Using a proof-of-concept urine test that decodes RNA molecules, it’s possible to pick out patients with the disease, scientists report October 2 in Nature Medicine. Because urine is in direct contact with bladder tumors, it’s “a very attractive fluid” to look for this type of cancer, says Stanford University oncologist Maximilian Diehn. The technology, still in its infancy, offers a glimpse of what future screening tests might entail.
Today’s liquid biopsies for cancer, which examine bodily fluids rather than tissue samples, largely focus on finding DNA that tumors shed into the blood. Diehn’s lab sought a different stream of information. The researchers analyzed RNA, DNA’s molecular cousin.
RNA isn’t as stable as DNA, so it hasn’t been researchers’ top target. But it carries info that DNA lacks, such as which genes are turned on. That’s important, Diehn says, “because it can tell you what the cancer is doing at any given moment.” Diehn and his colleagues previously developed a technique to analyze dribs of RNA floating in blood.
In samples from people with lung cancer, the team could read RNA signatures of the disease. Now, the researchers have shown that their technique is a whiz at detecting cancer in urine. The team tested their technique using samples from 515 cancer patients and healthy people.
It was sensitive enough to identify 95 out of 100 people with bladder cancer — even at early stages of disease. What’s more, the test also offered hints about cancer biology, such as the type of tumor and risk of recurrence. Those details could help doctors make decisions about treatments, Diehn says.
The researchers are now exploring their technique’s potential for picking up other cancers. Their evidence suggests that it can spot cancer in the kidney and prostate, organs also washed by urine. One day, Diehn says, he can imagine a multi-cancer urine test focused on tumors in the genitourinary tract.
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