Results of Repeat Sigmoidoscopy 3 Years After a Negative Examination
- Robert E. Schoen, MD, MPH;
- Paul F. Pinsky, PhD;
- Joel L. Weissfeld, MD, MPH;
- Robert S. Bresalier, MD;
- Timothy Church, PhD;
- Philip Prorok, PhD;
- John K. Gohagan, PhD;
- for the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Group
- Author Affiliations: Departments of Medicine and Epidemiology and the University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pa (Drs Schoen and Weissfeld); Division of Cancer Prevention, National Cancer Institute, Bethesda, Md (Drs Pinsky, Prorok, and Gohagan); Division of Gastrointestinal Medicine and Nutrition, M. D. Anderson Cancer Center, Houston, Tex (Dr Bresalier); and Division of Environmental and Occupational Health, University of Minnesota, Minneapolis (Dr Church).
Abstract
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.
