EGFR Mutation Testing in NSCLC (Adenocarcinoma) Samples

Introduction

EGFR is a protein found at high levels in many types of cancers, particularly non-small cell lung cancer (NSCLC). Activating mutations in the EGFR gene are present in a proportion of NSCLC tumours. Tumours with mutated EGFR show a higher likelihood of response to treatment with EGFR tyrosine kinase inhibitor drugs e.g. Iressa (Gefitinib).

Referral information

Biopsies, resections or cytology samples from patients with NSCLC that have not undergone chemotherapy. Formalin fixed paraffin embedded (FFPE) tissue is preferred. We recommend 10 x 10µM thick unstained, unmounted sections sealed in a clean 1.5mL Eppendorf tube. The tissue sample should have been reviewed by a histopathologist to determine suitability for testing and estimate tumour cell content. A 30% ratio of tumour to normal tissue in the submitted sample is required for optimum mutation detection. Other samples may be acceptable and macrodissection can be considered for samples with low tumour cell content, however, please contact the laboratory for guidance first.

Price & reporting times

NHS referrals to this service are paid for where there is an existing specialist commissioning contract for genetic testing. In other cases please contact the lab for prices.

Test Price (NHS) Price (non-NHS) TRT
EGFR exons 18-21 POA POA 7 days (urgent samples)

14 days (routine samples)

Test validation & quality assurance - information for users

EGFR mutations are detected in 10-15% of NSCLC (adenocarcinoma) samples, mutations are more likely to be present in never smokers, women and patients of East Asian descent. Presence or absence of a detectable EGFR mutation can be used to guide appropriate therapy. The test has been validated on DNA samples from a set of cell lines with EGFR mutations. All commonly reported activating EGFR mutations within exons 18-21 can be detected down to a level of at least 20% in the sample submitted for testing by Sanger sequencing. The Roche Cobas® assay detects a defined set of mutations which together account for over 95% of all EGFR activating mutations reported in NSCLC to a level of approximately 5%, however, a subset of rare activating mutations are not detected. Each sample is assayed in duplicate to ensure consistency. Failure to identify an EGFR mutation may be due to low levels of tumour tissue in the submitted sample.

Sample requirements

5 x 5µM FFPE unstained slide mounted sections (without coverslips) from a tissue block selected to have maximum neoplastic cell content. If neoplastic cell content is less than 30% and the sample is suitable for macrodissection, please send an accompanying H&E stained guide slide prepared from a neighbouring section with the region of neoplasia clearly marked out. Where neoplastic cell content is greater than 30%, 5 x 5 µM FFPE sections as unmounted scrolls in a clean, unused, tube or container manufactured under aseptic conditions is acceptable.

Referral guidelines

Please see our referral guidelines for more information.

OMIM Number(s) - 131550

Gene(s) - EGFR

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