title: Effect of flexible sigmoidoscopy screening on colorectal cancer incidence and mortality: a randomized clinical trial.
abstract: OBJECTIVE
  Colorectal cancer is a major health burden. Screening is recommended in many countries.
  
  
  OBJECTIVE
  To estimate the effectiveness of flexible sigmoidoscopy screening on colorectal cancer incidence and mortality in a population-based trial.
  
  
  METHODS
  Randomized clinical trial of 100,210 individuals aged 50 to 64 years, identified from the population of Oslo city and Telemark County, Norway. Screening was performed in 1999-2000 (55-64-year age group) and in 2001 (50-54-year age group), with follow-up ending December 31, 2011. Of those selected, 1415 were excluded due to prior colorectal cancer, emigration, or death, and 3 could not be traced in the population registry.
  
  
  METHODS
  Participants randomized to the screening group were invited to undergo screening. Within the screening group, participants were randomized 1:1 to receive once-only flexible sigmoidoscopy or combination of once-only flexible sigmoidoscopy and fecal occult blood testing (FOBT). Participants with positive screening test results (cancer, adenoma, polyp ≥10 mm, or positive FOBT) were offered colonoscopy. The control group received no intervention.
  
  
  METHODS
  Colorectal cancer incidence and mortality.
  
  
  RESULTS
  A total of 98,792 participants were included in the intention-to-screen analyses, of whom 78,220 comprised the control group and 20,572 comprised the screening group (10,283 randomized to receive a flexible sigmoidoscopy and 10,289 to receive flexible sigmoidoscopy and FOBT). Adherence with screening was 63%. After a median of 10.9 years, 71 participants died of colorectal cancer in the screening group vs 330 in the control group (31.4 vs 43.1 deaths per 100,000 person-years; absolute rate difference, 11.7 [95% CI, 3.0-20.4]; hazard ratio [HR], 0.73 [95% CI, 0.56-0.94]). Colorectal cancer was diagnosed in 253 participants in the screening group vs 1086 in the control group (112.6 vs 141.0 cases per 100,000 person-years; absolute rate difference, 28.4 [95% CI, 12.1-44.7]; HR, 0.80 [95% CI, 0.70-0.92]). Colorectal cancer incidence was reduced in both the 50- to 54-year age group (HR, 0.68; 95% CI, 0.49-0.94) and the 55- to 64-year age group (HR, 0.83; 95% CI, 0.71-0.96). There was no difference between the flexible sigmoidoscopy only vs the flexible sigmoidoscopy and FOBT screening groups.
  
  
  CONCLUSIONS
  In Norway, once-only flexible sigmoidoscopy screening or flexible sigmoidoscopy and FOBT reduced colorectal cancer incidence and mortality on a population level compared with no screening. Screening was effective both in the 50- to 54-year and the 55- to 64-year age groups.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT00119912.
authors.affiliation: Department of Medicine, Sorlandet Hospital Kristiansand, Kristiansand, Norway2Institute of Health and Society, University of Oslo, Oslo, Norway3Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts4Department of Biostatistics Harvard School of Public Health, Boston, Massachusetts.
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Holme
authors.affiliation: Institute of Health and Society, University of Oslo, Oslo, Norway3Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts5Harvard-MIT Division of Health Sciences and Technology, Boston, Boston, Massachusetts, Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: Magnus
authors.initials: M
authors.lastname: Løberg
authors.affiliation: Institute of Health and Society, University of Oslo, Oslo, Norway3Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts5Harvard-MIT Division of Health Sciences and Technology, Boston, Boston, Massachusetts, Telemark Hospital Skien, Skien, Norway.
authors.forename: Mette
authors.initials: M
authors.lastname: Kalager
authors.affiliation: Department of Medicine, Sorlandet Hospital Kristiansand, Kristiansand, Norway2Institute of Health and Society, University of Oslo, Oslo, Norway3Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, Harvard-MIT Division of Health Sciences and Technology, Boston, Boston, Massachusetts, Department of Transplantation Medicine, Oslo University Hospital, Oslo, Norway.
authors.forename: Michael
authors.initials: M
authors.lastname: Bretthauer
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts4Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts5Harvard-MIT Division of Health Sciences and Technology, Boston, Boston, Massachusetts.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Hernán
authors.affiliation: Institute of Health and Society, University of Oslo, Oslo, Norway.
authors.forename: Eline
authors.initials: E
authors.lastname: Aas
authors.affiliation: Department of Pathology, Oslo University Hospital, Oslo, Norway.
authors.forename: Tor J
authors.initials: TJ
authors.lastname: Eide
authors.affiliation: School of Pharmacy, University of Oslo, Norway.
authors.forename: Eva
authors.initials: E
authors.lastname: Skovlund
authors.affiliation: Department of Pharmacology and Clinical Neuroscience, Clinical Pharmacology Unit, Umeå University, Umeå, Sweden.
authors.forename: Jørn
authors.initials: J
authors.lastname: Schneede
authors.affiliation: Department of Oncology, Oslo University Hospital, Oslo, Norway.
authors.forename: Kjell Magne
authors.initials: KM
authors.lastname: Tveit
authors.affiliation: Institute of Health and Society, University of Oslo, Oslo, Norway7Telemark Hospital Skien, Skien, Norway13Cancer Registry of Norway, Oslo, Norway.
authors.forename: Geir
authors.initials: G
authors.lastname: Hoff
mesh_terms: D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D015994:Incidence; D057194:Intention to Treat Analysis; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D009780:Occult Blood; D012812:Sigmoidoscopy / Q000295:instrumentation