Using Risk for Advanced Proximal Colonic Neoplasia To Tailor Endoscopic Screening for Colorectal Cancer

  • Imperiale, Thomas F. MD
  • Wagner, David R. MS
  • Lin, Ching Y. BS
  • Larkin, Gregory N. MD
  • Rogge, James D. MD
  • Ransohoff, David F. MD
Annals of Internal Medicine 139(12):p 959-965, December 16, 2003.

Background:

Colonoscopic screening for colorectal cancer has been suggested because sigmoidoscopy misses nearly half of persons with advanced proximal neoplasia.

Objective:

To create a clinical index to stratify risk for advanced proximal neoplasia and to identify a subgroup with very low risk in which screening sigmoidoscopy alone might suffice.

Design:

Cross-sectional study.

Setting:

A company-based program of screening colonoscopy for colorectal cancer.

Patients:

Consecutive persons 50 years of age or older undergoing first-time screening colonoscopy between September 1995 and June 2001.

Measurements:

A clinical index with 3 variables was created from information on the first 1994 persons. Points were assigned to categories of age, sex, and distal findings. Risk for advanced proximal neoplasia (defined as an adenoma 1 cm or larger or one with villous histology, severe dysplasia, or cancer) was measured for each score. The index was tested on the next 1031 persons from the same screening program.

Results:

Of 1994 persons, 67 (3.4%) had advanced proximal neoplasia. A low-risk subgroup comprising 37% of the cohort had scores of 0 or 1 and a risk of 0.68% (95% CI, 0.22% to 1.57%). Among the validation group of 1031 persons, risk for advanced proximal neoplasia in the low-risk subgroup (comprising 47% of the cohort) was 0.4% (upper confidence limit of 1.49%). Application of this index detected 92% of persons with advanced proximal neoplasms and, if applied following screening sigmoidoscopy, could reduce the need for colonoscopy by 40%. The marginal benefit of colonoscopy among low-risk persons was small: To detect 7 additional persons with advanced proximal neoplasia, 1217 additional colonoscopies would be required.

Conclusions:

This clinical index stratifies the risk for advanced proximal neoplasia and identifies a subgroup at very low risk. If it is validated in other cohorts or groups, the index could be used to tailor endoscopic screening for colorectal cancer.

Copyright © 2003 American College of Physicians
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