New prostate cancer screening method combines existing tests to increase accuracy

Northwestern Medicine- is the first health care provider in the country to offer a new non-invasive blood test for prostate cancer that is nearly three times more accurate than the current standard prostate-specific antigen (PSA) blood test. Known as the Prostate Health Index (phi), the new test's accuracy will effectively remove the need for many men who test positive for elevated PSA levels to undergo a biopsy to achieve a reliable diagnosis.

According to the Centers for Disease Control and Prevention (CDC), prostate cancer is the most common type of non-skin cancer for men in America and is a leading cause of cancer death among men of all races. The most widely used screening test for prostate cancer is currently the PSA test, which measures the blood's level of PSA, a protein that is naturally produced by the prostate gland and is typically increased when cancer is present. While the PSA test is simple and non-invasive, its results can often indicate the possibility of prostate cancer when none is present.

"The PSA test is based on the fact that men with higher levels of the PSA protein are more likely to have prostate cancer," said William Catalona, MD, urologist at Northwestern Medicine and director of the Clinical Prostate Cancer Program at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. "The problem is that higher levels of PSA can also be caused by a benign enlargement or inflammation of the prostate, leading to many false-positives for cancer and ultimately unnecessarily invasive biopsies and an increased potential for patient harm."

In 2012, the U.S. Preventive Services Task Force called attention to the heightened risk of unnecessary patient harm caused by false-positives from PSA testing and released a recommendation calling for "a better test and better treatment options" for prostate cancer screening.

Because PSA testing isn't conclusive enough on its own, physicians normally advise men with increased PSA levels in the range of 4-10ng/mL to undergo a prostate biopsy. However, the phi test helps physicians distinguish prostate cancer from benign conditions by utilizing three different PSA markers (PSA, FreePSA and p2PSA) as part of a sophisticated algorithm to more reliably determine the probability of cancer in patients with elevated PSA levels. Because of the substantial increase in accuracy, results of a multi-center clinical study that Catalona led found a 31 percent reduction in unnecessary biopsies due to false-positives as a result of using the phi test.

In addition to being much more accurate and reducing the need for prostate biopsies, the new test also offers patients a screening option that still only requires a simple blood test. The phi test will become available to all healthcare providers within the first quarter of 2014, and was developed by Beckman Coulter and evaluated in a multi-center clinical research study lead by Catalona as the principal investigator.