Alternative Name
KRAS Mutation Testing
Methodology
Molecular
Test Description

Bi-directional sequencing of exons 2 and 3 of the KRAS gene. High-sensitivity sequencing is used for enhanced detection of mutations in codons 12, 13, 59, and 61.  For solid tumors, tumor enrichment is performed before extraction. Testing is available separately or in combination with BRAF, HRAS and NRAS in the RAS/RAF Panel. Testing is approved for specimens from the state of New York.  

Clinical Significance

Testing is recommended in colorectal cancer as mutations are associated with resistance and shorter overall survival with EGFR-antagonist therapies such as cetuximab or panitumumab. Testing in non-small cell lung cancer may provide prognostic information and predict poor response to EGFR tyrosine kinase inhibitors.

Specimen Requirements
  • FFPE solid tumor tissue: Paraffin block is preferred. Alternatively, send 1 H&E slide plus 5-10 unstained slides cut at 5 or more microns. Please use positively-charged slides and 10% NBF fixative. Do not use zinc fixatives.
  • Fine needle aspirate (FNA): Requisition must note specimen is FNA. Fresh cells in suspension, unstained air-dried smears (approx. 6-8 slides), or FFPE cell blocks are acceptable if pathologist attaches note verifying sample has >30% tumor or abnormal cells (required). Minimum 10^6 cells.
Storage and Transportation

Use cold pack for transporting block during summer to prevent block from melting. Slides can be packed at room temperature.

CPT Code(s)*
81275, 81276
Medicare MolDX CPT Code(s)*
81479
Turnaround Time

7 days

Level of Service
Global

*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.