Use of Colonoscopy to Screen Asymptomatic Adults for Colorectal Cancer

Reviewers: Li Liu, MD
Source: New England Journal of Medicine, Volume 343(14): 162-168, (July) 2000.

Précis: Colonoscopy is favored for colorectal cancer screening in asymptomatic adults

Introduction

Almost all colorectal cancers arise from adenomatous polyps that develop over a period of years. During this time, polyps can be detected and then removed by colonoscopic polypectomy. It has long been thought by many physicians that colonoscopy is superior to sigmoidoscopic screening in detecting asymptomatic colorectal cancers or polyps associated with a high risk of cancer. In this study, researchers looked at the prevalence and location of colonic neoplasia in asymptomatic patients.

Method

A total of 3,121 asymptomatic adults aged 50 to 75 years underwent colonoscopy.

Results

• 7.5% of the patients had one or more neoplastic lesions, usually characterized as small benign adenomas.
• Advanced disease, defined as an adenoma with a diameter of at least 10 mm or with villous features, high-grade dysplasia, or invasive cancer, was found in 10.5% of patients.
• Of the 128 patients with advanced proximal neoplasms, 52% of patients had no distal adenomas. Sigmoidoscopy alone may not have identified these patients.

Discussion

The authors concluded that colonoscopy should be used instead of sigmoidoscopy in screening for colorectal cancer. This study reinforced the growing concern among physicians that flexible sigmoidoscopy alone to screen persons for colorectal cancer is suboptimal.