KRAS mutations
RAS genes (H-RAS, K-RAS and N-RAS) code similar G proteins involved in growth and differentiation signals from the receptors tyrosine kinase to the core cells. The K-RAS gene is located on the short arm of chromosome 12 (12p12.1) and at a molecular level, there have been cases of colorectal cancer associated with mutations in codons 12, 13, 58-59 and 61, 117 and 146 respectively of this gene.
New therapeutic agents acting on the receptor of epidermal growth factor (EGFR), such as cetuximab and panitumumab, have proven effective against colorectal cancer. Tumors with somatic mutations in K-RAS gene (40%) are associated with a poor response to this type of treatment. 60% of patients with colorectal cancer have tumors that carry the wild type K-RAS gene (unmutated), which can benefit from EGFR antagonists based therapies.
The test detects the mutations at codons 12, 13, 58-59, 61, 117 and 146 (exons 2, 3 and 4) in the KRAS gene by PCR and / or pyrosequencing. These techniques can detect mutated sequences that are present in lower concentration (5-8%) compared to the Sanger-based detection (20%), ensuring the making of therapeutic decisions more accurate and reliable, identifying colorectal cancer patients that will likely respond to therapy with monoclonal anti EGFR.
