The prostate specific antigen era in the United States is over for prostate cancer: what happened in the last 20 years?

Evaluation of GSTP1 and APC methylation as indicators for repeat biopsy in a high-risk cohort of men with negative initial prostate biopsies

Study Type - Diagnostic (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? Hypermethylation of genes such as glutathione-S-transferase P1 (GSTP1) and adenomatous polyposis coli (APC) occurs with high frequency in prostate tumour tissue but is much less common in the benign prostate; however, the potential value of gene methylation biomarkers as an adjunct to biopsy histopathology has had little study. When measured in histologically benign prostate biopsy tissue, APC gene hypermethylation was found to have high negative predictive value and high sensitivity. GSTP1 hypermethylation was found to have lower performance than APC.

OBJECTIVE

To evaluate the performance of DNA methylation biomarkers in the setting of repeat biopsy in men with an initially negative prostate biopsy but a high index of suspicion for missed prostate cancer.

PATIENTS AND METHODS

We prospectively evaluated 86 men with an initial histologically negative prostate biopsy and high-risk features. All men underwent repeat 12-core ultrasonography-guided biopsy. DNA methylation of glutathione-S-transferase P1 (GSTP1) and adenomatous polyposis coli (APC) was determined using tissue from the initially negative biopsy and compared with histology of the repeat biopsy. The primary outcome was the relative negative predictive value (NPV) of APC compared with GSTP1, and its 95% confidence interval (CI).

RESULTS

On repeat biopsy, 21/86 (24%) men had prostate cancer. APC and GSTP1 methylation ratios below the threshold (predicting no cancer) produced a NPV of 0.96 and 0.80, respectively. The relative NPV was 1.2 (95% CI: 1.06-1.36), indicating APC has significantly higher NPV. Methylation ratios above the threshold yielded a sensitivity of 0.95 for APC and 0.43 for GSTP1. Combining both methylation markers produced a performance similar to that of APC alone. APC methylation patterns were consistent with a possible field effect or occurrence early in carcinogenesis.

CONCLUSIONS

APC methylation provided a very high NPV with a low percentage of false-negatives, in the first prospective study to evaluate performance of DNA methylation markers in a clinical cohort of men undergoing repeat biopsy. The potential of APC methylation to reduce unnecessary repeat biopsies warrants validation in a larger prospective cohort.

Clinical application of a 3D ultrasound-guided prostate biopsy system

OBJECTIVES

Prostate biopsy (Bx) has for 3 decades been performed in a systematic, but blind fashion using 2D ultrasound (US). Herein is described the initial clinical evaluation of a 3D Bx tracking and targeting device (Artemis; Eigen, Grass Valley, CA). Our main objective was to test accuracy of the new 3D method in men undergoing first and follow-up Bx to rule out prostate cancer (CaP).

MATERIALS AND METHODS

Patients in the study were men ages 35-87 years (66.1 ± 9.9), scheduled for Bx to rule out CaP, who entered into an IRB-approved protocol. A total of 218 subjects underwent conventional trans-rectal US (TRUS); the tracking system was then attached to the US probe; the prostate was scanned and a 3D reconstruction was created. All Bx sites were visualized in 3D and tracked electronically. In 11 men, a pilot study was conducted to test ability of the device to return a Bx to an original site. In 47 men, multi-parametric 3 Tesla MRI, incorporating T2-weighted images, dynamic contrast enhancement, and diffusion-weighted imaging, was performed in advance of the TRUS, allowing the stored MRI images to be fused with real-time US during biopsy. Lesions on MRI were delineated by a radiologist, assigned a grade of CaP suspicion, and fused into TRUS for biopsy targeting.

RESULTS

3D Bx tracking was completed successfully in 180/218 patients, with a success rate approaching 95% among the last 50 men. Average time for Bx with the Artemis device was 15 minutes with an additional 5 minutes for MRI fusion and Bx targeting. In the tracking study, an ability to return to prior Bx sites (n=32) within 1.2 ± 1.1 mm SD was demonstrated and was independent of prostate volume or location of Bx site. In the MRI fusion study, when suspicious lesions were targeted, a 33% Bx-positivity rate was found compared with a 7% positivity rate for systematic, nontargeted Bx (19/57 cores vs. 9/124 cores, P=0.03).

CONCLUSION

Use of 3D tracking and image fusion has the potential to transform MRI into a clinical tool to aid biopsy and improve current methods for diagnosis and follow-up of CaP.

Risk factors for incidental prostate cancer-who should not undergo vaporization of the prostate for benign prostate hyperplasia?

BACKGROUND

Vaporization of the prostate (e.g., using laser devices) for treatment of benign prostatic hyperplasia does not allow for subsequent histological examination. Therefore, patients should be counseled about the risk of missing an incidental prostate cancer (incPCa). In this study the risk of an incPCa was determined based on all preoperative parameters.

METHODS

Thousand three hundred and fifty seven (04/2004-09/2008) patients underwent transurethral resection of the prostate (TURP) in our department. Cases with less than 10 g removed tissue, PSA >20 ng/ml or with known PCa were excluded. Data of the remaining 1,000 consecutive patients were collected retrospectively and statistically analyzed using SAS.

RESULTS

Mean age was 69.4 (36-96) years, mean PSA 4.41 (0.08-19.5) ng/ml, mean weight of removed tissue 30.9 (10-110) g. An incPCa was detected in 111 cases. Thirty-four out of these were considered to be clinically relevant (relPCa; stage T1b and/or Gleason sum ≥7). In univariate analysis age, volume of the prostate and body mass index correlated with incPCa while age, volume of the prostate and PSA correlated with relPCa. Predictive parameters for a multivariate logistic regression model are age and body mass index for incPCa and age, prostate volume, and number of prior biopsies for relPCa.

CONCLUSIONS

More than 1 in 10 patients undergoing TURP has an incPCa and 3.4% have a relPCa. Patients should be counseled carefully about the risk of missing especially relPCa when undergoing vaporization of the prostate. Our model significantly improves prediction of relPCa compared to PSA and digital examination alone.

Suitability of PSA-detected localised prostate cancers for focal therapy: experience from the ProtecT study

Background:

Contemporary screening for prostate cancer frequently identifies small volume, low-grade lesions. Some clinicians have advocated focal prostatic ablation as an alternative to more aggressive interventions to manage these lesions. To identify which patients might benefit from focal ablative techniques, we analysed the surgical specimens of a large sample of population-detected men undergoing radical prostatectomy as part of a randomised clinical trial.

Methods:

Surgical specimens from 525 men who underwent prostatectomy within the ProtecT study were analysed to determine tumour volume, location and grade. These findings were compared with information available in the biopsy specimen to examine whether focal therapy could be provided appropriately.

Results:

Solitary cancers were found in prostatectomy specimens from 19% (100 out of 525) of men. In addition, 73 out of 425 (17%) men had multiple cancers with a solitary significant tumour focus. Thus, 173 out of 525 (33%) men had tumours potentially suitable for focal therapy. The majority of these were small, well-differentiated lesions that appeared to be pathologically insignificant (38–66%). Criteria used to select patients for focal prostatic ablation underestimated the cancer's significance in 26% (34 out of 130) of men and resulted in overtreatment in more than half. Only 18% (24 out of 130) of men presumed eligible for focal therapy, actually had significant solitary lesions.

Conclusion:

Focal therapy appears inappropriate for the majority of men presenting with prostate-specific antigen-detected localised prostate cancer. Unifocal prostate cancers suitable for focal ablation are difficult to identify pre-operatively using biopsy alone. Most lesions meeting criteria for focal ablation were either more aggressive than expected or posed little threat of progression.

Does body mass index "dilute" the predictive property of prostate-specific antigen for tumor volume at radical prostatectomy?

OBJECTIVE

To evaluate the effect of the body mass index (BMI) as it relates to the predictive value of the preoperative prostate-specific antigen (PSA) level regarding the tumor volume at radical prostatectomy. Stage migration with the widespread use of PSA screening is well documented; however, the association between the PSA level and tumor volume is less defined. Additionally, the effect of obesity on the serum PSA level might cause relative hemodilution and account for the decreased predictive ability of the PSA level to determine the tumor volume in the modern era.

METHODS

We identified 14 293 patients who had undergone radical prostatectomy for prostate cancer from 1987 to 2007 and had a documented BMI. Using the clinicopathologic variables, we examined the relationship among the BMI, preoperative PSA level, and tumor volume at radical prostatectomy using multiple linear regression analysis.

RESULTS

An elevated BMI was associated with an increased pathologic Gleason score (P < .0001), increased tumor volume (P < .0001), and increased prostate size (P < .0001). The preoperative PSA level correlated significantly with the tumor volume (P < .0001). No significant correlation was found between the BMI and preoperative PSA level (P = .39). On multivariate analysis, controlling for the BMI, the preoperative PSA level remained a significant predictor of the tumor volume (P < .0001). The interaction between the preoperative PSA level and BMI in the prediction of the tumor volume was not statistically significant (P = .56), suggesting that the BMI does not affect the association between the PSA level and tumor volume.

CONCLUSION

Our results have shown that the predictive ability of the PSA level for tumor volume is not affected by the BMI. There does not appear to be a need to correct the serum PSA level in relation to the BMI when used in preoperative prediction models of the tumor volume.

Prostate cancer: an emerging threat to the health of aging men in Asia

The aim of this study was to determine and examine the possible reasons for the difference in prostate cancer incidence between Asian men and North American men by literature review. Data regarding cancer incidence and mortality were obtained from the database of the International Agency for Research on Cancer (IARC). A literature review was conducted by studying related articles published in peer-reviewed journals such as the The New England Journal of Medicine, Journal of Clinical Oncology, A Cancer Journal for Clinicians and Asian Journal of Andrology. To evaluate the early diagnosis and survival rates, the mortality-to-incidence rate ratio (MR/IR) was calculated from the IARC data. By comparing prostate cancer data between Asian men and North American men, we found that differences in the incidence rate and MR/IR could be attributed largely to a lack of annual prostate cancer screening with serum prostate-specific antigen (PSA) in most Asian countries. It is likely that PSA screening also contributes significantly to the differences in prostate cancer mortality rates. Prostate cancer has the highest incidence rate among five common malignancies in Asian Americans. However, the MR/IR ratio of prostate cancer is the lowest among cancers. These data seem to further support the usefulness of PSA screening, even though the percentage of low risk cancers is greater in prostate cancer than in other cancers. The low incidence rate of prostate cancer does not reflect the actual statistics of this disease in Asia. The data from limited institutions in many Asian countries seem to bias the true incidence and mortality rates. To improve this situation, incorporating PSA screening for prostate cancer, as well as constructing a nationwide cancer registration system, will be helpful.

Mediated decision support in prostate cancer screening: a randomized controlled trial of decision counseling

OBJECTIVE

This randomized trial was conducted to assess the impact of a mediated decision support intervention on primary care patient prostate cancer screening knowledge, decisional conflict, informed decision making (IDM), and screening.

METHODS

Before a routine office visit, 313 male patients eligible for prostate cancer screening completed a baseline telephone survey and received a mailed brochure on prostate cancer screening. At the visit, participants were randomized to either an enhanced intervention (EI) or a standard intervention (SI) group. Before meeting with their physician, EI Group men had a nurse-led "decision counseling" session, while SI Group men completed a practice satisfaction survey. An endpoint survey was administered. Survey data, encounter audio-recordings, and chart audit data were used to assess study outcomes.

RESULTS

Knowledge increased in the EI Group (mean difference of +0.8 on a 10-point scale, p=0.001), but decisional conflict did not change (mean difference of -0.02 on a 4-point scale, p=0.620). The EI Group had higher IDM (rate ratio=1.30, p=0.029) and lower screening (odds ratio=0.67, p=0.102).

CONCLUSION

Nurse-mediated decision counseling increased participant prostate cancer screening knowledge, and influenced informed decision making and screening.

PRACTICE IMPLICATIONS

Nurses trained in decision counseling can facilitate shared decision making about screening.

Urinary estrogen metabolites and prostate cancer risk: a pilot study

BACKGROUND

The high incidence of and few identified risk factors for prostate cancer underscore the need to further evaluate markers of prostate carcinogenesis. The aim of this pilot study was to evaluate urinary estrogen metabolites as a biomarker of prostate cancer risk.

METHODS

Using a liquid chromatography-tandem mass spectrometry method, urinary concentrations of 15 estrogen metabolites were determined in 77 prostate cancer cases, 77 healthy controls, and 37 subjects who had no evidence of prostate cancer after a prostate biopsy.

RESULTS

We observed an inverse association between the urinary 16-ketoestradiol (16-KE2) and 17-epiestriol (17-epiE3)--metabolites with high estrogenic activity--and prostate cancer risk. Men in the lowest quartile of 16-KE2, had a 4.6-fold risk of prostate cancer (OR=4.62, 95% CI=1.34-15.99), compared with those in the highest quartile.

CONCLUSIONS

We observed modest differences in estrogen metabolite concentrations between prostate cancer patients and subjects without cancer. Larger studies with both androgen and estrogen measurements are needed to confirm these results to clarify further whether estrogen metabolites are independent biomarkers for prostate cancer risk and whether androgen/estrogen imbalance influences prostate cancer risk.

Epigenetic analyses in blood cells of men suspected of prostate cancer predict the outcome of biopsy better than serum PSA levels

Lymphocytes from the peripheral blood of patients with prostate cancer-the most frequent (noncutaneous) tumor in men-display epigenetic aberrations (altered modes of allelic replication) characteristic of the malignant phenotype. The present study aims to determine whether replication aberrations add certainty to the suspicion of prostate cancer provided by the prostate-specific antigen (PSA) blood test. The allelic replication mode (whether synchronous or asynchronous) was exemplified for RB1 and AML1. These two genes normally exhibit a synchronous mode of allelic replication. Fluorescence in situ hybridization (FISH) replication assay was used for replication analyses. The FISH assays were applied to PHA-stimulated lymphocytes, established from peripheral blood samples of 35 men referred to biopsy due to suspected prostate cancer. Following biopsy 13 out of these 35 men were found positive for prostate malignancy. The FISH assay-showing asynchronous or synchronous RB1 and AML1 replication-was able to predict, respectively, the results of all biopsy-positive men and in 18 out of the 22 biopsy-negative ones. These measurements, distinguishing biopsy-positive from biopsy-negative men, were highly significant (P < 10(-8); 100% sensitivity and 81.8% specificity). Yet, distinguishing between the two groups of men based on the PSA measurements was nonsignificant (P > 0.70). The FISH replication assay applied to peripheral blood lymphocytes of 35 men referred for biopsy significantly predicted the outcome of the pathological examination, more precisely than the serum PSA test. As such, the epigenetic alteration offers a potential noninvasive blood marker, complementary to the PSA, for a preliminary prostate cancer diagnosis.

Upgrade in Gleason score between prostate biopsies and pathology following radical prostatectomy significantly impacts upon the risk of biochemical recurrence

OBJECTIVE

•To determine the effect of an upgrade in Gleason score between initial prostate biopsy and final prostatectomy specimen on the risk of postoperative biochemical recurrence.

PATIENTS AND METHODS

•A total of 1629 patients with paired biopsy and radical prostatectomy histology were identified from two prospectively recorded prostate cancer databases. •Information on key clinical and pathological characteristics as well as prostate-specific antigen follow-up was recorded. •Patients who experienced an upgrade in their Gleason score were compared with corresponding patients with concordant tumours of the lower and higher grade. •Kaplan-Meier curves and multivariate models were generated to examine the impact of Gleason score upgrade on the risk of postoperative biochemical recurrence.

RESULTS

•Overall, 466 patients (28.6%) experienced an upgrade in their Gleason score post radical prostatectomy, in 88.4% of cases involving a change in a single Gleason score point. •Patients upgraded from Gleason 6 (3 + 3) to Gleason 7 (3 + 4) had pathological characteristics that were very similar to Gleason 7 (3 + 4) concordant tumours, with an identical risk of biochemical recurrence. In contrast, patients upgraded from Gleason score 6 (3 + 3) to Gleason 7 (4 + 3) had tumours with pathological characteristics intermediate between the two concordant groups, which was mirrored by their risk of biochemical recurrence. •Patients with Gleason 7 tumours who experienced a change in the predominant pattern from 3 + 4 to 4 + 3 had tumours that resembled Gleason 7 (4 + 3) concordant tumours, with a similar risk of biochemical recurrence. In contrast, patients upgraded from Gleason 7 to Gleason >7 had tumours with intermediate pathological characteristics, and a risk of biochemical recurrence that was significantly different to concordant tumours of the lower and higher grade. •In multivariate models, a change in Gleason score was an independent predictor of biochemical recurrence in the preoperative setting only. •Although a difference in Gleason score was an independent predictor of recurrence in concordant tumours in models based on postoperative variables, an upgrade in Gleason score in discordant tumours was not, with differences in co-segregated adverse pathological characteristics being more predictive.

CONCLUSIONS

•Patients experiencing an upgrade in their Gleason score between biopsy and final specimen exhibit significantly more aggressive pathological features than corresponding concordant tumours, and a higher risk of biochemical recurrence post radical prostatectomy. •As Gleason score can be more accurately assessed preoperatively than other prognostic tumour features, continued effort is required to identify those most at risk of upgrading, and to refine biopsy strategies to reduce sampling error.

Serum Mac-2BP does not distinguish men with high grade, large volume prostate cancer from men with benign prostatic hyperplasia

BACKGROUND

Mac-2 binding protein (Mac-2BP) is a secreted protein that has been used as a serum prognostic marker for several types of cancers. A previous study showed that serum Mac-2BP was significantly higher (∼2-fold) in men with prostate cancer compared to healthy men. We investigated whether serum Mac-2BP could distinguish men with high grade, large volume prostate cancer from men with benign prostatic hyperplasia (BPH).

METHODS

A commercially available ELISA kit was used to measure Mac-2BP in paired pre- and post-prostatectomy sera from 10 men with high grade, large volume prostate cancer, in pre-operative sera from 50 untreated men with high grade, large volume prostate cancer, and in sera from 50 men with clinical symptoms of BPH and biopsy-negative for prostate cancer. Results were analyzed by Student's t-test and receiver operating characteristic (ROC) curves.

RESULTS

Levels of Mac-2BP did not decrease in post-prostatectomy sera, and Mac-2BP values were not significantly different in the sera of men with prostate cancer versus those with BPH.

CONCLUSION

Serum Mac-2BP does not appear to originate in the prostate and it is unlikely that Mac-2BP can be used for the differential diagnosis of prostate cancer versus BPH.

Significance of predicted tumor volume as a predictor of pathologic stage in patients undergoing radical prostatectomy

PURPOSE

The purpose of this study was to evaluate whether predicted tumor volume could predict pathologic stage in patients undergoing radical prostatectomy.

MATERIALS AND METHODS

The clinical and pathologic data of 236 patients who underwent a 12-core needle biopsy followed by radical prostatectomy were obtained from our database and reviewed retrospectively.

RESULTS

Observed tumor volume correlated best with serum prostate-specific antigen (PSA) level (r=0.677, p<0.001) and the number of positive biopsy cores (r=0.489, p<0.001). Stepwise multiple linear regression analysis was used to develop a model for predicting tumor volume before radical prostatectomy. All explanatory variables except PSA and the number of positive biopsy cores were eliminated, yielding the equation ([predicted tumor volume]=0.381x[PSA]+0.921x[No. of positive biopsy cores]-0.992). Tumor volume predicted by this equation correlated strongly with observed tumor volume (r=0.722, p<0.001). This was also true when a different cohort of 159 patients was analyzed (r=0.638, p<0.001). The areas under the receiver operating characteristic curves of predicted tumor volume were 68.5% for extracapsular extension, 75.7% for seminal vesicle invasion, and 70.4% for positive surgical margin. Kaplan-Meier curves revealed that predicted tumor volume correlated significantly with biochemical recurrence-free survival (p<0.001; log-rank test).

CONCLUSIONS

Our findings suggest that tumor volume predicted on the basis of PSA levels and number of positive biopsy cores may predict pathologic stage with reasonable accuracy.

[Does the criterion for prostate biopsy indication impact its accuracy? A prospective population-based outpatient clinical setting study]

INTRODUCTION

Prostate specific antigen (PSA) and digital rectal examination (DRE) are the main tests for initial prostate investigation; there is no consensus about the best criterion for prostate biopsies. We aim to check the accuracy of different criteria in this context including PSA derivatives to detect prostate cancer.

MATERIAL AND METHODS

Four different criteria for indication of prostate biopsy were compared: (A) PSA-density (>15 ng/ ml/ cc); (B) PSA > 2,5 ng/ml; (C) PSA-velocity (> 0.7 ng/ ml/ year); (D) free/total PSA ratio (<15%). All biopsies and histopathological examinations were performed by the same urologist and pathologist, respectively.

RESULTS

The study was performed on 180 consecutive biopsies with 37.7% overall cancer detection rate: 29 (16.1%) performed following criterion A, 42 (23.3%) criterion B, 65 (36.1%) criterion C and 44 (24.4%) criterion D. Based on PSA criteria alone, the predictive positive value (PPV) was 37.9% for criterion A, 33.3% for B, 32.3% for C and 50.0% for criterion D, respectively, (p > 0.05). Associating positive DRE with changed PSA, the PPV increased to 50%, 50%, 43.9% and 68.2% for criteria A, B, C and D, respectively (p>0.05). In univariate analysis, DRE (positive versus negative), PSA level (>10 ng/ ml versus <4.0 ng/ ml), free/total PSA ratio (<10% versus >15%) and age were associated with PC. In multivariate analysis only positive DRE was associated with prostate cancer.

CONCLUSIONS

All the criteria of PSA derivatives are complementary and useful predictors of cancer risk. However, a positive DRE increased the PPV of PSA derivatives. New tools are needed to improve the accuracy of prostate cancer detection.

Serum prostate-specific antigen value adjusted for non-cancerous prostate tissue volume in patients undergoing radical prostatectomy: a new predictor of biochemical recurrence in localized or locally advanced prostate cancer

The aim of this study was to investigate the significance of serum prostate-specific antigen (PSA) value adjusted for total tumor volume (PSA/tumor volume) and serum PSA value adjusted for non-cancerous prostate tissue volume (NCPV) (PSA/NCPV) as a predictor of pathological findings and clinical outcome after radical prostatectomy. Clinical and pathological data of 407 patients (median age: 66.5 years; range: 41.8-85.7 years) were reviewed retrospectively. The median follow-up period was 18.1 months (range: 1.0-107.8 months). Biochemical recurrence was defined as detectable PSA levels (greater than 0.2 ng ml(-1)) and the time of biochemical recurrence was taken to be the first time PSA became detectable. In the multivariate model, PSA/NCPV was an independent predictor of extracapsular extension and positive surgical margin (P<0.05), but PSA/tumor volume was not. Kaplan-Meier curves revealed that PSA/NCPV correlated with biochemical recurrence-free survival (P<0.001; log-rank test) but PSA/tumor volume did not (P=0.275; log-rank test). PSA/NCPV was also a significant independent prognostic factor for biochemical recurrence-free survival on multivariate Cox proportional hazard analysis (P=0.004, relative risk=2.42). Our findings suggest that PSA/NCPV is associated independently with extracapsular extension and surgical margin status and may be an independent prognostic variable of PSA recurrence after radical prostatectomy.

Correlation between serum prostate-specific antigen and cancer volume in prostate glands of different sizes

OBJECTIVES

To further evaluate the relationship of prostate-specific antigen (PSA) with prostate size and tumor volume in a contemporary surgical series. Although early studies showed a strong correlation between PSA and tumor volume, it has been suggested that PSA is no longer a valid marker for prostate cancer and only correlates with prostate size.

METHODS

From 2003 to 2009, 1234 men with data on prostate weight and total tumor volume underwent radical prostatectomy by a single surgeon. Prostate size was classified into tertiles: small (≤ 41.2 g), medium (41.3-54.5 g), and large (≥ 54.6 g). Pearson correlation coefficients were used to examine the relationship of PSA with prostate size and tumor volume across different prostate sizes.

RESULTS

Median preoperative PSA was 4.9 ng/mL (standard deviation ± 4.6), mean prostate size was 51.7 g, and mean tumor volume was 5.6 cm(3). PSA had a significant correlation with prostate size only at a prostate weight ≥ 54.6 g (P = .02). Regardless of prostate size, PSA had a more robust significant correlation with tumor volume than with prostate size (all P < .0001).

CONCLUSIONS

PSA was significantly correlated with prostate size only in the largest prostate glands, but was significantly associated with tumor volume in small, medium, or large prostates. Thus, PSA continues to be a better marker for tumor volume than for prostate size.

Olfactory detection of prostate cancer by dogs sniffing urine: a step forward in early diagnosis

BACKGROUND

Volatiles organic compounds (VOCs) in urine have been proposed as cancer biomarkers.

OBJECTIVE

To evaluate the efficacy of prostate cancer (PCa) detection by trained dogs on human urine samples.

DESIGN, SETTING, AND PARTICIPANTS

A Belgian Malinois shepherd was trained by the clicker training method (operant conditioning) to scent and recognize urine of people having PCa. All urine samples were frozen for preservation and heated to the same temperature for all tests. After a learning phase and a training period of 24 mo, the dog's ability to discriminate PCa and control urine was tested in a double-blind procedure. Urine was obtained from 66 patients referred to a urologist for elevated prostate-specific antigen or abnormal digital rectal examination. All patients underwent prostate biopsy and two groups were considered: 33 patients with cancer and 33 controls presenting negative biopsies.

MEASUREMENTS

During each "run," the dog was asked to signal a cancer urine among six samples containing only one cancer urine and five randomly selected controls. Sensitivity and specificity of the test were assessed.

RESULTS AND LIMITATIONS

The dog completed all the runs and correctly designated the cancer samples in 30 of 33 cases. Of the three cases wrongly classified as cancer, one patient was rebiopsied and a PCa was diagnosed. The sensitivity and specificity were both 91%.

CONCLUSIONS

This study shows that dogs can be trained to detect PCa by smelling urine with a significant success rate. It suggests that PCa gives an odor signature to urine. Identification of the VOCs involved could lead to a potentially useful screening tool for PCa.

Organ-wide telomeric status in diseased and disease-free prostatic tissues

BACKGROUND

Telomere attrition occurs early in the development of prostatic adenocarcinoma. However, little is known about either telomere status in benign prostatic hyperplasia (BPH), or the spatial and organ-wide distribution of potential telomere aberrations throughout all areas of prostatic glands affected by cancer or BPH.

METHODS

Slot blot titration assay was used to determine telomere DNA content (TC), a proxy for telomere length, in macrodissected tissue consisting of 54 normal samples from 5 disease-free prostates, 128 BPH samples from 4 non-cancerous prostates, and 45 tumor, 73 BPH, and 4 prostatic intraepithelial neoplasia (PIN) samples from 5 cancerous prostates.

RESULTS

Compared to TC in normal prostate samples (n = 54; TC mean = 0.98), tumor samples displayed telomere attrition (n = 45; TC mean = 0.67). TC in PIN samples was similar to tumors. TC in BPH samples from cancerous prostates was similar to TC in tumors and also displayed telomere shortening (n = 73; TC mean = 0.76), whereas BPH samples from non-cancerous prostates displayed longer telomeres (n = 128; TC mean = 1.06). In prostates affected by adenocarcinoma, areas of potential telomere attrition occurred in histologically normal tissues through the entire gland. However, three-dimensional zoning revealed a pattern of increasing TC as a function of distance from the primary (index) tumor.

CONCLUSIONS

Spatial distributions of TC in prostate specimens indicate a complex "field effect" with varying contributions from both cancer and BPH. The observation that telomere length variations occur in fields of histologically normal tissues surrounding the tumor is of clinical importance, as it may have implications for the diagnosis and focal therapy of prostate cancer.

The relationship between prostate-specific antigen and prostate cancer risk: the Prostate Biopsy Collaborative Group

PURPOSE

The relationship between prostate-specific antigen (PSA) level and prostate cancer risk remains subject to fundamental disagreements. We hypothesized that the risk of prostate cancer on biopsy for a given PSA level is affected by identifiable characteristics of the cohort under study.

EXPERIMENTAL DESIGN

We used data from five European and three U.S. cohorts of men undergoing biopsy for prostate cancer; six were population-based studies and two were clinical cohorts. The association between PSA and prostate cancer was calculated separately for each cohort using locally weighted scatterplot smoothing.

RESULTS

The final data set included 25,772 biopsies and 8,503 cancers. There were gross disparities between cohorts with respect to both the prostate cancer risk at a given PSA level and the shape of the risk curve. These disparities were associated with identifiable differences between cohorts: for a given PSA level, a greater number of biopsy cores increased the risk of cancer (odds ratio for >6- versus 6-core biopsy, 1.35; 95% confidence interval, 1.18-1.54; P < 0.0005); recent screening led to a smaller increase in risk per unit change in PSA (P = 0.001 for interaction term) and U.S. cohorts had higher risk than the European cohorts (2.14; 95% confidence interval, 1.99-2.30; P < 0.0005).

CONCLUSIONS

Our results suggest that the relationship between PSA and risk of a positive prostate biopsy varies, both in terms of the probability of prostate cancer at a given PSA value and the shape of the risk curve. This poses challenges to the use of PSA-driven algorithms to determine whether biopsy is indicated.

High-risk localized prostate cancer: role of radical prostatectomy

PURPOSE OF REVIEW

The paucity of randomized trials comparing curative management strategies for high-risk prostate cancer makes treatment decisions in this patient population difficult. Although in the past, high-risk patients have primarily been sent for radiation therapy due to concerns that surgery was not likely to be curative and associated with high side-effect profile, there is renewed interest in radical prostatectomy as the primary treatment for high-risk disease.

RECENT FINDINGS

Multiple case series have recently been reported that demonstrate the long-term efficacy of radical prostatectomy in a high-risk population with 15-year prostate cancer-specific survival of over 80%. Comparisons of different treatment options using nonrandomized trials demonstrate improved outcomes with surgery compared with watchful waiting or radiation therapy.

SUMMARY

Radical prostatectomy is an acceptable treatment alterative, which provides long-term durable disease control for men with high-risk prostate carcinoma.

Kallikreins on steroids: structure, function, and hormonal regulation of prostate-specific antigen and the extended kallikrein locus

The 15 members of the kallikrein-related serine peptidase (KLK) family have diverse tissue-specific expression profiles and putative proteolytic functions. The kallikrein family is also emerging as a rich source of disease biomarkers with KLK3, commonly known as prostate-specific antigen, being the current serum biomarker for prostate cancer. The kallikrein locus is also notable because it is extraordinarily responsive to steroids and other hormones. Indeed, at least 14 functional hormone response elements have been identified in the kallikrein locus. A more comprehensive understanding of the transcriptional regulation of kallikreins may help the field make more informed hypotheses about the physiological functions of kallikreins and their effectiveness as biomarkers. In this review, we describe the organization of the kallikrein locus and the structure of kallikrein genes and proteins. We also focus on the transcriptional regulation of kallikreins by androgens, progestins, glucocorticoids, mineralocorticoids, estrogens, and other hormones in animal models and human prostate, breast, and reproductive tract tissues. The interaction of the androgen receptor with androgen response elements in the promoter and enhancer of KLK2 and KLK3 is also summarized in detail. There is evidence that all kallikreins are regulated by multiple nuclear receptors. Yet, apart from KLK2 and KLK3, it is not clear whether all kallikreins are direct transcriptional targets. Therefore, we argue that gaining more detailed information about the mechanisms that regulate kallikrein expression should be a priority of future studies and that the kallikrein locus will continue to be an important model in the era of genome-wide analyses.

A four-kallikrein panel predicts prostate cancer in men with recent screening: data from the European Randomized Study of Screening for Prostate Cancer, Rotterdam

PURPOSE

We have developed a statistical prediction model for prostate cancer based on four kallikrein markers in blood: total, free, and intact prostate-specific antigen (PSA), and kallikrein-related peptidase 2 (hK2). Although this model accurately predicts the result of biopsy in unscreened men, its properties for men with a history of PSA screening have not been fully characterized.

EXPERIMENTAL DESIGN

A total of 1,501 previously screened men with elevated PSA underwent initial biopsy during rounds 2 and 3 of the European Randomized Study of Screening for Prostate Cancer, Rotterdam, with 388 cancers diagnosed. Biomarker levels were measured in serum samples taken before biopsy. The prediction model developed on the unscreened cohort was then applied and predictions compared with biopsy outcome.

RESULTS

The previously developed four-kallikrein prediction model had much higher predictive accuracy than PSA and age alone (area under the curve of 0.711 versus 0.585, and 0.713 versus 0.557 with and without digital rectal exam, respectively; both P < 0.001). Similar statistically significant enhancements were seen for high-grade cancer. Applying the model with a cutoff of 20% cancer risk as the criterion for biopsy would reduce the biopsy rate by 362 for every 1,000 men with elevated PSA. Although diagnosis would be delayed for 47 cancers, these would be predominately low-stage and low-grade (83% Gleason 6 T(1c)).

CONCLUSIONS

A panel of four kallikreins can help predict the result of initial biopsy in previously screened men with elevated PSA. Use of a statistical model based on the panel would substantially decrease rates of unnecessary biopsy.

Changes in Serum Prostate-Specific Antigen Levels after Potassium-Titanyl-Phosphate (KTP) Laser Vaporization of the Prostate

Purpose

The prostate-specific antigen (PSA) level decreases after transurethral resection of the prostate (TURP). However, changes in the PSA level after potassium-titanyl-phosphate (KTP) laser vaporization of the prostate are not well known. The aim of this study was to investigate the effect of KTP laser vaporization of the prostate on PSA levels in patients with benign prostatic hyperplasia (BPH).

Materials and Methods

Serum PSA levels were checked before and 1, 3, 6, and 12 months after the procedure in patients who underwent KTP laser vaporization between October 2004 and August 2008. Patients with prostate cancer, a history of urinary retention, or prostatitis during the follow-up period were excluded. The results for 278 patients were studied.

Results

The mean age of the patients was 69.0±6.7 years (range, 50-91 years) and the mean preoperative PSA level was 2.72±2.93 ng/ml. The PSA level tended to be increased at 1 month after the operation (3.18±3.23 ng/ml, p=0.032) but decreased within 3 months and became stabilized after 6 months at 1.79±1.82 ng/ml (p<0.001).

Conclusions

PSA levels may increase after KTP laser vaporization for a certain period of time, but eventually decrease and become stabilized after 6 months. Therefore, it may be appropriate to wait up to 3 months if the PSA level rises after the procedure, and further investigation should be considered if the PSA level still remains high after 6 months.

Radical prostatectomy: influence on serum and urinary androgen levels

BACKGROUND

The role of the prostate as an active endocrine organ and the hormonal changes after radical prostatectomy (RP) has not been well studied. The objective of this study was to investigate the serum and urine hormonal changes after RP.

METHODS

Fifty-five healthy men with localized prostate cancer were enrolled in this cross-sectional study at a single academic center. We measured serum levels of testosterone, dihydrotestosterone (DHT), sex hormone binding globulin (SHBG), luteinizing hormone (LH), and follicle stimulating hormone (FSH) in all 55 patients preoperatively and in 53 patients 90 days postoperatively. Free testosterone was calculated in all patients. Inhibin B levels was analyzed in 44 patients pre- and postoperatively. Steroid urine profile including testosterone, DHT, 5alpha-androstane-3alpha,17beta-diol (3alphaAdiol), and androsterone (ADT) was also determined preoperatively and 90 days postoperatively in 18 patients.

RESULTS

There were 53% increase in serum LH (P < 0.0001), 21% increase in serum FSH (P < 0.0001), and 13% decrease in DHT levels (P < 0.03). There were no significant changes in any other serum hormone investigated. Urinary levels of DHT glucuronides (DHT-G) decreased by 67% (P < 0.0003) while Androsterone-G and 3alphaAdiol-G increased by 37% (P = 0.019) and 44% (P = 0.023), respectively. There were no alterations in the urinary levels of the other steroids investigated. Inhibin B levels correlated inversely with both FSH (r = -0.67, P < 0.0001) and LH (r = -0.51, P = 0.0004).

CONCLUSION

RP leads to significant increases in serum gonadotropins and significant DHT decrease in both serum and urine. These hormonal changes are independent of inhibin B.

Methylated genes as potential biomarkers in prostate cancer

Prostate cancer is the most common malignancy of the urogenital tract. Although controversial, prostate-specific antigen (PSA) testing is widely used for screening and follow-up of prostate cancer, but because of its limited specificity and sensitivity, PSA is not an ideal test. We currently lack the necessary tools to differentiate between latent disease with little likelihood of clinical manifestation and aggressive tumours that are likely to metastasize and lead to potentially lethal disease. DNA methylation is an important epigenetic mechanism of gene regulation and plays essential roles in tumour initiation and progression. Currently, aberrant promoter hypermethylation has been investigated in specific genes from the following groups: tumour-suppressor genes, proto-oncogenes, genes involved in cell adhesion, and genes involved in cell-cycle regulation. Glutathione S-transferase P1 (GSTP1) has been shown to be a biomarker for prostate cancer. Other genes, e.g. CD44, PTGS2, E-cadherin, CDH13, and cyclin D2 have been found to be prognostic markers for prostate cancer. In cell samples derived from the urine, the presence of the hypermethylation of either GSTP1 or RASS1a has been shown to be both sensitive and specific for detecting prostate cancer. Several studies have found that analysis of hypermethylation using a panel of tumour-suppressor genes yielded better results for detecting prostate cancer than the analysis of single-gene methylation. Hence, these different panels (e.g. GSTP1, APC, PTGS2, T1G1 and EDNRB) are of interest for detecting prostate cancer. Also, the methylation profile of multiple regulatory genes might be altered at the time of cancer relapse. Thus, preliminary results on the use of the methylation status of specific genes as potential tumour biomarkers for the early diagnosis and the risk stratification of patients with prostate cancer are promising.

Clinical stage T1c prostate cancer: evaluation with endorectal MR imaging and MR spectroscopic imaging

PURPOSE

To assess the diagnostic accuracy of endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging for prediction of the pathologic stage of prostate cancer and the presence of clinically nonimportant disease in patients with clinical stage T1c prostate cancer.

MATERIALS AND METHODS

The institutional review board approved-and waived the informed patient consent requirement for-this HIPAA-compliant study involving 158 patients (median age, 58 years; age range, 40-76 years) who had clinical stage T1c prostate cancer, had not been treated preoperatively, and underwent combined 1.5-T endorectal MR imaging-MR spectroscopic imaging between January 2003 and March 2004 before undergoing radical prostatectomy. On the MR images and combined endorectal MR-MR spectroscopic images, two radiologists retrospectively and independently rated the likelihood of cancer in 12 prostate regions and the likelihoods of extracapsular extension (ECE), seminal vesicle invasion (SVI), and adjacent organ invasion by using a five-point scale, and they determined the probability of clinically nonimportant prostate cancer by using a four-point scale. Whole-mount step-section pathology maps were used for imaging-pathologic analysis correlation. Receiver operating characteristic curves were constructed and areas under the curves (AUCs) were estimated nonparametrically for assessment of reader accuracy.

RESULTS

At surgical-pathologic analysis, one (0.6%) patient had no cancer; 124 (78%) patients, organ-confined (stage pT2) disease; 29 (18%) patients, ECE (stage pT3a); two (1%) patients, SVI (stage pT3b); and two (1%) patients, bladder neck invasion (stage pT4). Forty-six (29%) patients had a total tumor volume of less than 0.5 cm(3). With combined MR imaging-MR spectroscopic imaging, the two readers achieved 80% accuracy in disease staging and AUCs of 0.62 and 0.71 for the prediction of clinically nonimportant cancer.

CONCLUSION

Clinical stage T1c prostate cancers are heterogeneous in pathologic stage and volume. MR imaging may help to stratify patients with clinical stage T1c disease for appropriate clinical management.

Other biomarkers for detecting prostate cancer

Prostate-specific antigen (PSA) has been used for detecting prostate cancer since 1994. Although it is the best cancer biomarker available, PSA is not perfect. It lacks both the sensitivity and specificity to accurately detect the presence of prostate cancer. None of the PSA thresholds currently in use consistently identify patients with prostate cancer and exclude patients without cancer. Novel approaches to improve our ability to detect prostate cancer and predict the course of the disease are needed. Additional methods for detecting prostate cancer have been evaluated. Despite the discovery of many new biomarkers, only a few have shown some clinical value. These markers include human kallikrein 2, urokinase-type plasminogen activator receptor, prostate-specific membrane antigen, early prostate cancer antigen, PCA3, alpha-methylacyl-CoA racemase and glutathione S-transferase pi hypermethylation. We review the reports on biomarkers for prostate cancer detection, and their possible role in the clinical practice.

Characteristics of prostate cancers found in specimens removed by radical cystoprostatectomy for bladder cancer and their relationship with serum prostate-specific antigen level

Prostate cancer mass screening using serum prostate-specific antigen (PSA) has been conducted widely in the world. However, little is known about the true prevalence of prostate cancer in the 'normal' PSA range (4.0 ng/mL or less). The aim of the present study was to elucidate the clinicopathological features of prostate cancer occurring in men with a wide range of PSA levels. The study comprised 349 male patients who underwent radical cystoprostatectomy for bladder cancer. Patients who had had treatment for known prostate cancer were excluded. Tissue specimens were reviewed microscopically. Ninety-one patients (26.1%) were found to have prostate cancer, and 68 (74.7%) of these 91 cancers were considered to be clinically significant. Both increasing patient age and PSA level were significantly correlated with an increased incidence of both all and significant prostate cancers. Sixty-five (21.9%) among 297 patients with PSA < 4.0 ng/mL had prostate cancer, and 45 (69.2%) of the 65 cancers were significant cancers. Eighteen patients had prostate cancers 0.5 mL or more in volume. Among the 18 patients, the PSA level was 4 ng/mL or more in 11, and 3 ng/mL or more in 15. Our study shows that prostate cancer is a common finding in radical cystoprostatectomy specimens excised because of bladder cancers, and a significant proportion of these cancers are clinically significant. PSA still appears to be a useful screening tool for detecting prostate cancers with significant volume.