Polyps with different grades of dysplasia and their distribution in the colorectum.

ABSTRACT

BACKGROUND/AIMS: To determine the role of adenomatous polyps in the development of colorectal cancers, we examined the relationship between the distribution and polyps with different grades of dysplasia (low, high), or/and cancers in the colorectum. METHODOLOGY: The distribution of 527 polyps with low-grade dysplasia was compared with that of 121 polyps with high-grade dysplasia, and 10 colorectal cancer lesions with adenomatous polyps in 361 patients who underwent total colonoscopy. RESULTS: The distribution rate of polyps at the distal colon and rectum into polyps with high-grade dysplasia significantly increased in comparison to that into polyps with low-grade dysplasia, respectively (p<0.002). The percentage of polyps with high-grade dysplasia measuring >1 cm significantly increased in comparison to that with low-grade dysplasia measuring >1 cm (p<0.00001). In patients with both adenomatous polyps and colorectal cancers, the polyps with high-grade dysplasia at the distal sites of cancerous lesions increased significantly more than at the proximal sites of cancerous lesions (p<0.05). Polyps with high-grade dysplasia have malignant potentials to intermediate between polyps with low-grade dysplasia and colorectal cancers in our study. CONCLUSIONS: The different distributions of different grades thus suggested that polyps with different grades of dysplasia at various colorectal sites were found to have different malignant potentials for cancer development.