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AUA 2017

AUA 2017: Prostate Health Index Density Improves Detection of Clinically-Significant Prostate Cancer

Boston, MA (UroToday.com) There are a variety of nascent biomarkers in prostate cancer (PC), many of which were evaluated in development and validation studies presented this year at the AUA. Some well-known and widely used markers include PSA, free PSA, PSA density, 4k score, and prostate health index (PHI), just to name a few. PHI is calculated via a formula that integrates free PSA, total PSA, and one of the truncated pro-PSA isoforms easily detected in blood. The AUC for predicting significant prostate cancer for PHI is 0.76, and for PSA density is 0.7. Both of these are significantly better than total PSA (AUC 0.56) alone. Investigators therefore intelligently hypothesized that combining PHI and PSA density would further improve the discriminatory capability of PHI testing.

Dr. Druskin presents a prospective analysis of 118 patients from Johns Hopkins evaluating the discriminatory power of “PHI density” in predicting clinically significant PC. Significant PC was defined as Gleason score >=7 or Gleason score 6 cancer in >2 cores or >50% of any positive core. The ROC curve for PHI density demonstrated a significantly better AUC at 0.84 than the aforementioned PSA-related tests. In other words, PHI density has more discriminatory ability in identifying clinically significant prostate cancer than other available tests.

At a PHI density cutoff of 0.43, the test was 98% sensitive and 38% specific. 80% of men with a PHI score >1.21 had clinically significant prostate cancer. Using PHI density can help avoid 38% of unnecessary biopsies at the cost of missing 2% of clinically significant cancers.

The main limitation to the study is the sample size, but now that it is being prospectively studied, this shouldn’t be an issue for long. More importantly, there is a shifting understanding in what we classify as “clinically significant” PC. The test characteristics are entirely dependent on this definition, so care should be taken to individualize risk prediction when counseling a patient using biomarker-based decision-making.

PHI density is an exciting, strongly discriminative, method for detecting clinically significant PC. It is relatively cost-friendly and utilizes volume measurements that are easily obtained via transrectal ultrasound and/or MRI. As further data validating this test is published, one could expect rapid adoption of PHI density by Urologists who are looking to avoid unnecessary biopsies.

Presented By: Sasha Druskin, MD; Johns Hopkins Medical Institutions

Written By: Shreyas Joshi, MD, Fox Chase Cancer Center, Philadelphia, PA
Twitter: @ssjoshimd

at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA