Polyps in a low-risk colonic cancer population in Colombia, South America.

Colonic polyps were systematically searched for in 508 specimens collected from unselected autopsies in individuals more than 10 years of age from Medellín, Colombia, a low-incidence geographic region for colorectal cancer. Adenomatous polyps have a low prevalence rate in both sexes, comparable to that found in Cali, Colombia and other populations with low risk for cancer. They were found more frequently in the right side of the colon and are rare in the sigmoid colon. They begin to appear in the third decade of life in both sexes. Prevalence rates for single and multiple polyps increase with age in both sexes, males showing higher rates than females at every age group. Adenomatous polyps in this population are usually less than 3 mm in diameter and do not show villous changes or epithelial atypia. Hyperplastic polyps were more frequently observed than adenomatous polyps and rates show a progressive increase with age in both sexes. Multiplicity also increases with age. Most polyps are located in the low rectum and sigmoid followed by the cecum and ascending colon. Usually hyperplastic polyps are smaller than 3 mm in diameter and do not show epithelial atypia. Juvenile polyps were infrequently found in this series because children less than 10 years old were excluded. Diverticular disease was also rare and, when found, was not associated with adenomatous polyps. The association between adenomatous polyps and colonic cancer is discussed based on findings in this report.