Study on Second Forward View Examination in the Right Colon

It is estimated that there are about 1.4 million patients with colorectal cancer (CRC) worldwide, with a rising trend in CRC incidence in many Asian Pacific countries. In Hong Kong, colorectal cancer ranks first in cancer incidence and second in cancer mortality based on data from 2013. CRC is one of the most preventable cancers because its development in general follows an adenoma-carcinoma sequence. Adenomas are considered precursor lesions for CRC. While early detection and removal of colorectal adenoma by screening colonoscopy with polypectomy reduce CRC incidence and mortality, interval cancers (cancers that develop after a colonoscopy and before the next scheduled colonoscopy) may still occur and were reported to account for up to 10.5% of CRC. The protective effect of colonoscopy against cancer in the right colon has not been consistently demonstrated. Interval CRC has been associated with proximal colon location, small lesion, flat lesion, missed lesion, inadequate examination, incomplete resection of lesion, tumor biology, and low adenoma detection rate (ADR). High ADR (eg, ≥ 20%) has been associated with a reduced risk of interval CRC. Methods that can improve polyp detection in the right colon such as retroflexed examination of the right colon, second forward view examination of the right colon, use of colonic fold flattening device, colonoscope with an increased field of view may potentially reduce the risk of interval CRC, but data is still limited. Performance of a second forward view (SFV) examination of the right colon may be the easiest and safest from a practical standpoint when compared to other options (eg, additional training is often needed for retroflexed examination of the right colon since there may be a potentially higher risk of perforation in endoscopists not familiar with the technique, additional equipment is needed when using a colonic fold flattening device, or a colonoscope with an increased field of view). Our current study aims