Background: A national survey in Taiwan has shown that Chinese herbal therapy increases the risk of chronic kidney disease. However, it is unknown whether herbal therapy will increase the risk of urological cancers. The purpose of this study was to determine whether Chinese herbalists are at higher risk for urological cancers.
Methods: We studied all Chinese herbalists in Taiwan that were registered in the Chinese Herbalist Labor Union between 1985 and 2000. We retrospectively followed their survival status and causes of death using the National Mortality Registry Database from 1985 to 2004. Standardized mortality ratios (SMRs) for urological cancers in herbalists were calculated and compared with those of the general population of Taiwan.
Results: A total of 6548 Chinese herbalists were enrolled and 88,289 person-years were accrued during the observation period. After adjustment for age and sex, the SMR for urological cancers was significantly higher for Chinese herbalists than for the general population (SMR = 3.10; 95% CI: 1.41–5.87). When further stratified by location, the SMR for kidney cancer and other urinary organ cancers (SMR = 3.81; 95% CI: 1.39–8.28) except bladder cancer (SMR = 2.26; 95% CI: 0.47–6.59) were significantly higher for the Chinese herbalists. The SMR for chronic and unspecified nephritis, renal failure, and renal sclerosis were also significantly higher for herbalists (SMR = 2.40; 95% CI: 1.40–3.84).
Conclusions: Chinese herbalists have a significantly higher risk for urological cancers. This increased risk among herbalists highlights the urgent need for safety assessments of Chinese herbs.