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Prevalence of adenomas and hyperplastic polyps in carriers of HNPCC (LYNCH Syndrome).

1007 Background: The aim of this study was to estimate the prevalence of adenomas and hyperplastic polpys in a large cohort of individuals with HNPCC. These prevalences have been estimated previously in smaller studies and the results found to be variable.


METHODS
392 individuals enrolled in the CAPP2 study - a chemoprevention trial - classified as HNPCC and with a detected mutation in one of the mismatch repair genes (hMSH2, hMLH1 or hMSH6) were studied. Information about the number, size, and location of adenomas and hyperplastic polyps found at the recruits' first life time colonoscopy was analysed in a cross-sectional study.


RESULTS
The prevalence of adenomas and hyperplastic polyps in the whole study population was 18% and 10 % respectively. Increased age was a predictor for detecting an adenoma at first colonoscopy going from 7.3% in the under 35 years of age to 33.3% in the oldest age group >55 years of age. There was no differences in prevalence between males and females for adenomas, but males were about 50% more likely to have a hyperplastic polyp (non significant). A significant positive correlation was found between the adenomas and hyperplastic polyps in the study population. The adenomas were evenly distributed in the colon but the hyperplastic polyps were primarily located in the distal colon.


CONCLUSION
The positive correlation between adenomas and hyperplastic polyps shows that hyperplastic polyps may serve as a marker for synchronous adenomas. No significant financial relationships to disclose.