A pooled analysis of advanced colorectal neoplasia diagnoses after colonoscopic polypectomy

Abstract

Background & aims: Limited data exist regarding the actual risk of developing advanced adenomas and cancer after polypectomy or the factors that determine risk.

Methods: We pooled individual data from 8 prospective studies comprising 9167 men and women aged 22 to 80 with previously resected colorectal adenomas to quantify their risk of developing subsequent advanced adenoma or cancer as well as identify factors associated with the development of advanced colorectal neoplasms during surveillance.

Results: During a median follow-up period of 47.2 months, advanced colorectal neoplasia was diagnosed in 1082 (11.8%) of the patients, 58 of whom (0.6%) had invasive cancer. Risk of a metachronous advanced adenoma was higher among patients with 5 or more baseline adenomas (24.1%; standard error, 2.2) and those with an adenoma 20 mm in size or greater (19.3%; standard error, 1.5). Risk factor patterns were similar for advanced adenomas and invasive cancer. In multivariate analyses, older age (P < .0001 for trend) and male sex (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.19-1.65) were associated significantly with an increased risk for metachronous advanced neoplasia, as were the number and size of prior adenomas (P < .0001 for trend), the presence of villous features (OR, 1.28; 95% CI, 1.07-1.52), and proximal location (OR, 1.68; 95% CI, 1.43-1.98). High-grade dysplasia was not associated independently with metachronous advanced neoplasia after adjustment for other adenoma characteristics.

Conclusions: Occurrence of advanced colorectal neoplasia is common after polypectomy. Factors that are associated most strongly with risk of advanced neoplasia are patient age and the number and size of prior adenomas.

Figure 1. Study-Specific and Pooled Multivariate Odds Ratios of Advanced Colorectal Neoplasia (Advanced Adenoma and Cancer) for Baseline Adenoma Characteristics

Odds ratios (ORs) are adjusted for age, sex, race, smoking status, BMI, family history of colorectal cancer, history of polyp or adenoma prior to the baseline examination, and the baseline adenoma characteristics. ORs for number and size of adenomas represent an increase in risk per adenoma and per 10mm increment, respectively. The black squares and horizontal lines correspond to the study-specific multivariate ORs and 95% confidence intervals (CIs), respectively. The area of the black square reflects the study-specific weight (inverse of the variance). The pooled ORs are based on data from 8814 patients due to missing data on baseline adenoma size and number for 353 individuals. The diamond represents the pooled multivariate OR and 95% CIs. The solid line represents an OR of 1.0. The abbreviations for the studies are listed in Table 1.