Increased Risks of Upper Tract Urothelial Carcinoma in Male and Female Chinese Herbalists

Background/Purpose: It has been shown that herbs that contain aristolochic acid induce urological cancer. Chinese herbalists have easy access to such herbs. Our previous mortality study has shown a significantly increased risk of urological cancer in female but not male herbalists. To re-examine this risk in male herbalists, the incidence of urological cancer was analyzed. Methods: We enrolled all 6550 Chinese herbalists in Taiwan registered during 1985-2000, and we retrospectively followed the development of cancer until 2001 by analysis of data collected from the Taiwan Cancer Registry. Standardized incidence ratios (SIRs) were calculated for urological cancers in herbalists and compared with those for the general population in Taiwan. Results: There were 30 newly diagnosed cases of urological cancer and most of them were transitional cell carcinoma (93.1%). The mean age at diagnosis for urothelial carcinoma was 51.6 years, and 51.9% were in the upper urinary tract. After adjustment for age and sex, the SIR for all urological cancers was 3.51 [(95% confidence interval (Cl): 2.37-5.01]. When stratified by location, the SIRs for kidney and upper urinary tract cancers and bladder cancer were 4.24 (95% Cl: 2.47-6.80) and 2.86 (95% Cl: 1.52-4.89), respectively. When analyzed by sex, the SIRs for all urological cancers, kidney and upper urinary tract cancers, and bladder cancer were also significantly increased in male herbalists. Conclusion: The significant risk of urothelial carcinoma noted in male herbalists increases our suspicion that this is an occupational disease that renders regular health assessment of herbalists an urgent necessity.