The Role of Digital Rectal Examination Prostate Volume Category in the Early Detection of Prostate Cancer: Its Correlation with the Magnetic Resonance Imaging Prostate Volume

Abstract

Purpose: To relate the prostate volume category (PVC) assessed with digital rectal examination (DRE)-small, median, and large-and the prostate volumes (PVs) assessed with magnetic resonance imaging (MRI) and transrectal ultrasound (TRUS). To compare the clinically significant prostate cancer (csPCa) discrimination ability of two predictive models based on DRE-PVC and MRI-PV.

Materials and methods: A prospective trial of 2,090 men with prostate-specific antigen >3 ng/mL and/or PCa suspicious DRE were prospectively recruited in 10 centers from Catalonia (Spain), between 2021 and 2022, in whom DRE-PVC was assessed. Pre-biopsy MRI, and 12-core TRUS-random biopsy was always performed after 2- to 6-core TRUS-fusion targeted biopsy of prostate imaging-report and data system >3 lesions. In 370 men (17.7%) the DRE-PVC was unconclusive. Among the 1,720 men finally analyzed the csPCa (grade group >2) detection was 42.4%.

Results: The median (interquartile range) of TRUS and MRI-PVs of small prostates were 33 mL (19-37 mL) and 35 mL (23-30 mL), p=0.410; in median prostates they were 51 mL (38-58 mL) and 55 mL (48-63 mL) respectively, p<0.001; in large prostates 80 mL (60-100 mL) and 95 mL (75-118 mL) respectively, p<0.001. The predictive models sharing the MRI-PV and DRE-PVC showed areas under the curves of 0.832 (95% confidence interval [CI], 0.813-0.851) and 0.828 (95% CI, 0.809-0.848) respectively, p=0.632, as well as similar net benefit and clinical utility.

Conclusions: PVC was unconclusive in 17% of DREs. MRI-PV overestimated the TRUS-PV in median and large prostates. The predictive models based on MRI-PV and DRE-PVC showed similar efficacy to predict csPCa. PVC assessed with DRE is helpful to predict the csPCa risk before MRI.

Keywords: Digital rectal examination; Magnetic resonance imaging; Predictive model; Prostate volume; Prostate volume category; Transrectal ultrasound.

Fig. 1. Boxplots showing the TRUS and MRI-prostate volumes corresponding to each DRE-prostate volume category. TRUS: transrectal ultrasound, MRI: magnetic resonance imaging, DRE: digital rectal examination.

Fig. 2. Clinically significant prostate cancer discrimination ability of the models sharing the MRI-prostate volume (PV) and the DRE-prostate volume category (PVC). MRI: magnetic resonance imaging, DRE: digital rectal examination, AUC: areas under the curve, CI: confidence interval.

Fig. 3. Decision curve analysis showing the similar net benefit obtained with the models sharing MRI-prostate volume (PV) and DRE-prostate volume category (PVC) over biopsying all men. MRI: magnetic resonance imaging, DRE: digital rectal examination.

Fig. 4. Clinical utility curve showing the similar utility of the models sharing the MRI-prostate volume (A) and DRE-prostate volume category (B), in terms of saved prostate biopsies and undetected csPCa. MRI: magnetic resonance imaging, DRE: digital rectal examination, csPCa: clinically significant prostate cancer.

Fig. 5. Clinically significant prostate cancer discrimination ability improvement of the model developed to save multiparametric MRI exams when DRE prostate volume category (PVC) is shared. MRI: magnetic resonance imaging, DRE: digital rectal examination, AUC: areas under the curve, CI: confidence interval.

Fig. 6. Nomogram of the csPCa predictive model developed to save multiparametric MRI exams which shares DRE prostate volume category (PVC). csPCa: clinically significant prostate cancer, MRI: magnetic resonance imaging, DRE: digital rectal examination, PSA: prostate-specific antigen.