Ongoing colorectal cancer risk despite surveillance colonoscopy: the Polyp Prevention Trial Continued Follow-up Study
Background
Despite regular colonoscopy, interval colorectal cancer (CRC) may occur. Long-term studies examining CRC rates in patients with previous colonoscopy are lacking.
Objective
We examined the rate of interval CRC in the Polyp Prevention Trial Continued Follow-up Study (PPT-CFS), an observational study of PPT participants that began after the PPT ended.
Design
Prospective.
Setting
A national U.S. community-based polyp prevention trial.
Main Outcome Measurements
Medical records of patients with CRC were collected, reviewed, and abstracted in a standardized fashion.
Results
Among 2079 PPT participants, 1297 (62.4%) agreed to participate in the PPT-CFS. They were followed for a median of 6.2 years after 4.3 years of median follow-up in the main PPT. Nine cases of CRC were diagnosed over 7626 person-years of observation (PYO), for an incidence rate of 1.2/1000 PYO. The ratio of CRCs observed compared with that expected by Surveillance, Epidemiology, and End Results was 0.64 (95% CI, 0.28-1.06). Including all CRCs (N = 22) since the beginning of the PPT, the observed compared with expected rate by Surveillance, Epidemiology, and End Results was 0.74 (95% CI, 0.47-1.05). Of patients in whom CRC developed in the PPT-CFS, 78% had a history of an advanced adenoma compared with only 43% of patients who remained cancer free (P = .04).
Limitation
A relatively small number of interval cancers were detected.
Conclusions
Despite frequent colonoscopy during the PPT, in the years after the trial, there was a persistent ongoing risk of cancer. Subjects with a history of advanced adenoma are at increased risk of subsequent cancer and should be followed closely with continued surveillance.
Abbreviations: CFS, Continued Follow-up Study, CRC, colorectal cancer, PPT, Polyp Prevention Trial, PYO, person-years of observation, SEER, Surveillance, Epidemiology, and End Results
To access this article, please choose from the options below
DISCLOSURE: All authors disclosed no financial relationships relevant to this publication.
See CME section; p. 139.
PII: S0016-5107(09)01912-9
doi:10.1016/j.gie.2009.05.010
© 2010 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Continuing Medical Education Exam: January 2010
