Predictive modeling for the presence of prostate carcinoma using clinical, laboratory, and ultrasound parameters in patients with prostate specific antigen levels ? 10 ng/mL

The role of the digital rectal examination in subsequent screening visits in the European randomized study of screening for prostate cancer (ERSPC), Rotterdam

BACKGROUND

The value of digital rectal examination (DRE) as a screening test for prostate cancer (PC) is controversial in the current prostate-specific antigen (PSA) era.

OBJECTIVES

To determine (1) the additional value of a suspicious DRE for the detection of PC in men with an elevated PSA level in subsequent screenings and (2) the tumour characteristics of PCs detected in men with a suspicious DRE.

DESIGN, SETTING, PARTICIPANTS

Within the screening study, from 1997-2006 men aged 55-75 years were invited for an every 4-yr PSA determination. A PSA level > or =3.0ng/ml prompted a DRE and a transrectal ultrasound (TRUS)-guided, lateralized sextant biopsy. Throughout the three screenings of the ERSPC, Rotterdam, 5040 biopsy sessions were evaluated.

MEASUREMENTS

We determined the positive predictive values (PPVs) of a suspicious DRE and normal DRE, which entailed, respectively, the proportion of PCs detected in men with a suspicious DRE or normal DRE divided by, respectively, all biopsied men with a suspicious DRE or normal DRE.

RESULTS AND LIMITATIONS

At initial screening, the PPV of a suspicious DRE, in conjunction with an elevated PSA level, to detect PC was 48.6% compared to 22.4% for men with a normal DRE. Both PPVs decreased in consecutive screens: respectively, 29.9% versus 17.1% (screen 2) and 21.2% versus 18.2% (screen 3). Respectively, 71.0% (p<0.001), 68.8% (p<0.001), and 85.7% (p=0.002) of all PCs with a Gleason score >7 were detected in men with a suspicious DRE at screens 1, 2, and 3. A limitation is that only biopsied men were evaluated.

CONCLUSIONS

At initial and subsequent screenings, the chance of having cancer at biopsy was higher in men with a suspicious DRE compared to men with a normal DRE (to a lesser extent in subsequent screenings), and the combination of a PSA level > or =3.0ng/ml with a suspicious DRE resulted in detecting significantly more PCs with Gleason score >7. DRE may be useful in more selective screening procedures to decrease unnecessary biopsies and overdiagnosis.

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.

Comparison of two different artificial neural networks for prostate biopsy indication in two different patient populations

OBJECTIVES

Different artificial neural networks (ANNs) using total prostate-specific antigen (PSA) and percentage of free PSA (%fPSA) have been introduced to enhance the specificity of prostate cancer detection. The applicability of independently trained ANN and logistic regression (LR) models to different populations regarding the composition (screening versus referred) and different PSA assays has not yet been tested.

METHODS

Two ANN and LR models using PSA (range 4 to 10 ng/mL), %fPSA, prostate volume, digital rectal examination findings, and patient age were tested. A multilayer perceptron network (MLP) was trained on 656 screening participants (Prostatus PSA assay) and another ANN (Immulite-based ANN [iANN]) was constructed on 606 multicentric urologically referred men. These and other assay-adapted ANN models, including one new iANN-based ANN, were used.

RESULTS

The areas under the curve for the iANN (0.736) and MLP (0.745) were equal but showed no differences to %fPSA (0.725) in the Finnish group. Only the new iANN-based ANN reached a significant larger area under the curve (0.77). At 95% sensitivity, the specificities of MLP (33%) and the new iANN-based ANN (34%) were significantly better than the iANN (23%) and %fPSA (19%). Reverse methodology using the MLP model on the referred patients revealed, in contrast, a significant improvement in the areas under the curve for iANN and MLP (each 0.83) compared with %fPSA (0.70). At 90% and 95% sensitivity, the specificities of all LR and ANN models were significantly greater than those for %fPSA.

CONCLUSIONS

The ANNs based on different PSA assays and populations were mostly comparable, but the clearly different patient composition also allowed with assay adaptation no unbiased ANN application to the other cohort. Thus, the use of ANNs in other populations than originally built is possible, but has limitations.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Potential predictive factors of positive prostate biopsy in the Japanese population

INTRODUCTION

There are numerous arguments for the predictive factors of positive prostate biopsies, differing according to race and region. This study aimed to determine predictive factors for a positive prostate biopsy in East Asian, especially Japanese men, using clinical, laboratory, and transrectal ultrasound (TRUS) findings.

METHODS

Data were collected from 466 men who underwent a prostate biopsy for suspected prostate cancer. Variables analyzed including age, digital rectal examination (DRE) findings, prostate-specific antigen (PSA) level, PSA density, prostate volume, and TRUS findings. Logistic regression analysis and the Mann-Whitney U test were used for this study.

RESULTS

Logistic regression analysis showed that significant predictors for a positive prostate biopsy for all patients were positive DRE results, prostate volume, and hypoechoic lesions on TRUS. Especially in the patients with PSA levels <10 ng/ml, the significant predictor for positive biopsy was prostate volume. The Mann-Whitney U test showed that significant predictors for a positive prostate biopsy in all patients were PSA density >0.15, positive DRE results, and prostate volume <25 cm(3). Especially in patients with PSA levels <10 ng/ml, significant predictors for a positive prostate biopsy were prostate volume <25 cm(3) and PSA density >0.15. Additionally, even if the data were confined to those patients with seven or more core biopsies, all the predictive factors shown in all patients were significant predictors in this category.

CONCLUSION

This study investigated potential predictors for positive prostate biopsy and demonstrated that prostate volume was an independent predictive factor for positive prostate biopsy in patients with PSA levels <10 ng/ml. In the future, we may be able to use our findings to create a nomogram for predicting positive prostate biopsy in Japanese men.

Assessment of Prostate-Specific Antigen Doubling Time in Prediction of Prostate Cancer on Needle Biopsy

OBJECTIVES

Prostate-specific antigen (PSA) kinetics have failed to predict for the presence of prostate cancer in screening populations in which many patients harbor subclinical disease. We hypothesized that the prebiopsy PSA doubling time (PSADT) and PSA velocity (PSAV) could predict for cancer detection in a referral population with a suspicion of prostate cancer.

METHODS

Data were collected from 1699 consecutive veterans with a PSA level of 10 ng/mL or less who underwent prostate biopsy. Logistic regression analysis was performed on the following: age, race, family history, digital rectal examination findings, PSA, PSA density, PSADT, PSAV, prostate volume, and ultrasound lesions. Model building was accomplished with 70% of the data, and validation was done using the remaining 30%. These data were also analyzed using classification and regression tree analysis.

RESULTS

Using logistic regression analysis (P <0.05) on the model building set, prostate cancer was associated with age (older than 70 years), PSA level (greater than 2.9 ng/mL), PSA density (more than 0.12 ng/mL/cm3), digital rectal examination findings, and the presence of a lesion on ultrasonography. A PSADT of 2 to 5 years was marginally associated with prostate cancer detection (odds ratio 1.6, 95% confidence interval 1.1 to 2.3), and a PSADT of less than 2 years or longer than 5 years and PSAV were not predictive. On classification and regression tree analysis, PSADT was not selected as a predictive factor. Furthermore, neither PSADT nor PSAV was predictive of Gleason score 7 or worse cancer.

CONCLUSIONS

In contrast to its prognostic value after the diagnosis of prostate cancer has been established, PSA kinetics offer little to clinical decision making as predictors of cancer or high-grade cancer in men with a PSA level of 10 ng/mL or less.

PSA and new biomarkers within multivariate models to improve early detection of prostate cancer

This review gives an overview of the use of prostate-specific antigen (PSA) and percent free-PSA (%fPSA)-based artificial neural networks (ANNs) and logistic regression models (LR) to reduce unnecessary prostate biopsies. There is a clear advantage in including clinical data such as age, digital rectal examination and transrectal ultrasound (TRUS) variables like prostate volume and PSA density as additional factors to tPSA and %fPSA within ANNs and LR models. There is also positive impact of tPSA and fPSA assays on the outcome of ANNs. New markers provide additional value within ANNs but to prove their clinical usefulness further testing is necessary.

The value of different screening tests in predicting prostate biopsy outcome in screening for prostate cancer data from a multicenter study (ERSPC)

BACKGROUND

Although serum PSA testing is widely used as a screening test for prostate cancer (PC), it is known that it is not specific for PC. The study described here focuses on the value of screening tests next to PSA in identifying men with an elevated risk of having PC and the differences between three centers of the European Randomised study of Screening for Prostate Cancer (ERSPC).

METHODS

The study population consists of 2,483 men with a PSA > or =4.0 ng/ml, all biopsied. We assessed data on age, serum PSA level at initial and repeat screening, prostate volume, number of positive DRE and TRUS findings, number of previous negative biopsies, and PPV of the three centers and overall. Using logistic regression analysis, predictors for biopsy outcome at repeat screening in men with a PSA value > or =4.0 ng/ml were determined on the complete dataset and per center.

RESULTS

In 2,483 men biopsied, 665 cancers were detected (PPV = 26.8%). Data show that all predictors except prostate volume loose their predictive value in men previously biopsied. In men not previously biopsied, the predictive value of DRE and TRUS vary considerably among the three centers.

CONCLUSIONS

Looking at the differences in the predictive value of screening tests in three "comparable" centers, generasibility is not as straightforward as it seems. Using a nomogram for predictive purposes developed elsewhere will require a thorough knowledge of the patient population of which it is derived, and one should interpret its results with a critical mind.

Free PSA isoforms and intact and cleaved forms of urokinase plasminogen activator receptor in serum improve selection of patients for prostate cancer biopsy

Clinicians currently use simple cut-points, such as serum prostate-specific antigen (PSA) >or=4 ng/ml, to decide whether to recommend further work-up for prostate cancer (PCa). As an alternative strategy, we evaluated multivariable models giving probabilities of a PCa diagnosis based on PSA and several circulating novel biomarkers. We measured total PSA, free PSA (fPSA), fPSA subfractions (single-chain fPSA-I and multichain fPSA-N), total human glandular kallikrein 2 (hK2) and full-length and cleaved forms of soluble urokinase plasminogen activator receptor (suPAR) in pretreatment serum from 355 men referred for prostate biopsy. Age and total PSA were combined in a "base" regression model to predict biopsy outcome. We then compared this base model to models supplemented by various combinations of circulating markers, using concordance index (AUC) to measure diagnostic discrimination. PCa prediction was significantly enhanced by models supplemented by measurements of suPAR fragments and fPSA isoforms. Addition of these markers improved bootstrap-corrected AUC from 0.611 for a cut-point and 0.706 for the base model to 0.754 for the full model (p=0.005). This improved diagnostic accuracy was also seen in subanalysis of patients with PSA 2-9.99 ng/ml and normal findings on DRE (0.652 vs. 0.715, p=0.039). In this setting, hK2 did not add diagnostic information. Measurements of individual forms of suPAR and PSA isoforms contributed significantly to discrimination of men with PCa from those with no evidence of malignancy.

External validation of the Prostate Cancer Prevention Trial risk calculator in a screened population

OBJECTIVES

To evaluate the recently developed Prostate Cancer Prevention Trial (PCPT) prostate cancer risk calculator in the San Antonio Center of Biomarkers of Risk for Prostate Cancer (SABOR) cohort of the Early Detection Research Network, a younger and more ethnically diverse population than that in the PCPT.

METHODS

From 3488 SABOR participants, we identified 446 who had undergone prostate biopsy and had undergone prostate-specific antigen measurement and digital rectal examination before biopsy. Most biopsies were performed for abnormal digital rectal examination findings, a prostate-specific antigen level of more than 2.5 ng/mL, or elevated risk because of a first-degree relative with prostate cancer. We evaluated the operating characteristics of the PCPT calculator for detecting prostate cancer in this cohort of SABOR participants. Of the 446 men in this cohort, 24% were younger than 55 years of age.

RESULTS

Of the 446 men who had undergone biopsy, 148 (33.2%) had prostate cancer. The observed SABOR prostate cancer rates increased with increasing PCPT risk: 15.7%, 39.0%, 48.8%, and 100.0% for a PCPT risk calculator value of less than 25%, 25% to 50%, 50% to 75%, and greater than 75%, respectively. The PCPT risk calculator had an area under the receiver operating characteristic curve of 65.5% (95% confidence interval 60.2% to 70.8%, P < 0.0001), was greater in African-American men (area under curve of 80.0%, 95% confidence interval 67.8% to 92.2%) than in other races (P = 0.02), and was not different in Hispanic men (P > 0.05).

CONCLUSIONS

The results of our study have shown that the PCPT risk calculator, available from the Internet and incorporating the current best panel of risk factors, is valid in other, more diverse, populations.

An abnormal digital rectal examination is an independent predictor of Gleason > or =7 prostate cancer in men undergoing initial prostate biopsy: a prospective study of 790 men

OBJECTIVE

To evaluate our experience with a referral population of 790 patients undergoing initial prostate biopsy in the prostate-specific antigen (PSA) era, to assess the role of a digital rectal examination (DRE) in predicting the outcome of prostate needle biopsy (PNB) and to evaluate if DRE findings were associated with cancer grade.

PATIENTS AND METHODS

We analysed 790 consecutive men who had an initial PNB from September 1999 to July 2005 by one urologist (C.P.). All data were collected in a prospective database. Multivariate logistic regression analysis was used to determine the relationship between an abnormal DRE and the presence of cancer and cancer grade on PNB.

RESULTS

An abnormal DRE was an independent predictor for prostate cancer on multivariate analysis (odds ratio 2.18, 95% confidence interval 1.53-3.10, P < 0.001). In all patients biopsied, an abnormal DRE was associated with a Gleason sum of > or = 7 on multivariate analysis (odds ratio 3.39, 2.07-5.53, P = 0.001).

CONCLUSION

A DRE is a useful and important tool to use when assessing patients for a PNB. An abnormal DRE independently predicted high-grade disease in these men. These results might have important implications in the prediction of men with other than indolent prostate cancer.

African-American race is a predictor of prostate cancer detection: incorporation into a pre-biopsy nomogram

OBJECTIVES

To construct a pre-biopsy predictive model incorporating several clinical variables, including African-American (AA) or Caucasian race, to predict the risk of prostate cancer detection on prostate biopsy, as traditionally AA men have had a higher incidence of prostate cancer than Caucasian men, but previous predictive tools for prostate cancer have not incorporated the effect of race.

PATIENTS AND METHODS

We evaluated 9473 patients undergoing initial prostate biopsy at three equal-access healthcare institutes from 1993 to 2003. At each biopsy session, patient age, race, serum prostate-specific antigen level (PSA), digital rectal examination (DRE) findings, number of biopsy cores taken, year of biopsy, and pathological findings were recorded. A logistic regression model was constructed to evaluate predictors of cancer detection based on pre-biopsy variables. The model was internally validated using the bootstrap statistical method, and a nomogram was constructed.

RESULTS

Prostate cancer was diagnosed in 1895 (33%) AA men and 991 (26%) Caucasians. AA men had a significantly higher mean serum PSA level than Caucasians, at 13.0 and 8.5 ng/mL, respectively (P < 0.001). The mean ages were similar between AA and Caucasian men (P = 0.23), but Caucasian men had a higher incidence of an abnormal DRE (P < 0.001). On multivariate analysis, age, race, year of biopsy, PSA level, DRE, and number of cores taken were all statistically significant (P < 0.001). Hazard ratios were (controlling for year of biopsy); age (1.30), Caucasian race (0.74), PSA level (1.47), DRE (1.75), and number of cores taken (1.19). The predicted model had a boot-strapped concordance index of 0.75.

CONCLUSION

AA race remains an independent predictor of prostate cancer detection in men undergoing initial prostate biopsy. This nomogram is the first to individualise the risk by AA or Caucasian race in a predictive model for counselling men on their probability of having cancer at the time of their first biopsy.

Prostate cancer nomograms: an update

OBJECTIVE

Several nomograms have been developed to predict outcomes related to prostate cancer (PCa).

METHODS

We provide a descriptive and an analytic comparison of nomograms. Further, we report a set of recent PCa nomograms, in which we recorded predictor variables, number of patients used to develop each nomogram, and nomogram-specific features. Moreover, accuracy estimates and type of validation are considered.

RESULTS

Our findings suggest a demand for updated nomograms in selected fields of PCa outcomes. Moreover, an increasing number of nomograms address important end points such as prostate-specific antigen recurrence, distant metastases, or androgen-independent PCa-specific survival.

CONCLUSION

Our results suggest that nomograms are available for many PCa-related outcomes. They represent a valid methodologic approach if correct criteria are met.

Initial biopsy outcome prediction--head-to-head comparison of a logistic regression-based nomogram versus artificial neural network

OBJECTIVES

Nomograms and artificial neural networks (ANNs) represent alternative methodologic approaches to predict the probability of prostate cancer on initial biopsy. We hypothesized that, in a head-to-head comparison, one of the approaches might demonstrate better accuracy and performance characteristics than the other.

METHODS

A previously published nomogram, which relies on age, digital rectal examination, serum prostate-specific antigen (PSA), and percent-free PSA, and an ANN, which relies on the same predictors plus prostate volume, were applied to a cohort of 3980 men, who were subjected to multicore systematic prostate biopsy. The accuracy and the performance characteristics were compared between these two approaches.

RESULTS

The accuracy of the nomogram was 71% versus 67% for the ANN (p=0.0001). Graphical exploration of the performance characteristics demonstrated virtually perfect predictions for the nomogram. Conversely, the ANN underestimated the observed rate of prostate cancer.

CONCLUSIONS

A 4% increase in predictive accuracy implies that the use of the nomogram instead of the ANN will result in 40 additional patients who will be correctly classified between benign and cancer.

A comparison of first and repeat (four years later) prostate cancer screening in a randomized cohort of a symptomatic men aged 55-75 years using a biopsy indication of 3.0 ng/ml (results of ERSPC, Rotterdam)

BACKGROUND

The identification of predictors for prostate biopsy outcome at two screening rounds using a PSA>or=3.0 ng/ml as biopsy indication.

MATERIALS AND METHODS

We compared predictors by means of descriptive statistics and logistic regression analysis in men (55-75 years) biopsied in either the 1st or 2nd screening round of ERSPC Rotterdam (interval 4 years).

RESULTS

Positive predictors for biopsy outcome in both screening rounds were an increased PSA level in the absence of a previous negative biopsy (PrevNB), DRE and TRUS suspicious and a positive family history (PFH). A higher than median prostate volume was a consistent negative predictor. Having had a PrevNB at initial screening strongly reduced the chance of cancer detection at repeat screening and in addition canceled the predictive potential of PSA.

CONCLUSION

If "detecting prostate cancer efficiently" were the aim, this study indicates that a "PSA only based biopsy threshold" may be replaced by another criterion incorporating, e.g., DRE, TRUS and prostate volume in men who were biopsied in the preceding 4 year interval.

Nanomedicine

The intricate problems associated with the delivery and various unnecessary in vivo transitions of proteins and drugs needs to be tackled soon to be able to exploit the myriad of putative therapeutics created by the biotechnology boom. Nanomedicine is one of the most promising applications of nanotechnology in the field of medicine. It has been defined as the monitoring, repair, construction and control of human biological systems at the molecular level using engineered nanodevices and nanostructures. These nanostructured medicines will eventually turn the world of drug delivery upside down. PEGylation (i.e. the attachment of polyethylene glycol to proteins and drugs) is an upcoming methodology for drug development and it has the potential to revolutionise medicine by drastically improving the pharmacokinetic and pharmacodynamic properties of the administered drug. This article provides a total strategy for improving the therapeutic efficacy of various biotechnological products in drug delivery. This article also presents an extensive analysis of most of the PEGylated proteins, peptides and drugs, together with extensive clinical data. Nanomedicines and PEGylation, the latest offshoots of nanotechnology will definitely pave a way in the field of drug delivery where targeted delivery, formulation, in vivo stability and retention are the major challenges.

Development of a nomogram to predict probability of positive initial prostate biopsy among Japanese patients

OBJECTIVES

Several nomograms for prostate cancer detection have recently been developed. Because the incidence of prostate cancer is lower among Asian men, nomograms based on Western populations cannot be directly applied to Japanese men. We, therefore, developed a model for predicting the probability of a positive initial prostate biopsy using clinical and laboratory data from a Japanese male population.

METHODS

Data were collected from 834 Japanese male referrals who underwent initial prostate biopsies as individual screening. We analyzed age, total prostate-specific antigen (PSA) level, free/total PSA (f/t PSA) ratio, prostate volume, and digital rectal examination findings. Of these data, we randomly reserved 20% for study validation. Logistic regression analysis estimated relative risk, 95% confidence intervals, and P values.

RESULTS

Independent predictors of a positive biopsy result included elevated PSA levels, decreased f/T PSA ratio, advanced age, small prostate volume, and abnormal digital rectal examination findings. We developed a predictive nomogram for an initial positive biopsy using these variables. The area under the receiver operating characteristic curve for the model was 81.8%, which was significantly greater than that of the prediction based on PSA alone (area under the receiver operating characteristic curve 67.8%). If externally validated, applying this model could reduce unnecessary biopsy procedures by 32% and reduce the overall need for prostate biopsies by 26%.

CONCLUSIONS

In this study of a Japanese population, incorporating clinical and laboratory data into a prebiopsy nomogram significantly improved the prediction of prostate cancer compared with predictions based solely on the individual factors.

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.

Recent advances on multiple tumorigenic cascades involved in prostatic cancer progression and targeting therapies

Recent advances on differently-expressed gene products and their functions during the progression from localized androgen-dependent states into androgen-independent and metastatic forms of prostate cancer are reported. The expression levels of numerous oncogenes and tumor suppressor genes in distinct prostatic cancer epithelial cell lines and tissues relative to normal prostate cells are described. This is carried out to identify the signaling elements that are altered during the initiation, progression and metastatic process of prostate cancer. Additional information on the interactions between certain deregulated signaling pathways such as androgen receptor (AR), estrogen receptors, epidermal growth factor receptor (EGFR), hedgehog and Wnt/beta-catenin cascades in controlling the proliferation, survival and invasion of tumor prostate epithelial cells during the disease progression is described. The emphasis is on the critical functions of the AR and EGF-EGFR systems at all stages during prostate carcinogenesis. Of therapeutic interest, new strategies for the diagnosis and treatment of localized and metastatic forms of prostate cancer by targeting multiple tumorigenic signaling elements are also reported.

Development and validation of a nomogram predicting the outcome of prostate biopsy based on patient age, digital rectal examination and serum prostate specific antigen

PURPOSE

We developed and validated a nomogram which predicts presence of prostate cancer (PCa) on needle biopsy.

MATERIALS AND METHODS

We used 3 cohorts of men who were evaluated with sextant biopsy of the prostate and whose presenting prostate specific antigen (PSA) was not greater than 50 ng/ml. Data from 4,193 men from Montreal, Canada were used to develop a nomogram based on age, digital rectal examination (DRE) and serum PSA. External validation was performed on 1,762 men from Hamburg, Germany. Data from these men were subsequently used to develop a second nomogram in which percent free PSA (%fPSA) was added as a predictor. External validation was performed using 514 men from Montreal. Both nomograms were based on multivariate logistic regression models. Predictive accuracy was evaluated with areas under the receiver operating characteristic curve and graphically with loess smoothing plots.

RESULTS

PCa was detected in 1,477 (35.2%) men from Montreal, 739 (41.9%) men from Hamburg and 189 (36.8%) men from Montreal. In all models all predictors were significant at 0.05. Using age, DRE and PSA external validation AUC was 0.69. Using age, DRE, PSA and %fPSA external validation AUC was 0.77.

CONCLUSIONS

A nomogram based on age, DRE, PSA and %fPSA can highly accurately predict the outcome of prostate biopsy in men at risk for PCa.

Improved detection of prostate cancer using classification and regression tree analysis

PURPOSE

To build a decision tree for patients suspected of having prostate cancer using classification and regression tree (CART) analysis.

PATIENTS AND METHODS

Data were uniformly collected on 1,433 referred men with a serum prostate-specific antigen (PSA) levels of < or = 10 ng/mL who underwent a prostate biopsy. Factors analyzed included demographic, laboratory, and ultrasound data (ie, hypoechoic lesions and PSA density [PSAD]). Twenty percent of the data was randomly selected and reserved for study validation. CART analysis was performed in two steps, initially using PSA and digital rectal examination (DRE) alone and subsequently using the remaining variables.

RESULTS

CART analysis selected a PSA cutoff of more than 1.55 ng/mL for further work-up, regardless of DRE findings. CART then selected the following subgroups at risk for a positive biopsy: (1) PSAD more than 0.165 ng/mL/cc; (2) PSAD < or = 0.165 ng/mL/cc and a hypoechoic lesion; (3) PSAD < or = 0.165 ng/mL/cc, no hypoechoic lesions, age older than 55.5 years, and prostate volume < or = 44.0 cc; and (4) PSAD < or = 0.165 ng/mL/cc, no hypoechoic lesions, age older than 55.5 years, and 50.25 cc less than prostate volume < or = 80.8 cc. In the validation data set, specificity and sensitivity were 31.3% and 96.6%, respectively. Cancers that were missed by the CART were Gleason score 6 or less in 93.4% of cases. Receiver operator characteristic curve analysis showed that CART and logistic regression models had similar accuracy (area under the curve = 0.74 v 0.72, respectively).

CONCLUSION

Application of CART analysis to the prostate biopsy decision results in a significant reduction in unnecessary biopsies while retaining a high degree of sensitivity when compared with the standard of performing a biopsy of all patients with an abnormal PSA or DRE.

Nomographic representation of logistic regression models: a case study using patient self-assessment data

Logistic regression models are widely used in medicine, but difficult to apply without the aid of electronic devices. In this paper, we present a novel approach to represent logistic regression models as nomograms that can be evaluated by simple line drawings. As a case study, we show how data obtained from a questionnaire-based patient self-assessment study on the risks of developing melanoma can be used to first identify a subset of significant covariates, build a logistic regression model, and finally transform the model to a graphical format. The advantage of the nomogram is that it can easily be mass-produced, distributed and evaluated, while providing the same information as the logistic regression model it represents.

Digital rectal examination (DRE) does not influence total serum levels of prostate specific antigen (tPSA), in individuals without prostate pathology

OBJECTIVE

To evaluate if the digital rectal examination (DRE) performed before determination of total serum prostate specific antigen (tPSA) influences the levels of this protein.

MATERIALS AND METHODS

Forty-eight men without a diagnosis of prostate pathology were assessed for tPSA levels, before and 30 minutes after DRE examination. Values of tPSA in the individuals' serum were measured by the electrochemoluminescence (ECLIA), in Roche's Elecys 1010 analyzer.

RESULTS

DRE examination induced a modest elevation in tPSA values in 34 of the 48 men, with a variation in mean elevation from 2.19% in the age range >/= 70 years to 11.96% in the age range of 60-69 years. Additionally, moderate decreases in values were detected in 11 individuals and 3 did not present any alteration following the procedure. Differences in mean values of tPSA, pre- and post-DRE were not statistically significant, neither in the total sample of individuals or in the age range groups.

CONCLUSION

DRE examination does not significantly influence the tPSA values in individuals under study.

A Histopathologic Screening Method for Rational Use of Organs from Prostate-Specific Antigen-Positive Multiorgan Donors: The Italian Emilia-Romagna Region Experience

Reduction of waiting-list length requires extension of the organ-donor pool to elderly males bearing an higher risk of prostate cancer incidence. Prostate-cancer screening in organ donors is currently based on prostate-specific antigen (PSA) assays (total PSA and free/total PSA). However, the specificity of these assays is restricted, limiting risk-benefit analysis. Since 2001, 33 multiorgan donor candidates presenting within Emilia-Romagna (Italy) with suspect ultrasonography or abnormal PSA values were submitted to a histopathologic screening method of the entire prostate based on extemporary frozen-section analysis (maximum 1 hour) of over 50% of the organ at 0.1 mm cutting levels. Extemporary diagnosis of adenocarcinoma was made in 12 (36%) cases, corresponding to 4.5% of the male candidates aged more than 50 years in the donor pool. In all cases, the final diagnosis confirmed the extemporary analysis. As well as maximizing safety, this novel approach should permit more refined risk-benefit analysis.

Efficacy of transferrin-conjugated paclitaxel-loaded nanoparticles in a murine model of prostate cancer

Chemotherapy remains the preferred choice of treatment for prostate cancer but modest drug response and significant toxicity by conventional methods of administration limit their efficacy. In our study, we determined the efficacy of paclitaxel (Tx)-loaded biodegradable nanoparticles (NPs) on tumor inhibition. We hypothesized that NPs following conjugation to transferrin (Tf) ligand (NPs-Tf) would enhance the therapeutic efficacy of the encapsulated drug. The antiproliferative activity of NPs was determined in human prostate cancer cell line (PC3) and their effect on tumor inhibition in a murine model of prostate cancer. NPs (approximately 220 nm in diameter, 5.4% w/w drug loading) under in vitro conditions exhibited sustained release of the encapsulated drug (60% release in 60 days). The IC50 (concentration of drug for 50% inhibition of cell growth) of the drug with Tf-conjugated NPs (Tx-NPs-Tf) was about 5-fold lower than that with unconjugated NPs (Tx-NPs) or drug in solution. Animals that received a single-dose intratumoral injection of Tx-NPs-Tf (Tx dose= 4 mg/kg) demonstrated complete tumor regression and greater survival rate than those that received either Tx-NPs or Tx-Cremophor EL formulation. In conclusion, sustained release NPs demonstrated greater antitumor activity following their conjugation to Tf ligand.