Incidence and predictors of adenoma after surgery for colorectal cancer

Patients with colorectal cancer (CRC) are at increased risk for developing metachronous premalignant and malignant lesions. However, its real incidence and underlying risk factors are still unclear, and therefore quality measures for colonoscopy under this indication have not been completely established. The aim of this study was to assess the incidence of and risk factors for the development of adenomas after surgery for CRC.

A total of 535 patients submitted to curative surgery for CRC between January 2008 and December 2011 were selected and their clinical records and surveillance colonoscopies were reviewed.

During a median follow-up of 62 months, 39.4% of the patients developed adenomas, 17.6% advanced adenomas and 3.4% developed metachronous cancers. Male sex [adjusted odds ratio (AOR)=1.99; 95% confidence interval (CI): 1.29-3.07] was an independent risk factor for adenomas during follow-up and absence of a high-quality baseline colonoscopy was the only independent risk factor for advanced adenomas (AOR=1.78; 95% CI: 1.03-3.07) and metachronous cancer (AOR=7.05; 95% CI: 1.52-32.66). In patients who had undergone a high-quality colonoscopy at baseline and at the first follow-up, the presence of adenomas (odds ratio=12.30; 95% CI: 2.30-66.25) and advanced adenomas (odds ratio=10.50; 95% CI: 2.20-50.18) in the first follow-up colonoscopy was a risk factor for the development of metachronous advanced adenomas during the subsequent surveillance.

Undergoing a high-quality baseline colonoscopy is the most important factor for reducing the incidence of advanced lesions after CRC surgery. All patients remain at high-risk for adenomas and advanced adenomas, but standardized follow-up should be adjusted after the first year of follow-up.