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Chinese herbal products containing aristolochic acid were associated with urinary tract cancer
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A linear dose-response relationship has been confirmed between Chinese herbal products containing aristolochic acid, such as Guan Mu Tong, and risk for urinary tract cancer.
Previous reports in Taiwan have claimed that Chinese herbal products, specifically products containing aristolochic acid, were linked to renal failure. In addition, findings from studies around the world have shown an association between aristolochic acid and urothelial cancer. In 2003, Taiwan banned products containing the herb.
To examine the association between products containing aristolochic acid and urinary tract cancer researchers conducted a population-based study of 4,594 patients diagnosed with urinary tract cancer between January 2001 and December 2002. These patients were compared to 174,701 controls.
A prescription of more than 60 g of Mu Tong was independently associated with increased risk for urinary tract cancer. With a prescription of 61 g to 100 g the odds ratio for urinary tract cancer was 1.6 (95% CI, 1.3-2.1); for 101 g to 200 g the OR was 2.0 (95% CI, 1.4-2.7) and for more than 200 g the OR was 2.1 (95% CI, 1.3-3.4).
A prescription of more than 150 mg of aristolochic acid was also independently associated with elevated risk for urinary tract cancer as well. For 151 mg to 250 mg the OR for urinary tract cancer was 1.4 (95% CI, 1.1-1.8); for 251 mg to 500 mg the OR was 1.6 (95% CI, 1.2-2.1) and for more than 500 mg the OR was 2.0 (95% CI, 1.4-2.9).
Other factors independently associated with elevated risk for new occurrence of urinary cancer included being a man, older age, residence in a township where black foot disease was endemic and having a history of chronic urinary tract infection.
“In addition to a ban on products that may contain any amount of aristolochic acid, we also recommend continued surveillance of herbs or Chinese herbal products that might be adulterated with aristolochic acid-containing herbs,” the researchers wrote. “Finally, patients with a history of aristolochic acid nephropathy or consumption of Mu Tong or Fangchi before they were banned should be monitored regularly for urinary cancer.”
Lai M. J Natl Cancer Inst. 2009;doi:10.1093/jnci/djp467.