Background and aim: Patients with multiple (hyperplastic polyposis) or large hyperplastic polyps (HPs) predominantly in the right-sided colon, have been reported to have an increased risk of colorectal cancer (CRC). This prospective study was conducted to clarify the distribution of various sized HPs using magnifying pan-mucosal chromoendoscopy and its relationship with synchronous CRC.
Methods: Patients eligible for this study had an initial total colonoscopy. Indigo carmine dye was sprayed throughout the whole colon and rectum, and diagnoses were made using magnifying colonoscopy.
Results: A total of 263 patients were enrolled, and a total of 3060 HPs were observed in 226 (86%) patients. The prevalence of patients with intermediate size (> or = 6 mm) HPs was 8.7% (n = 23) and that of patients with large HPs (> or = 10 mm) was 0.8% (n = 2). Of 3060 HPs, the numbers of diminutive (< 6 mm), intermediate size and large HPs were 3020, 38 and two, respectively, and 5.0%, 42.1% and 100% of these were located in the right-sided colon, respectively. Synchronous CRC was observed in 64 (24%) of 263 patients. Compared to patients without HPs, patients with intermediate size HPs showed a significant increase in odds ratio (OR) for synchronous CRC (OR = 4.9: 95% CI [1.3-18.2]), but there was no significant association between synchronous CRC and patients with diminutive or large HPs.
Conclusions: Compared to diminutive HPs, intermediate size and large HPs were predominantly located in the right-side colon. Moreover, intermediate size HPs were significantly correlated with synchronous CRC.