Results of repeat sigmoidoscopy 3 years after a negative examination.
BACKGROUND
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.


METHODS
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.


METHODS
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.
Schoen
Robert E
RE
Department of Medicine, University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, PA, USA. rschoen@pitt.edu
Pinsky
Paul F
PF
Weissfeld
Joel L
JL
Bresalier
Robert S
RS
Church
Timothy
T
Prorok
Philip
P
Gohagan
John K
JK
D000236:Adenoma / Q000175:diagnosis* / Q000453:epidemiology; D000368:Aged; D003110:Colonic Neoplasms / Q000175:diagnosis* / Q000453:epidemiology; D003111:Colonic Polyps / Q000175:diagnosis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D012812:Sigmoidoscopy; D013997:Time Factors