Tumor biopsy is often required to characterize indeterminate nodules. Radial endobronchial ultrasound (rEBUS) bronchoscopy is often used due to a low rate of complications but its sensitivity is limited for small nodules.~The investigators hypothesized that methylation analysis on cfDNA floating in supernatant derived from rEBUS specimens could improve rEBUS sensitivity.~The primary outcome of this pilot, diagnostic validation, monocentric study is the sensitivity of targeted (9 genes panel) methylation analysis on supernatant cfDNA to detect a malignant nodule.~Secondary outcomes include the comparison of supernatant to pathology and plasma cfDNA methylation analysis.~Specificity, negative predictive value (NPV), positive predictive value (PPV) of targeted (9 genes panel) methylation analysis on supernatant cfDNA to detect a malignant nodule will be analyzed.~60 patients planned for a rEBUS bronchoscopy for one, two or three < 20 mm nodule, without mediastinal or extra thoracic lesions (cT1N0M0) will be included.~The day of the rEBUS bronchoscopy, 2 7.5 mL blood samples are collected. rEBUS samples' supernatant, usually discarded, is saved.~Cell free DNA is extracted from these biological specimens at the Laboratory of Oncological Medical Biology (LBMO) in Toulouse University Cancer Institute and tested for methylation (targeted analysis on 9 genes).~The patients will be followed for one year to obtain a final diagnosis and correlate it with tissue, nodule supernatant and plasma methylation analyses.
Lung cancer screening is based on low dose CT scan (LDCT), a highly sensitive but poorly specific tool.~Complementary specific approaches are thus strongly needed, among which cell-free DNA (cfDNA) genotyping has been proven highly specific but of low sensitivity (25 to 50% for stage I diseases) due to inconstant tumor shed. Tumor biopsy is thus often required and radial endobronchial ultrasound (rEBUS) bronchoscopy is a minimally invasive approach (<3% complications) but of limited sensitivity in cases of nodules < 20 mm.~The investigators hypothesized that methylation analysis on cfDNA floating in supernatant derived from rEBUS specimens could improve rEBUS sensitivity