The PHI test is a new blood test that may eventually replace the PSA test when testing for prostate cancer. It is a simple, noninvasive blood test that is three times more specific than PSA in detecting prostate cancer. Controversy remains surrounding the use of the PSA test to screen for prostate cancer. This is due to the belief that the PSA test may lead to over-diagnosis and over-treatment in men with low-grade, less aggressive forms of the disease.