Utility and Safety of Endosonography in the Diagnosis of Small Cell Lung Cancer: A Prospective Single-Center Observational Study

Background: Endosonography (i.e., endoscopic ultrasound with bronchoscope fine-needle aspiration, EUS-B-FNA and endobronchial ultrasound-guided transbronchial needle aspi- ration, EBUS-TBNA) is a widely used technique in the diagnosis and staging of non-small cell lung cancer. Limited data are available in diagnosing small cell lung cancer (SCLC), and no studies have specifically investigated the diagnostic accuracy of EUS-B-FNA in these patients. The study aims at evaluating the sensitivity and safety of endosonography in the diagnosis of SCLC. Methods: A prospective, single-center, observational study was conducted in Italy. All patients diagnosed with SCLC who underwent EUS-B-FNA and/or EBUS-TBNA were enrolled. The sensitivity of EUS-B-FNA and EBUS-TBNA were assessed using pathological confirmation as the gold standard. Results: A total of 72 pa- tients (38 (53%) males) with confirmed SCLC were included in the study. EUS-B-FNA was performed in 31 (43%) patients and EBUS-TBNA in 44 (61.1%) patients; both procedures were performed in three (4.2%). The overall sensitivity of endosonography was 97.2%. The sensitivity of EUS-B-FNA and EBUS-TBNA was 96.8% and 90.9%, respectively. No differences were observed in the sensitivity of both techniques when sampling lymph nodes vs. pulmonary parenchymal lesions (p = 0.99). The overall complication rate was 5.6%. No major complications were reported. Conclusions: Endosonography is a highly accurate and safe technique in diagnosing SCLC. EUS-B-FNA alone demonstrates excellent sensitivity, supporting its extensive role as a valuable diagnostic tool. The combined use of both techniques may further optimize diagnostic yield in the diagnosis of SCLC.