Impact of Immune-Related Adverse Event Frequency, Severity, and Corticosteroid Use on Immune Checkpoint Inhibitor Efficacy in Non–Small Cell Lung Cancer

Background/Objectives: Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape of non-small cell lung cancer (NSCLC), introducing a distinct spectrum of immune-related toxicities (irAEs). However, the real-world impact of irAEs and corticosteroid use on treatment outcomes remains uncertain. Methods: We conducted a multicenter, retrospective study including patients with advanced NSCLC treated with ICIs alone or in combination with chemotherapy between April 2017 and December 2023. Clinical records were reviewed to collect data on irAEs and corticosteroid administration. Efficacy and safety outcomes were compared according to irAE occurrence, grade, and corticosteroid use. Results: Among 452 patients, 151 (33.4%) experienced irAEs of any grade, and 37 (8.2%) developed grade ≥3 events. The most common irAEs were dermatologic (11.1%), endocrine disorders (9.1%), and arthritis (5.5%). Corticosteroids were administered for irAE management in 60 patients (13.3%). Patients who developed irAEs achieved significantly improved progression-free survival (median PFS: 23.2 vs. 4.2 months; HR = 0.29; p