The American College of Gastroenterology High Definition Chromocolonoscopy Study: Findings and Implications for Colorectal Cancer Screening

Abstract

Purpose: Non-polypoid (flat and depressed) colon neoplasms are an increasingly recognized precursor for colorectal cancer (CRC) in Western populations. High-definition chromoscopy is used to increase the yield of colonoscopy for non-polypoid lesions; however, its role in average-risk patients undergoing routine screening remains uncertain. Methods: Average-risk patients referred for screening colonoscopy at 4 medical centers in the U.S. were randomized to high-definition chromocolonoscopy or high-definition white light colonoscopy. The primary outcomes, patients with at least one adenoma and number of adenomas per patient, were compared between the 2 groups. Secondary outcomes included patients with flat or depressed lesions, as defined by the Paris classification. Results: A total of 660 patients were randomized (chromocolonoscopy: 321, white light: 339). Overall, the mean number of adenomas per patient was 1.2 ± 2.1, the mean number of flat polyps per patient was 1.4 ± 1.9, and the mean number of flat adenomas per patient was 0.5 ± 1.0. There were no significant differences between the 2 groups in the number of patients with a least one adenoma (55.5% versus 48.4%, p=0.07), number of adenomas per patient (1.3 ± 2.4 versus 1.1 ± 1.8, p=0.08), number of advanced adenomas per patient (0.06 ± 0.37 versus 0.04 ± 0.25, p=0.3), and number of advanced adenomas < 10 mm per patient (0.02 ± 0.26 versus 0.01 ± 0.14, p=0.4). Two invasive cancers were found, one in each group; neither was a flat lesion. Chromocolonoscopy detected significantly more flat adenomas per patient (0.6 ± 1.2 versus 0.4 ± 0.9, p=0.01), adenomas < 5 mm in diameter per patient (0.8 ± 1.3 versus 0.7 ± 1.1, p=0.03) and non-neoplastic lesions per patient (1.8 ± 2.3 versus 1.0 ± 1.3, p < 0.0001). Conclusion: High-definition chromocolonoscopy did not result in an increase in overall adenoma detection, and yielded a modest increase in flat adenoma and small adenoma detection, compared with high-definition white light colonoscopy. Our findings do not support the routine use of high-definition chromocolonoscopy for CRC screening in average-risk patients. The high adenoma detection rates observed in this study may be due to the high definition technology. A direct comparison of the adenoma detection rates of highdefinition colonoscopy compared to standard definition colonoscopy appears warranted. Am J Gastroenterol 2009; 104:S560-S576; doi:10.1038/ajg.2009.492