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New prostate cancer test designed to use urine instead of blood

A team of researchers at UC Irvine are developing a what it hopes will be a more reliable prostate cancer test that uses urine instead of blood. It involves urinating on a stick coated with a virus that attracts a protein associated with the disease. It would also be very inexpensive.

Every year roughly 240,000 men in the US are diagnosed with prostate cancer. The current testing method often finds tumors that are low risk and can lead patients to get dangerous and expensive surgeries they don't need, but a study published Wednesday in the Journal of the American Chemical Society suggests an alternative that's about the size of a home pregnancy test. 

Instead of drawing blood and waiting several days for results, "you take it home, you pee on it in your bathroom, you press a button and it tells you if you've got a urinary tract infection or something much more serious than that," explains UC Irvine researcher Reginald Penner.

Scientists at UC Irvine have been working to develop this test since 2005. 

The key to this new approach is a protein called PSMA. It shows up in the urine of of people with prostate cancer.

First, the UC Irvine team genetically modified a virus to attract just PSMA.

"It's like a magnet to this protein," says Kritika Mohan, a UC Irvine graduate student with the Gregory Weiss Laboratory who is also working on the project.

The researchers then created a tiny plastic film filled with these modified viruses and coated part of a  urine test stick with it. So when someone urinates on the stick, the viruses capture any PSMA present. If they find some, the test is positive; if they don't, it is negative.

Mohan says the test should even be able to tell how much PSMA is in the urine, letting a patient know how serious the cancer is.

The testing stick is about the size of a pencil, although the researchers are hoping to make it even smaller as they continue their work.

Dr Howard Sandler, a prostate cancer specialist with Cedars Sinai Medical Center, says that ability to distinguish between aggressive and slow growing cancers would make the test very useful.

"To me that's one of the missing pieces in our current prostate cancer world," says Sandler.

Doctors currently test for a protein called PSA in the blood. But PSA levels can rise for many reasons other than cancer, and the blood test often detects slow growing prostate tumors that may not need treatment.

"And that's a major reason why the U.S. Preventative Services task force gave PSA a D rating," Sandler points out. He says the organization doesn't recommend using PSA to test for prostate cancer.

He says this new urine test shows promise because it focuses on PSMA, which is only known to show up when cancer is present. But Sandler wonders how specific the test will be.

"Can it really find cancers that need treatment and ignore the cancers that don't need treatment?" he asks. "Because we do have a problem with over-treatment in prostate cancer."

This urine based approach isn't the only new prostate cancer test in the works. A company called Genomic Health announced a promising genetics based test earlier this month. It uses genomic information gathered from a patient's existing needle biopsy sample to assess the aggressiveness of the prostate cancer. That test would cost close to $4,000. UC Irvine's Reginald Penner hopes his test will sell for $10.

Penner says the next step is to test the device with cancer patients. His team is also working on expanding the test to look for bladder cancer and multiple myeloma as well.

"We are very excited about what should be possible using this technology," Penner says.

The test is still in development, but according to Penner, a private company has already licensed the patent. He hopes to see a urine based prostate test on the market in five years.

This story was updated on May 23, 2013.