The use of Chinese herbal products that contain aristolochic acid is associated with an increased risk of urinary tract cancer, according to the results of a study published in the Journal of the National Cancer Institute.
Previous research has indicated that Chinese herbal products containing aristolochic acid (such as Guan Mu Tong) have been linked to renal failure and urinary tract cancer. In 2003, Taiwan banned products that contained the herb.
Researchers conducted a population-based, case-control study in Taiwan in order to examine the association between the herb and subsequent development of urinary tract cancer. The study included 4,594 patients with urinary tract cancer (newly diagnosed between 2001 and 2002) and 174,701 control subjects selected from the National Health Insurance reimbursement database.
The results of the study indicated that there is a linear dose-response relationship between consumption of the herb and risk for urinary tract cancer. A prescription of more than 60 grams of the herb was associated with an increased risk and the risk continued to increase with increased dosage. The risk was independent of arsenic exposure, which has also been linked to urinary cancer.
The researchers concluded that consumption of herbs containing aristolochic acid placed patients at risk of developing urinary tract cancer. Ingestion of the herb accounted for 3% of all urinary tract cancers diagnosed between 2001 and 2002 in Taiwan.
 Lai MN, Wang SH, Chen PC, et al. Population-based case-control study of Chinese herbal products containing aristolochic acid and urinary tract cancer risk. Journal of the National Cancer Institute. 2010; 102: 179-186.