Molecular and Histological Characteristics of Serrated Lesions of the Colon

Different subtypes of serrated lesions have been recently described. Among them, both sessile serrated polyp/adenoma (SSP/A) and traditional serrated adenoma (TSA) could have malignant potential through the serrated pathway or CIMP. These lesions, as a potential source of interval cancer, should also be considered in colorectal cancer (CRC) population-based screening programs. It is believed that this new described pathway could be responsible for up to 30% of all CRC.
Unlike the traditional adenoma, serrated lesions are difficult to diagnose because of their particular endoscopic appearance and their still unclear histological criteria. Furthermore, they have specific molecular changes and, through them, they could evolve into CRC faster than the adenoma. The real prevalence of the serrated lesions and their specific risk for developing new synchronous/metachronous lesions, or even malignancy, remains unknown. For all these reasons, we don’t know if these patients could constitute a different CRC-risk group and if specific recommendations are needed during their follow-up.
This is a prospective longitudinal study developed within the framework of the CRC-screening program in the Valencian Community (Spain). We expect to include a total of 700 individuals who will be followed during 10 years.
In our study, we will collect epidemiologic variables related to the patient, variables related to all the polyps, and mutational (BRAF, KRAS, MSI), and CpG-island methylation status of serrated lesions. Strict endoscopic and histological criteria will be applied for the diagnosis of serrated lesions. All lesions detected at the index colonoscopy and during follow-up will be evaluated.
The purpose of this study is to correlate epidemiologic data, histological characteristics and the molecular profile of the serrated lesions with findings during follow-up, in order to define stratified groups according to their risk of developing new lesions or CRC in the future.