BERKELEY, CA (UroToday.com) - The relationship between smaller prostate volume (PV) and high-grade prostate carcinoma (HGPCa) has been an issue of interest since the publication of the Prostate Cancer Prevention Trial. This relationship was assessed in two different ways in the literature -- the results of prostate biopsy or the pathology of radical prostatectomy (RP) specimens. However, we think that there was an important bias in the assessment of the relationship regarding the RP cohort because either all of these patients had PCa at a stage that fit into a definitive therapy, or their data set did not include any benign patients. Recently, two different studies were submitted by the same institute for the assessment of the relationship between PV and HGPCa (Liu et al., Ngo et al.). They initially showed in their RP cohort that there was a significant relationship between PV and HGPCa in patients with clinical stage T1c prostate cancer but not in ≥T2 (Liu et al.). Secondly, they evaluated this relationship in the prostate biopsy cohort (Ngo et al.) and they found a significant relationship with PV and HGPCa in the entire group and digital rectal examination (DRE)-negative patients while they did not find one in DRE-positive patients. They concluded that if there was a real, significant relationship, it should be shown in all groups and stages. Thus, we aimed to assess the relationship between PV and HGPCa in patients with benign and suspicious DRE in our prostate biopsy cohort.
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Between 2009-2012, 759 consequent initial transrectal systematic 12-core prostate biopsies were included. PVs were calculated with transrectal ultrasound. Only prostate adenocarcinomas (PCa) were included to study. For standardization, patients with missing data and those exposed any form of hormonal or radiation therapy were excluded. Patients were categorized with DRE (negative or positive) and Gleason sum (< 7: low grade PCa (LGPCa), ≥ 7: HGPCa).
Median patient age, tPSA, and PV were 65 years (inter quartile range (IQR) 60-72), 8.1 ng/ml (IQR 5.45-13.90), and 45.6 cc (IQR 32.3-71.20), respectively. Median PV was significantly lower in patients with HGPCa in all DRE status compared to patients without HGPCa.
In order to evaluate whether detection of HGPCa was affected by PV, a logistic regression (LR) analysis was performed. There was a significantly increased risk of HGPCa with each 10 cc decrease of PV (PV/10), older age, and higher logPSA levels, both in DRE negative and positive patients, and in the whole cohort in univariate LR analyses. In multivariate LR analyses, the significant relationship between HGPCa and PV/10 continued in the whole group, and DRE positive and DRE negative groups. There was no significant relationship between LGPCa and PV/10. In addition to analyzing the data, a ROC curve was constructed for tPSA and PV variables for the detection of PCa. From the ROC curve, a significantly statistical concordance was found between the detection of HGPCa and PV (AUC: 0.63, p < 0.001), as well as between HGPCa and tPSA (AUC: 0.73, p < 0.001). However, the concordance of tPSA was significantly higher compared to PV in ROC curve analyses (p=0.002).
In conclusion, there is a significant relationship between HGPCa and decreasing PV/10 in DRE-negative and positive patients free from the limitation of selection bias originating from RP cohort. The continued significant relationship, both in DRE negative and positive groups, decreased the probability of the ascertainment bias. These findings reinforce the evidence for the negative relation between HGPCa and decreasing PV.
Murat Üstüner, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Kocaeli University, School of Medicine
Department of Urology
Umuttepe, Kocaeli, Turkey