414P Tumor-associated microRNAs as prognostic biomarkers in limited stage small cell lung cancer

Background: Limited-stage small cell lung cancer (LS-SCLC) accounts for approximately one-third of SCLC diagnoses and poses unique therapeutic challenges in daily clinical practice.Concurrent chemoradiotherapy (CRT) was the standard first-line treatment until the recent introduction of immunotherapy (IO) in LS-SCLC.However, real-world data on this disease setting in Spain are still limited.This study aimed to describe demographics, treatment patterns, and clinical outcomes of LS-SCLC patients (pts) based on data from the Spanish Thoracic Tumors Registry (TTR). Methods:The analysis included pts with LS-SCLC (stage I-III) aged 18 years, registered in the Spanish TTR between January 2016 and September 2025.Patients who underwent surgery as first-line therapy or with combined SCLC/NSCLC histology were excluded.Baseline demographics and clinical characteristics, treatment patterns and therapies at progression were described.Effectiveness outcomes included objective response rate (ORR), progression-free survival (PFS), and overall survival (OS), analyzed by Kaplan-Meier methodology.Results: A total of 1,374 pts were included; median age at diagnosis 64.7 years, 67.4% male and most were current or former smokers (97.5%).Comorbidities were present in 85.2% of pts, being the most common hypertension (44.8%), dyslipidaemia (31.9%) and COPD (20.7%).ECOG PS was 0-1 in 89.4% of cases and 2 in 10.6%.The most frequent first-line (1L) treatment was CRT (71.0%): 68.4% cCRT and 31.6%sCRT.In the concomitant regimens, 54.3% of pts received cisplatin vs 27.3% in the sequential regimens.The objective response rate to 1L treatment was 63.3%, Median PFS was 10.6 months (95% CI 6.4-28.5)and median OS was 22.2 months (95% CI 11.7-52.8).OS rates at 12, 24 and 36 months were 74.3%, 47.7% and 35.3%, respectively.Following disease progression, the most common 2L therapies were platinum doublet (41.7%), platinum doublet + IO (11.9%), topoisomerase I inhibitors (17.7%), and other treatments (28.4%). Conclusions:This study enables the description and characterization of the realworld population of pts with LS-SCLC in Spain, providing insights into their management prior to the introduction of IO into clinical practice.Clinical trial identification: NCT02941458.