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BRAF mutations in aberrant crypt foci and hyperplastic polyposis.
Robyn Beach1, Annie On-On Chan, Tsung-Teh Wu
1Department of Pathology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX, 77030-4095, USA.
The American Journal of Pathology
|March 29, 2005
Summary
BRAF mutations are common in hyperplastic polyps (HPs) from patients with hyperplastic polyposis, unlike sporadic HPs. This suggests distinct pathways in HP development, impacting colorectal cancer risk.
Area of Science:
- Gastroenterology
- Molecular Biology
- Oncology
Background:
- Hyperplastic polyposis (HP) involves multiple hyperplastic polyps (HPs) and elevates colorectal cancer risk.
- Aberrant crypt foci (ACF) are considered early colorectal cancer precursor lesions.
Purpose of the Study:
- To investigate BRAF mutation prevalence in various colorectal polyp types from patients with hyperplastic polyposis.
- To compare BRAF mutation status with clinicopathological features and other genetic alterations in these polyps.
Main Methods:
- DNA sequencing was used to analyze BRAF mutations in ACF, sporadic HPs, and HPs, serrated adenomas, admixed polyps, tubular adenomas, and carcinomas from patients with hyperplastic polyposis.
- Marginal logistic regression compared BRAF mutation status with clinicopathological features and genetic alterations.
Main Results:
- BRAF mutations were infrequent in ACF (2%) and sporadic HPs (6%).
- In contrast, BRAF mutations were prevalent in HPs (43%), serrated adenomas (75%), admixed polyps (33%), tubular adenomas (30%), and carcinomas (33%) from patients with hyperplastic polyposis.
- BRAF mutation status correlated with polyp presence, younger age, larger polyp size, right colon location, and specific gene methylation (p16, MINT31).
Conclusions:
- BRAF mutation status is heterogeneous within hyperplastic polyposis, indicating diverse pathogenic mechanisms for HPs.
- These findings suggest distinct subsets within the hyperplastic polyposis phenotype, influencing colorectal cancer development.