Effect of steroid therapy on survival in patients with metastatic solid tumors experiencing immune-related adverse events

Immune checkpoint inhibitors (ICIs) improve survival in solid tumors but can cause immune-related adverse events (irAEs) that often require systemic steroids. The impact of steroid dose and timing on ICI efficacy remains unclear. We conducted a single-center retrospective study of 466 patients with metastatic solid tumors treated with ICIs between June 2016 and September 2024. Steroids for irAEs were categorized as high dose (≥1 mg/kg prednisolone-equivalent) or low dose (≤0.5 mg/kg). Overall survival (OS), progression-free survival (PFS), and post-irAE OS/PFS were evaluated. IrAEs occurred in 182 (39.1%) patients, and 81 (17.4%) received systemic steroids. IrAE occurrence was associated with reduced mortality risk. Among patients with irAEs, steroid use increased mortality (p = 0.035) without significantly affecting PFS. High-dose steroids were linked to worse post-irAE OS (p = 0.002) and PFS (p = 0.034), while low-dose steroids showed no detrimental effect. Early initiation ( < 2 months) of high-dose steroids demonstrated the strongest negative association. High-dose steroids, particularly when started early, are associated with significantly worse survival after irAEs in metastatic solid tumors. These findings support managing irAEs with the lowest effective steroid dose and encourage exploration of steroid-sparing strategies. Subtype-specific analyses were limited by small sample sizes and should be interpreted cautiously.