ABSTRACT
BACKGROUND: The presence of somatic mutations in the KRAS gene has been identified as a reliable strong negative predictor for the response to targeting the epidermal growth factor receptor (EGFR), in patients with metastatic colorectal cancer and the use of anti-EGFR monoclonal antibodies such as Cetuximab and Panitumumab is now restricted to patients with no detectable KRAS mutations. Between 30 and 40 % of colorectal cancers contain a mutated KRAS oncogene. The aim of this study was to evaluate concordance between three methods to analyze KRAS mutational status in regard to clinical testing. METHODS: We analyzed KRAS mutations in codons 12 and 13 of exon 2 in one hundred formalin-fixed paraffin-embedded (FFPE) colorectal cancer samples by three different methods: Direct Sequencing and two commercial kits on allele-specific oligonucleotide hybridization (KRAS StripAssay, Vienna Lab.) and Amplification Refractory Mutation System/Scorpions (ARMS/S; TheraScreen KRAS Mutation kit DxS) based on q-PCR. RESULTS: We have found similar frequencies of KRAS mutations by TheraScreen and Strip-Assay (44 and 48 %), with a κ value of 0.90, indicating almost perfect agreement between methods. The frequency by direct sequencing was much lower (26 %) and the κ values were 0.67 (compared to TheraScreen) and 0.57 (compared to Strip-Assay) indicating low sensitivity. CONCLUSIONS: On analyzing KRAS mutation in FFPE tumor samples, direct sequencing sensitivity is too low to be used in a clinical setting. Choosing between ARMS/S; TheraScreen KRAS Mutation kit DxS and KRAS StripAssay, Vienna Lab, will depend on laboratory facilities and expertise.
Subject(s)
Colorectal Neoplasms/genetics , Proto-Oncogene Proteins/genetics , ras Proteins/genetics , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Codon , Colorectal Neoplasms/metabolism , Colorectal Neoplasms/pathology , ErbB Receptors/genetics , Humans , Mutation , Proto-Oncogene Proteins p21(ras) , Sequence Analysis, ProteinABSTRACT
Colorectal cancer metastasis is the result of several interacting processes at the end of which cancer cells survive in distant organs. Penetration of primary tumor cells into blood is central to the whole phenomenon of metastasis and is a common step in all cancer types. The detection of circulating tumor cells (CTC) in peripheral blood of patients with colorectal cancer could have clinical usefulness in three aspects: 1) as evidence of early dissemination, and then as a risk factor of clinical recurrence, 2) as a relevant risk factor for metastatic progression and worse prognosis, and 3) as predictive marker of response to treatment.
Subject(s)
Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/pathology , Neoplastic Cells, Circulating , Humans , Treatment OutcomeABSTRACT
The use of drugs to treat cancer based on molecular targets is common fact, especially those targeting kinases that are involved in the cellular signalling pathways. The anti-tyrosine receptor drugs are among the most developed, some of them having already been approved by the FDA and the EMEA for breast cancer, colorectal, lung GIST and renal cancer treatment. Although these drugs are currently focused on a single target, the future challenge is to hit several targets simultaneously, along with combined chemotherapy. Thus we are facing the beginning of a new era in the battle against cancer.
