title: Screening for colorectal cancer with flexible sigmoidoscopy: is a 5-yr interval appropriate? A comparison of the detection of neoplasia 3 yr versus 5 yr after a normal examination.
abstract: BACKGROUND
  The recommended interval for colorectal cancer screening with flexible sigmoidoscopy (FS) was recently lengthened from 3 to 5 yr. Direct evidence supporting the longer interval is lacking. The appropriateness of the longer interval has been questioned.
  
  
  OBJECTIVE
  To compare the incidence of neoplasia detected on FS in individuals who had undergone an FS either 3 yr or 5 yr after a normal examination.
  
  
  METHODS
  Subjects were drawn from 5,359 individuals who underwent two FS examinations performed for colorectal cancer screening. Examinations were performed by gastroenterologists at a single academic medical center between 1987 and 2002. A total of 2,146 subjects with a normal baseline examination and a follow-up examination 3 and 5 yr later was included.
  
  
  METHODS
  To compare the incidence of neoplasia, including advanced neoplasia, detected 3 yr versus 5 yr after a normal FS.
  
  
  RESULTS
  915 subjects underwent FS at 3 yr and 1,231 subjects at 5 yr after a normal examination. Neoplasia was detected in 3.2% of the 3-yr and 4.3% of the 5-yr subjects (p=0.17). No significant differences were detected in the pathology, multiplicity, or size of neoplasms between the 3- and 5-yr groups. Advanced neoplasms occurred in 0.9% (including one adenocarcinoma) of subjects at 3 yr and 1.1% of subjects at 5 yr (p=0.67).
  
  
  CONCLUSIONS
  Few individuals will develop rectosigmoid neoplasms 3 or 5 yr after a normal FS. The majority of neoplasms detected are low-risk lesions. A screening interval of 5 yr after a normal FS does not portend an increased risk of advanced neoplasms including cancer. This direct evidence supports the current recommendations of a 5-yr interval for colorectal cancer screening with FS.
authors.affiliation: Department of Gastroenterology and Hepatology, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: Carol A
authors.initials: CA
authors.lastname: Burke
authors.forename: Kareem
authors.initials: K
authors.lastname: Elder
authors.forename: Rocio
authors.initials: R
authors.lastname: Lopez
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011446:Prospective Studies; D012812:Sigmoidoscopy; D018709:Statistics, Nonparametric; D013997:Time Factors