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This PCR assay uses the FDA-approved, Roche cobas® KRAS Mutation Test kit to detect the most common missense point mutations in codons 12 and 13 of KRAS exon 2. KRAS is a G-protein that is a key component of the EGFR signal transduction pathway. Mutated KRAS protein is constitutively activated and tumors carrying these activating mutations have been shown to be resistant to anti-EGFR directed therapy. Please note that current guidelines for colorectal carcinoma molecular testing recommend that patients being considered for anti-EGFR therapy must undergo RAS mutation testing to determine eligibility. According to joint guidelines recently issued by ASCP, CAP, AMP and ASCO (see reference below), all patients with colorectal carcinoma being considered for anti-EGFR therapy must undergo “extended” RAS mutation testing that includes the following mutations: KRAS codons 12 and 13 (exon 2), KRAS codons 59 and 61 (exon 3), KRAS codons 117 and 146 (exon 4), NRAS codons 12 and 13 (exon 2) NRAS codons 59 and 61 (exon 3), and NRAS codons 117 and 146 (exon 4). PhenoPath recommends ordering RAS mutation testing in a reflexive manner, starting with this FDA-approved cobas® KRAS Mutation Test to test for KRAS exon 2 mutations, followed by extended RAS mutation testing if a KRAS exon 2 mutation is not detected (see Extended RAS Panel). REFERENCE: Sepulveda AR, et al. Molecular Biomarkers for the Evaluation of Colorectal Cancer: Guideline From the American Society for Clinical Pathology, College of American Pathologists, Association for Molecular Pathology, and American Society of Clinical Oncology. J Mol Diagn 2017 19(2):187225.
Organ: Colon & Other GI
CPT Code(s): 81275; 88381 may apply (reference only; CPTs may vary)
Turnaround Time: Within 3-6 business days of receipt
Formalin-fixed, paraffin-embedded (FFPE) tissue block (preferred) or unstained slides (10 slides are usually sufficient)