Test Catalog

Test ID: KRASD    
Cell-Free DNA KRAS 12, 13, 61,146, Blood

Useful For Suggests clinical disorders or settings where the test may be helpful

As an alternative to invasive tissue biopsies for the determination of KRAS 12, 13, 61,146 (G12A, G12C, G12D, G12R, G12S, G12V, G13D, Q61K, Q61L, Q61R, Q61H, and A146T) mutation status


Selection of patients with colorectal cancer who are most likely to benefit from epidermal growth factor receptor (EGFR)-targeted therapies

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test evaluates cell-free DNA (cfDNA) in the peripheral blood for the presence of KRAS mutations at codons 12, 13, 61, and 146 (G12A, G12C, G12D, G12R, G12S, G12V, G13D, Q61K, Q61L, Q61R, Q61H, and A146T) in patients with colorectal cancer and can be used to assess eligibility for targeted therapies.


This test is not validated for serial monitoring of patients with cancer. This test is also not intended as a screening test to identify cancer.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Approximately 30% to 50% of colorectal cancers (CRC) have mutations in KRAS. Most occur in hotspot regions in codons 12, 13, 61, and 146. These mutations lead to constitutive activation of the RAS/MAPK pathway downstream of epidermal growth factor receptor (EGFR), limiting the effectiveness of anti-EGFR therapies, such as cetuximab and panitumumab, which inhibit ligand-mediated activation of EGFR. Therefore, identification and quantitation of these mutations is critical in selecting the appropriate therapy.


This test uses DNA extracted from peripheral blood to evaluate for the presence of KRAS (G12A, G12C, G12D, G12R, G12S, G12V, G13D, Q61K, Q61L, Q61R, Q61H, and A146T) mutations. A positive result indicates the presence of an activating KRAS mutation and may be useful for guiding the treatment of individuals with colorectal cancer.

Interpretation Provides information to assist in interpretation of the test results

An interpretive report will be provided.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Patients with a negative test result may still harbor a KRAS mutation. Mutation testing of a tissue specimen for KRAS mutations should be considered for patients with who have a negative result with this test.


The limit of detection of this assay for the detection of KRAS mutations is influenced by the amount of cell-free DNA (cfDNA) in the blood. This is a biological variable that cannot be controlled.


This assay was designed to detect mutations in KRAS codons 12, 13, 61, and 146 (G12A, G12C, G12D, G12R, G12S, G12V, G13D, Q61K, Q61L, Q61R, Q61H, and A146T).


This test has not been clinically validated for use as a tool to monitor response to therapy or for early detection of tumors.


This test cannot differentiate between somatic and germline alterations.

Supportive Data

This test has been evaluated by our laboratory as an alternative to assessing paraffin-embedded tumor specimens for KRAS mutations in patients with colorectal cancer. 

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Schwarzenbach H, Hoon DS, Pantel K: Cell-free nucleic acids as biomarkers in cancer patients. Nat Rev Cancer 2011;11(6):426-437

2. Allegra CJ, Rumble BR, Hamilton SR, et al: Extended RAS Gene Mutation Testing in Metastatic Colorectal Carcinoma to Predict Response to Anti-Epodermal Growth Factor Receptor Monoclonal Antibody Therapy: ASCO Provisional Clinical Opinion update 2015. J Clin Oncol 2016 Jan 10;34(2):179-185

3. Olmedillas Lopez S, Garcia-Olmo DC, Garcia-Arranz M, et al: KRAS G12V Mutation Detection by Droplet Digital PCR in Circulating Cell-Free DNA of Colorectal Cancer Patients. Int J Mol Sci 2016;17:484