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Updated: Feb 12, 2026
Detection of Rare Mutations in CtDNA Using Next Generation Sequencing
Published on: August 24, 2017
Comparison of plasma ctDNA and tissue/cytology-based techniques for the detection of EGFR mutation status in advanced
E Arriola1, A Paredes-Lario2, R García-Gomez3
1Medical Oncology Department, Hospital del Mar, Passeig Marítim 25-29, 08003, Barcelona, Spain. EArriola@parcdesalutmar.cat.
Purpose:
The analysis of epidermal growth factor receptor (EGFR) mutations in many patients with advanced non-small-cell lung cancer (aNSCLC) has provided the opportunity for successful treatment with specific, targeted EGFR tyrosine kinase inhibitors. However, this therapeutic decision may be challenging when insufficient tumor tissue is available for EGFR mutation testing. Therefore, blood surrogate samples for EGFR mutation analysis have been suggested.
Methods:
Data were collected from the Spanish cohort of patients in the large, non-interventional, diagnostic ASSESS study (NCT01785888) evaluating the utility of circulating free tumor-derived DNA from plasma for EGFR mutation testing. The incidence of EGFR mutation in Spain and the level of concordance between matched tissue/cytology and plasma samples were evaluated.
Results:
In a cohort of 154 eligible patients, EGFR mutations were identified in 15.1 and 11.0% of tumor and plasma samples, respectively. The most commonly used EGFR mutation testing method for the tumor tissue samples was the QIAGEN Therascreen® EGFR RGQ PCR kit (52.1%). Fragment Length Analysis + PNA LNA Clamp was used for the plasma samples. The concordance rate for EGFR mutation status between the tissue/cytology and plasma samples was 88.8%; the sensitivity was 45.5%, and the specificity was 96.7%.
Conclusions:
The high concordance between the different DNA sources for EGFR mutation testing supports the use of plasma samples when tumor tissue is unavailable.
Insights
Plasma testing for epidermal growth factor receptor (EGFR) mutations is a viable alternative when tumor tissue is insufficient for advanced non-small-cell lung cancer (aNSCLC) patients. High concordance between tissue and plasma samples supports this approach for targeted therapy decisions.
Area of Science:
- Oncology
- Molecular Diagnostics
- Genetics
Background:
- Advanced non-small-cell lung cancer (aNSCLC) treatment relies on epidermal growth factor receptor (EGFR) mutation status.
- EGFR mutation testing is crucial for selecting targeted therapies, such as EGFR tyrosine kinase inhibitors.
- Limited tumor tissue availability poses a challenge for accurate mutation analysis.
Purpose of the Study:
- To evaluate the utility of plasma-based circulating free DNA for EGFR mutation testing in aNSCLC patients.
- To determine the incidence of EGFR mutations in the Spanish patient cohort.
- To assess the concordance between EGFR mutation status in matched tumor and plasma samples.
Main Methods:
- Analysis of data from the Spanish cohort of the ASSESS study (NCT01785888).
- Evaluation of circulating free tumor-derived DNA from plasma for EGFR mutation detection.
- Comparison of results from tissue/cytology samples with plasma samples.
Main Results:
- EGFR mutations were detected in 15.1% of tumor samples and 11.0% of plasma samples from 154 patients.
- The concordance rate between tissue/cytology and plasma samples for EGFR mutation status was 88.8%.
- Plasma testing demonstrated high specificity (96.7%) but lower sensitivity (45.5%) compared to tissue analysis.
Conclusions:
- Plasma-derived DNA is a valuable surrogate for EGFR mutation testing when tumor tissue is insufficient.
- The high concordance supports the use of liquid biopsies for guiding targeted therapy in aNSCLC.
- Plasma testing offers a non-invasive method to assess EGFR mutation status, facilitating treatment decisions.
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