normal persons aged 50 - 75 years were invited to participate , 5495 persons being allocated at r and om to H-II and FS and 5483 to H-II alone .  RESULTS In spite of a lower compliance ( 40 % versus 56 % ) for the combined procedure , the diagnostic yield of colorectal neoplasia was higher than for H-II alone ( 12 CRC versus 4 CRC , and 72 large adenomas versus 14 ) . Within 24 - 62 months after screening there were fewer CRCs detected after  H-II + FS than after H-II alone . The stage distribution was less favorable than in screen-detected cases . CONCLUSION One FS may not be an optimal way of screening , but FS deserves to be evaluated in r and omized population studies including repeated H-II tests in the control arm BACKGROUND A single flexible sigmoidoscopy at around the age of 60 years has been proposed as an effective strategy for colorectal cancer ( CRC ) screening . METHODS We conducted a r and omized controlled trial to evaluate the effect of flexible sigmoidoscopy screening on CRC incidence and mortality . A question naire to assess the eligibility and interest in screening was mailed to 236,568 men and women , aged 55 - 64 years , who were r and omly selected from six trial centers in Italy . Of the 56,532 respondents , interested and eligible subjects were r and omly assigned to the intervention group ( invitation for flexible sigmoidoscopy ; n = 17,148 ) or the control group ( no further contact ; n = 17,144 ) , between June 14 , 1995 , and May 10 , 1999 .  Flexible sigmoidoscopy was performed on 9911 subjects . Intention-to-treat and per- protocol analyses were performed to compare the CRC incidence and mortality rates in the intervention and control groups . Per- protocol analysis was adjusted for noncompliance . RESULTS A total of 34,272 subjects ( 17,136 in each group ) were included in the follow-up analysis . The median follow-up period was 10.5 years for incidence and 11.4 years for mortality ; 251 subjects were diagnosed with CRC in the intervention group and 306 in the control group . Overall incidence rates in the intervention and control groups were 144.11 and 176.43 , respectively , per 100,000 person-years . CRC-related death was noted in 65 subjects in the intervention group and 83 subjects in the control group . Mortality rates in the intervention and control groups were 34.66 and 44.45 , respectively , per 100,000 person-years . In the intention-to-treat analysis , the rate of CRC incidence was statistically significantly reduced in the intervention group by 18 % ( rate ratio [ RR ] = 0.82 , 95 % confidence interval [ CI ] = 0.69 to 0.96 ) , and the mortality rate was non-statistically significantly reduced by 22 % ( RR = 0.78 ; 95 % CI = 0.56 to 1.08 ) compared with the control group . In the per- protocol analysis , both CRC incidence and mortality rates were statistically significantly reduced among the screened subjects ; CRC incidence was reduced by 31 % ( RR = 0.69 ; 95 % CI = 0.56 to 0.86 ) and mortality was reduced by 38 % ( RR = 0.62 ; 95 % CI = 0.40 to 0.96 ) compared with the control group . CONCLUSION A single flexible sigmoidoscopy screening between ages 55 and 64 years was associated with a substantial reduction of CRC incidence and mortality BACKGROUND We wanted to assess the worry created by a screening program for colorectal cancer with fecal occult blood testing . METHODS Six thous and three hundred and sixty-six individuals ( 47 % men ; 53 % women ) were asked to what extent they were worried when they received an invitation letter including a Hemoccult II test ( HII ) . The question naire was supplemented by a structured telephone interview of a selected number of individuals with different outcome of the HII . RESULTS Three thous and four hundred and eighty-six subjects performed the HII test , and 3548 ( 56 % ) answered the question naire . Eighty-four per cent ( n = 2932 ) of the participants and 21 % ( n = 616 ) of the non- participants completed the question naire . Half of the participants ( 54 % ) were not worried at all , but 16 % , more women than men , felt severe worry , which lasted less than 1 week in 59 % . In 4.7 % of the participants daily life was negatively influenced by the invitation letter . In the telephone interview 19 % reported severe worry before they received the result of the first test , and in 5.8 % daily life was negatively affected . The worry rate increased to 60 % in the groups with an initial positive HII test , and in 15 % daily life was negatively influenced . After the examination the worry decreased in most but was still pronounced in 10 % . One year after the work-up 96 % declared that they appreciated the study . Subjects with only elementary school education expressed more worry than those with a higher level of education ( P < 0.05 ) . CONCLUSIONS Severe worry in connection with the invitation was reported by a minority of the invited participants , more women than men . The worry increased among those who had a positive test but decreased after the examination . One year after the work-up most appreciated the study BACKGROUND There is growing evidence that faecal-occult-blood ( FOB ) screening may reduce colorectal cancer ( CRC ) mortality , but this reduction in CRC mortality has not been shown in an unselected population -based r and omised controlled trial . The aim of this study was to assess the effect of FOB screening on CRC mortality in such a setting . METHODS Between February , 1981 , and January , 1991 , 152,850 people aged 45 - 74 years who lived in the Nottingham area of the UK were recruited to our study . Participants were r and omly allocated FOB screening ( 76,466 ) or no screening ( controls ; 76,384 ) . Controls were not told about the study and received no intervention . Screening-group participants were sent a Haemoccult FOB test kit with instructions from their family doctor . FOB tests were not rehydrated and dietary restrictions were imposed only for retesting borderline results . Individuals with negative FOB tests at the first screening , together with those who tested positive but in whom no neoplasia was found on colonoscopy , were invited to take part in further screening every 2 years . Screening was stopped in February , 1995 , by which time screening-group participants had been offered FOB tests between three and six times . Screening-group participants who had a positive test were offered full colonoscopy . All participants were followed up until June , 1995 . The primary outcome measure was CRC mortality . FINDINGS Of the 152,850 individuals recruited to the study , 2599 could not be traced or had emigrated and were excluded from the analysis . Thus , there were 75,253 participants in the screening group and 74,998 controls . 44,838 ( 59.6 % ) screening-group participants completed at least one screening . 28,720 ( 38.2 % ) of these individuals completed all the FOB tests they were offered and 16,118 ( 21.4 % ) completed at least one screening but not all the tests they were offered . 30,415 ( 40.4 % ) did not complete any test . Of 893 cancers ( 20 % stage A ) diagnosed in  screening-group participants ( CRC incidence of 1.49 per 1000 person-years ) , 236 ( 26.4 % ) were detected by FOB screening , 249 ( 27.9 % ) presented after a negative FOB test or investigation , and 400 ( 44.8 % ) presented in non-responders . The incidence of cancer in the control group ( 856 cases , 11 % stage A ) was 1.44 per 1000 person-years . Median follow-up was 7.8 years ( range 4.5 - 14.5 ) . 360 people died from CRC in the screening group compared with 420 in the control group-a 15 % reduction in cumulative CRC mortality in the screening group ( odds ratio=0.85 [ 95 % ; CI 0.74 - 0.98 ] , p = 0.026 ) . INTERPRETATION Our findings together with evidence from other trials suggest that consideration should be given to a national programme of FOB screening to reduce CRC mortality in the general population The authors estimated components of variance and intraclass correlation coefficients ( ICCs ) to aid in the design of complex surveys and community intervention studies by analyzing data from the Health Survey for Engl and 1994 . This cross-sectional survey of English adults included data on a range of lifestyle risk factors and health outcomes . For the survey , households were sample d in 720 postal code sectors nested within 177 district health authorities and 14 regional health authorities . Study subjects were adults aged 16 years or more .  ICCs and components of variance were estimated from a nested r and om-effects analysis of variance . Results are presented at the district health authority , postal code sector , and household levels . Between-cluster variation was evident at each level of clustering . In these data , ICCs were inversely related to cluster size , but design effects could be substantial when the cluster size was large . Most ICCs were below 0.01 at the district health authority level , and they were mostly below 0.05 at the postal code sector level . At the household level , many ICCs were in the range of 0.0 - 0.3 . These data may provide useful information for the design of epidemiologic studies in which the units 
    Output:
    
There is high quality evidence that both flexible sigmoidoscopy and faecal occult blood testing reduce colorectal cancer mortality when applied as screening tools .
There is low quality indirect evidence that screening with either approach reduces colorectal cancer deaths more than the other .