Epidemiologic characteristics of urinary system tumors and Balkan nephropathy in an endemic region of Bulgaria

Abstract

In the endemic region of Vratza district, Bulgaria a close epidemiologic similarity was observed between endemic nephropathy (EN) and urinary tract tumors, in particular neoplasms of renal pelvis and ureter. They correlate geographically, affect more women as well as middle aged people, elicit very high incidence rates, reveal a tendency for familial aggregation of cases. In hyperendemic villages age-adjusted annual incidence rates per 100,000 were 43.5 in men and 74.2 in women for tumors of renal pelvis and ureter and 38.7 and 24.6, accordingly, for tumors of urinary bladder. Urinary tract tumors were often multiple, especially in patients with EN, and as a rule they originate from the uroepithelium. Among all patients with urinary system tumors (UST) 27.3% were also registered for EN while UST were found in 6.5% of the EN patients. In patients with concurrent occurrence of EN and UST nephropathy was first registered in 51% of the cases against in 18% for UST. The observed epidemiologic similarity between En and urinary tract tumors, their location in urinary system and the fact that they frequently combine is seen as a proof of a close etiologic and pathogenic relationship between the two diseases.