EGFR Mutation Testing in plasma (cfDNA)

Introduction

EGFR-activating mutations are detected in ~11% of NSCLC (adenocarcinoma) UK patients and these patients show a higher likelihood of response to treatment with EGFR tyrosine kinase inhibitors. Adequate biopsy material is not always available as patients may be too unwell or the neoplastic cell content is too low for EGFR mutation analysis. DNA circulating in plasma from blood can be used as an alternative where a biopsy is inadequate as DNA is shed from tumour tissue at increased level in patients with active or advanced disease. Blood samples must reach the laboratory within 24hrs of sampling (ideally within 6hrs). Where this is not possible please contact the laboratory for advice.

Referral information

Blood samples from patients with a diagnosis of NSCLC where biopsy material is not available or inadequate (e.g. too little material, neoplastic cell content <10%). Alternatively blood samples from patients with biopsy proven EGFR mutated disease who have progressed following EGFR-TKI therapy where the results are being used to monitor progression, molecular resistance or enrolment on clinical trials.

Price & reporting times

Test Price (NHS) Price (non-NHS) TRT *
Qiagen Therascreen

Roche cobas®

POA POA 14 days

Test validation & quality assurance - information for users

The EGFR cfDNA test has been validated in house for both assays.

Qiagen Therascreen detects the common activating mutations c.2155G>A p.(Gly719Ser), c.2155G>T p.(Gly719Cys), c.2156G>C p.(Gly719Ala), c.2303G>T p.(Ser768Ile), c.2573T>G p.(Leu858Arg), c.2582T>A p.(Leu861Gln), c.2369C>T p.(Thr790Met), 19 different deletions in exon 19 and 3 different insertions in exon 20, down to a 1% admixture.

The Roche Cobas® EGFR assay detects the common mutations c.2155G>A p.(Gly719Ser), c.2155G>T p.(Gly719Cys), c.2156G>C p.(Gly719Ala), c.2303G>T p.(Ser768Ile), c.2369C>T p.(Thr790Met), c.2573T>G p.(Leu858Arg) and c.2573_2574delinsGT p.(Leu858Arg) in exons 18, 20 and 21, 29 different deletions in exon 19 and 5 different insertions in exon 20, down to an admixture of 5%.

A subset of rare activating mutations is not detected by either assay. Analytical sensitivity declines in patients that have commenced chemotherapy.

Sample requirements

Minimum of 12ml EDTA blood sample. The sample should ideally reach the laboratory within 6 hours of being taken, if this is not possible then it should arrive within 24 hours of being taken.

Referral guidelines

Please see our referral guidelines for more information.

OMIM Number(s) - 131550

Gene(s) - EGFR

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