Serum albumin and toxicity burden in patients with solid tumors receiving tyrosine kinase inhibitors: A real-world cohort study from Saudi Arabia.

e23359 Background: Tyrosine kinase inhibitors (TKIs) are widely used across multiple malignancies; however, treatment-related toxicities remain a major cause of hospitalization, treatment modification, and reduced quality of life. Serum albumin is a routinely measured biomarker reflecting nutritional status, systemic inflammation, and disease burden, and may influence drug exposure for highly protein-bound TKIs. Real-world data examining the relationship between baseline albumin levels and clinically meaningful toxicity outcomes with TKIs remains limited. Methods: We conducted a retrospective cohort study of adult cancer patients treated with TKIs at King Fahad Medical City, a tertiary care hospital in Saudi Arabia. Patients were stratified by baseline serum albumin (< 3.5 vs. ≥3.5 g/dL). Treatment-related toxicities were identified through detailed medical record review and categorized chronologically as first, second, and third documented adverse events. Outcomes included toxicity incidence and severity, toxicity-related hospitalization or emergency department (ED) visits, treatment discontinuation, and time to first documented toxicity. Time-to-event analyses were performed using Kaplan–Meier methods with log-rank testing, and Cox proportional hazards regression was used for multivariable analyses. Results: A total of 369 patients were included; 121 (31.7%) had baseline hypoalbuminemia. Patients with hypoalbuminemia had more advanced disease, poorer performance status, and greater metastatic burden. The overall incidence of first documented toxicity was similar between groups (61.2% vs. 61.7%; p = 0.92). However, toxicity-related hospitalization or ED visits following the first toxicity were more frequent among patients with hypoalbuminemia (29.0% vs 17.7%; p = 0.014). Median time to first toxicity was shorter in the hypoalbuminemia group (29.4 months) compared with patients with normal albumin (not reached; log-rank p = 0.015). In univariate analysis, normal albumin was associated with a lower risk of toxicity (HR 0.67, 95% CI 0.49–0.93), though this association was attenuated after multivariable adjustment. No significant differences in overall survival were observed between groups. Conclusions: Baseline hypoalbuminemia was associated with earlier onset of TKI-related toxicity and increased toxicity-related hospitalization or ED visits, despite similar overall toxicity rates. Serum albumin may serve as a pragmatic clinical marker to identify patients at higher risk of early, clinically consequential toxicity in real-world TKI practice, supporting closer monitoring and proactive supportive care strategies at treatment initiation.