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MA05 - Innovative Techniques in Pulmonology and the Impact on Lung Cancer (ID 378)
- Event: WCLC 2016
- Type: Mini Oral Session
- Track: Pulmonology
- Presentations: 1
MA05.10 - Cell-Free DNA Testing for EGFR Mutations in Clinical Practice - Facts and Figures from an Austrian Lung Cancer Center (ID 5255)
16:00 - 17:30 | Author(s): T. Gitter
Detection of EGFR mutations using cell-free DNA in plasma has recently emerged as a novel diagnostic approach to lung carcinoma. This “liquid biopsy” (LB) may also be useful for monitoring disease activity in EGFR-mutated tumors as well as in the management of EGFR-tyrosine kinase inhibitor (TKI) therapy. We present data collected in one year of use and report on applicability and diagnostic value in daily clinical practice.
EGFR Mutations were analyzed using the semi-quantitative Roche cobas® EGFR Mutation Test v2, comprising 42 mutations. Cell free DNA was extracted from EDTA-Blood with the Qiagen QIAsymphony circulating DNA Kit. LB was initially used for follow-up of known EGFR-mutated tumors and/or in patients under TKI-therapy. Subsequently, we introduced routine LB testing in the primary diagnostic workup of lung cancer patients.
From July 2015 to June 2016 we performed a total of 92 liquid biopsies in 77 patients (60% male, mean age 65y) in whom EGFR mutations could be detected in 10 cases (13%). EGFR status from histological samples was available in 40 patients, in 14 (18%) of them mutations were reported. Compared to histological EGFR status, LB reached a sensitivity and specificity of 0.57 and 0.96, respectively. A total of 9 patients had multiple LB testing during follow-up. Three of them initially had detectable mutations by LB, which turned undetectable upon tumor-specific treatment. Two patients remained EGFR-positive during follow-up despite of therapy, whereas four patients remained negative throughout follow-up and therapy. Resistance mutations under TKI-therapy were not observed. Primary LB (before initiation of any tumor-specific therapy) was obtained from 47 patients (72% male, mean age 66y). EGFR mutations by LB were detected in 2 patients (4%; 1 Ins. Exon-20, 1 L858R), while histology revealed EGFR mutations in 2 out of 22 patients (9%; both L858R). Comparison yielded a sensitivity of 0.5 and a specificity of 0.95 for LB.
Testing for EGFR mutations using cell-free DNA has been established as a new powerful tool in the field of pulmonary oncology. Apart from sole detection of EGFR mutations, especially the application of LB in following patients over time will provide valuable new opportunities in clinical routine and decision making
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