[Prevalence of adenomas and carcinomas of the colon. Results of the rectosigmoid exam].Rev Gastroenterol Mex. 2001 Jul-Sep; 66(3):131-6.RG
Colon adenomas are precursors for colon carcinoma. Their prevalence has been estimated at 20-30% in the general population and 40-60% in developed countries. They are classified as tubular, villous; or mixed, and as low- or high-risk lesions, which have any of the following characteristics: Being larger than 1 cm; having a villous component, or showing moderate to severe dysplasia.
To analyze the results of a series of colonoscopies, carried out from 1993 to 1999 in a private hospital in Mexico City, with regard to the following: Prevalence of colon adenomas and carcinoma prevalence in different age groups, distribution by gender; frequency of single vs synchronous lesions; presence or absence of distal and/or proximal lesions as markers of neoplasia and finally, prevalence of proximal lesions in the absence of distal lesions.
A retrospective analysis of a database of 701 colonoscopies, which the author carried out from January 1993 to December 1999.
The prevalence of colon adenoma was 14.69%. The prevalence of high-risk adenomas or carcinoma was 6.7%. In 29.72% of the cases, there were concurrent lesions. These were more common in male patients. The probability of finding a proximal lesion where there was a distal adenoma was greater (17.80%) than in the absence of the latter (6.05%), but the probability of a high-risk lesion was similar whether there was a distal lesion or not (2.73 vs 2.86%). Ninety percent of high-risk proximal lesions had no distal adenoma.
It was found that the prevalence of colon adenomas for the various age groups was lower than in the figures published for developed countries. Synchronic lesions were also less common. The results of this study support the use of colonoscopy as a screening test for adenomas and carcinoma of the colon, because the absence of distal lesions does not exclude the presence of high-risk neoplasia of the proximal colon.