KRAS Hotspot PCR Analysis
Test Mnemonic
KRASID
CPT Codes
- 81275 - QTY (1)
- 81276 - QTY (1)
- ALT Code 81479 - QTY (1)
Aliases
- KRAS
- KRASGN
Performing Laboratory
Cleveland Clinic Laboratories
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 10 mm square | Block, Formalin fixed paraffin | Formalin-fixed, paraffin-embedded block | Ambient | Ambient | Formalin-fixed paraffin-embedded tissue slides. Transport and store slides at ambient temperature. Three unstained sections FFPE tissue on charged, unbaked slides or scrolls, plus one H&E stained section with best tumor area circled by a pathologist. Provide the percentage of tumor cells present, minimum 10%. |
| 10 mm square | Cell block, formalin fixed paraffin | Formalin-fixed, paraffin-embedded block | Ambient | Ambient | Formalin-fixed paraffin-embedded cell block slides. Transport and store slides at ambient temperature. Three unstained sections FFPE cell block tissue on charged, unbaked slides. Provide the percentage of tumor cells present, minimum 10%. |
| 10 mm square | Aspirate, fine needle | Slide | Ambient | Ambient | One alcohol fixed cytology slide. Tissue adequacy must be assessed by cytopathologist. |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | FFPET slides and scrolls, cell block slides and alcohol fixed slides are stable at ambient temperature indefinitely. |
| Refrigerated | FFPET slides and scrolls, cell block slides and alcohol fixed slides are stable at ambient temperature indefinitely. |
| Frozen | Unacceptable. |
Days Performed
Mon - Fri
Turnaround Time
3 days
Methodology
| Name | Description |
|---|---|
| Real-Time Polymerase Chain Reaction (RT-PCR) |
Special Info
Detects 21 known mutations of the KRAS gene.
Clinical Info
The KRAS Hotspot PCR Analysis rapidly identifies specific KRAS mutations in solid tumors, guiding diagnosis, prognosis, and treatment planning. This assay rapidly identifies 21 KRAS variants that are oncogenic and clinically relevant in exons 2, 3, and 4 of the KRAS gene using real-time PCR technology. KRAS hotspot testing can be indicated in colorectal, non-small cell lung cancer, pancreatic cancer, hepatobiliary cancer, and others to determine eligibility for targeted therapies, including therapies targeting KRAS G12C mutations. KRAS mutations in colorectal cancer are associated with resistance to targeted EGFR therapies. This test only detects hotspot mutations in KRAS. It should be considered when KRAS-only targeted testing is required, when tumor material is limited, and/or rapid turnaround time is necessary. For more comprehensive solid tumor testing, please refer to the Targeted Oncology Panel.
Clinical Limitation
The assay limit of detection (LOD) is 5% variant allele fraction. Specimens must contain at least 10% tumor cells; if less than 10% tumor is utilized, a negative result is of indeterminate significance. Only 21 KRAS variants can be detected by this technology; refer to the gene list on the Supporting Document tab for specific details. A negative result does not preclude the possibility of an alternative hotspot variant. Tumor heterogeneity, tumor burden, specimen degradation, or other technology limitations may affect the sensitivity and LOD. Interfering substances, specifically formalin, decalcification agents, fixation agents containing heavy metals, or preservation of buffy coats using Hank’s Balanced Salt Solution (HBSS), can affect assay performance. Cross-reactivity can occur in this assay. This test cannot distinguish between somatic and germline variants.