The feasibility of molecular testing on cell blocks created from brush tip washings in the assessment of peripheral lung lesions.

BACKGROUND: With the rapid development of genotype-guided therapies, molecular testing is becoming important in the management of lung cancer. Bronchoscopy is one of the most common investigations performed to diagnose and investigate lung cancer. Given the limited samples often produced by bronchoscopy, this study aims to evaluate the feasibility of performing molecular testing on cell blocks created from bronchoscope cytology brush tip washings (BTW).

METHODS: Patients with positive brush cytology for tumour cells had cell blocks created from the BTW. Mutations were detected using amplicon-based massively parallel sequencing of targeted regions of EGFR, KRAS, and BRAF genes.

RESULTS: A total of 45 patients were included in this study. Of those, 91% had adequate specimens for molecular analysis and 66% of patients with adenocarcinoma had mutations detected. Bronchial brush tip wash cell blocks were the sole specimen available for molecular testing in 27 (60%) patients.

CONCLUSIONS: The findings of this study demonstrate that molecular testing can be performed on cell blocks created from BTW and this technique may allow for an increase in bronchoscope specimens amenable to molecular testing without further increasing morbidity and mortality.