Risk factors of colorectal cancer after screening colonoscopy

In the era of populational screening programs for colorectal cancer, evaluation of their quality and efficacy becomes an important issue. One of the main criteria taken into account when assessing the quality of a screening program is related to the risk of colorectal cancer developing in the period between the screening colonoscopy and the control examination. The objective of this article consists in presenting the results of the doctoral research carried out by dr. Paulina Wieszcza, a beneficient of the Polpharma Scientific Foundation scholarship. The objective of the doctoral dissertation was to investigate and discuss the relationship between the definition of risk groups as well as the quality of the study and the risk of colorectal cancer developing after the screening colonoscopy. The risk of colorectal cancer developing following adenomas being removed during the screening colonoscopy procedure was assessed using data obtained from the Colorectal Cancer Screening Program and the National Cancer Registry databases. The quality of the study was assessed on the basis of literature evidence regarding the adenoma detection rates (ADR). A total of 236.089 patients were included in colorectal cancer risk analyses, with at least one adenoma being detected in a screening study in 17.7% of cases. Over the follow-up period (median of 7 years, maximum duration of 14 years), colorectal cancer was detected in 439 patients. It was demonstrated that when the high-risk group was defined as patients presenting with adenomas ≥ 20 mm in diameter or high grade dysplasia rather than patients with ≥ 3 adenomas or adenomas ≥10 mm in diameter with high grade dysplasia or villous component (current definition), the number of patients requiring intensive surveillance can be reduced by 74% without any impact on the risk in the low-risk group. The literature review revealed a total of three studies which clearly showed that the risk of colorectal cancer significantly decreased with the increase in the endoscopist’s ADR. Restricting the high-risk group to patients with adenomas ≥ 20 mm in diameter or high-grade dysplasia facilitates optimized care being delivered to patients with a significantly increased risk of colorectal cancer. Scientific evidence is available for the important role of endoscopist’s ADR as the key parameter of the quality of colonoscopic examination.