LOS ANGELES, CA (Catholic Online) - Even if the PSA test indicates a high risk of cancer, it's often unable to differentiate between a slow-growing, nonlethal cancer and that of a clinically significant cancer, Wei said.

This may soon change. The prostate cancer antigen-3, or PCA3 test, is readily available for use. The test has yet to be approved by the Food and Drug Administration and measures urine levels of the genetic material mRNA. According to Wei, high levels of mRNA indicate an increased risk of cancer, and the results of a PCA3 test can add reliability to those of a PSA test to reduce false positives.

A potential test measuring levels of gene fusion TMPRSS2-ERG could give doctors a better idea of whether their patient's cancer is clinically significant or not, Wei says.

In the United States last year, there were nearly 218,000 new cases and 32,050 deaths from prostate cancer, according to the National Cancer Institute. The cancer usually affects older men, and PSA tests are the main way of screening for the cancer.

While there is no recommended age to start screening for prostate cancer, doctors generally agree men should start at age 40 or 50. 

When Dr. Wei sees an abnormal PSA level, he doesn't tell his patient that he has cancer. He simply says there's an elevated chance of cancer. The patient can then choose whether or not to undergo a biopsy of the prostate, which has its own risks.

The chance of finding prostate cancer among men with elevated PSA levels is about one in three, but "the problem is the other two men who don't have cancer get a biopsy, perhaps unnecessarily," he said.

"When you multiply that for a million biopsies each year, that's a lot of men," he says.

Everything on the market now for prostate cancer screening is a derivative of the PSA test, in that those tests always look for a form of PSA in the blood, said Wei, who is also the principal investigator of a National Cancer Institute-funded clinical trial testing the effectiveness of PCA3 testing.

"But PCA3 is totally outside of the PSA box," Wei said. "This is so important because it uses a different mechanism to detect cancer risk."