KRAS Mutations (DNA)

Interpretation

Guidelines

• Genetics and Solid Tumor Diagnostic Testing
• Gynecologic Oncology (GYNPTH) Pathways
• Thoracic Oncology Reflex (THOR) Panel

Method

Next-generation sequencing.

The KRAS gene is sequenced and analyzed for mutations, including in KRAS codons 12, 13, 61, 117, and 146. This test can normally detect a heterozygous mutation if it is present in more than about 5% of the cells in the sample. This test was developed and its performance characteristics determined by the Department of Laboratory Medicine at the University of Washington.

Reference Range

See individual components

Ref. Range Notes

Results will be reported as either positive or negative for mutation.

References

• Skoulidis F, et al. Sotorasib for Lung Cancers with KRAS p.G12C Mutation. N Engl J Med. 2021 384(25):2371-2381. PMID: 34096690
• Karapetis CS, et al. K-ras mutations and benefit from cetuximab in advanced colorectal cancer. N Engl J Med 2008, 359:1757-65. 18946061
• Lièvre A, et al. KRAS mutations as an independent prognostic factor in patients with advanced colorectal cancer treated with cetuximab. J Clin Oncol 2008, 26:374-9. 18202412
Also see correspondence for a good meta-analysis: J Clin Oncol 2008;26:2601-2602.

Ordering & Collection

Specimen Type

Tumor Tissue, Purified DNA, accompanied by a PATHOLOGY REPORT for the tested tissue.

Collection

Requirements for Specimen Selection

• To ensure clinically relevant results, the most recent and/or metastatic sample is preferred to older specimens, provided sufficient tumor is present (see point 2).
• To ensure detection of all types of mutations there should be at least 10% tumor cells in the tissue area processed for DNA for mutation detection and 20% tumor cells for microsatellite instability evaluation. If there is more than one tissue block, please provide the block that has the greatest percentage of neoplastic nuclei.
• Tissue samples and pathology reports will be reviewed by directors upon receipt for acceptability prior to testing. Director consultation for tissue selection is available if needed (contact Genetics lab).

Specimen Types

Tissue samples

Send one of the following:

1. Slides: 1 slide at 4-micron thickness stained with hematoxylin-and-eosin (H&E) AND 10 unstained, non-baked slides at 10-micron thickness (a minimum of 5 unstained slides is acceptable). Unstained slides can be on charged or uncharged slides.
2. Tissue Blocks: Provide complete formalin-fixed tissue block containing tumor tissue. Tissue block will be returned at completion of testing.
3. Fresh/frozen tissue: 5 microgram tissue in cell culture medium or frozen tissue stored at -20C. Tumor percentage will not be determined prior to sequencing studies.

NOTE: In order to ensure that enough DNA is obtained, the minimum acceptable tissue area is 10 square millimeters when ten 10-micron slides are supplied (1 cubic millimeter of tissue).

Purified DNA

5 micrograms ANDa reference hematoxylin-and-eosin (H&E) stained slide and pathology report required.

Bone Marrow

1 to 2 mL Bone Marrow in LAVENDER TOP (EDTA) tube

Blood

6 mL blood in LAVENDER TOP (EDTA) tube.

Alternative specimens may be acceptable with approval (contact: 206-598-1149).

For ADD-ON after prior testing, contact Genetics lab.

Unacceptable samples

We cannot accept decalcified samples or tissue samples treated with fixatives other than formalin.

Quantity:

Requested:

• Tissue: 10 unstained slides (10-micron thickness) plus one H&E-stained slide.
• Extracted DNA: 5 microgram Bone Marrow: 2 mL
• Blood: 6 mL

Minimum:

• Tissue: 5 unstained slides (10-micron thickness) plus one H&E-stained slide.
• Extracted DNA: 100-250 nanograms Bone Marrow: 1 mL
• Blood: 3 mL

Forms & Requisitions

Genetics Requisition

Providers with access to the UW implementation of Epic (i.e., FHCC, HMC, SCCA, UWMC, UWNW) may order this test using the order "UW Genetics and Solid Tumor Test Request." See tip sheet for more information (internal link).

Handling Instructions

Attach a copy of the pathology report for the tumor sample being submitted.

Hold slides or tissue blocks at room temperature.

Outside Laboratories: Ship at room temperature.

Stability: unstained slides or tissue blocks stable at room temperature for at least 2 years

Quantity

Requested: Amounts as noted above
Minimum: Amounts as noted above

Processing

Receiving Instructions

Misc Sendout

Performance

Lab Department

Genetics(GEN)

Frequency

Run at least once a week; Typical Turnaround: 3 weeks *Turn around times may vary based on factors such as tissue acquisition and insurance preauthorization.

Available STAT?

No

Performing Location(s)

UW-MT	Genetics Attention: Genetics Lab Clinical lab, Room NW220 University of Washington Medical Center 1959 NE Pacific Street Seattle, WA 98195 Tel: 206-598–6429 M–F (7:30 AM–4:00 PM) Fax: 206-616-4584 Lab email: cgateam@uw.edu Tel (EXOME only): 206-543-0459	Faculty Jillian Buchan, PhD, FACMG Runjun Kumar, MD, PhD Regina Kwon, MD, MPH Christina Lockwood, PhD, DABCC, DABMGG Abbye McEwen, MD, PhD Colin Pritchard, MD, PhD Vera Paulson, MD, PhD Eric Konnick, MD, MS He Fang, PhD

Billing & Coding

CPT Codes

81275, 81276

LOINC

21703-4

Interfaced Order Code

UOW2114

Billing Comments

For pricing information, contact Client Support Services 206-520-4600 or 800-713-5198.