Prostate Health Index (phi) Predicts Aggressive Prostate Cancer
Astudy published in BJU International examined the use of the Prostate Health Index (phi) test as a tool in assessing risk for aggressive prostate cancer, defined as a Gleason score of 7 or greater upon biopsy.
The men in the study all had PSA levels from 2 to 10 ng/mL and a negative digital rectal examination. Of the 728 men who had biopsies, 118 (16.2%) had aggressive prostate cancer. Researchers found that higher phi scores predicted the risk of aggressive prostate cancer across a spectrum of values. Using phi also improved the predictive accuracy for aggressive disease with the Prostate Cancer Prevention Trial (PCPT) and European Randomized Study of Screening for Prostate Cancer (ERSPC) risk calculators. The authors also used their data to create a new risk assessment model that used age, previous biopsy, prostate volume, PSA, phi and aggressive prostate cancer. The authors concluded that using phi as part of risk assessment “leads to an improvement in the detection of aggressive prostate cancer, potentially reducing harms from unnecessary prostate biopsy and overdiagnosis.”
Dr. Catalona is a co-author of the study.
The Prostate Health Index (phi) is a simple blood test that is nearly 3 times more accurate in detecting prostate cancer than the free/total PSA test. The phi test measures three forms of PSA ([-2]proPSA, free PSA and total PSA), then uses a formula to calculate a combined PSA index to determine a patient’s probability of developing prostate cancer. See page 3 of the Winter 2016 QUEST for further information on the phi test and scores.
BJU Int. 2016 Oct 15. doi: 10.1111/bju.13676. [Epub ahead of print]