title: Colorectal-cancer incidence and mortality with screening flexible sigmoidoscopy.
abstract: BACKGROUND
  The benefits of endoscopic testing for colorectal-cancer screening are uncertain. We evaluated the effect of screening with flexible sigmoidoscopy on colorectal-cancer incidence and mortality.
  
  
  METHODS
  From 1993 through 2001, we randomly assigned 154,900 men and women 55 to 74 years of age either to screening with flexible sigmoidoscopy, with a repeat screening at 3 or 5 years, or to usual care. Cases of colorectal cancer and deaths from the disease were ascertained.
  
  
  RESULTS
  Of the 77,445 participants randomly assigned to screening (intervention group), 83.5% underwent baseline flexible sigmoidoscopy and 54.0% were screened at 3 or 5 years. The incidence of colorectal cancer after a median follow-up of 11.9 years was 11.9 cases per 10,000 person-years in the intervention group (1012 cases), as compared with 15.2 cases per 10,000 person-years in the usual-care group (1287 cases), which represents a 21% reduction (relative risk, 0.79; 95% confidence interval [CI], 0.72 to 0.85; P<0.001). Significant reductions were observed in the incidence of both distal colorectal cancer (479 cases in the intervention group vs. 669 cases in the usual-care group; relative risk, 0.71; 95% CI, 0.64 to 0.80; P<0.001) and proximal colorectal cancer (512 cases vs. 595 cases; relative risk, 0.86; 95% CI, 0.76 to 0.97; P=0.01). There were 2.9 deaths from colorectal cancer per 10,000 person-years in the intervention group (252 deaths), as compared with 3.9 per 10,000 person-years in the usual-care group (341 deaths), which represents a 26% reduction (relative risk, 0.74; 95% CI, 0.63 to 0.87; P<0.001). Mortality from distal colorectal cancer was reduced by 50% (87 deaths in the intervention group vs. 175 in the usual-care group; relative risk, 0.50; 95% CI, 0.38 to 0.64; P<0.001); mortality from proximal colorectal cancer was unaffected (143 and 147 deaths, respectively; relative risk, 0.97; 95% CI, 0.77 to 1.22; P=0.81).
  
  
  CONCLUSIONS
  Screening with flexible sigmoidoscopy was associated with a significant decrease in colorectal-cancer incidence (in both the distal and proximal colon) and mortality (distal colon only). (Funded by the National Cancer Institute; PLCO ClinicalTrials.gov number, NCT00002540.).
authors.affiliation: Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA. rschoen@pitt.edu
authors.forename: Robert E
authors.initials: RE
authors.lastname: Schoen
authors.forename: Paul F
authors.initials: PF
authors.lastname: Pinsky
authors.forename: Joel L
authors.initials: JL
authors.lastname: Weissfeld
authors.forename: Lance A
authors.initials: LA
authors.lastname: Yokochi
authors.forename: Timothy
authors.initials: T
authors.lastname: Church
authors.forename: Adeyinka O
authors.initials: AO
authors.lastname: Laiyemo
authors.forename: Robert
authors.initials: R
authors.lastname: Bresalier
authors.forename: Gerald L
authors.initials: GL
authors.lastname: Andriole
authors.forename: Saundra S
authors.initials: SS
authors.lastname: Buys
authors.forename: E David
authors.initials: ED
authors.lastname: Crawford
authors.forename: Mona N
authors.initials: MN
authors.lastname: Fouad
authors.forename: Claudine
authors.initials: C
authors.lastname: Isaacs
authors.forename: Christine C
authors.initials: CC
authors.lastname: Johnson
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Reding
authors.forename: Barbara
authors.initials: B
authors.lastname: O'Brien
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Carrick
authors.forename: Patrick
authors.initials: P
authors.lastname: Wright
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Riley
authors.forename: Mark P
authors.initials: MP
authors.lastname: Purdue
authors.forename: Grant
authors.initials: G
authors.lastname: Izmirlian
authors.forename: Barnett S
authors.initials: BS
authors.lastname: Kramer
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Miller
authors.forename: John K
authors.initials: JK
authors.lastname: Gohagan
authors.forename: Philip C
authors.initials: PC
authors.lastname: Prorok
authors.forename: Christine D
authors.initials: CD
authors.lastname: Berg
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D055088:Early Detection of Cancer; D004866:Equipment Contamination; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D020694:Sigmoidoscopes; D012812:Sigmoidoscopy / Q000295:instrumentation