Outcomes of colon surveillance after colorectal cancer screening with colonoscopy are uncertain.
Dr David Lieberman and colleagues from Oregon, USA conducted a prospective study to measure incidence of advanced neoplasia in patients within 5.5 years of screening colonoscopy.
The team assessed 3,121 asymptomatic subjects, aged 50 to 75 years.
The patients received screening colonoscopy between 1994 and 1997 in the Department of Veterans Affairs.
|76% of patients with neoplasia had colonoscopy within 5.5 years|
The team assessed 1,171 subjects with neoplasia, and 501 neoplasia-free controls assigned to colonoscopic surveillance over 5 years.
Cohorts were defined by baseline findings.
The team calculated relative risks for advanced neoplasia within 5.5 years.
Advanced neoplasia was defined as tubular adenoma greater than 10 mm, adenoma with villous histology, adenoma with high-grade dysplasia, or invasive cancer.
The researchers found that 76% of patients with neoplasia, and 60% of subjects without neoplasia at baseline had colonoscopy within 5.5 years.
The team noted that 2% of patients with no neoplasia had interval advanced neoplasia.
The researchers observed that the relative risk in patients with baseline neoplasia was 1.9 with 1 or 2 tubular adenomas less than 10 mm.
The team found that the relative risk with 3 or more tubular adenomas less than 10 mm was 5.
The relative risk was 6 with tubular adenomas 10 mm in size and for villous adenomas, and 7 for adenoma with high-grade dysplasia.
Dr Lieberman's team concluded, "There is a strong association between results of baseline screening colonoscopy and rate of serious incident lesions during 5.5 years of surveillance."
"Patients with 1 or 2 tubular adenomas less than 10 mm represent a low-risk group compared with other patients with colon neoplasia."