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A new study has linked herbal remedies to upper urinary tract cancers.

Genomic sequencing revealed a striking mutational signature of upper urinary tract cancers caused by aristolochic acid, a plant compound often used in herbal remedies for thousands of years to treat ailments like arthritis, gout and inflammation.

Aristolochic acid is found in the plant family "Aristolochia," a vine known as birthwort. While U.S. Food and Drug Administration has warned of its cancer-causing potential, botanical products and herbal remedies containing it can still be bought online.

Researchers have known of some of the mutations in upper urinary tract cancer patients exposed to the plant toxin.  However, the genome-wide spectrum of mutations associated with aristolochic acid exposure remained largely unknown.

In the latest study, researchers used whole-exome sequencing on 19 Taiwanese upper urinary tract cancer patients exposed to aristolochic acid, and seven patients with no suspected exposure to the toxin.

"Genome-wide sequencing has allowed us to tie aristolochic acid exposure directly to an individual getting cancer," Kenneth Kinzler, Ph.D., professor of oncology in the Johns Hopkins Kimmel Cancer Center's Ludwig Center for Cancer Genetics and Therapeutics, said in a news release.

"The technology gives us the recognizable mutational signature to say with certainty that a specific toxin is responsible for causing a specific cancer. Our hope is that using the more targeted whole-exome-sequencing process will provide the necessary data to guide public health decisions related to cancer prevention," Kinzler added.

The study found an average of 753 mutations in each tumor from the toxin-exposed group compared with 91 in tumors from the non-exposed group. Researchers said that the level of mutation found in the patients exposed to aristolochic acid is more than that found in melanomas caused by ultraviolet radiation and lung cancer caused by smoking.

Researchers said the group exposed to aristolochic acid had a large number of a particular, rare type of mistake in the ATCG chemical code of their DNA. The study found that 72 percent of the mutation type in the toxin-exposed tumors was A substituted with a T.

Researchers said the latest study shows how genomic sequencing could also be used to pinpoint a culprit carcinogen in some cancer clusters, which are usually large number of similar cancers occurring within a specific group of people, geographic area or period of time.

The findings are published in the journal Science Translational Medicine.