Serum free prostate specific antigen and prostate specific antigen density measurements for predicting cancer in men with prior negative prostatic biopsies

Predictive factors of prostate cancer diagnosis with PSA 4.0-10.0 ng/ml in a multi-ethnic Asian population, Malaysia

OBJECTIVES

To identify the associated factors determining prostate cancer detection using transrectal ultrasound (TRUS)-guided prostate biopsy, within a multi-ethnic Malaysian population with prostate specific antigen (PSA) between 4.0 and 10.0 ng/ml.

METHODS

Study subjects included men with initial PSA between 4.0 and 10.0 ng/ml that have undergone 12-core TRUS-guided prostate biopsy between 2009 and 2016. The prostate cancer detection rate was calculated, while potential factors associated with detection were investigated via univariable and multivariable analysis.

RESULTS

A total of 617 men from a multi-ethnic background encompassing Chinese (63.5%), Malay (23.1%) and Indian (13.3%) were studied. The overall cancer detection rate was 14.3% (88/617), which included cancers detected at biopsy 1 (first biopsy), biopsy 2 (second biopsy with previous negative biopsy) and biopsy ≥ 3 (third or more biopsies with prior negative biopsies). Indian men displayed higher detection rate (23.2%) and increased risk of prostate cancer development (OR 1.85, 95% CI 1.03-3.32, p < 0.05), compared to their Malay (9.8%) and Chinese (14.0%) counterparts. Multivariable analysis revealed that ethnicity and PSA density (PSAD) are independent factors associated with overall prostate cancer detection rate. A unit increase of PSAD reflected an increase in PSA after controlling for prostate volume.

CONCLUSION

Prostate cancer detection in Malaysia is comparatively lower. Our study suggests that ethnicity and PSA density should be considered when recommending first or repeat TRUS-guided prostate biopsy for prostate cancer detection in a multi-ethnic Malaysian population.

Impact of PSA density of transition zone as a potential parameter in reducing the number of unnecessary prostate biopsies in patients with psa levels between 2.6 and 10.0 ng/mL

Purpose:

To assess the accuracy of prostate-specific antigen (PSA) adjusted for the transition zone volume (PSATZ) in predicting prostate cancer by comparing the ability of several PSA parameters in predicting prostate cancer in men with intermediate PSA levels of 2.6 – 10.0 ng/mL and its ability to reduce unnecessary biopsies.

Materials and Methods:

This study included 656 patients referred for prostate biopsy who had a serum PSA of 2.6 – 10.0 ng/mL. Total prostate and transition zone volumes were measured by transrectal ultrasound using the prolate ellipsoid method. The clinical values of PSA, free-to-total (F/T) ratio, PSA density (PSAD) and PSATZ for the detection of prostate cancer were calculated and statistical comparisons between biopsy-positive (cancer) and biopsy-negative (benign) were conducted.

Results:

Cancer was detected in 172 patients (26.2%). Mean PSA, PSATZ, PSAD and F/T ratio were 7.5 ng/mL, 0.68 ng/mL/cc. 0.25 ng/mL/cc and 0.14 in patients with prostate cancer and 6.29 ng/mL, 0.30 ng/mL/cc, 0.16 ng/mL/cc and 0.22 in patients with benign biopsies, respectively. ROC curves analysis demonstrated that PSATZ had a higher area under curve (0,838) than F/T ratio (0.806) (P<0.001) and PSAD (0.806) (P<0.001). With a cut-off value of 0.22 ng/mL/cc, PSATZ had 100% of sensitivity and could have prevented 24% of unnecessary biopsies.

Conclusions:

PSATZ may be useful in enhancing the specificity of serum PSA. Compared to other PSA related parameters, it was better in differentiating between prostate cancer and benign prostatic enlargement. Also, PSATZ could reduce a significant number of unnecessary biopsies.

Re-examining Prostate-specific Antigen (PSA) Density: Defining the Optimal PSA Range and Patients for Using PSA Density to Predict Prostate Cancer Using Extended Template Biopsy

OBJECTIVE

To compare the predictive accuracy of prostate-specific antigen (PSA) density vs PSA across different PSA ranges and by prior biopsy status in a prospective cohort undergoing prostate biopsy.

MATERIALS AND METHODS

Men from a prospective trial underwent an extended template biopsy to evaluate for prostate cancer at 26 sites throughout the United States. The area under the receiver operating curve assessed the predictive accuracy of PSA density vs PSA across 3 PSA ranges (<4 ng/mL, 4-10 ng/mL, >10 ng/mL). We also investigated the effect of varying the PSA density cutoffs on the detection of cancer and assessed the performance of PSA density vs PSA in men with or without a prior negative biopsy.

RESULTS

Among 1290 patients, 585 (45%) and 284 (22%) men had prostate cancer and significant prostate cancer, respectively. PSA density performed better than PSA in detecting any prostate cancer within a PSA of 4-10 ng/mL (area under the receiver operating characteristic curve [AUC]: 0.70 vs 0.53, P < .0001) and within a PSA >10 mg/mL (AUC: 0.84 vs 0.65, P < .0001). PSA density was significantly more predictive than PSA in detecting any prostate cancer in men without (AUC: 0.73 vs 0.67, P < .0001) and with (AUC: 0.69 vs 0.55, P < .0001) a previous biopsy; however, the incremental difference in AUC was higher among men with a previous negative biopsy. Similar inferences were seen for significant cancer across all analyses.

CONCLUSION

As PSA increases, PSA density becomes a better marker for predicting prostate cancer compared with PSA alone. Additionally, PSA density performed better than PSA in men with a prior negative biopsy.

Neutrophil gelatinase-associated lipocalin as a screening test in prostate cancer

OBJECTIVE

Prostate specific antigen (PSA) with digital rectal examination is used for diagnosis of prostate cancer (PCa), where definite diagnosis can only be made by prostate biopsy. Recently neutrophil gelatinase-associated lipocalin (NGAL), a lipocalin family member glycoprotein, come into prominence as a cancer biomarker. This study is aimed to test serum NGAL as a diagnostic biomarker for PCa and discriminate PCa from benign prostatic hyperplasia (BPH).

MATERIAL AND METHODS

In this prospective study, 90 patients who underwent transrectal ultrasound-guided 12-core prostate biopsy between May 2015 and September 2015, were evaluated. Histopathologically diagnosed 45 PCa and 45 BPH patients were enrolled in this study. Serum NGAL and PSA levels of all participants were measured, then these data were evaluated by statistical programs.

RESULTS

When sensitivity fixed to 80% specificity of NGAL was better than PSA (49%, 31% respectively). Receiver operating characteristic (ROC) curve analysis showed that NGAL alone or its combined use with PSA have better area under curve (AUC) results than PSA alone (0.662, 0.693, and 0.623 respectively).

CONCLUSION

In conclusion NGAL gave promising results such as increased sensitivity and a better AUC values in order to distinguish PCa from BPH. NGAL showed a potential to be a non-invasive biomarker which may decrease the number of unnecessary biopsies.

PSA, PSA derivatives, proPSA and prostate health index in the diagnosis of prostate cancer

Currently, prostate- specific antigen (PSA) is the most common oncological marker used for prostate cancer screening. However, high levels of PSA in benign prostatic hyperplasia and prostatitis decrease the specificity of PSA as a cancer marker. To increase the specificity of PSA, PSA derivatives and PSA kinetics have been used. However, these new techniques were not able to increase the diagnostic specificity for prostate cancer. Therefore, the search for new molecules and derivatives of PSA continues. With the aim of increasing the specificity of prostate cancer diagnosis, proPSA and the Prostate Health Index have been introduced. In this review, the roles of PSA, PSA derivatives, proPSA and the Prostate Health Index in Prostate Cancer diagnosis are examined.

Activation profiles of human kallikrein-related peptidases by matrix metalloproteinases

The 15 human kallikrein-related peptidases (KLKs) are clinically important biomarkers and therapeutic targets of interest in inflammation, cancer, and neurodegenerative disease. KLKs are secreted as inactive pro-forms (pro-KLKs) that are activated extracellularly by specific proteolytic release of their amino-terminal pro-peptide, and this is a key step in their functional regulation. Physiologically relevant KLK regulatory cascades of activation have been described in skin desquamation and semen liquefaction, and work by a large number of investigators has elucidated pairwise and autolytic activation relationships among the KLKs with the potential for more extensive activation cascades. More recent work has asked whether functional intersection of KLKs with other types of regulatory proteases exists. Such studies show a capacity for members of the thrombostasis axis to act as broad activators of pro-KLKs. In the present report, we ask whether such functional intersection is possible between the KLKs and the members of the matrix metalloproteinase (MMP) family by evaluating the ability of the MMPs to activate pro-KLKs. The results identify MMP-20 as a broad activator of pro-KLKs, suggesting the potential for intersection of the KLK and MMP axes under pathological dysregulation of MMP-20 expression.

Circulating nucleic acids as biomarkers of prostate cancer

Prostate cancer, the most common cancer of western men, requires new biomarkers, especially given that the benefits of PSA testing remain uncertain. Nucleic acids can now be accurately and sensitively detected in human blood. Over the last decade, investigations into utility of circulating cell-free miRNA, DNA and mRNA as novel biomarkers have expanded exponentially. In the near future, they may be routinely used to accurately diagnose cancers, stratify indolent from aggressive disease and inform treatment decisions. However, advancement of such tests into clinical settings is hampered by technical problems with assay specificity and sensitivity, and small study sizes. This review highlights the different forms of circulating nucleic acids and those that show the most potential as viable biomarkers for prostate cancer.

The cutoff level of free/total prostate specific antigen (f/t PSA) ratios in the diagnosis of prostate cancer: a validation study on a Turkish patient population in different age categories

We investigated an optimal cutoff level of free/total PSA ratios (f/t PSA) in predicting prostate cancer in different age groups, focusing on the avoidance of unnecessary prostate biopsies. A total of 4955 men were enrolled into the study. Serum tPSA, fPSA, and f/t PSA ratios were determined for the study population. All males who had suspicious digital rectal examination and tPSA > 4 ng/mL underwent transrectal ultrasonography-guided prostate biopsy. Receiver operating characteristic (ROC) curves for each group were generated by plotting the sensitivity versus 1-specificity for the f/t PSA ratio. The sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were obtained using various f/t PSA ratio cutoffs for different age groups. There were 657 patients with a PSA level of 4-10 ng/mL. According to sensitivity and specificity f/t% PSA cutoff points were determined to be 10%, 15%, 15%, and 10% in 50-59 years, 60-69 years, >70 years, and all ages categories, respectively, in patients with initial PSA level of 4-10 ng/mL. f/t PSA ratio had an area under the curve (AUC) value of 0.81 (95% confidence level: 0.80-0.82) for all age groups in detecting prostate cancer. f/t PSA ratio has an AUC value of 0.669 (0.632-0.705) in detecting prostate cancer among patients with a PSA level of 4-10 ng/mL. Ten percent of f/t PSA ratio had the highest specificity with PLR and 30% f/t PSA ratio had the highest sensitivity with lower NLR in the all-age categories. The current study shows that the use of f/t PSA ratio in patients with PSA levels of 4-10 ng/mL should enhance the specificity of PSA screening and decrease the number of unnecessary biopsies. The age-related changes warrant further investigation in a large, multicentric, and multinational population to improve the clinical use of f/t PSA cutoffs.

Quantitative iodine-based material decomposition images with spectral CT imaging for differentiating prostatic carcinoma from benign prostatic hyperplasia

RATIONALE AND OBJECTIVES

To investigate the value of iodine-based material decomposition images produced via spectral computed tomography (CT) in differentiating prostate cancer (PCa) from benign prostate hyperplasia (BPH).

MATERIALS AND METHODS

Fifty-six male patients underwent CT examination with spectral imaging during arterial phase (AP), venous phase (VP), and parenchymal phase (PP) of enhancement. Iodine concentrations of lesions were measured and normalized to that of the obturator internus muscle. Lesion CT values at 75 keV (corresponding to the energy of polychromatic images at 120 kVp) were measured and also normalized; their differences between AP and VP, VP and PP, and PP and AP were also obtained. The two-sample t-test was performed for comparisons. A receiver operating characteristic curve was generated to establish the threshold for normalized iodine concentration (NIC).

RESULTS

Fifty-two peripheral lesions were found, which were confirmed by biopsy as 28 cases of PCa and 24 BPHs. The NICs of prostate cancers significantly differed from those of the BPHs: 2.38 ± 1.72 compared with 1.21 ± 0.72 in AP, respectively, and 2.67 ± 0.61 compared with 2.27 ± 0.77 in VP. Receiver operating characteristic analysis indicated that an NIC of 1.24 in the AP provided a sensitivity of 88% and a specificity of 71% for differentiating PCa from BPH.

CONCLUSIONS

Spectral CT imaging enabled quantitative depiction of contrast medium uptake in prostatic lesions and improved sensitivity and specificity for differentiating PCa from BPH.

A comparative performance analysis of total prostate-specific antigen, percentage free prostate-specific antigen, prostate-specific antigen velocity and urinary prostate cancer gene 3 in the first, second and third repeat prostate biopsy

Study Type - Diagnosis (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? Risk factor assessment in the repeat biopsy setting is affected by a decreasing diagnostic accuracy of each single risk factor (e.g. DRE, tPSA, %fPSA, complexed PSA, PSA density or PSAV] with increasing number of prostate biopsy sessions. PCA3 shows impressive diagnostic performance in the initial and early repeat biopsy settings. In a head-to-head comparison we demonstrate the concept that the number of previous repeat biopsy session strongly influences performance characteristics of biopsy risk factors, including PCA3. While the novel diagnostic marker would have avoided a considerable number of unnecessary biopsies in the first repeat biopsy scenario, its effects dissipated at second and ≥ third repeat biopsies.

OBJECTIVE

To compare the performance characteristics of prostate cancer risk factors such as total prostate-specific antigen (tPSA), percentage free PSA (%fPSA), PSA velocity (PSAV) and urinary prostate cancer gene 3 (PCA3) at first, second and ≥ third repeat biopsy session.

PATIENTS AND METHODS

Patients (n= 127) aged ≤70 years, with suspicious digital rectal examination (DRE) and/or persistently elevated age-specific total PSA levels (2.5-6.5 ng/mL) and/or suspicious prior histology (atypical small acinar proliferations [ASAPs]≥ two cores affected by high-grade prostatic intra-epithelial neoplasia [HGPIN]) undergoing either a first, second, or ≥ third repeat biopsy were investigated using a 12- or 24-core biopsy scheme. PSAV (≥ three values collected over ≥12 months) was calculated using the log-slope method. PCA3 scores were assessed using the Progensa assay®. After stratification according to the number of previous biopsies (first, second and ≥ third), calculation of specificity, positive and negative predictive values (PPV, NPV) and the proportion of avoided unnecessary repeat biopsies (PAB) compared with tPSA at fixed sensitivity thresholds (75, 85 and 95%) were performed. Finally, accuracy estimates (area under the curve [AUC]) were quantified for each repeat biopsy scenario.

RESULTS

At repeat biopsy, overall prostate cancer (PCa) detection was 34.6%. At first repeat biopsy, PCA3 predicted PCa best (AUC = 0.80) and would have avoided 72.2% of repeat biopsies (75% sensitivity) compared with tPSA. At second repeat biopsy, %fPSA demonstrated the highest accuracy (AUC = 0.82) and would have avoided 66.7% of repeat biopsies (75% sensitivity) compared with tPSA. At ≥ third repeat biopsy, again %fPSA demonstrated the highest accuracy (AUC = 0.70) and would have avoided 45.0% of repeat biopsies (75% sensitivity) compared with tPSA. The main limitation of our study resides in its small sample size.

CONCLUSIONS

The findings of the present study promote the concept that the number of previous repeat biopsy sessions strongly influences the performance characteristics of biopsy risk factors. Total PSA was no significant risk factor in the entire analysis. By contrast, %fPSA performed best at second and ≥ third repeat biopsy. PSAV's diagnostic potential was reserved to patients at second and ≥ third repeat biopsy. Finally, PCA3 demonstrated the highest diagnostic accuracy and potential to reduce unnecessary biopsies at first repeat biopsy. However, this advantage dissipated at second and ≥ third repeat biopsy.

Utility of percent free prostate-specific antigen in repeat prostate biopsy

OBJECTIVES

To assess the utility of the percent free prostate-specific antigen (%fPSA) for the prediction of prostate cancer in men undergoing repeat biopsy.

METHODS

A retrospective review was performed of 1037 patients in an institutional review board-approved repeat prostate biopsy database. A total of 617 patients who underwent 683 biopsies had all their data available for analysis. The patients were categorized as having undergone 1 repeat biopsy or >1 repeat biopsy.

RESULTS

The overall cancer detection rate was 27% and 22% in men who underwent 1 and >1 repeat biopsy, respectively. The area under the receiver operating characteristic curve for the %fPSA was 0.65 for men who underwent 1 repeat biopsy. Multivariate analysis demonstrated that a positive family history, decreasing %fPSA, and presence of high-grade intraepithelial neoplasia and/or atypical small acinar proliferation predicted for cancer. The univariate odds ratio for every 5% decrease in the %fPSA was 1.5 (95% confidence interval 1.2-1.7). The performance of %fPSA was further improved in men who underwent >1 repeat biopsy, with an area under the curve of 0.72. In men who underwent >1 repeat biopsy, multivariate analysis showed that a decreasing %fPSA, >20 cores removed, and high-grade intraepithelial neoplasia predicted for cancer. The univariate odds ratio for every 5% decrease in the %fPSA was 1.8 (95% confidence interval 1.4-2.3). A %fPSA cutoff of 10% achieved 90% and 91% specificity in the 1 repeat biopsy and >1 repeat biopsy groups, respectively.

CONCLUSIONS

%fPSA is useful in predicting for prostate cancer in the repeat biopsy population, particularly for those who have undergone multiple repeat biopsies. A persistently low %fPSA should prompt additional investigation in these men.

A four-kallikrein panel for the prediction of repeat prostate biopsy: data from the European Randomized Study of Prostate Cancer screening in Rotterdam, Netherlands

Background:

Most men with elevated levels of prostate-specific antigen (PSA) do not have prostate cancer, leading to a large number of unnecessary biopsies. A statistical model based on a panel of four kallikreins has been shown to predict the outcome of a first prostate biopsy. In this study, we apply the model to an independent data set of men with previous negative biopsy but persistently elevated PSA.

Methods:

The study cohort consisted of 925 men with a previous negative prostate biopsy and elevated PSA (⩾3 ng ml⁻¹), with 110 prostate cancers detected (12%). A previously published statistical model was applied, with recalibration to reflect the lower positive biopsy rates on rebiopsy.

Results:

The full-kallikrein panel had higher discriminative accuracy than PSA and DRE alone, with area under the curve (AUC) improving from 0.58 (95% confidence interval (CI): 0.52, 0.64) to 0.68 (95% CI: 0.62, 0.74), P<0.001, and high-grade cancer (Gleason ⩾7) at biopsy with AUC improving from 0.76 (95% CI: 0.64, 0.89) to 0.87 (95% CI: 0.81, 0.94), P=0.003). Application of the panel to 1000 men with persistently elevated PSA after initial negative biopsy, at a 15% risk threshold would reduce the number of biopsies by 712; would miss (or delay) the diagnosis of 53 cancers, of which only 3 would be Gleason 7 and the rest Gleason 6 or less.

Conclusions:

Our data constitute an external validation of a previously published model. The four-kallikrein panel predicts the result of repeat prostate biopsy in men with elevated PSA while dramatically decreasing unnecessary biopsies.

Risk factors for prostate cancer detection after a negative biopsy: a novel multivariable longitudinal approach

PURPOSE

To introduce a novel approach for the time-dependent quantification of risk factors for prostate cancer (PCa) detection after an initial negative biopsy.

PATIENTS AND METHODS

Data for 1,871 men with initial negative biopsies and at least one follow-up biopsy were available. Piecewise exponential regression models were developed to quantify hazard ratios (HRs) and define cumulative incidence curves for PCa detection for subgroups with specific patterns of risk factors over time. Factors evaluated included age, race, serum prostate-specific antigen (PSA) concentration, PSA slope, digital rectal examination, dysplastic glands or prostatitis on biopsy, ultrasound gland volume, urinary symptoms, and number of negative biopsies.

RESULTS

Four hundred sixty-five men had PCa detected, after a mean follow-up time of 2.8 years. All of the factors were independent predictors of PCa detection except for PSA slope, as a result of its correlation with time-dependent PSA level, and race. PSA (HR = 3.90 for > 10 v 2.5 to 3.9 ng/mL), high-grade prostatic intraepithelial neoplasia/atypical glands (HR = 2.97), gland volume (HR = 0.39 for > 50 v < 25 mL), and number of repeat biopsies (HR = 0.36 for two v zero repeat biopsies) were the strongest predictors. Men with high-risk versus low-risk event histories had a 20-fold difference in PCa detection over 5 years.

CONCLUSION

Piecewise exponential models provide an approach to longitudinal analysis of PCa risk that allows clinicians to see the interplay of risk factors as they unfold over time for individual patients. With these models, it is possible to identify distinct subpopulations with dramatically different needs for monitoring and repeat biopsy.

A completed KLK activome profile: investigation of activation profiles of KLK9, 10, and 15

We previously reported the activation profiles of the human kallikrein-related peptidases (KLKs) as determined from a KLK pro-peptide fusion-protein system. That report described the activity profiles of 12 of the 15 mature KLKs versus the 15 different pro-KLK sequences. The missing profiles in the prior report, involving KLK9, 10, and 15, are now described. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mass spectrometry, and N-terminal sequence analyses show that KLK9 and 10 exhibit low hydrolytic activities towards all of the 15 pro-KLK sequences, while KLK15 exhibits significant activity towards both Arg- and Lys-containing KLK pro-sequences. The ability of KLK15 to activate pro-KLK8, 12, and 14 is confirmed using recombinant pro-KLK proteins, and shown to be significant for activation of pro-KLK8 and 14, but not 12. These additional data for KLK9, 10, and 15 now permit a completed KLK activome profile, using a KLK pro-peptide fusion-protein system, to be described. The results suggest that KLK15, once activated, can potentially feed back into additional pro-KLK activation pathways. Conversely, KLK9 and 10, once activated, are unlikely to participate in further pro-KLK activation pathways, although similar to KLK1 they may activate other bioactive peptides.

Utility of a 3-Dimensional Transrectal Ultrasound-guided Prostate Biopsy System for Prostate Cancer Detection

The 3-D transrectal ultrasound (TRUS)-guided prostate biopsy system is a novel device that allows precise needle placement in a template fashion. We evaluate its utility for prostate cancer (PCa) detection. A retrospective analysis was performed evaluating 68 prospective patients at the Duke Prostate Center who underwent a prostate biopsy using a 3-D TRUS-guided system. After creation of a three-dimensional map of the prostate, a computer algorithm identified an ideal biopsy scheme based on the measured dimensions of the prostate. The system then used a fixed template that allowed prostate biopsy at specific locations with the ability to target the same region of the prostate in the future if needed. For all patients, a 12-core biopsy pattern was used to cover medial and lateral areas of the base, mid-gland, and apex. In total, 68 patients underwent 3-D TRUS-guided prostate biopsies between April 2006 and November 2007 for prostate cancer detection. The indication for prostate biopsy was PSA ≥ 4.0 ng/ml in 47 (69%) patients, abnormal digital rectal examination (DRE) in 17 (25%), and atypia on previous biopsy in 4 (6%) patients. Prostate cancer was detected in 18 patients (26.5%) and 7 (10.3%) had atypical small acinar proliferation (ASAP). The highest frequency (55.5%) from all cases of cancer detected was identified when 3-D TRUS biopsy was used as the initial biopsy. This study demonstrates that a 3-D TRUS-guided biopsy system translates to a more frequent detection of prostate cancer among patients undergoing an initial prostate biopsy than a subsequent one. More comprehensive studies are warranted to corroborate and extend the results of this study.

Practical approaches to proteomic biomarkers within prostate cancer radiotherapy trials

INTRODUCTION

Proteomic biomarkers may be useful for monitoring therapeutic response and to triage cancer patients to best therapy.

OBJECTIVES

In this review, we highlight the importance of specimen acquisition, preparation and analysis in radiotherapy proteomic studies. We also discuss practical approaches for the design and execution of clinical proteomic studies using our recent experience based on specimens accrued during prostate cancer radiation therapy.

DISCUSSION AND CONCLUSIONS

Numerous proteomic methods are being employed, including high-throughput mass spectrometry and immunoassays, and using solid tissues, blood and urine for analysis. Given the potential complexity of cytokine and other protein responses, there is a need to assess proteomic signatures within serial samples as longitudinal studies during a course of fractionated radiotherapy (RT).

Activation profiles of human kallikrein-related peptidases by proteases of the thrombostasis axis

The human kallikrein-related peptidases (KLKs) comprise 15 members (KLK1-15) and are the single largest family of serine proteases. The KLKs are utilized, or proposed, as clinically important biomarkers and therapeutic targets of interest in cancer and neurodegenerative disease. All KLKs appear to be secreted as inactive pro-forms (pro-KLKs) that are activated extracellularly by specific proteolytic release of their N-terminal pro-peptide. This processing is a key step in the regulation of KLK function. Much recent work has been devoted to elucidating the potential for activation cascades between members of the KLK family, with physiologically relevant KLK regulatory cascades now described in skin desquamation and semen liquefaction. Despite this expanding knowledge of KLK regulation, details regarding the potential for functional intersection of KLKs with other regulatory proteases are essentially unknown. To elucidate such interaction potential, we have characterized the ability of proteases associated with thrombostasis to hydrolyze the pro-peptide sequences of the KLK family using a previously described pro-KLK fusion protein system. A subset of positive hydrolysis results were subsequently quantified with proteolytic assays using intact recombinant pro-KLK proteins. Pro-KLK6 and 14 can be activated by both plasmin and uPA, with plasmin being the best activator of pro-KLK6 identified to date. Pro-KLK11 and 12 can be activated by a broad-spectrum of thrombostasis proteases, with thrombin exhibiting a high degree of selectivity for pro-KLK12. The results show that proteases of the thrombostasis family can efficiently activate specific pro-KLKs, demonstrating the potential for important regulatory interactions between these two major protease families.

A panel of kallikrein markers can reduce unnecessary biopsy for prostate cancer: data from the European Randomized Study of Prostate Cancer Screening in Göteborg, Sweden

BACKGROUND

Prostate-specific antigen (PSA) is widely used to detect prostate cancer. The low positive predictive value of elevated PSA results in large numbers of unnecessary prostate biopsies. We set out to determine whether a multivariable model including four kallikrein forms (total, free, and intact PSA, and human kallikrein 2 (hK2)) could predict prostate biopsy outcome in previously unscreened men with elevated total PSA.

METHODS

The study cohort comprised 740 men in Göteborg, Sweden, undergoing biopsy during the first round of the European Randomized study of Screening for Prostate Cancer. We calculated the area-under-the-curve (AUC) for predicting prostate cancer at biopsy. AUCs for a model including age and PSA (the 'laboratory' model) and age, PSA and digital rectal exam (the 'clinical' model) were compared with those for models that also included additional kallikreins.

RESULTS

Addition of free and intact PSA and hK2 improved AUC from 0.68 to 0.83 and from 0.72 to 0.84, for the laboratory and clinical models respectively. Using a 20% risk of prostate cancer as the threshold for biopsy would have reduced the number of biopsies by 424 (57%) and missed only 31 out of 152 low-grade and 3 out of 40 high-grade cancers.

CONCLUSION

Multiple kallikrein forms measured in blood can predict the result of biopsy in previously unscreened men with elevated PSA. A multivariable model can determine which men should be advised to undergo biopsy and which might be advised to continue screening, but defer biopsy until there was stronger evidence of malignancy.

Values for free/total prostate-specific antigen ratio as a function of age: necessity of reference validation in a Turkish population

BACKGROUND

The aim of this study was to evaluate age-related changes in free/total prostate-specific antigen (f/t PSA) ratio, focusing on the avoidance of unnecessary prostate biopsies.

METHODS

A total of 898 men aged 30-88 years without a history of prostate surgery and disease were enrolled into the study. Serum tPSA, fPSA and f/t PSA ratios were determined for the study population and for different age categories. All males who had suspicious digital rectal examination and tPSA >4 ng/mL underwent transrectal ultrasonography-guided prostate biopsy. Receiver operating characteristic (ROC) curves for each group were generated by plotting the sensitivity vs. 1-specificity for the f/t PSA ratio. The sensitivity and specificity were obtained using different f/t PSA ratio cutoffs for different age groups.

RESULTS

Prostate cancer was detected in 63 patients (7%). Age-specific cutoffs were determined according to likelihood ratios at the levels of 10%, 15% and 15% f/t PSA ratio for ages 50-59, 60-69 and >/=70 years, respectively. However, a single cutoff of 10% is recommended across all age ranges (positive likelihood ratio 2.36). ROC curves demonstrated that the area under the curve (AUC) was significant for all patients with initial PSA of 4-10 ng/mL (AUC 0.703-0.796), except for the >/=70-year age group (AUC 0.549).

CONCLUSIONS

The current study showed that the use of f/t PSA ratio in patients with PSA levels of 4-10 ng/mL should enhance the specificity of PSA screening and decrease the number of unnecessary biopsies. f/t PSA levels may show dissimilarities according to age and ethnicity, so further studies are warranted to identify this relationship.

Activation profiles and regulatory cascades of the human kallikrein-related peptidases

The human kallikrein (KLK)-related peptidases are the largest family of serine peptidases, comprising 15 members (KLK1-15) and with the majority (KLK4-15) being identified only within the last decade. Members of this family are associated with important diseased states (including cancer, inflammation, and neurodegeneration) and have been utilized or proposed as clinically important biomarkers or therapeutic targets of interest. All human KLKs are synthesized as prepro-forms that are proteolytically processed to secreted pro-forms via the removal of an amino-terminal secretion signal peptide. The secreted inactive pro-KLKs are then activated extracellularly to mature peptidases by specific proteolytic release of their amino-terminal propeptide. Although a key step in the regulation of KLK function, details regarding the activation of the human pro-KLKs (i.e. the KLK "activome") are unknown, to a significant extent, but have been postulated to involve "activation cascades" with other KLKs and endopeptidases. To characterize more completely the KLK activome, we have expressed from Escherichia coli individual KLK propeptides fused to the amino terminus of a soluble carrier protein. The ability of 12 different mature KLKs to process the 15 different pro-KLK peptide sequences has been determined. Various autolytic and cross-activation relationships identified using this system have subsequently been characterized using recombinant pro-KLK proteins. The results demonstrate the potential for extensive KLK activation cascades and, when combined with available data for the tissue-specific expression of the KLK family, permit the construction of specific regulatory cascades. One such tissue-specific cascade is proposed for the central nervous system.

Influence of prostate volume and percent free prostate specific antigen on prostate cancer detection in men with a total prostate specific antigen of 2.6 to 10.0 ng/ml

PURPOSE

Percent free prostate specific antigen and prostate specific antigen density have been independently shown to increase the specificity of prostate cancer screening in men with prostate specific antigen levels between 4.1 and 10.0 ng/ml. Recent data suggest the total prostate specific antigen cutoff for performing a biopsy should be 2.6 ng/ml. We assessed the influence of percent free prostate specific antigen and prostate volume on cancer detection in men with a prostate specific antigen between 2.6 and 10.0 ng/ml.

MATERIALS AND METHODS

From 1991 to 2005 all transrectal ultrasound guided prostate biopsies (5,587) for abnormal digital rectal examination and/or increased age specific prostate specific antigen were evaluated. A total of 1,072 patients with a prostate specific antigen between 2.6 and 10.0 ng/ml and any percent free prostate specific antigen were included in study. The cancer detection rate was calculated for each percent free prostate specific antigen/volume stratum.

RESULTS

Prostate cancer was detected in 296 patients (27.6%). The mean age and prostate specific antigen of the patients with benign pathology and prostate cancer were similar. Mean percent free prostate specific antigen was 17.5% and 14.1% (p>0.05), and the mean volume was 62.0 and 46.0 cc (p=0.001), respectively. The strongest risk factors for a positive biopsy were percent free prostate specific antigen (odds ratio 0.004, p<0.001), volume (OR 0.977, p<0.001) and digital rectal examination (OR 1.765, p=0.007), but not total prostate specific antigen (p=0.303). When stratified by volume and percent free prostate specific antigen, distinct risk groups were identified. The probability of detecting cancer inversely correlated with prostate volume and percent free prostate specific antigen.

CONCLUSIONS

In men with prostate specific antigen levels between 2.6 and 10.0 ng/ml, the probability of detecting cancer was inversely proportional to prostate volume and percent free prostate specific antigen. This table may assist in predicting patient risk for harboring prostate cancer.

Spectral clustering for TRUS images

Background

Identifying the location and the volume of the prostate is important for ultrasound-guided prostate brachytherapy. Prostate volume is also important for prostate cancer diagnosis. Manual outlining of the prostate border is able to determine the prostate volume accurately, however, it is time consuming and tedious. Therefore, a number of investigations have been devoted to designing algorithms that are suitable for segmenting the prostate boundary in ultrasound images. The most popular method is the deformable model (snakes), a method that involves designing an energy function and then optimizing this function. The snakes algorithm usually requires either an initial contour or some points on the prostate boundary to be estimated close enough to the original boundary which is considered a drawback to this powerful method.

Methods

The proposed spectral clustering segmentation algorithm is built on a totally different foundation that doesn't involve any function design or optimization. It also doesn't need any contour or any points on the boundary to be estimated. The proposed algorithm depends mainly on graph theory techniques.

Results

Spectral clustering is used in this paper for both prostate gland segmentation from the background and internal gland segmentation. The obtained segmented images were compared to the expert radiologist segmented images. The proposed algorithm obtained excellent gland segmentation results with 93% average overlap areas. It is also able to internally segment the gland where the segmentation showed consistency with the cancerous regions identified by the expert radiologist.

Conclusion

The proposed spectral clustering segmentation algorithm obtained fast excellent estimates that can give rough prostate volume and location as well as internal gland segmentation without any user interaction.

Circulating biomarkers for prostate cancer

Due to its significant applicability for early detection, risk prediction and follow-up evaluation, prostate specific antigen (PSA) has revolutionized our ability to treat prostate cancer patients. With the prevalent use of PSA for early detection during the last two decades, disease characteristics have been altered towards early detected, localized tumors with a high chance of cure following local therapy. This advantage faces the risk of overdetection and overtreatment. In addition, PSA lacks both, sensitivity and specificity to accurately detect patients at risk of prostate cancer. Therefore, novel biomarkers are urgently needed to improve identification of men at risk of having the disease and to predict the natural behaviour of the tumor. Recent advances in the evaluation of high-throughput technologies have led to the discovery of novel candidate markers for prostate cancer. This article will briefly discuss current PSA-based strategies and review several novel biomarkers for prostate cancer, detectable in blood.

Prostate-specific antigen adjusted for the transition zone volume as a second screening test: a prospective study of 248 cases

AIM

This study was conducted to verify the effectiveness of prostate-specific antigen adjusted for the transition zone volume (PSATZ), and its availability as a second screening test for prostate cancer detection.

MATERIALS AND METHODS

Total prostate-specific antigen (PSA) and free PSA was measured in male patients who visited our outpatient department for voiding difficulty or screening for prostate cancer. Patients who had an intermediate PSA level between 4.0 and 10.0 ng/mL, with an apparently normal prostate on a digital rectal examination, were enrolled. PSATZ, free-to-total PSA ratio (F/T ratio) and PSA density (PSAD) were calculated and statistical comparisons between biopsy-positive (cancer) and biopsy-negative patients (benign) were conducted.

RESULTS

Of 248 patients, 51 (20.6%) had prostate cancer and 197 (79.4%) had benign prostatic hyperplasia (BPH) on pathologic examination. Mean PSA, PSAD, F/T ratio and PSATZ were 7.48 +/- 1.77 ng/mL, 0.23 +/- 0.09 ng/mL per mL, 0.14 +/- 0.08 and 0.71 +/- 0.44 ng/mL per mL in patients with prostate cancer and 6.59 +/- 1.60 ng/mL, 0.16 +/- 0.07 ng/mL per mL, 0.21 +/- 0.11 and 0.36 +/- 0.30 ng/mL per mL in patients with benign, respectively. Receiver operating characteristics (ROC) curve analysis demonstrated that PSATZ predicted the biopsy outcome better than F/T ratio. With a cut-off value of 0.37 ng/mL per mL, PSATZ had a sensitivity of 74.5% and a specificity of 72.6% for predicting prostate cancer. The maximal cut-off value that preserves 100% of sensitivity was 0.2, and at this cut-off value, 16.1% of unnecessary biopsies could be reduced.

CONCLUSIONS

Prostate-specific antigen adjusted for the transition zone volume may be more useful than other strategies in detecting prostate cancer in patients with intermediate PSA levels of 4.0-10.0 ng/mL. It can be used as a second screening test to reduce unnecessary biopsy.

Cloning and sequencing of the cynomolgus monkey prostate specific antigen cDNA

BACKGROUND

Prostate-specific antigen (PSA) is an invaluable tumor marker for the detection of early prostate cancer, and can be a target for active immunotherapy of prostate cancer. We wanted to assess the usefulness of the cynomolgus monkey (Macaca fascicularis) as a relevant animal model to evaluate PSA-specific therapies.

METHODS

RNA was isolated from the prostate of cynomolgus monkeys, and PSA gene products were amplified by reverse transcriptase-polymerase chain reaction using primers from conserved regions of human and rhesus monkey (Macaca mulatta) PSA genes. These amplified products were then sequenced.

RESULTS

The cynomolgus PSA amino acid sequence is 89.7% identical to the human PSA gene, and 99.2% identical to the rhesus PSA amino acid sequence. Like the human and rhesus PSA genes, an open-reading frame of 261 amino acids was identified for the cynomolgus gene. Expression of the cynomolgus PSA gene appears to be restricted to the prostate, as it is in humans.

CONCLUSIONS

The high identity between human and cynomolgus PSA sequences suggests that the cynomolgus monkey should be studied further for its potential as a large animal model to evaluate PSA-specific therapies.

Prostate needle biopsies containing prostatic intraepithelial neoplasia or atypical foci suspicious for carcinoma: implications for patient care

PURPOSE

We identified information critical for patient treatment on prostate needle biopsies diagnosed with prostatic intraepithelial neoplasia or atypical foci suspicious for carcinoma.

MATERIALS AND METHODS

A search was performed using the MEDLINE database and referenced lists of relevant studies to obtain articles addressing the significance of finding PIN or atypical foci suspicious for carcinoma on needle biopsy.

RESULTS

There were certain results concerning PIN. 1) Low grade PIN should not be documented in pathology reports due to poor interobserver reproducibility and a relatively low risk of cancer following re-biopsy. 2) The expected incidence of HGPIN on needle biopsy is between 5% and 8%. 3) Although the diagnosis of HGPIN is subjective, interobserver reproducibility for its diagnosis is fairly high among urological pathologists, and yet only moderate among pathologists without special expertise in prostate pathology. 4) The median risk recorded in the literature for cancer following the diagnosis of HGPIN on needle biopsy is 24.1%, which is not much higher than the risk reported in the literature for repeat biopsy following a benign diagnosis. 5) The majority of publications that compared the risk of cancer in the same study following a needle biopsy diagnosis of HGPIN to the risk of cancer following a benign diagnosis on needle biopsy show no differences between the 2 groups. 6) Clinical and pathological parameters do not help stratify which men with HGPIN are at increased risk for a cancer diagnosis. 7) A major factor contributing to the decreased incidence of cancer following a diagnosis of HGPIN on needle biopsy in the contemporary era is related to increased needle biopsy core sampling, which detects many associated cancers on initial biopsy, such that re-biopsy, even with good sampling, does not detect many additional cancers. 8) It is recommended that men do not need routine repeat needle biopsy within the first year following the diagnosis of HGPIN, while further studies are needed to confirm whether routine repeat biopsies should be performed several years following a HGPIN diagnosis on needle biopsy. There were certain results concerning atypical glands suspicious for carcinoma. 1) An average of 5% of needle biopsy pathology reports are diagnosed as atypical glands suspicious for carcinoma. 2) Cases diagnosed as atypical have the highest likelihood of being changed upon expert review and urologists should consider sending such cases for consultation in an attempt to resolve the diagnosis as definitively benign or malignant before subjecting the patient to repeat biopsy. 3) Ancillary techniques using basal cell markers and AMACR (alpha-methyl-acyl-coenzyme A racemase) can decrease the number of atypical diagnoses, and yet one must use these techniques with caution since there are numerous false-positive and false-negative results. 4) The average risk of cancer following an atypical diagnosis is approximately 40%. 5) Clinical and pathological parameters do not help predict which men with an atypical diagnosis have cancer on repeat biopsy. 6) Repeat biopsy should include increased sampling of the initial atypical site, and adjacent ipsilateral and contralateral sites with routine sampling of all sextant sites. Therefore, it is critical for urologists to submit needle biopsy specimens in a manner in which the sextant location of each core can be determined. 7) All men with an atypical diagnosis need re-biopsy within 3 to 6 months.

CONCLUSIONS

It is critical for urologists to distinguish between a diagnosis of HGPIN and that of atypical foci suspicious for cancer on needle biopsy. These 2 entities indicate different risks of carcinoma on re-biopsy and different recommendations for followup.

Recursive partitioning for risk stratification in men undergoing repeat prostate biopsies

BACKGROUND

The current study was performed to identify risk factors and risk groups for carcinoma detection in men undergoing repeat prostate biopsies.

METHODS

The medical records of all men who had a negative initial prostate biopsy and underwent at least one repeat biopsy between 1992 and 2003 were reviewed to extract age, race, family history of prostate carcinoma, body mass index, referral indication, all prostate-specific antigen (PSA) values, digital rectal examination, PSA density (PSAD), the presence of a hypoechoic lesion, and the presence of high-grade prostatic intraepithelial neoplasia (HGPIN) on initial biopsy. Risk factors for a subsequent diagnosis of prostate carcinoma were identified using the log-rank test and a stepwise, stratified Cox regression model. Based on the risk factors identified by Cox regression analysis, recursive partitioning was further used for risk stratification.

RESULTS

A total of 373 patients underwent 975 biopsy procedures. During a median follow-up of 37.0 months, prostate carcinoma was detected in 107 of 373 patients (28.9%). Independent predictors of a positive biopsy (P < 0.05) were PSA doubling time (PSADT), PSAD, referral indication, the presence of HGPIN, patient age, and family history of prostate carcinoma. Recursive partitioning identified 4 distinct risk groups that were characterized by their PSADT and PSAD and the presence of HGPIN and had estimated 2-year and 5-year carcinoma detection rates of 3 +/- 1% and 21 +/- 4%, 28 +/- 5% and 40 +/- 7%, 22 +/- 6% and 58 +/- 8%, and 66 +/- 9% and 100%, respectively.

CONCLUSIONS

The authors identified a series of independent risk factors for prostate carcinoma detection after an initial negative prostate biopsy and characterized clinically meaningful and distinct patient risk groups. Despite a negative initial biopsy, patients with high-risk features remain at risk for the detection of prostate carcinoma.

Induction of Th1-type immunity and tumor protection with a prostate-specific antigen DNA vaccine

Prostate specific antigen (PSA) is a serum marker that is widely used in the detection and monitoring of prostate cancer. Though PSA is a self-antigen, T cell responses to PSA epitopes have been detected in healthy men and prostate cancer patients, suggesting it may be used as a target for active immunotherapy of prostate cancer. A PSA DNA vaccine (pPSA) was evaluated in mice and monkeys for its ability to induce antigen-specific immune responses. Mice immunized intradermally with pPSA demonstrated strong PSA-specific humoral and cellular immunity. The anti-PSA immune responses were skewed toward Th1, as shown by high IFNgamma and IL-2 production. The immune response was sufficient to protect mice from challenge with PSA-expressing tumor cells. Tumor protection was durable in the absence of additional vaccination, as demonstrated by protection of vaccinated mice from tumor rechallenge. Furthermore, pPSA vaccination induced PSA-specific antibody titers in male cynomolgus monkeys, which express a closely related PSA gene. These results demonstrate that vaccination with pPSA may be able to break tolerance and can induce an immune response that mediates tumor protection.

Current usefulness of free/total PSA ratio in the diagnosis of prostate cancer at an early stage

The aim of our study was to evaluate five different free/total PSA (f/t PSA) kits for the diagnosis of early stage prostate cancer. We compared the PSA density and the f/t PSA ratio to differentiate between benign prostatic hyperplasia (BPH) and prostate cancer. This prospective study included a total of 120 patients with suspected prostate cancer (PSA between 4 and 15 ng/ml) observed over a period of 30 months. All patients had a blood test as well as a prostate biopsy prior to inclusion. Serum immunoassay total-PSA (t PSA) and free-PSA (f PSA) were carried out using five different assay kits: IMX Abbott (A), Kryptor Brahms (B), Immulite DPC (D), IRMA Immunotech (I) and IRMA DiaSorin (S). The results were compared to determine sensitivity, specificity, threshold values, and to differentiate between BPH and cancer. No difference was found between assay reproducibility and variation in the assays, however, only a slight variation was observed in the mean t PSA values, whereas a significant difference was found with f/t PSA. Receiver operating curves were generated for t-PSA and f/t PSA. The area under the curves did not show any significant differences for either t PSA or f/t PSA. A low comparative variability between the five kits tested for tPSA was observed, which suggest that the f/t PSA ratio has no current usefulness in the initial diagnosis of prostate cancer, particularly in patients with larger prostates. Furthermore, no prognostic value was found for surgically positive margins in radical prostatectomy.

Clinical relevance of genetic instability in prostatic cells obtained by prostatic massage in early prostate cancer

We investigated whether genetic lesions such as loss of heterozygosity (LOH) are detected in prostatic cells obtained by prostatic massage during early diagnosis of prostate cancer (CaP) and discussed their clinical relevance. Blood and first urine voided after prostatic massage were collected in 99 patients with total prostate-specific antigen (PSA) between 4 and 10 ng ml⁻¹, prior to prostate biopsies. Presence of prostatic cells was confirmed by quantitative RT–PCR analysis of PSA mRNA. Genomic DNA was analysed for LOH on six chromosomal regions. One or more allelic deletions were found in prostatic fluid from 57 patients analysed, of whom 33 (58%) had CaP. Sensitivity and specificity of LOH detection and PSA free to total ratio <15% for positive biopsy were respectively 86.7 and 44% (P=0.002) for LOH, and 55 and 74% (P=0.006) for PSA ratio <15%. Analysis of LOH obtained from prostatic tumours revealed similar patterns compared to prostatic fluid cells in 86% of cases, confirming its accuracy. The presence of LOH of urinary prostatic cells obtained after prostatic massage is significantly associated with CaP on biopsy and may potentially help to identify a set of patients who are candidates for further prostate biopsies.

Prostate cancer detection on urinalysis for alpha methylacyl coenzyme a racemase protein

PURPOSE

We assessed the feasibility of a novel urinary test for prostate cancer based on the presence of alpha methylacyl coenzyme A racemase (AMACR) protein in voided urine specimens obtained after prostate biopsy.

MATERIALS AND METHODS

Clean catch voided urine specimens were prospectively collected from 26 consecutive men immediately after transrectal ultrasound guided prostate biopsy for suspected malignancy. The presence of AMACR was evaluated in a blinded manner by Western blot analysis and correlated with biopsy results and patient clinical information.

RESULTS

AMACR was detected in the urine in 18 of 26 patients (69%). AMACR was detected in all 12 patients with biopsy confirmed adenocarcinoma of the prostate (100% sensitivity, 95% CI 75 to 100), in 5 of 12 with no evidence of cancer on biopsy (58% specificity, 95% CI 29 to 78) and in 1 of 2 (50%, 95% CI 3 to 80) with atypia on biopsy. Overall AMACR detection was associated with cancer status by prostate biopsy in 21 of 26 patients (86%).

CONCLUSIONS

We report the feasibility of a novel, noninvasive, nonprostate specific antigen based molecular approach to detect prostate cancer in voided urine. To our knowledge this is the first report of AMACR protein detection in the urine of patients with prostate cancer. A screening test based on urinary AMACR may develop into a useful adjunct to serum prostate specific antigen and digital rectal examination for identifying men at increased risk for harboring prostate cancer despite negative biopsy. Such a test has potential application for stratifying patients into low and high risk groups for surveillance vs repeat biopsy.

Molecular Detection of Prostate Cancer: A Role for GSTP1 Hypermethylation

OBJECTIVE

Prostate cancer is a leading cause of cancer-related mortality and morbidity in Western world. Curative treatment is feasible provided the disease is diagnosed in its earliest stages, but current screening methodologies are characterized by low specificity. DNA-based markers are a class of new and promising tools for cancer detection. Promoter hypermethylation is a common epigenetic alteration affecting cancer-related genes.

METHODS

We critically reviewed the most relevant reports on prostate cancer detection using DNA methylation analysis in prostate tissue and body fluids.

RESULTS

The epigenetic silencing of the glutathione-S-transferase P1 (GSTP1) gene is the most common (>90%) genetic alteration so far reported in prostate cancer. Methylation-specific PCR (MSP) methods allowed for the successful detection of GSTP1 methylation in body fluids (serum, plasma, urine, and ejaculates) from prostate cancer patients. In addition, the development of highly specific quantitative MSP assays augmented standard histopathology for the diagnosis of prostate cancer in tissue biopsies, accurately distinguishing benign from malignant prostate lesions.

CONCLUSIONS

Further advances in the epigenetic characterization of prostate cancer are likely to yield powerful tools for patient diagnosis and management.

Clinical, biochemical and pathological features of initial and repeat transrectal ultrasonography prostate biopsy positive patients

BACKGROUND

Using sextant biopsy, 16-41% of prostate cancers were diagnosed on repeat biopsy. The objective of the present study was to compare the differences in the clinical, biochemical and pathological features between patients with positive results on initial and repeat biopsies, with an aim to identify factors that can be used to improve the detection rate of transrectal ultrasound (TRUS) biopsy of the prostate.

METHODS

Between February 2000 and April 2001, 222 patients with a mean age of 64 years (range 38-85) underwent TRUS-guided 10-core prostate biopsy for either abnormal prostate specific antigen (PSA) levels (>4 ng/mL) and/or abnormal digital rectal examination (DRE). Of this number, 165 patients underwent their first biopsy, whereas 45 and 12 patients had had one or two previous biopsies, respectively.

RESULTS

Prostate cancer detection rates for the initial biopsy group (n = 165), second biopsy group (n = 45) and third biopsy group (n = 12) were 29.7, 23.0 and 41.7%, respectively. Six patients who had a negative first 10-core biopsy underwent a second 10-core biopsy and one patient (16%) was found to have cancer. Apart from total prostate volume, there were no significant statistical differences between the patient age, mean total PSA, PSA density, PSA-transition zone density, DRE and TRUS findings between the initial and repeat biopsy groups of subjects who had cancer. Those who had cancer detected only on repeat biopsies had larger prostate glands (P = 0.041).

CONCLUSION

Patients who had cancer detected only on repeat biopsies had bigger prostate glands, supporting the hypothesis that TRUS sextant biopsy as a technique suffers the error of under-sampling in a bigger prostate.

GSTP1 CpG island hypermethylation as a molecular biomarker for prostate cancer

Somatic hypermethylation of CpG island sequences at GSTP1, the gene encoding the pi-class glutathione S-transferase, appears to be characteristic of human prostatic carcinogenesis. To consider the potential utility of this epigenetic alteration as a biomarker for prostate cancer, we present here a comprehensive review of the literature describing somatic GSTP1 changes in DNA from prostate cells and tissues. GSTP1 CpG island hypermethylation has been detected in prostate cancer DNA using a variety of assay techniques, including (i) Southern blot analysis (SB), after treatment with (5-m)C-sensitive restriction endonucleases, (ii) the polymerase chain reaction, following treatment with (5-m)C-sensitive restriction endonucleases (RE-PCR), (iii) bisulfite genomic sequencing (BGS), and (iv) bisulfite modification followed by the polymerase chain reaction, using primers selective for target sequences containing (5-m)C (MSP). In the majority of the case series so far reported, GSTP1 CpG island hypermethylation was present in DNA from at least 90% of prostate cancer cases. When analyses have been carefully conducted, GSTP1 CpG island hypermethylation has not been found in DNA from normal prostate tissues, or from benign prostatic hyperplasia (BPH) tissues, though GSTP1 CpG island hypermethylation changes have been detected in DNA from candidate prostate cancer precursor lesions proliferative inflammatory atrophy (PIA) and prostatic intraepithelial neoplasia (PIN). Using PCR methods, GSTP1 CpG island hypermethylation has also been detected in urine, ejaculate, and plasma from men with prostate cancer. GSTP1 CpG island hypermethylation, a somatic epigenetic alteration, appears poised to serve as a molecular biomarker useful for prostate cancer screening, detection, and diagnosis.

Predictors of prostate cancer after initial negative systematic 12 core biopsy

PURPOSE

We determined the cancer detection rate at initial systematic 12 core (S12C) biopsy and identified features associated with cancer at repeat S12C biopsy after an initial negative S12C biopsy in patients with prostate specific antigen (PSA) parameters associated with a higher risk of prostate cancer.

MATERIALS AND METHODS

Between February 1999 and June 2002, 841 patients underwent initial S12C biopsy. Of these patients 99 underwent repeat S12C biopsy after initial negative S12C because of a percent free-to-total PSA of 15.0 or less and/or a yearly PSA velocity of 0.75 ng/ml or greater. The association between parameters revealed by initial biopsy and cancer at repeat biopsy was assessed.

RESULTS

Of the 99 patients 21 (21.2%) had cancer at repeat biopsy. Age (p = 0.01), PSA transitional zone density (p = 0.05), and high grade PIN at initial biopsy (p = 0.01) were associated with cancer at repeat biopsy.

CONCLUSIONS

In this select group of patients with PSA parameters associated with a higher risk of prostate cancer the cancer detection rate after initially negative S12C biopsy was 21%. Patients with high grade PIN on initial biopsy, advanced age and higher PSA transition zone density are at increased risk for cancer at repeat biopsy. Larger prospective studies are required to confirm these results and construct a nomogram that determines the probability of finding prostate cancer at subsequent biopsy.

No reason for immediate repeat sextant biopsy after negative initial sextant biopsy in men with PSA level of 4.0 ng/mL or greater (ERSPC, Rotterdam)

OBJECTIVES

In the early detection of prostate cancer (CaP) uncertainty exists concerning the most appropriate biopsy procedure. Within the European Randomized Study of Screening for Prostate Cancer (ERSPC) lateralized sextant biopsies are used. False-negative results of sextant biopsies have led to the extensive use of procedures using 12 or more biopsy cores. The ERSPC offers the opportunity to study the yield of repeat biopsies after 4 years in men who had negative sextant biopsies and a prostate-specific antigen (PSA) level of 4.0 mg/mL or more at the first screening round.

METHODS

Between August 1996 and May 1998, a total of 6876 men (age 55 to 74 years) were randomized to the screening arm and actually underwent screening. The numbers and levels of biopsy indicators, as well as possible predictors for biopsy outcome, in the second screening round, such as prostate volume, volume change over time, prostate-specific antigen density (PSAD), PSA velocity, and age, were calculated and compared for participants with positive and negative biopsies in round 2. The positive predictive value (PPV) and detection rates, as well as parameters of aggressiveness, were evaluated for second-round biopsy-detected and interval CaP cases.

RESULTS

Of the 728 men with a PSA level of 4.0 mg/mL or more who underwent biopsy at initial screening, 553 were eligible for a second screening visit after 4 years. Of these, 272 (49.2%) actually underwent screening. Eighteen CaP cases were detected with 217 biopsies, indicated by a PSA level of 3.0 ng/mL or more (PPV 8.3%). Eight interval cases were identified by linking to the Cancer Registry. These 26 cases would have increased the PPV and detection rate of the initial screening round from 36.1% to 39.7% and from 3.8% to 4.2%, respectively. Most of these cases (23 of 26 or 88.5%) were organ confined and amenable to potentially curative treatment.

CONCLUSIONS

Although the results of this study may have been biased by the low rate of availability/eligibility of participants for rescreening (after 4 years), the proportion of cancers detected after a previous lateral sextant biopsy indicated by a PSA value of 4.0 mg/mL or more (PPV 8.3%) fell far short of the overall PPV at rescreening (PPV 20%). The features of most cancers that were possibly missed during the first round allowed a potentially curative approach. The ERSPC study group found no reason to change the ERSPC protocol.

The atypical GATA protein TRPS1 represses androgen-induced prostate-specific antigen expression in LNCaP prostate cancer cells

Prostate-specific antigen (PSA) is considered as an important marker for prostate cancer. Regulation of PSA gene expression is mediated by androgens bound to androgen receptors via androgen response elements (AREs) in its promoter and far upstream enhancer regions. In addition, GATA proteins contribute to PSA gene transcription by interacting with GATA motifs present in the PSA enhancer sequence. The TRPS1 gene contains a single GATA zinc finger domain and not only binds to forward consensus GATA motifs but also to an inverse GATA motif overlapping the ARE III in the far upstream enhancer of the PSA gene. Overexpression of TRPS1 in androgen-dependent human LNCaP prostate cancer cells inhibited the transcription of a transiently transfected PSA enhancer/promoter-driven luciferase reporter construct. Furthermore, overexpression of TRPS1 reduced the androgen-induced endogenous PSA levels secreted in culture medium of LNCaP cells. Our results suggest a role of TRPS1 in androgen regulation of PSA gene expression.

[Transrectal ultrasound-guided punch biopsies of the prostate. Indication, technique, results, and complications]

The golden standard for diagnosis of prostate cancer is transrectal ultrasound-guided systematic biopsy (TRUS-Bx). The optimal number of cylinders, sampling design, and indications for repeat biopsy are still in a state of flux. At the beginning of the 1980s, considerable doubts persisted regarding the benefit of ultrasound-guided punch biopsy for the diagnosis of prostate cancer. The examination on a chair with a fixed ultrasound head caused the patient substantial discomfort. Besides, in the pre-PSA era, most prostate carcinomas were detected by palpation and digitally guided biopsies were easily obtained. Indeed, the DRU procedure alone exhibited low sensitivity. Keetch et al. found that in only 25% of patients with abnormal palpatory findings and PSA between 4 and 20 ng/ml was a carcinoma revealed upon biopsy. On the other hand, patients with suspicious palpatory findings and proven malignancy suffered more frequently from locally advanced and systemic metastasizing tumors. As a result of restaging based on PSA, in most series more than half of the detected carcinomas presented normal palpatory findings. Ultrasound examination made precise imaging of zonal structures possible and thus offered the advantage of precision guidance for tissue biopsy despite lower sensitivity and specificity for diagnosis of suspicious lesions. Furthermore, calculation of prostate volume was possible. At the end of the 1980s, Hodge defined the systematic sextant biopsy as the first golden standard for early detection of prostate cancer. This meant the systematic removal of three punch cylinders from both lateral lobes of the prostate in the parasagittal midline at various levels (apex, middle, and base).

Clinical and pathologic features of prostate cancer detected after repeat false-negative biopsy in a screening population

BACKGROUND

The present study was designed to investigate whether the clinical or pathologic features of prostate cancer (PCa) are related to the number of repeat biopsies required to establish the diagnosis of PCa.

METHODS

Between February 1993 and August 2000, 653 patients were evaluated in this retrospective study. All patients underwent transrectal ultrasound-guided biopsy of the prostate prior to radical retropubic prostatectomy. The pathologic findings of specimens obtained at radical prostatectomy and pelvic lymph node dissection as well as PSA levels, findings on DRE, prostate volumes, transition zone volumes, and age were analyzed separately for all PCa patients diagnosed at the first set of biopsies (group A) and compared with the data of those diagnosed at the 2nd-5th set of biopsies (group B). In a second step, we compared the results obtained from patients diagnosed at the 2nd set of biopsies (group B1) with those of patients diagnosed at the 3rd to 5th set of biopsies (group B2).

RESULTS

Gleason scores, pathologic tumor stages, and tumor volumes in group B were found to be significantly decreased compared to group A. But from the 2nd to 5th serial biopsy no further decrease in pathologic stage, Gleason score, or tumor volume was observed. On the contrary, there was a tendency towards higher tumor stages and Gleason scores. Of the tumors detected after the second false-negative set of biopsies almost 70% were lesions with Gleason scores of 6 or higher.

CONCLUSIONS

False-negative results at the first needle biopsy are predictive of a lower pathologic stage and grade as well as smaller tumor volumes of PCa diagnosed at repeat sets of biopsies. False-negative results on repeat biopsy, however, have no prognostic significance for the tumor stage of PCas detected at subsequent sets of biopsies.

Biology of prostate-specific antigen

The human kallikrein (hk) family, located on chromosome 19, encodes prostate-specific antigen (PSA [or hK3]), hK2, hK4, and hK15 (prostin), as well as other serine proteases. Although PSA has been used in the detection of prostate cancer for several years, much remains unknown about its function and forms. The regulatory mechanisms of PSA are vital to its understanding. A particular mechanism by which PSA forms complexes with either alpha1-antichymotrypsin or alpha2-macroglobulin may provide important information for disease detection and progression. Data are emerging that show that active hK2, hK4, and hK15 may be important to convert pro-PSA to the active PSA enzyme. This information, along with insights into the precise mechanisms of PSA expression, may be used to suggest that PSA and, perhaps, other members of the hK family contribute critical control mechanisms to tumor invasion or progression. Although much remains to be revealed on the role of these gene products in the detection and progression of prostate cancer, findings from studies that show sensitive signaling of the disease > or =20 years before the diagnosis of clinically significant prostate cancer may alter screening procedures and improve treatment options.

Testing in Serum for Human Glandular Kallikrein 2, and Free and Total Prostate Specific Antigen in Biannual Screening for Prostate Cancer

PURPOSE

We investigated the value of serum measurements for glandular kallikrein 2 (hK2), and free (f) and total (t) prostate specific antigen (PSA) in a second round of biannual screening for prostate cancer.

MATERIALS AND METHODS

In 1995 to 1996, 5,853 of 9,811 randomly selected men in Göteborg, Sweden 50 to 66 years old had PSA measurements. Of 660 men 611 with tPSA 3 ng/ml or greater underwent biopsy and 145 had cancer. All were re-invited 2 years later for PSA testing, and 506 of 596 men with tPSA 3 ng/ml or greater underwent biopsy and 113 cancers were detected. We analyzed hK2, tPSA and fPSA in 423 of 453 (93%) men who underwent biopsy in 1997 to 1998 who were also screened in 1995 to 1996.

RESULTS

The 99 of 423 (23%) men who underwent biopsy diagnosed with prostate cancer in 1997 to 1998 had significantly different tPSA, percent fPSA and hK2 x tPSA/fPSA compared to the men with negative biopsies from 2 years earlier. The largest area under curve was obtained for hK2 x tPSA/fPSA in serum from 1995 to 1996 and from 1997 to 1998, but the difference was not significant compared to tPSA and percent fPSA. In serum from 1997 to 1998 measurements of hK2 x tPSA/fPSA gave significantly higher specificity than tPSA at 85% sensitivity, and significantly higher specificity than tPSA and percent fPSA at 70% to 75% sensitivity. In addition, levels of hK2 and hK2 x tPSA/fPSA manifested a significantly greater 2-year increase in men with cancer compared to those with benign biopsies.

CONCLUSIONS

In men with tPSA levels 3.0 ng/ml or greater who were not diagnosed with cancer during a first round of screening, hK2 measurements enhanced specificity compared to tPSA testing at moderately high sensitivity, and manifested a greater 2-year increase in men with cancer.

When to biopsy and when to stop biopsying

With the widespread use of serum prostate-specific antigen (PSA) and transrectal ultrasound-guided needle biopsy of the prostate in men with suspected prostate cancer, physicians are faced with the dilemma of treating a patient with a high index of suspicion of prostate cancer but with an initial set of negative biopsies. For the initial biopsy, the optimal number of biopsy cores for detecting prostate cancer in prostate biopsy remains controversial; it is also often unclear who should undergo a repeat prostatebiopsy and when to stop biopsying.