Results of repeat sigmoidoscopy 3 years after a negative examination

JAMA. 2003 Jul 2;290(1):41-8. doi: 10.1001/jama.290.16.2123-b.


Context: The necessary frequency of endoscopic colorectal cancer screening after a negative examination is uncertain.

Objective: To examine the yield of adenomas and cancer in the distal colon found by repeat flexible sigmoidoscopy (FSG) 3 years after a negative examination.

Design, setting, and participants: Participants were drawn from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO), a randomized, controlled community-based study of cancer screening. The mean (SD) age was 65.7 (4.0) years at study entry (1993-1995) and 61.6% were men. Individuals underwent screening FSG at baseline and at 3 years as part of the protocol and were referred to their personal physicians for further evaluation of screen-detected abnormalities. Results from subsequent diagnostic evaluations were tracked in a standardized fashion. Of 11 583 eligible for repeat screening FSG 3 years after an initial negative examination, 9317 (80.4%) returned.

Main outcome measures: Polyp or mass detection in distal colon at year 3 repeat FSG; incidence of adenoma or cancer in distal colon at year 3 examination; determination of reason for detection (increased depth of insertion or improved preparation at the year 3 examination or detection in a previously examined area).

Results: A total of 1292 returning participants (13.9%) had a polyp or mass detected by FSG 3 years after the initial examination. In the distal colon, 3.1% (292/9317) were found to have an adenoma or cancer. The incidence of advanced adenoma (n = 72) or cancer (n = 6) in the distal colon was 78 (0.8%) of 9317. Of individuals with advanced distal adenomas detected at the year 3 examination, 80.6% (58/72) had lesions found in a portion of the colon that had been adequately examined at the initial sigmoidoscopy.

Conclusions: Repeat FSG 3 years after a negative examination will detect advanced adenomas and distal colon cancer. Although the overall percentage with detected abnormalities is modest, these data raise concern about the impact of a prolonged screening interval after a negative examination.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoma / diagnosis*
  • Adenoma / epidemiology
  • Aged
  • Colonic Neoplasms / diagnosis*
  • Colonic Neoplasms / epidemiology
  • Colonic Polyps / diagnosis
  • Female
  • Follow-Up Studies
  • Humans
  • Incidence
  • Logistic Models
  • Male
  • Middle Aged
  • Randomized Controlled Trials as Topic
  • Sigmoidoscopy*
  • Time Factors