Prospective evaluation of the proportion of sessile serrated adenoma/polyps in endoscopically diagnosed colorectal polyps with hyperplastic features

摘要

Background and study aims: Sessile serrated adenoma/polyps (SSA/Ps) are considered precursors of colorectal cancers with microsatellite instability. However, it is still difficult to differentiate SSA/Ps from hyperplastic polyps endoscopically; therefore, the prevalence of SSA/Ps remains uncertain in clinical practice. This study aimed to clarify the proportion of SSA/Ps in endoscopically diagnosed colorectal polyps with hyperplastic features (E-HPs). Patients and methods: Patients aged ≥?40 years undergoing colonoscopy for standard clinical indications at our center were prospectively enrolled between June 2013 and May 2014. During colonoscopy, 0.05?% indigo carmine dye was sprayed throughout the colorectum to highlight lesions. All detected lesions were diagnosed by high definition magnifying narrow-band imaging and were resected endoscopically or surgically, apart from rectosigmoid E-HPs ≤?5?mm. The number of rectosigmoid E-HPs?≤?5?mm was recorded, and some were resected for use as tissue samples. Results: A total of 343 patients (male: 42.9?%; mean age: 61.5 years) were included. Among 3838 E-HPs (distal: 96.4?%) detected in 294 patients, 792 were resected and analyzed. All of 21 SSA/Ps identified in 17 patients were included in E-HPs, and the overall proportion of SSA/Ps in E-HPs was 2.7?%. However, this proportion increased with the size of E-HPs (≤?5 mm: 0.7?%; 6?–?9 mm: 29.0?%; ≥?10 mm: 70?%) and was higher in the proximal colon than in the distal colorectum (10.9?% vs. 0.9?%). In addition, no SSA/P was found in the rectum, and no SSA/P had cytological dysplasia. Conclusions: The overall proportion of SSA/Ps in E-HPs was 2.7?%, although this proportion was higher in the proximal colon and increased with the size of E-HPs. SSA/Ps were common in routine colonoscopy, with a prevalence of at least 5.0?%. Study registration: UMIN000010832.