Prognostic Value of the Inflammatory Burden Index (IBI) in Metastatic Urothelial Carcinoma Prior to First-Line...

Background and Objectives: The systemic inflammatory response is important in cancer prognosis and progression. The inflammatory burden index (IBI) provides information about both inflammation and the immune response. Urothelial carcinomas are immunogenic; therefore, it has been suggested that inflammatory indices may predict disease prognosis. The aim of this study was to investigate the effects of systemic inflammatory indices, particularly the inflammatory burden index, on disease progression and overall survival in patients with metastatic urothelial cancer (affecting the bladder and upper urinary system) before first-line treatment and to demonstrate their prognostic importance. Materials and Methods: Within the scope of the study, the medical records of 130 patients who received systemic treatment for metastatic urothelial carcinoma at the medical oncology clinic were retrospectively reviewed. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal threshold values for IBI. Survival rates were calculated using the Kaplan-Meier method, and survival differences between groups were compared with the log-rank test. Univariate and multivariate analyses were performed using the Cox proportional hazards regression model to evaluate prognostic factors. Results: A total of 130 patients were included in the study. The median age was 64.9 years (IQR: 57.2-70.5). The primary tumor location was the bladder in 84.6% of patients, while the remaining 15.4% originated from the ureter and renal pelvis. In first-line systemic treatment, patients received a median of 4 cycles (IQR: 3-6). The median number of total treatment lines administered for metastatic disease was 1 (IQR: 1-2). In progression-free survival (PFS) analyses, the median PFS was 9.20 (95% CI 6.55-11.85) months in the IBI-low group (n = 47) and 5.82 (95% CI 4.56-7.07) months in the IBI-high group (n = 83) (p < 0.001). The median OS was calculated to be 18.96 (95% CI 16.61-21.30) months in the IBI-low group (n = 47), while it was found to be 9.50 (95% CI 7.70-11.29) months in the IBI-high group (n = 83) (p < 0.001). In multivariate analysis, high IBI and the presence of brain metastasis were found to be associated with the risk of progression. In terms of overall survival, the presence of brain metastasis, the presence of visceral metastasis, ECOG PS status, receipt of maintenance therapy, LMR, and the IBI score showed statistically significant prognostic effects. Conclusions: In metastatic urothelial carcinoma, the IBI was identified as an independent prognostic factor associated with progression-free and overall survival. These findings suggest that the IBI may have potential utility as a prognostic biomarker; however, larger, multicenter, and prospective studies are required to further validate its clinical applicability.