Assessment of epidermal growth factor receptor mutation by endobronchial ultrasound-guided transbronchial needle...

Area of Science:

• Oncology
• Pulmonology
• Molecular Diagnostics

Background:

• Somatic mutations in the epidermal growth factor receptor (EGFR) gene are crucial biomarkers for predicting the efficacy of EGFR tyrosine kinase inhibitors (TKIs).
• Many non-small cell lung cancer (NSCLC) patients present with inoperable disease, necessitating minimally invasive diagnostic techniques.
• Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has proven effective for lymph node staging in lung cancer, yielding histologic core samples suitable for genetic analysis.

Purpose of the Study:

• To develop and assess the feasibility of detecting EGFR mutations in samples acquired via EBUS-TBNA.
• To evaluate EBUS-TBNA as a method for obtaining tissue for genetic analysis in lung cancer patients.

Main Methods:

• Forty-six patients with primary lung cancer and metastatic adenocarcinoma in hilar/mediastinal lymph nodes diagnosed by EBUS-TBNA were included.
• DNA was extracted from paraffin-embedded lymph node samples.
• EGFR mutations in exons 19 and 21 were analyzed using a loop-hybrid mobility shift assay and confirmed by direct sequencing.

Main Results:

• Of 43 eligible cases, 11 (25.6%) showed EGFR mutations.
• Detected mutations included an exon 19 in-frame deletion (E746-A750del) in one case, exon 21 point mutations (L858R) in nine cases, and a double point mutation (L858R+L861V) in one case.
• All identified EGFR mutations were validated by direct sequencing.

Conclusions:

• EGFR mutations can be readily detected in metastatic lymph nodes obtained through EBUS-TBNA.
• EBUS-TBNA facilitates genetic profiling of tumor cells within lymph nodes.
• This technique holds promise for guiding EGFR-TKI therapy decisions in the near future.