Molecular characterization of patients at risk for hereditary colorectal cancer

• Grant number: 16/01888-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): May 01, 2016
• Effective date (End): December 31, 2017
• Field of knowledge: Biological Sciences - Genetics - Human and Medical Genetics
• Principal Investigator: Edenir Inêz Palmero
• Grantee: Mariana Bianchi Carneiro
• Host Institution: Hospital do Câncer de Barretos. Fundação Pio XII (FP). Barretos , SP, Brazil

Abstract

The Lynch syndrome is a hereditary predisposition syndrome to cancer, with autosomal dominant mainly caused by germline mutations in the genes of the MMR system (mismatch repair system) repair DNA damage. Individuals with Lynch syndrome have a colorectal cancer development risk of 60% to 80% (compared to 5%, which is the risk to the general population) and, in addition, have an increased risk of developing extracolonic tumors (cancer endometrial, ovarian, gastric cancer, urinary tract, biliary tract, among others). Identify patients at risk for hereditary cancer is critical for targeting to specific behaviors of cancer screening, allowing the detection of the disease in less advanced stages and thus increasing the possibility of cure. Although family history of cancer and age at diagnosis are strong indications of the presence of a hereditary predisposition to cancer syndrome, numerous publications emphasize the importance of some molecular and histopathological findings that help in this identification. Although there are internationally established protocols for this purpose have not been evaluated in the Brazilian population, which has its own characteristics. Thus, this project aims to evaluate the risk of heredity in 250 patients under 50 years of age who have colorectal cancer without polyposis, operated in Barretos Cancer Hospital and whose paraffin block lies stored at the Department of Pathology of the HCB. Patients will be characterized from the clinical point of view (clinical data will be obtained from chart review), histopathological (slides containing tumor material will be reviewed by an experienced pathologist and characterized a series of typical tumor parameters containing high microsatellites instability) and molecular (all patients have the tumor DNA extracted and analyzed for the presence of microsatellite instability, presence of p.V600E mutation in BRAF, besides the presence of methylation of MLH1 gene). We hope, therefore, perform a detailed characterization of molecular, histopathological and clinical features of a group of Brazilian patients with CRC diagnosed at the age of 50 years, characterization that can help identify patients at risk for hereditary colorectal cancer, reducing spending on genetic tests unnecessarily, and enable patients in identified risk are targeted to specific programs for monitoring and treatment.