Adequacy of Lymph Node Transbronchial Needle Aspirates Using Convex Probe Endobronchial Ultrasound for Multiple Tumor Genotyping Techniques in Non–Small-Cell Lung Cancer

Introduction Adequate tumor acquisition is essential to identify somatic molecular alterations in non–small-cell lung cancer (NSCLC), such as epidermal growth factor receptor ( EGFR ) mutations and anaplastic lymphoma kinase ( ALK ) translocations. The success and failure rates for tumor genotyping of tissue obtained from fine-needle aspirates of nodal tissue using a convex probe endobronchial ultrasound (CP-EBUS) and other diagnostic modalities in routine NSCLC care have not been described. Methods Clinicopathologic data, tumor genotype success and failure rates were retrospectively compiled and analyzed from 207 patient-tumor samples sent for routine tumor genotype in clinical practice, including 42 patient-tumor samples obtained from hilar or mediastinal lymph nodes using CP-EBUS. Results The median age of the patients was 65 years, 62.3% were women, 77.8% were white, 26.6% were never smokers, 73.9% had advanced NSCLC, and 84.1% had adenocarcinoma histology. Tumor tissue was obtained from CP-EBUS–derived hilar or mediastinal nodes in 42 cases (20.2% of total). In this latter cohort, the overall success rate for EGFR mutation analysis was 95.2%, for Kirsten rat sarcoma viral oncogene homolog ( KRAS ) mutation 90.5%, and for ALK fluorescence in situ hybridization 90.5%. In the complete 207 tumors, the success rate for EGFR was 92.3%, for KRAS 91.8%, and for ALK 89.9%. The failure rates were not significantly different when comparing CP-EBUS–derived nodal tissue versus all other samples or versus surgical biopsies of mediastinal nodes, but were significantly lower than image-guided percutaneous transthoracic core-needle biopsies. Conclusions The success rate of multiple tumor genomic analyses techniques for EGFR , KRAS , and ALK gene abnormalities using routine lung cancer tissue samples obtained from hilar or mediastinal lymph nodes by means of CP-EBUS exceeds 90%, and this method of tissue acquisition is not inferior to other specimen types. Tumor genotype techniques are feasible in most CP-EBUS–derived samples and therefore further expansion of routine tumor genotype for the care of patients with NSCLC may be possible using targeted sample acquisition through CP-EBUS.