By not only diagnosing colorectal cancer (CRC) at an early stage, but also removing precursor lesions (adenomas), colonoscopy with polypectomy reduces the risk of developing and dying from CRC. Approximately 90% of polyps are less than 10 mm and are easily removed by competent endoscopists. Laterally spreading lesions (LST) and sessile lesions of the colon, also known as advanced mucosal neoplasia (AMN) are underrecognised types of lesions that are more likely to progress to cancer. They include sessile serrated polyps (SSP), an emerging entity of flat polyps with malignant potential. Detection of hemoglobin (a component of blood) in stool is an established validated screening tool for CRC. Its specific role in the prediction of AMN, and particularly SSPs is yet to be defined. Blood tests measuring the level of tumour derived methylated deoxyribonucleic acid (DNA) in blood circulating have been demonstrated to have clinical utility for detection of CRC and AMN. A blood based CRC screening test has the potential to increase compliance. This study aims to determine the clinical utility of stool and blood methylation tests for detection of AMN and SSPs. Stool and blood will be obtained from consenting patients referred for endoscopic removal of known ANM and SSP (study arm) as well as from consenting patients scheduled for colonoscopy screening (control arm). The level of stool hemoglobin and methylated tumour derived DNA in circulation will be measured in the two study groups. Cutoff values will be generated to assess best predictive capability of high risk lesions based on these tests.
The purpose of this study is to determine the clinical utility of stool and blood methylation tests for detection of advanced mucosal neoplasia (AMN) and sessile serrated polyps (SSP).