KRASgenotyping is mandatory in metastatic colorectal cancer treatment prior to undertaking antiepidermal growth factor receptor (EGFR) monoclonal antibody therapy.BRAFV600E mutation is often present in colorectal carcinoma with CpG island methylator phenotype and microsatellite instability. Currently,KRASandBRAFevaluation is based on molecular biology techniques such as SNaPshot or Sanger sequencing. As molecular testing is performed on formalin-fixed paraffin-embedded (FFPE) samples, immunodetection would appear to be an attractive alternative for detecting mutations. Thus, our objective was to assess the validity of KRAS and BRAF immunodetection of mutations compared with the genotyping reference method in colorectal adenocarcinoma.KRASandBRAFgenotyping was assessed by SNaPshot. A rabbit anti-human KRAS polyclonal antibody was tested on 33 FFPE colorectal tumor samples with knownKRASstatus. Additionally, a mouse anti-human BRAF monoclonal antibody was tested on 30 FFPE tumor samples with knownBRAFstatus. KRAS immunostaining demonstrated both poor sensitivity (27%) and specificity (64%) in detectingKRASmutation. Conversely, BRAF immunohistochemistry showed perfect sensitivity (100%) and specificity (100%) in detecting V600E mutation. Although molecular biology remains the reference method for detectingKRASmutation, immunohistochemistry could be an attractive method for detectingBRAFV600E mutation in colorectal cancer.
MicroRNAs in colorectal cancer: translation of molecular biology into clinical application