Comparison of Molecular-Genetic Concordance of the Primary Tumor and Brain Metastases of Colorectal Cancer

"For molecular genetic research, archival formalin-fixed and paraffin-embedded tumor blocks will be used. Research method - HRM-PCR sequencing to determine mutation status of KRAS, NRAS and BRAF (RotorGene 6000, ABI Prism 3500) and fragmentation analysis to determine MSI (ABI Prism 3500) Subject to study: mutations in the KRAS, NRAS, BRAF genes, as well as MSI status and HER2neu expression (± amplification) Somatic mutations in the RAS family genes are planned to be studied in exons 2 (codons 12 and 13), exon 3 (codon 61) and exon 4 (codon 146). In the case of the BRAF gene - exon 15 (codons 597-601). Determination of microsatellite instability is planned using five markers: BAT25, BAT26, NR21, NR24, NR27, associated with structural and functional disorders of the DNA unpaired base repair system.~Assessment of HER2 gene status is planned by immunohistochemical (IHC) screening of HER2neu expression. IHC-screening of HER2-status will be performed using an antibody clone 4B5 (Ventana)."