Patients with one to two tubular adenomas <1 cm in size without high-grade dysplasia (low-risk group) are considered at low risk for colorectal cancer.
However, it is uncertain whether they have the same risk of subsequent advanced neoplasia as those with no neoplasia at baseline colonoscopy.
Dr Hassan and colleagues from Italy compared incidence of metachronous advanced neoplasia between patients in the low-risk adenoma group, and those without neoplasia at index colonoscopy.
Relevant publications were identified by MEDLINE/EMBASE and other databases for the period 1992–2013.
Studies comparing the incidence of post-polypectomy advanced neoplasia (adenomas ≥10 mm/high-grade dysplasia/villous or cancer) between the low-risk group and patients without colorectal neoplasia at the first colonoscopy were included.
The team extracted detection rates for advanced neoplasia at endoscopic surveillance.
|The incidence of advanced neoplasia ws about 4% in those with low-risk adenoma|
|Alimentary Pharmacology & Therapeutics|
Study quality was ascertained according to Newcastle–Ottawa Scale.
Forest plot was produced based on random-effect models.
The research team assessed inter-study heterogeneity using the I2 statistic.
The team identified 7 studies that provided data on 11,387 patients.
Mean surveillance periods ranged between 2 and 5 years.
Altogether, 267 patients with post-polypectomy advanced neoplasia were detected in the 2 groups.
The researchers found that the incidence of advanced neoplasia was almost 2% in those without neoplasia, and about 4% in those with low-risk adenoma, respectively, corresponding to a relative risk of 1.8.
Inter-study heterogeneity was only moderate.
The team observe no publication bias.
Dr Hassan's team comments, "Patients with low-risk adenomas at baseline had a higher risk of metachronous advanced neoplasia than the group with no adenomas at baseline, though the absolute risk was low in both groups."