Limitations of overlapping cores in systematic and MRI-US fusion biopsy.

OBJECTIVES: To evaluate the clinically-significant prostate cancer (csCaP) detection rate of systematic (SBx) vs. targeted biopsy (TBx), after accounting for the overlapping systematic cores within the MRI regions of interest. MATERIALS AND METHODS: We identified 398 consecutive men who underwent both transperineal systematic and targeted biopsy between January 2015 to January 2019. We reclassified overlapping systematic cores in the MRI regions of interest as target cores. The detection rates of SBx and TBx were compared using McNemar's test. RESULTS: Detection rate of csCaP (grade group ≥2) was 42% (168/398). Median number of systematic and targeted cores were 23 (IQR 19-29) and 9 (IQR 6-12) respectively. A median of 3 (IQR 2-4) overlapping systematic cores were reclassified as targeted cores. After accounting for overlap, csPC detection rate on SBx decreased from 37% and 21% while the csCaP detection rate of TBx increased from 34% to 39% (both P < 0.001), with TBx having a better detection rate (39% vs. 21%, P < 0.001). A previous negative biopsy was associated with a lower risk of having csCaP on non-targeted SBx (OR 0.27, 95% CI: 0.12 - 0.58, P = 0.001). Only 5% (13/243) of those who had no cancer detected on TBx had csCaP on non-targeted SBx compared to 45% (70/155) of those who had csCaP on TBx (P< 0.001). CONCLUSIONS: The utility of SBx in detecting csCaP decreases after accounting for overlap into the MRI region of interest, especially in men with a prior negative biopsy. Overlapping systematic cores improve the csCaP detection rate on TBx.

External validation and comparison of magnetic resonance imaging-based predictive models for clinically significant prostate cancer.

PURPOSE: Several multiparametric magnetic resonance imaging (mpMRI)-based models have been developed with significant improvements in diagnostic accuracy for clinically significant prostate cancer (csCaP), but lack proper external validation. We therefore sought to externally validate and compare all published mpMRI-based csCaP risk prediction models in an independent Asian population. PATIENTS AND METHODS: A total of 449 men undergoing combined transperineal fusion-targeted/systematic prostate biopsy at our specialist center between 2015 to 2019 were retrospectively analyzed. csCaP was defined as lesions with ISUP (International Society of Urological Pathology) grade group ≥2. The performance of 6 mpMRI-based risk models (MRI-ERSPC-3/4, Distler, Radtke, Mehralivand, van Leeuwen and He) were evaluated in terms of discrimination, calibration and clinical utility, using area under the receiver operating characteristic curve (AUC), calibration curves and decision curve analyses. RESULTS: A total of 202 (45%) subjects were diagnosed with csCaP. All models demonstrated excellent accuracy with AUCs ranging from 0.75 to 0.86, and most significantly outperformed mpMRI PIRADSv2.0 (Prostate Imaging Reporting and Data System version 2.0) alone. The models by Mehralivand and He showed good calibration to our validation population, with respective intercepts of -0.08 and -0.84. All models were nevertheless recalibrated to the csCaP prevalence in our population for analysis. Decision curve analysis showed that above a threshold probability of 10%, all mpMRI-based models demonstrated superior net benefit compared to mpMRI PIRADSv2.0 or a biopsy-all-men strategy. The van Leeuwen model had the greatest net benefit, avoiding 39% of unnecessary biopsies while missing only 4% of csCaP, at a threshold probability of 15%. CONCLUSIONS: The mpMRI-based risk models demonstrate excellent discrimination and clinical utility and are easy to apply in practice, suggesting that individualized risk-based approaches can be considered over mpMRI alone to avoid unnecessary biopsies.

Prostate-specific antigen levels among Chinese, Malays and Indians in Singapore from a community-based study.

The purpose of this study was to examine the distribution of prostate-specific antigen levels among Chinese, Malays and Indians in Singapore, taking the effect of age into consideration. The study was carried out as part of the Singapore Prostate Awareness Week from 23-26th February 2004. Men above 50 years old went to four government-restructured hospitals to participate in the study. Participants filled up a questionnaire and provided 5 ml of blood for measurement of PSA levels using the Abbott IMx Total PSA assay (Abbott Laboratories). 3,486 men responded to the study, comprising 92.8% Chinese, 3.0% Malays, 2.5% Indians and 1.8% Others. 92.7% of them had PSA levels of 4 microg/L or less. There were no significant differences (p<0.05) between the mean PSA levels of Chinese (1.60 microg/L), Malays (1.39 microg/L), Indians (1.23 microg/L) and Others (1.70 microg/L). PSA levels were significantly associated with age (Spearman's r= 0.27, p<0.01). PSA levels increased with each 10-year age group and these trends were significant (p<0.0001) across both PSA group levels and age groupings. In the 50-60 years age groups, the prevalence of PSA levels >4 mug/L were 1.1% and 3.7% respectively. This rose rapidly to 11.3% and 23.5% for age groups >60-70 and >80 years respectively. Our study shows that the median PSA levels in the Caucasian population in the USA are higher than those of Chinese, Malays and Indians in Singapore. PSA levels were positively associated with age. It may be more appropriate to offer PSA testing to men who are >60 years old rather than the current >50 years.

Fluorescence detection of bladder cancer using urine cytology.

Bladder cancer is the fourth most common malignant disease worldwide, accounting for 4% of all cancer cases. In Singapore, it is the ninth most common form of cancer. The high mortality rate in bladder cancer can be reduced by early treatment following pre-cancerous screening. Currently, the gold standard for screening bladder tumors is histological examination of biopsy specimens, which is both invasive and time-consuming. In this study, ex vivo urine fluorescence cytology was investigated to offer an alternative timely and biopsy-free means for detecting bladder cancers. Sediments in patient urine samples were extracted and incubated with a novel photosensitizer, hypericin. Laser confocal microscopy was used to capture the fluorescence images at an excitation wavelength of 488 nm. Images were subsequently processed to single out the exfoliated bladder cancer cells from the other cells based on the cellular size. Intensity histograms of each targeted cell and feature vectors, derived from the histogram moments, were used to represent each sample. A difference in the distribution of the feature vectors of normal and low-grade cancerous bladder cancer cells were observed. A diagnostic algorithm for discriminating between normal and low-grade cancerous cells is elucidated in this report. This study suggests that the fluorescence intensity profiles of hypericin in bladder cells can potentially provide an automated quantitative means of early bladder cancer diagnosis.