#2373 Malignant tumors of the urinary bladder and Balkan endemic nephropathy – a 45 year study

Abstract Background and Aims Balkan endemic nephropathy (BEN) is a chronic interstitial kidney disease limited geographically to specific regions. The wider importance of BEN is reflected in its associations with malignant tumors of the urothelium. For researchers, malignant tumors of the urinary bladder (MTUB) have been less studied and perhaps considered less interesting compared to malignant tumors of the upper urothelium. Balkan endemic nephropathy (BEN) is a chronic interstitial kidney disease limited geographically to specific regions. The wider importance of BEN is reflected in its associations with malignant tumors of the urothelium. For researchers, malignant tumors of the urinary bladder (MTUB) have been less studied and perhaps considered less interesting compared to malignant tumors of the upper urothelium. Method Balkan endemic nephropathy (BEN) is a chronic interstitial kidney disease limited geographically to specific regions. The wider importance of BEN is reflected in its associations with malignant tumors of the urothelium. For researchers, malignant tumors of the urinary bladder (MTUB) have been less studied and perhaps considered less interesting compared to malignant tumors of the upper urothelium. Results During the observed period, there were a total of 1447 cases of MTUB - 1109 (76.64%) male patients and 338 (33.36%) female patients. The average annual incidence rate (AAIR) of MTUB in endemic settlements for the observed period (1978-2024) is 15.64; in hypoendemic areas is 13.89, and in non-endemic areas is 14.62. The AAIR of MTUB in endemic settlements is 1.13 times higher than the rate in hypoendemic areas and 1.07 times higher compared to non-endemic settlements. It is noteworthy that in the first period of observation, the AAIR of MTUB in endemic areas is 2.24 times higher than the rate in hypoendemic areas and 4.09 times higher than the rate in non-endemic areas. However, in the second and third periods of the study, it is significantly lower compared to the rates in hypoendemic and non-endemic areas. The linear trend of MTUB for the observed period in endemic settlements is negative without statistical significance (y = −0.012x + 701; r2 = 0.048), while in non-endemic areas, it is positive and statistically significant (y = 1.340x + 0.172; r2 = 0.647). Conclusion The higher frequency of MTUB in the Jablanica district over the 45-year study of the region with BEN is limited to the first part of the research and may indicate a common nephropathogenic and carcinogenic etiological factor, confirming a positive correlation between BEN and malignant urothelial tumors. At the same time, in the last 25 years of the observed period, there has been a drastic decline in the frequency of both BEN and MTUB, as well as malignant tumors of the upper urothelium.