Clinical study on urothelial tumors of dye workers in Wakayama City

Between January 1951 and December 31, 1990 urothelial tumors were detected in 112 of 1,085 male dye workers (10.3%) in Wakayama City who were formerly engaged in manufacturing of benzidine and/or beta-naphthylamine. The period from exposure to the chemicals to development of the tumor was a mean of 24.1 +/- 9.4 years. A peak incidence of urothelial tumors was observed also approximately 25 years after the peak period of manufacturing these intermediate products of dyes. The mean period from exposure to such carcinogenic chemicals to the onset of the disease was estimated to be 25 years. Of the 78 patients with primary bladder cancer diagnosed since 1969, 43 (55.1%) had tumors diagnosed mostly as a result of a positive urinary cytology test obtained as part of a screening program and 35 (44.9%) had tumors diagnosed as the result of symptoms. Ten patients (24.4%) in the screened group had been treated with total cystectomy by the last followup examination compared with 17 (50.0%) in the symptomatic group. The 10-year cumulative survival rates were significantly (p less than 0.05) higher in the screened patients (75.1%) than in the symptomatic patients (55.1%). Our results indicate that screening of high risk populations with urinary cytology tests is effective for early diagnosis and treatment of urothelial tumors, and it improves patient prognosis. Furthermore, the biological behavior of occupational urothelial tumors may be different from that of urothelial tumors in the general population.