The Importance of Complete Colonoscopy and Exploration of the Cecal Region

Abstract

Examination of the left colon alone misses right-sided lesions. Colonoscopy is the most sensitive colonic imaging test for adenomas. An additional advantage of colonoscopy is the ability to remove precancerous polyps at the time of their detection. A right-sided shift of initial and recurrent adenoma with aging and female gender has been reported. Therefore, total colonoscopy is needed for screening and surveillance. Clinically, right-sided cancer is likely to be detected at a more advanced stage, with severe symptoms, such as passage trouble or abdominal mass. Morphologically, flat-type tumors are significantly encountered in right-sided colon, while polypoid-type ones are substantially more dominant in the left colon. Histologically, poorly differentiated, mucinous and signet-ring cell tumors are frequently seen in the right colon. From the molecular aspect, both colorectal cancers (CRC) with a high frequency of CpG island methylation and those with microsatellite instability, have been frequently detected in the right-sided colon of elderly people. Moreover, sessile serrated adenomas or polyps (SSAP) are more prevalent in the proximal colon. The presence of large SSAPs (10 mm or larger in size) is also reported to be a risk factor for CRC, particularly CRC of the proximal colon.