Identification of risk factors for gastrointestinal immune–related adverse events associated with immune check point inhibitors

Gastrointestinal (GI) toxicities are among the most common and potentially severe immune-related adverse events (irAEs), and data on risk factors remain limited. This study aimed to identify risk factors for GI-irAEs in patients treated with ICIs. We conducted a retrospective analysis of patients with any type of malignant tumor who received ICIs between January 2020 and January 2022. GI-irAEs were defined as the onset of diarrhea during the observation period. Univariate analysis was employed to explore associations between GI-irAEs and patient characteristics. Of the 485 patients screened, 361 were eligible for analysis. GI-irAEs occurred in 29 patients (8.03%). Patients with GI cancer demonstrated shorter event-free survival (EFS) compared to those with non-GI cancer (2.33, 95% CI: 1.03–4.95; <i>p</i> = 0.0275). Additionally, ≥ grade 2 GI-irAEs were observed in 14 patients (3.88%). Patients with GU cancer had a significantly higher incidence of GI-irAEs (odds ratio: 3.26, 95%CI 1.21–8.71, <i>p</i> = 0.0497) and exhibited shorter EFS (hazard ratio: 3.07, 95%CI: 1.05–8.96; <i>p</i> = 0.0273) compared to those with non-GU cancer. Our findings suggest that GI cancer may be a risk factor for developing GI-irAEs, while GU cancer may predispose patients to ≥ grade 2 GI-irAEs.