***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 To which groups of patients can the results of clinical trials be applied ? This question is often inappropriately answered by reference to the trial entry criteria . Instead , the benefit and harm ( adverse events , discomfort of treatment , etc ) of treatment could be assessed separately for individual patients . Patients at greatest risk of a disease will have the greatest net benefit as benefit to patients usually increases with risk while harm remains comparatively fixed . To assess net benefit , the relative risks should come from ( a meta- analysis of ) r and omised trials ; the risk in individual patients should come from multivariate risk equations derived from cohort studies . However , before making firm conclusions , the assumptions of fixed adverse effects and constant reduction in relative risk need to be checked 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 : It has recently been suggested that all-cause mortality is a more appropriate end point than disease specific mortality in cancer screening trials , and that disease specific mortality is biased in favour of screening . This suggestion is based partly on supposed inconsistencies between all-cause mortality results and disease specific results in cancer screening trials , and alleged increases in deaths from causes other than breast cancer among breast cancer cases diagnosed among women invited to screening . METHODS : We used data from the Swedish Two-County Trial of mammographic screening for breast cancer , in which 77 080 women were r and omised to an invitation to screening and 55 985 to no invitation .  We estimated relative risks ( RRs ) ( invited v control ) of death from breast cancer , death from other causes within the breast cancer cases , and death from all causes within the breast cancer cases . RRs were adjusted for age and took account of the longer follow up of breast cancer cases in the invited group due to lead time . RESULTS : There was a significant 31 % reduction in breast cancer mortality in the invited group ( RR 0.69 , 95 % confidence interval ( CI ) 0.58–0.80 ; p<0.001 ) . There was no significant increase in deaths from other causes among breast cancer cases in the invited group ( RR 1.12 , 95 % CI 0.96–1.31 ; p=0.14 ) . A significant 19 % reduction in deaths from all causes was observed among breast cancer cases in the group invited to screening ( RR 0.81 , 95 % CI 0.72–0.90 ; p<0.001 ) . A more conservative estimation gave a significant 13 % reduction ( RR 0.87 , 95 % CI 0.78–0.97 ; p=0.01 ) . These findings are consistent with the magnitude of the reduction in breast cancer mortality . CONCLUSIONS : Invitation to screening was associated with a reduction in deaths from all causes among breast cancer cases , consistent with high participation rates in screening . There is no significant evidence of bias in cause of death classification in the Two-County Trial , and as breast cancer mortality is the targeted clinical outcome in breast cancer screening , it is the appropriate end point in a breast cancer screening trial . All-cause mortality is a poor and inefficient surrogate for breast cancer mortality 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 BACKGROUND In 1993 , a r and omized controlled trial in Minnesota showed , after 13 years of follow-up , that annual fecal occult blood testing was effective in reducing colorectal cancer mortality by at least 33 % . Biennial screening ( i.e. , every 2 years ) result ed in only a 6 % mortality reduction . Two European trials ( in Engl and and in Denmark ) subsequently showed statistically significant 15 % and 18 % mortality reductions with biennial screening . Herein , we provide up date d results -through 18 years of follow-up -- from the Minnesota trial that address the apparent inconsistent findings among the trials regarding biennial screening . METHODS From 1976 through 1977 , a total of 46551 study subjects , aged 50 - 80 years , were recruited and r and omly assigned to an annual screen , a biennial screen , or a control group . A screen consisted of six guaiac-impregnated fecal occult blood tests ( Hemoccult ) prepared in pairs from each of three consecutive fecal sample s. Participants with at least one of the six tests that were positive were invited for a diagnostic examination that included colonoscopy . All participants were followed annually to ascertain incident colorectal cancers and deaths . RESULTS The numbers of deaths from all causes were similar among the three study groups . Cumulative 18-year colorectal cancer mortality was 33 % lower in the annual group than in the control group ( rate ratio , 0.67 ; 95 % confidence interval [ CI ] = 0.51 - 0.83 ) . The biennial group had a 21 % lower colorectal cancer mortality rate than the control group ( rate ratio , 0.79 ; 95 % CI = 0.62 - 0.97 ) . A marked reduction was also noted in the incidence of Dukes ' stage D cancers in both screened groups in comparison with the control group . CONCLUSION The results from this study , together with the other two published r and omized trials of fecal occult blood screening , are consistent in demonstrating a substantial , statistically significant reduction in colorectal cancer mortality from biennial screening Background : Three large r and omised trials have shown that screening for colorectal cancer using faecal occult blood ( FOB ) tests can reduce the mortality from this disease . Two national pilot studies have recently been launched in the UK to investigate the feasibility of population screening for colorectal cancer in the National Health Service . The largest of the r and omised trials was conducted in Nottingham and r and omised 152 850 individuals between the ages of 45 and 74 years to receive biennial Haemoccult ( FOB ) test kit ( intervention group ) or to a control group .  Aims : We have compared the mortality in the intervention group compared with the control group . Methods : The 152 850 r and omised individuals were followed up through local health records and central flagging ( Office for National Statistics ) over a median follow up period of 11 years . Results : At a median follow up of 11 years there was a 13 % reduction in colorectal cancer mortality ( 95 % confidence interval 3–22 % ) in the intervention group despite an uptake at first invitation of only approximately 50 % . The mortality reduction for those accepting screening was 27 % . The reduction in mortality was independent of sex and site of tumour . There was no significant difference in mortality from causes other than colorectal cancer between the intervention and control groups . Conclusions : Although the reduction in colorectal cancer mortality was sustained , further follow up of this population is required to determine whether a significant reduction in the incidence of colorectal cancer will be achieved BACKGROUND The most widely accepted end point in r and omized cancer screening trials is disease-specific mortality . The validity of this end point , however , rests on the assumption that cause of death can be determined accurately . An alternative end point is all-cause mortality , which depends only on the accurate ascertainment of deaths and when they occur . We compared disease-specific and all-cause mortality in published r and omized cancer-screening trials to indirectly assess the validity of the disease-specific mortality end point . METHODS We examined all 12 published r and omized trials of cancer screening for which both end points 
    Output:
    
This review confirms previous research demonstrating that FOBT screening reduces the risk of CRC mortality .
The results also indicate that there is no difference in all-cause mortality between the screened and nonscreened population