WCE 2017: Prostate-specific Antigen Density as a Predictor of Gleason Score Upgrading

Vancouver, Canada (UroToday.com) Derek Bos, a third year clinical urology resident of McMaster University at St. Josephs Healthcare Hamilton, presented on the possible use of prostate-specific antigen density as a predictor of prostate cancer Gleason score. The Gleason score of clinically localized prostate cancer is so commonly underestimated at the initial biopsy that 57% of prostate cancer cases have an upgraded post-operative Gleason score. As this can lead to possibly fatal diagnoses of prostate cancer, researchers have been attempting to find a more reliable method of identifying the actual Gleason score. One hypothesis postulates that prostate-specific antigen (PSA) density could be an indicator of the true Gleason score of the cancer. Therefore. Dr. Bos aimed to explore the potential association between PSA density and Gleason score upgrading. 

The research team retrospectively reviewed a prospectively collected database of 399 patients who underwent robot-assisted radical prostatectomy (RARP) at St. Joseph's Healthcare Hamilton. They divided the population into two cohorts based on the presence of post-operative Gleason score upgrading. For each patient, they collected data on basic patient demographics, pathological Gleason score PSA density, and associated preoperative biopsy characteristics. Dr. Bos and his team finally applied a logistic regression model to determine the predictors of upgrade including the baseline demographics and disease-specific variables.

A total of 118 (30%) of the 399 patients had Gleason score upgrading post-RARP. The mean pre-operative Gleason score in the upgraded versus non-upgraded cohort was 7.1+/-0.6 and 6.2+/-0.5, respectively. Therefore, it appears that biopsy Gleason scores could be an independent predictor of pathological upgrading. Additionally, both elevated PSA density and the ratio of positive cores were positively correlated to pathological upgrading (p=0.09, p=0.06, respectively). In the end, however, no association was demonstrated between typical pathological parameters such as margin status, extracapsular extension, or lymph-vascular invasion. 

Dr. Bos concluded that, in this population of patients undergoing RARP for clinically localized prostate cancer, pre-operative Gleason scores and PSA densities were both associated with pathological upgrading, though the PSA density was not significant. Dr. Bos cautioned that there were some possibly significant study limitations such as the fact the data was collected at a single tertiary center, the retrospective design of the study, and the lack of standardization in the pathological interpretation of the prostate biopsies. He also commented on the contrasting results between his study and other literature suggesting that the ratio of positive cores to the number of cores sampled is a significant indicator of Gleason score upgrade. The outcomes of this study do suggest caution for physicians when suggesting active surveillance to patients with biopsy Gleason scores of 7 due to the higher probability of upgrade.

Presented by: Dr. Derek Bos 

Authors: Derek Bos, Jen Hoogenes, K Kim, Forough Farrokhyar, Bobby Shayegan
Affiliation: McMaster University, St. Josephs Healthcare Hamilton

Written by: Vinay Cooper, Department of Urology, University of California – Irvine at the 35th World Congress of Endourology – September 12-16, 2017, Vancouver, Canada