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Molecular Diagnostics

EGFR Mutation

EGFR Mutation is a Molecular Diagnostics laboratory test reference in the LabPedia Medical Laboratory Library. Somatic EGFR mutation testing in non-small cell lung cancer; identifies TKI-sensitizing and resistance variants to guide targeted therapy.

Also known asEGFR genotyping; EGFR TKI mutation panel

Overview

EGFR assays detect activating and resistance mutations (commonly exon 19 deletions, L858R, T790M, and others on the validated panel) in tumor DNA or circulating tumor DNA.

Clinical Importance

Guide EGFR TKI therapy selection in NSCLC

Detect resistance mutations at progression when indicated

Specimen Requirements

  • Specimen: formalin-fixed paraffin-embedded (FFPE) tissue, fresh/frozen tissue, or cytology material as validated
  • Tumor content: pathologist assessment of neoplastic cellularity often required before testing
  • Handling: minimize fixation delays and harsh acid decalcification that damage nucleic acids
  • Input: provide adequate tissue; microdissection may be used to enrich tumor

Analytical Method

PCR-based hotspot assays or NGS panels interrogate EGFR exons. Liquid biopsy (ctDNA) may be used when tissue is inadequate, with acknowledgment of lower sensitivity for some alterations. Report lists covered variants and limitations.

Instruments Used

Automated analyzers

  • Applied Biosystems / Thermo Fisher real-time PCR systems (e.g., QuantStudio-class)
  • Roche Cobas molecular / LightCycler systems
  • Cepheid GeneXpert cartridge PCR systems
  • BioFire FilmArray syndromic PCR systems
  • Illumina next-generation sequencing platforms
  • Thermo Fisher Ion Torrent sequencing platforms
  • Digital PCR systems (e.g., Bio-Rad QX / QIAGEN QIAcuity-class)
  • Specialized BCR-ABL quantitative PCR systems / kits

Manual methods

  • Manual RNA/DNA extraction with real-time PCR or sequencing workflows

Reference Values

Molecular cutoffs, units (IU/mL, copies/mL, Ct), reportable ranges, and variant classifications are assay- and laboratory-specific. Always interpret against the performing laboratory report, manufacturer IFU, and current CLSI / CAP / AMP / ACMG guidance as adopted locally. Limit of detection and inhibition controls are essential for negative results.

Mutation not detected / detected (variant specified). Therapy associations follow oncology guidelines and drug labels; verify current recommendations.

Interpretation

Common Causes of Increased Results

  • Sensitizing EGFR mutation detected; supports EGFR TKI eligibility when clinical stage/indication align
  • T790M or other resistance variants; interpret for next-line targeted options per guidelines

Common Causes of Decreased Results

  • No EGFR mutation in covered regions; consider broader NGS for other drivers

Clinical Significance

  • NSCLC precision oncology

Factors Affecting Results

Pre-analytical

  • Insufficient tumor cellularity
  • Decalcification damaging DNA

Analytical

  • PCR inhibition (heparin, humic acids, excess hemoglobin; assay-dependent)
  • Extraction failure or pipetting/contamination in amplification areas
  • Probe/primer mismatch with sequence variants causing false negatives
  • Calibration/QC failure; expired reagents

Post-analytical

  • Reporting Ct or raw copies without assay-specific interpretive rules
  • Misapplying another laboratory’s LOD or units
  • Variant classification without current ACMG/AMP framework when required

Advantages and Limitations

Advantages

  • Directly actionable for targeted therapy

Limitations

  • Hotspot panels miss rare variants outside design
  • Tissue and plasma results are not identical

Clinical Pearls

EGFR 'negative' only means negative for what was tested; ask whether the panel covered exon 20 insertions you care about.

Related Laboratory Tests

References

Authoritative textbooks, guidelines, and reviews supporting this laboratory test reference. Verify reference intervals, critical limits, and method details against institutional protocols and current guideline editions.

Textbooks

  • McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021. (Molecular diagnostics chapters, verify current edition.)
  • Buckingham L. Molecular Diagnostics: Fundamentals, Methods, and Clinical Applications. 3rd ed. F.A. Davis; 2019. (Verify current edition and institutional adoption.)

CLSI and Professional Guidelines

  • Clinical and Laboratory Standards Institute (CLSI). Consult current CLSI molecular method documents available through your laboratory, document numbers and editions change; do not treat any single CLSI title as universal.
  • Institutional molecular laboratory standard operating procedures (SOPs), assay manufacturer instructions for use (IFU), and locally adopted accreditation requirements. Always verify current local practice.
  • Clinical and Laboratory Standards Institute (CLSI). Molecular method evaluation and related documents (verify current CLSI editions applicable to the assay).
  • College of American Pathologists. Molecular pathology accreditation and proficiency testing expectations (verify current CAP checklist requirements).
  • Association for Molecular Pathology (AMP). Practice guidelines and position statements for molecular diagnostics (verify current AMP documents for the assay).
  • American College of Medical Genetics and Genomics (ACMG). Standards and guidelines for interpretation of sequence variants and related genetic testing practice (verify current ACMG documents).

WHO Publications

  • World Health Organization. Laboratory and diagnostic guidance relevant to molecular testing (verify current WHO publication for the assay/pathogen).

Frequently Asked Questions

Common questions about using this EGFR Mutation laboratory test Medical Laboratory Library reference in Medical Laboratory Science education.

What is the EGFR Mutation laboratory test reference used for?

This Medical Laboratory Library page summarizes the clinical importance of EGFR Mutation. Review the Clinical Importance section for why the test is ordered in laboratory medicine practice.

Where can I find EGFR Mutation specimen requirements?

See the Specimen Requirements section on this page for specimen information related to EGFR Mutation. Confirm collection details against your laboratory protocol.

Where are EGFR Mutation reference values listed?

See the Reference Values section on this Laboratory Library page. Reference ranges can vary by method and population, so verify intervals with your laboratory.

How do I interpret EGFR Mutation results?

Use the Interpretation section for laboratory interpretation framing, including increased and decreased result patterns when provided. Do not treat educational text as a patient-specific diagnosis.

What analytical method is used for EGFR Mutation?

See the Analytical Method section for principle and method notes. Method details may differ by instrument and institutional SOP.

Are related laboratory tests linked from EGFR Mutation?

Yes. The Related Laboratory Tests section lists connected references for continued lookup in the Medical Laboratory Library.

How can I continue learning after reading EGFR Mutation?

Use Continue learning links on this page for related Academy lessons, medical laboratory quizzes, or laboratory case studies when available for this Molecular Diagnostics topic.

What are the clinical pearls for EGFR Mutation?

See the Clinical Pearls section for concise laboratory practice notes associated with EGFR Mutation. Apply pearls alongside institutional protocols.

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