Molecular analysis of peripheral non-squamous non-small cell lung cancer sampled by radial EBUS

Treatment optimization of non-squamous non-small-cell lung cancers (nonSq-NSCLC) relies on the molecular analysis of the tumour. We aimed to assess the predictive factors of molecular analysis feasibility (MAF) from samples of peripheral nonSq-NSCLC obtained by radial endobronchial ultrasound bronchoscopy (r-EBUS) and 1.5 mm microbiopsy forceps.

We reviewed data from consecutive peripheral lung nodules sampled with r-EBUS between January 2012 and July 2014 at a single French University Hospital. nonSq-NSCLC were systematically analysed for EGFR, KRAS, ALK, HER2, PI3K and BRAF throughout the study, and c-MET and ROS1 alterations for the last 10 months.

Of 111 nonSq-NSCLC diagnosed by r-EBUS (113 procedures, mean nodule diameter 28 ± 15 mm), 88 were analysed for EGFR and ALK, 87 for KRAS, 86 for HER2, PI3K and BRAF and 14 for c-MET. Forty-one mutations were identified (23 KRAS, 10 EGFR, 2 BRAF, 1 HER2 and 5 ALK rearrangements). Four c-MET overexpressions were noted. MAF rose from 67% for the first 57 procedures to 89% for the last 56 procedures (P = 0.02) likely due to a higher number of biopsies performed (2 ± 1 vs 3 ± 2, P = 0.005). Upper or middle lobe location (OR 1.19, 95% CI: 1.02-1.38, P = 0.03), and at least three biopsies (OR 1.20, 95% CI: 1.04-1.40, P = 0.02) were predictive factors of MAF. Percentage of tumour cells, size of lesion and distance to the pleura did not correlate with MAF.

Multi-gene molecular analysis could be performed in nearly 80% of paraffin-embedded biopsies or smear specimens sampled by r-EBUS assisted bronchoscopy of peripheral tumoral lung nodules.