Can DNA sampling from the rectal mucosa be a novel tool for the detection of colorectal cancer?

INTRODUCTION

The objective was to evaluate a new method for DNA sampling from the rectal mucosa for the detection of colorectal cancer or any clinically significant pathology in the colon and rectum.

METHODS

This prospective cohort study included patients scheduled for colonoscopy (group 1, n = 185) or colonic resection because of suspected colorectal cancer (group 2, n = 62). A test instrument with a balloon-holding end was introduced through a proctoscope into the rectum to collect exfoliated cells, from which DNA was isolated and quantified.

RESULTS

The detection of colorectal cancer in group 1 showed a sensitivity for the DNA cut-off levels 1.5, 2, and 2.5 microg/ml of 100%, 80%, and 60%, and a specificity of 37%, 46%, and 56%, respectively. In group 2, for the same cut-off levels, the sensitivity was 73%, 61%, and 55%, and the specificity was 67%, 67%, and 67%, respectively.

CONCLUSIONS

This novel technique is a safe and easy way of collecting DNA from the rectal mucosa. The sensitivity and specificity of the test were too low to be acceptable for a screening test. The low sensitivity and specificity in this study could be explained by the diversity within the study groups as many patients presented with long-term history of colorectal disease and surgical interventions in the past.