Over- and Underdiagnosis of Prostate Cancer: The Dangers

Blood-Based DNA Methylation Analysis by Multiplexed OBBPA-ddPCR to Verify Indications for Prostate Biopsies in Suspected Prostate Cancer Patients

Current prostate carcinoma (PCa) biomarkers, including total prostate-specific antigen (tPSA), have unsatisfactory diagnostic sensitivity and specificity resulting in overdiagnosis and overtreatment. Previously, we described an optimised bias-based preamplification-digital droplet PCR (OBBPA-ddPCR) technique, which detects tumour DNA in blood-derived cell-free DNA (cfDNA) of cancer patients. The current study investigated the performance of newly developed OBBPA-ddPCR-based biomarkers. Blood plasma samples from healthy individuals (n = 90, controls) and PCa (n = 39) and benign prostatic hyperplasia patients (BPH, n = 40) were analysed. PCa and BPH patients had tPSA values within a diagnostic grey area of 2-15 ng/mL, for whom further diagnostic validation is most crucial. Methylation levels of biomarkers RASSF1A, MIR129-2, NRIP3, and SOX8 were found significantly increased in PCa patients compared to controls. By combining classical PCa risk factors (percentage of free PSA compared to tPSA (QfPSA) and patient's age) with cfDNA-based biomarkers, we developed PCa risk scores with improved sensitivity and specificity compared to established tPSA and QfPSA single-marker analyses. The diagnostic specificity was increased to 70% with 100% sensitivity for clinically significant PCa patients. Thus, prostate biopsies could be avoided for 28 out of 40 BPH patients. In conclusion, the newly developed risk scores may help to confirm the clinical decision and prevent unnecessary prostate biopsy.

Increased Sensitivity of Detection of RASSF1A and GSTP1 DNA Fragments in Serum of Prostate Cancer Patients: Optimisation of Diagnostics Using OBBPA-ddPCR

Identification of aberrant DNA methylation is a promising tool in prostate cancer (PCa) diagnosis and treatment. In this study, we evaluated a two-step method named optimised bias-based preamplification followed by digital PCR (OBBPA-dPCR). The method was used to identify promoter hypermethylation of 2 tumour suppressor genes RASSF1A and GSTP1 in the circulating cell-free DNA (cfDNA) from serum samples of PCa patients (n = 75), benign prostatic hyperplasia (BPH, n = 58), and healthy individuals (controls, n = 155). The PCa cohort was further subdivided into subgroups comprising (I) patients with Gleason Scores (GS) ≤ 7 (n = 55), (II) GS ≥ 8 (n = 10), and (III) patients with metastatic PCa diagnosis (n = 10). We found that RASSF1A methylation levels were significantly increased in all 3 PCa subgroups compared to the controls and BPH cohorts (p < 0.01 for all comparisons). Fractional abundances of methylated GSTP1 DNA fragments were significantly increased in subgroup III of metastatic PCa patients (p < 0.001). RASSF1A methylation analysis was found to be beneficial as a complementary biomarker where further diagnostic validation is most crucial. In combination with free PSA, RASSF1A methylation status helps to identify PCa patients with GS ≥ 8 and grey-zone total PSA values between 2-10 ng/mL. In our study, PCR biases between 80-90% were sufficient to detect minute amounts of tumour DNA with high signal-to-noise ratios as well as high analytical sensitivity and specificity. Both RASSF1A and GSTP1 exhibited strongly increased DNA methylation levels in all metastatic PCa patients. Our data indicates a superior sensitivity of epigenetic biomarker analyses in early detection of PCa metastases that should also help to improve PCa therapy.

Improving diagnosis of genitourinary cancers: Biomarker discovery strategies through mass spectrometry-based metabolomics

The genitourinary oncology field needs integration of results from basic science, epidemiological studies, clinical and translational research to improve the current methods for diagnosis. MS-based metabolomics can be transformative for disease diagnosis and contribute to global health parity. Metabolite panels are promising to translate metabolomic findings into the clinics, changing the current diagnosis paradigm based on single biomarker analysis. This review article describes capabilities of the MS-based oncometabolomics field for improving kidney, prostate, and bladder cancer detection, early diagnosis, risk stratification, and outcome. Published works are critically discussed based on the study design; type and number of samples analyzed; data quality assessment through quality assurance and quality control practices; data analysis workflows; confidence levels reported for identified metabolites; validation attempts; the overlap of discriminant metabolites for the different genitourinary cancers; and the translation capability of findings into clinical settings. Ongoing challenges are discussed, and future directions are delineated.

Feasibility of detecting prostate cancer by ultraperformance liquid chromatography-mass spectrometry serum metabolomics

Prostate cancer (PCa) is the second leading cause of cancer-related mortality in men. The prevalent diagnosis method is based on the serum prostate-specific antigen (PSA) screening test, which suffers from low specificity, overdiagnosis, and overtreatment. In this work, untargeted metabolomic profiling of age-matched serum samples from prostate cancer patients and healthy individuals was performed using ultraperformance liquid chromatography coupled to high-resolution tandem mass spectrometry (UPLC-MS/MS) and machine learning methods. A metabolite-based in vitro diagnostic multivariate index assay (IVDMIA) was developed to predict the presence of PCa in serum samples with high classification sensitivity, specificity, and accuracy. A panel of 40 metabolic spectral features was found to be differential with 92.1% sensitivity, 94.3% specificity, and 93.0% accuracy. The performance of the IVDMIA was higher than the prevalent PSA test. Within the discriminant panel, 31 metabolites were identified by MS and MS/MS, with 10 further confirmed chromatographically by standards. Numerous discriminant metabolites were mapped in the steroid hormone biosynthesis pathway. The identification of fatty acids, amino acids, lysophospholipids, and bile acids provided further insights into the metabolic alterations associated with the disease. With additional work, the results presented here show great potential toward implementation in clinical settings.

The relationship between Prostate CAncer gene 3 (PCA3) and prostate cancer significance

OBJECTIVE

To evaluate the relationship between Prostate CAncer gene 3 (PCA3) and prostate cancer significance.

PATIENTS AND METHODS

Clinical data from two multi-centre European open-label, prospective studies evaluating the clinical utility of the PCA3 assay in guiding initial and repeat biopsy decisions were analysed. First-catch urine was collected after digital rectal examination (three strokes per lobe) and the PCA3 score was determined using the PROGENSA(®) PCA3 assay. Transrectal ultrasound-guided biopsy (≥8 cores) and radical prostatectomy (RP) specimens were analysed by the local pathologist. The relationship between biopsy and RP outcomes with the PCA3 score was assessed.

RESULTS

Of the 1009 men enrolled, 348 (34%) had a positive biopsy. The median and mean PCA3 scores were statistically significantly lower in men with biopsy Gleason score <7 vs ≥7, with clinical stage T1c vs T2a-T2c, T3a cancers, with ≤33% vs >33% positive biopsy cores and with 'biopsy indolent' vs 'biopsy significant' prostate cancer (indolent prostate cancer defined by biopsy Epstein criteria). In all, 175 men with a positive biopsy had a RP: median and mean PCA3 scores were statistically significantly lower in men with pathological Gleason score <7 vs ≥7, and with pathological stage T2a-T2c vs T3a-T3b cancers.

CONCLUSIONS

The PCA3 score may combined with traditional tools aid in identifying men with clinically insignificant prostate cancer, as shown by biopsy and RP pathological features including biopsy Epstein criteria, who could be candidates for active surveillance. Treatment selection should be based on a combination of clinical and pathological variables. If one wants to use a threshold point to guide treatment decisions in clinical practice, a PCA3 score threshold of 20 may have the highest utility for selecting men with clinically insignificant prostate cancer in whom active surveillance may be appropriate; a PCA3 score threshold of 50 may be used to identify men at high risk of harbouring significant prostate cancer who are candidates for RP. Although the association between the PCA3 score and prostate cancer aggressiveness needs further evaluation, the inclusion of the PCA3 score into patient management strategies may provide clinicians with another tool to more accurately determine the course of treatment.

Clinical evaluation of the PCA3 assay in guiding initial biopsy decisions

PURPOSE

We evaluated the clinical utility of the PCA3 assay in guiding initial biopsy decisions in prostate cancer.

MATERIALS AND METHODS

A European, prospective, multicenter study enrolled men with a serum total prostate specific antigen of 2.5 to 10 ng/ml scheduled for initial biopsy. After digital rectal examination first catch urine was collected. PCA3 scores were determined using the PROGENSA(®) PCA3 assay and compared to biopsy outcome. The diagnostic accuracy of PCA3 was compared to total prostate specific antigen, prostate specific antigen density and %free prostate specific antigen.

RESULTS

In 516 men the positive biopsy rate was 40%. An increasing PCA3 score corresponded with an increasing probability of a positive biopsy. The mean PCA3 score was higher in men with a positive vs a negative biopsy (69.6 vs 31.0, median 50 vs 18, p <0.0001). The PCA3 score was independent of age, total prostate specific antigen and prostate volume. The PCA3 score (cutoff of 35) had a sensitivity of 64% and specificity of 76%. ROC analysis showed a significantly higher AUC for the PCA3 score vs total prostate specific antigen, prostate specific antigen density and %free prostate specific antigen. The PCA3 score was significantly higher in men with biopsy Gleason score 7 or greater vs less than 7, greater than 33% vs 33% or fewer positive cores and significant vs indolent prostate cancer. Inclusion of PCA3 in multivariable models increased their predictive accuracy by up to 5.5%.

CONCLUSIONS

The PROGENSA PCA3 assay can aid in guiding biopsy decisions. It is superior to total prostate specific antigen, prostate specific antigen density and %free prostate specific antigen in predicting initial biopsy outcome, and may be indicative of prostate cancer aggressiveness.

[MRI and prostatic cancer: measurements of kinetic perfusion parameters of gadolinium with a computerized-aided diagnostic tool (CAD)]

OBJECTIVES

To assess with a CAD in the peripheral (ZP) and transitional (ZT) zones the areas with modifications of the kinetic parameter Kep (ratio of exchanges between vascular compartment and extravascular extracellular spaces) in prostatic cancers with DCE MRI before radical prostatectomy.

METHODS

Forty-two consecutive patients (mean age 67 years, mean PSA: 8.9 ng/ml) with a prostatic cancer proved after a set of 12 biopsies underwent, before radical prostatectomy, a dynamic MRI (1.5T) with a surface coil after injection of gadolinium. We look with a CAD for foci of voxels with an abnormal Kep in ZP and/or in ZT. Foci of abnormal voxels computerized were compared with histological results of radical prostatectomies: prostates were shared in 12 sectors (six peripheral and six central) and a total of 504 sectors were studied. The links between prostatic capsule and foci of voxels with elevated Kep were systematically evaluated. The location and the local extension of the various cancerous foci were estimated. A comparison with the results of the T2W and T1 DCE MRI sequences without use of the CAD was made.

RESULTS

Eighty-eight percent of investigated patients revealed at least a cancerous focus associated with a group of pathological voxels. Hundred and seventy-eight of the 504 investigated prostatic sectors revealed a cancerous lesion after radical prostatectomy (RP) and 116 a focus of voxels with a pathological Kep being linked to 71 isolated lesions, some of them filling several sectors (47 peripheral and 24 transitional). The automatic research with the software of foci of voxels with a parameter Kep more than 2,2 per minute to detect a cancerous lesion had a sensitivity by sector less than the reading without CAD (69% in ZP and 58% in ZT against respectively, 85 and 66% (p<0.01) but seemed more specific: 98% in PZ and 95% in ZT against respectively, 80 and 82% (p<0.01). After RP, 16 cancers were classified Pt2, 10 Pt2R+ and 16 Pt3. The CAD had a better accuracy (74%) than T2W MRI (60%) to look for an extracapsular extension (EPE) or a risk of positive margins: 86% of extraprostatic extension and 60% of positive margins were near a focus of pathological voxels.

CONCLUSIONS

CAD allowed a computerized qualitative and quantitative study of DCE MRI. It identified and localized with a good specificity the significant foci. A focus of voxels with elevated Kep against the capsule increased significantly the risk of an extraprostatic extension or a positive margin after radical prostatectomy.

The Prostate Cancer gene 3 assay: indications for use in clinical practice

The Prostate CAncer gene 3 (PCA3) assay is a novel tool that might aid in the diagnosis of prostate cancer and that might indicate the significance of the disease. In this review we discuss five clinical cases in which the PCA3 assay can be considered, based on scientific evidence and key patient cases from real-life clinical practice. The PCA3 assay might be used to guide biopsy decisions in: (i) Men with an elevated serum total prostate specific antigen (tPSA) level and one or more previous negative biopsies; (ii) men with a normal tPSA level and a family history of prostate cancer; (iii) men with an elevated tPSA level (2.5-10 ng/mL) and no previous biopsy; (iv) men with an elevated tPSA level and a concomitant urinary condition. In addition, in men diagnosed with prostate cancer, the PCA3 assay could aid in the decision of whether active therapy is needed or active surveillance is appropriate.

The self-management of uncertainty among men undertaking active surveillance for low-risk prostate cancer

Asymptomatic men with low-risk, early-stage prostate cancer are eligible for active surveillance (AS), which offers a means to monitor the cancer while delaying treatment. However, AS operates within a unique set of circumstances that advocate monitoring, rather than immediate treatment, and men's health practices are central to coping with the inherent uncertainty of living with an untreated cancer. A qualitative study was completed to describe the range of men's self-management strategies used to overcome AS-related uncertainty. The study findings reveal two strategies. First, positioning prostate cancer as benign through stoicism and solitary discourses were common to men intent on "living a normal life." Second, men committed to "doing something extra" complemented AS protocols, and often collaborated with their wives to focus on diet as an adjunct therapy. Although most participants exhibited typical men's health practices, it is clear that tailored AS psychosocial interventions will benefit men and their families.

Development and External Validation of an Extended 10-Core Biopsy Nomogram

OBJECTIVES

To test the accuracy of a previously externally validated sextant biopsy nomogram in referred men exposed to > or =10 or more biopsy cores. Moreover, we explored the hypothesis that a more accurate predictive tool could be developed.

METHODS

Previous nomogram predictors (age, digital rectal examination, prostate-specific antigen, and percent free PSA) were used to assess the accuracy of our previous nomogram in a cohort consisting of 2900 men referred for prostatic evaluation. Moreover, these variables were complemented with sampling density (SD) (i.e., ratio of gland volume and the number of planned biopsy cores) within multivariable logistic regression models (LRM) predicting presence of prostate cancer (pCA) on the initial 10 or more core biopsy. The LRMs were used to develop and internally validate (200 bootstrap resamples) a new nomogram in 1162 men from Hamburg, Germany. The LRMs' external validity was tested in three separate cohorts (Hamburg, n=582; Milan, n=961; Seattle, n=195).

RESULTS

The contemporary external validation of the previously validated sextant nomogram demonstrated 70% accuracy. Internal validation of the new nomogram demonstrated 77% accuracy, and external cohorts demonstrated 73-76% accuracy.

CONCLUSIONS

In the era of extended biopsy schemes, previously developed predictive models are less accurate in predicting the probability of pCA on initial biopsy. We developed a new tool that allows obtaining more accurate predictions. Moreover, before biopsy, it also allows defining the ideal ratio between gland volume and the number of planned biopsy cores that would yield the ideal biopsy rate.