Assessment of Chemosensitivity-related Aberrant Methylation of Nonsmall Cell Lung Cancer by EBUS-TBNA.

BACKGROUND: Multigene aberrant methylation profiling may predict response to chemotherapy in lung cancer. The purpose of this study was to analyze the feasibility of detecting aberrant methylation in biopsy samples obtained by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).
METHODS: Lymph node samples from 30 patients with nonsmall cell lung cancer diagnosed as metastatic carcinoma by EBUS-TBNA were analyzed. Histologic cores obtained by EBUS-TBNA were separately stored at -80°C. DNA was extracted from EBUS-TBNA samples and bisulfate modification was performed. We evaluated the methylation status of a panel of 6 genes (FANCF, Reprimo, TMS1/ASC, activated protein-2α, CHFR, and ATM) using methylation-specific polymerase chain reaction. Twenty-four patients with adenocarcinoma or squamous cell carcinoma metastasis received platinum-based combination chemotherapy. We reviewed their response to chemotherapy in correlation to the methylation status.
RESULTS: Bisulfate modification was successfully performed in all samples using DNA obtained from EBUS-TBNA samples by checking p16 unmethylation expression. Aberrant methylation was detected as follows: 9 cases of FANCF (30.0%), 14 cases of Reprimo (46.7%), 10 cases of TMS1/ASC (33.3%), and 19 cases of activated protein-2α (63.3%). In response to chemotherapy, there were 1 complete response, 6 partial response, 12 stable disease, and 5 progressive disease (PD) cases. The number of methylated genes was significantly smaller in the PD group than in the non-PD groups (P=0.0435).
CONCLUSIONS: Aberrant methylation analysis can be performed in metastatic lymph nodes sampled by EBUS-TBNA. EBUS-TBNA allows for genetic evaluations of tumor cells and may help to guide the most effective treatment strategies in the near future.