Staging of early prostate cancer: a proposed tumor volume-based prognostic index

Quantitative magnetic resonance imaging in prostate cancer: A review of current technology

Prostate cancer (PCa) imaging forms an important part of PCa clinical management. Magnetic resonance imaging is the modality of choice for prostate imaging. Most of the current imaging assessment is qualitative i.e., based on visual inspection and thus subjected to inter-observer disagreement. Quantitative imaging is better than qualitative assessment as it is more objective, and standardized, thus improving interobserver agreement. Apart from detecting PCa, few quantitative parameters may have potential to predict disease aggressiveness, and thus can be used for prognosis and deciding the course of management. There are various magnetic resonance imaging-based quantitative parameters and few of them are already part of PIRADS v.2.1. However, there are many other parameters that are under study and need further validation by rigorous multicenter studies before recommending them for routine clinical practice. This review intends to discuss the existing quantitative methods, recent developments, and novel techniques in detail.

Prostate MRI percentage tumor involvement or "PI-RADS percent" as a predictor of adverse surgical pathology

BACKGROUND

This study assesses magnetic resonance imaging (MRI) prostate % tumor involvement or "PI-RADs percent" as a predictor of adverse pathology (AP) after surgery for localized prostate cancer (PCa). Two separate variables, "All PI-RADS percent" (APP) and "Highest PI-RADS percent" (HPP), are defined as the volume of All PI-RADS 3-5 score lesions on MRI and the volume of the Highest PI-RADS 3-5 score lesion each divided by TPV, respectively.

METHOD

An analysis was done of an IRB approved prospective cohort of 557 patients with localized PCa who had targeted biopsy of MRI PIRADs 3-5 lesions followed by RARP from April 2015 to May 2020 performed by a single surgeon at a single center. AP was defined as ISUP GGG ≥3, pT stage ≥T3 and/or LNI. Univariate and multivariable analyses were used to evaluate APP and HPP at predicting AP with other clinical variables such as Age, PSA at surgery, Race, Biopsy GGG, mpMRI ECE and mpMRI SVI. Internal and External Validation demonstrated predicted probabilities versus observed probabilities.

RESULTS

AP was reported in 44.5% (n = 248) of patients. Multivariable regression showed both APP (odds ratio [OR]: 1.10, 95% confidence interval [CI]: 1.04-1.14, p = 0.0007) and HPP (OR: 1.10; 95% CI: 1.04-1.16; p = 0.0007) were significantly associated with AP with individual area under the operating curves (AUCs) of 0.6142 and 0.6229, respectively, and AUCs of 0.8129 and 0.8124 when incorporated in models including preoperative PSA and highest biopsy GGG.

CONCLUSIONS

Increasing PI-RADS Percent was associated with a higher risk of AP, and both APP and HPP may have clinical utility as predictors of AP in GGG 1 and 2 patients being considered for AS.

PATIENT SUMMARY

Using PIRADs percent to predict AP for presurgical patients may help risk stratification, and for low and low volume intermediate risk patients, may influence treatment decisions.

Is tumour volume an independent predictor of outcome after radical prostatectomy for high-risk prostate cancer?

BACKGROUND

Preoperative PSA, ISUP grade group (GG), prostate examination and multiparametric MRI (mpMRI) form the basis of prostate cancer staging. Unlike other solid organ tumours, tumour volume (TV) is not routinely used aside from crude estimates such as maximum cancer core length. The aim of this study is to assess the role of TV as a marker for oncological outcomes in high-risk non-metastatic prostate cancer.

METHODS

A prospectively maintained database of patients undergoing minimally invasive (laparoscopic or robot-assisted laparoscopic) radical prostatectomy at a UK centre between 2007 and 2019 were analysed. A total of 251 patients with NCCN high or very high-risk prostate cancer were identified. Primary outcome measure was time to biochemical recurrence (BCR) and the secondary outcome was time to treatment failure (TTF). TV was measured on the pathological specimen using the stacking method. Multivariable cox regression analysis was used to identify factors predicting BCR and TFF. TV as a predictor of BCR and TFF was further analysed through time-dependent receiver operating characteristic (ROC) curves. Kaplan-Meier survival estimates were used to evaluate TV cut-off scores.

RESULTS

Median follow up was 4.50 years. Four factors were associated with BCR and TFF on multivariable analysis (TV, pathological GG, pathological T stage, positive margin >3 mm). Area under the Curve (AUC) for TV as a predictor of BCR and TTF at 5 years was 0.71 and 0.75, respectively. Including all 4 variables in the model increased AUC to 0.84 and 0.85 for BCR and TFF. A 2.50 cm TV cut off demonstrated a significance difference in time to BCR, p < 0.001.

CONCLUSIONS

Pathological tumour volume is an independent predictor of oncological outcomes in high risk prostate cancer but does not add significant prognostic value when combined with established variables. However, the option of accurate TV measurement on mpMRI raises the possibility of using TV as useful marker for preoperative risk stratification.

Correlation of Likert scores III–V with increasingly worse pathology in radical prostatectomy specimens significant only for men aged <60 or PSAD >0.15, with age <60 as good as PSAD <0.15 at discriminating lower risk in Likert III

Objectives:

This study aimed to compare Likert scores with radical prostatectomy specimens.

Methods:

This study examined 443 men with validated pre-biopsy magnetic resonance imaging results and used cross-tabulation and chi-square significance testing with National Comprehensive Cancer Network risk categories.

Results:

The mean prostate-specific antigen (PSA) was 10, and the mean age was 64 years. Comparing Likert III to Likert V and Likert IV to Likert V, both (each p=0.02) were significantly associated with higher prostate cancer risk groups, but Likert III versus Likert IV was not ( p=0.1). Within the subgroup PSA density (PSAD) <0.15 ( n=140), the correlation of Likert score and final pathological risk group was lost ( p=0.5), but it was not lost within the subgroup PSAD >0.15 ( n=281; p=0.045 III vs. IV only and p=0.055 overall). Within the subgroup age <60 ( n=104), the correlation of Likert score and final pathological risk group was significant ( p=0.006 for III vs. IV and p=0.04 overall), whereas within the subgroup age >60 ( n=339) this significant difference was lost ( p=0.34). Further subgroup analysis within Likert III ( n=86) found that men <60 ( n=22) had neither high-grade (G3 or G4 or G5) nor very high-risk disease. There were only two high-risk cases, both of which were G2T3a (2/22; 10%). In men with Likert III and PSAD <0.15 ( n=31), there were seven high-risk and two very high-risk cases (9/31; 25%). This difference was not significant ( p=0.31)

Conclusion:

With these two findings, we recommend that men <60 with Likert III can be counselled like men with Likert III and PSAD <0.15, that they are unlikely to have unfavourable or high-risk disease and that they may wish to avoid biopsy or treatment.

Level of evidence:

Level 1b.

Algorithms applied to spatially registered multi-parametric MRI for prostate tumor volume measurement

Background

Prostate tumor volume correlates with critical components of cancer staging such as Gleason score (GS) grade, predicted disease progression, and metastasis. Therefore, non-invasive tumor volume measurement may elevate clinical management. Radiology assessments of multi-parametric MRI (MP-MRI) commonly visually examine individual images to determine possible tumor presence. This study combines registered MP-MRI into a single image that display normal tissue and possible lesions. This study tests and exploits the vector nature of spatially registered MP-MRI by using supervised target detection algorithms (STDA) and color display and psychovisual analysis (CIELAB) to non-invasively estimate prostate tumor volume.

Methods

MRI, including T1, T2, diffusion [apparent diffusion coefficient (ADC)], dynamic contrast enhanced (DCE) images, were resampled, rescaled, translated, and stitched to form spatially registered Multi-parametric cubes. The multi-parametric or multi-spectral signatures (7-component or T1, T2, ADC, etc.) that characterize the prostate tumors were inserted into target detection algorithms with conical decision surfaces (adaptive cosine estimator, ACE). Various detection thresholds were applied to discriminate tumor from normal tissue. In addition, tumor appeared as yellow in color images that were created by assigning red to washout from DCE, green to high B from diffusion, and blue to autonomous diffusion image. The yellow voxels in the three-channel hypercube were visually identified by a reader and recording voxels that exceed a threshold in the b* component of the CIELAB algorithm. The number of reported tumor voxels were converted to volume based on spatial resolution and slice separation. The tumor volume measurements were quantitatively validated by comparing the tumor volume computations to the pathologist's assessment of the histology of sectioned whole mount prostates from 26 consecutive patients with prostate adenocarcinoma who underwent radical prostatectomy. This study analyzed tumors exceeding 1 cc and that also took up contrast material (18 patients).

Results

High correlation coefficients for tumor volume measurements using supervised target detection and color analysis vs. histology from wholemount prostatectomy were computed (R=0.83 and 0.91, respectively). A linear fit for tumor volume measurements using for supervised target detection and color analysis vs. tumor measurements from radical prostatectomy (after correcting for shrinkage from the radical prostatectomy) results in a slope of 1.02 and 3.02, respectively. A polynomial fit for the color analysis to the histology found (R=0.95). Voxels exceeding a threshold in the b* part of the CIELAB algorithm yielded correlation coefficients (0.71, 0.80) offsets (0.01 cc, -0.63 cc) and slopes (1.99, 0.89) against the wholemount prostatectomy and color analysis, respectively.

Conclusions

Supervised target detection and color display and analysis applied to registered MP-MRI non-invasively estimates prostate tumor volumes >1 cc and displaying angiogenesis.

Cancer core length from targeted biopsy: an index of prostate cancer volume and pathological stage

OBJECTIVE

To study the relationship of maximum cancer core length (MCCL), on targeted biopsy (TB) of magnetic resonance imaging (MRI)-visible index lesions, to volume of that tumour found at radical prostatectomy (RP).

PATIENTS AND METHODS

In all, 205 men undergoing fusion biopsy and RP were divided into two groups: 136 in whom the MCCL came from an index MRI-visible lesion (TB) and 69 in whom MCCL came from a non-targeted lesion (non-targeted biopsy [NTB]). MRI was 3-T multi-parametric and biopsy was via MRI-ultrasonography fusion.

RESULTS

In the TB group, MCCL correlated with volume of clinically significant index tumours (ρ = 0.44-0.60, P < 0.01). The correlation was similar for first and repeat biopsy and for transition and peripheral zone lesions (ρ = 0.42-0.49, P < 0.01). No correlations were found in the NTB group. TB MCCL (6-10 and >10 mm) and MRI lesion diameter (>20 mm) were independently associated with tumour volume. TB MCCLs >10 mm and Gleason scores >7 were each associated with pathological T3 disease (odds ratios 5.73 and 5.04, respectively), but MRI lesion diameter lesion was not.

CONCLUSIONS

MCCL on a TB from an MRI-visible lesion is an independent predictor of both cancer volume and pathological stage. This relationship does not exist for MCCL from a NTB core. Quantifying CCL on MRI-TBs may have a value, not previously described, to risk-stratify patients with prostate cancer before treatment.

Practically scheduling hormone therapy for prostate cancer using a mathematical model

Hormone therapy is one of the popular therapeutic methods for prostate cancer. Intermittent androgen suppression (IAS) is the method which stops and resumes hormone therapy repeatedly. The efficacy of IAS differs depending on patients; both the cases have been reported where the relapse of cancer happened and did not happen, for the patients who had undergone IAS. For the patients who cannot avoid the relapse of cancer by IAS, we should delay the relapse of cancer as later as possible. Here we compared some practical methods of determining when to stop and restart hormone therapy for IAS using an existing mathematical model of prostate cancer. The method we suggest is to determine the ratio of on-treatment period and off-treatment period sparsely for each cycle, namely the "sparse search." We also compared the performance of the sparse search with the exhaustive search and the model predictive control. We found that the sparse search can find a good treatment schedule without failure, and the computational cost is not so high compared to the exhaustive method. In addition, we focus on the model predictive control (MPC) method which has been applied to the scheduling of IAS in some existing studies. The MPC is computationary efficient, although it does not always find an optimal schedule in the numerical experiments here. We believe that the MPC method might be also promising because of its reasonable computational costs and its possibility of expanding of the model.

Evaluating the size criterion for PI-RADSv2 category 5 upgrade: is 15 mm the best threshold?

PURPOSE

The purpose of the study was to determine if the ≥ 15 mm threshold currently used to define PIRADS 5 lesions is the optimal size threshold for predicting high likelihood of clinically significant (CS) cancers.

MATERIALS

Three hundred and fifty-eight lesions that may be changed from category 4 to 5 or vice versa on the basis of the size criterion (category 4: n = 288, category 5: n = 70) from 255 patients were evaluated. Kendall's tau-b statistic accounting for inter-lesion correlation, generalized estimation equation logistic regression, and receiver operating curve analysis evaluated two lesion size-metrics (lesion diameter and relative lesion diameter-defined as lesion diameter/prostate volume) for ability to identify CS (Gleason grade ≥ 3 + 4) cancer at targeted biopsy. Optimal cut-points were identified using the Youden index. Analyses were performed for the whole prostate (WP) and zone-specific sub-cohorts of lesions in the peripheral and transition zones (PZ and TZ).

RESULTS

Lesion diameter showed a modest correlation with Gleason grade (WP: τB = 0.21, p < 0.0001; PZ: τB = 0.13, p = 0.02; TZ: τB = 0.32, p = 0.001), and association with CS cancer detection (WP: AUC = 0.63, PZ: AUC = 0.59, TZ: AUC = 0.74). Empirically derived thresholds (WP: 14 mm, PZ: 13 mm, TZ: 16 mm) performed similarly to the current ≥ 15 mm standard. Lesion relative lesion diameter improved identification of CS cancers compared to lesion diameter alone (WP: τB = 0.30, PZ: τB = 0.24, TZ: τB = 0.42, all p < 0.0001). AUC also improved for WP and PZ lesions (WP: AUC = 0.70, PZ: AUC = 0.68, and TZ: AUC = 0.74).

CONCLUSIONS

The current ≥ 15 mm diameter threshold is a reasonable delineator of PI-RADS category 4 and category 5 lesions in the absence of extraprostatic extension to predict CS cancers. Additionally, relative lesion diameter can improve identification of CS cancers and may serve as another option for distinguishing category 4 and 5 lesions.

Prostate imaging features that indicate benign or malignant pathology on biopsy

Accurate diagnosis of clinically significant prostate cancer is essential in identifying patients who should be offered treatment with curative intent. Modifications to the Gleason grading system in recent years show that accurate grading and reporting at needle biopsy can improve identification of clinically significant prostate cancers. Extracapsular extension of prostate cancer has been demonstrated to be an adverse prognostic factor with greater risk of metastatic spread than organ-confined disease. Tumor volume may be an independent prognostic factor and should be considered in conjunction with other factors. Multi-parametric magnetic resonance imaging (MP-MRI) has become an increasingly important tool in the diagnosis and characterization of prostate cancer. MP-MRI allows T2-weighted (T2W) anatomical imaging to be combined with functional and physiological assessment. Diffusion-weighted imaging (DWI) has shown greater sensitivity, specificity and negative predictive value compared to prostate specific antigen (PSA) testing and T2W imaging alone and has a more positive correlation with Gleason score and tumour volume. Dynamic gadolinium contrast-enhanced (DCE) imaging can exhibit difficulties in distinguishing prostatitis from malignancy in the peripheral zone, and between benign prostatic hyperplasia (BPH) and malignancies in the transition zone (TZ). Computer aided diagnosis utilizes software to aid radiologists in detecting and diagnosing abnormalities from diagnostic imaging. New techniques of quantitative MRI, such as VERDICT MRI use tissue-specific factors to delineate different cellular and microstructural phenotypes, characterizing tissue properties with greater detail. Proton MR spectroscopic imaging (MRSI) is a more technically challenging imaging modality than DCE and DWI MRI. Over the last decade, choline and prostate-specific membrane antigen (PSMA) positron emission tomography (PET) have developed as better tools for staging than conventional imaging. While hyperpolarized MRI shows promise in improving the imaging and differentiation of benign and malignant lesions there is further work required. Accurate reading and interpretation of diagnostic investigations is key to accurate identification of abnormal areas requiring biopsy, sparing those in whom benign or indolent disease can be managed by non-invasive means. Embracing and advancing existing technologies is essential in furthering this process.

Differential expression of E-cadherin and P-cadherin in pT3 prostate cancer: correlation with clinical and pathological features

Cadherins seem to play and important role in prostate cancer (PCa) progression. E-cadherin loss of expression has been associated with poor prognosis; P-cadherin's role is still elusive. Although pT3 PCa is often considered "high-risk cancer," it does not exhibit an uniformly poor prognosis. Herein, we assessed the prognostic value and survival impact of E-cadherin and P-cadherin immunoexpression in pT3 PCa. Radical prostatectomy (RP) specimens from 102 pT3 PCa patients treated between 1991 and 2014 in a single institution were designated for E-cadherin and P-cadherin immunoexpression analysis. A representative block from each specimen was selected for tissue micro-array (TMA) construction, using 3 cores per case. E-cadherin immunoexpression was assessed via a digital image analysis system. For P-cadherin, scoring criteria for HER2 in gastric cancer were used. Clinical records of all patients were reviewed for baseline clinical/pathologic characteristics and follow-up data. E-cadherin-low PCa patients displayed worse disease-specific survival (DSS), although not reaching statistical significance (HR 2.65, 95%CI 0.81-7.88). However, considering the pT3b group only, those with low E-cadherin immunoexpression displayed significantly worse overall-survival (OS) and DSS (HR 3.69, 95%CI 1.18-11.50; HR 5.90, 95%CI 1.40-24.81). No significant differences in survival were found for P-cadherin differential immunoexpression. Furthermore, an association between E-cadherin and P-cadherin immunoexpression (p = 0.019) was found, as among E-cadherin-low PCa, 96.6% were P-cadherin negative. We demonstrated that low E-cadherin immunoexpression discriminates among pT3b PCa patients those with poorer survival and which might benefit from specific therapy. The role of P-cadherin in PCa seems context-dependent deserving further investigation.

Hallmarks in prostate cancer imaging with Ga68-PSMA-11-PET/CT with reference to detection limits and quantitative properties

BACKGROUND

Gallium-68-labeled prostate-specific antigen positron emission tomography/computed tomography imaging (Ga68-PSMA-11-PET/CT) has emerged as a potential gold standard for prostate cancer (PCa) diagnosis. However, the imaging limitations of this technique at the early state of PCa recurrence/metastatic spread are still not well characterized. The aim of this study was to determine the quantitative properties and the fundamental imaging limits of Ga68-PSMA-11-PET/CT in localizing small PCa cell deposits.

METHODS

The human PCa LNCaP cells (PSMA expressing) were grown and collected as single cell suspension or as 3D-spheroids at different cell numbers and incubated with Ga68-PSMA-11. Thereafter, human HCT116 cells (PSMA negative) were added to a total cell number of 2 × 10⁵ cells per tube. The tubes were then pelleted and the supernatant aspirated. A whole-body PET/CT scanner with a clinical routine protocol was used for imaging the pellets inside of a cylindrical water phantom with increasing amounts of background activity. The actual activity bound to the cells was also measured in an automatic gamma counter. Imaging detection limits and activity recovery coefficients as a function of LNCaP cell number were obtained. The effect of Ga68-PSMA-11 mass concentration on cell binding was also investigated in samples of LnCaP cells incubated with increasing concentrations of radioligand.

RESULTS

A total of 1 × 10⁴ LNCaP cells mixed in a pellet of 2 × 10⁵ cells were required to reach a 50% detection probability with Ga68-PSMA-11-PET/CT without background. With a background level of 1 kBq/ml, between 4 × 10⁵ and 1 × 10⁶ cells are required. The radioligand equilibrium dissociation constant was 27.05 nM, indicating high binding affinity. Hence, the specific activity of the radioligand has a profound effect on image quantification.

CONCLUSIONS

Ga68-PSMA-11-PET detects a small number of LNCaP cells even when they are mixed in a population of non-PSMA expressing cells and in the presence of background. The obtained image detection limits and characteristic quantification properties of Ga68-PSMA-11-PET/CT are essential hallmarks for the individualization of patient management. The use of the standardized uptake value for Ga68-PSMA-11-PET/CT image quantification should be precluded.

Multi-parametric MRI imaging of the prostate-implications for focal therapy

The primary goal of a focal therapy treatment paradigm is to achieve cancer control through targeted tissue destruction while simultaneously limiting deleterious effects on peri-prostatic structures. Focal therapy approaches are employed in several oncologic treatment protocols, and have been shown to provide equivalent cancer control for malignancies such as breast cancer and renal cell carcinoma. Efforts to develop a focal therapy approach for prostate cancer have been challenged by several concepts including the multifocal nature of the disease and limited capability of prostate ultrasound and systematic biopsy to reliably localize the site(s) and aggressiveness of disease. Multi-parametric MRI (mpMRI) of the prostate has significantly improved disease localization, spatial demarcation and risk stratification of cancer detected within the prostate. The accuracy of this imaging modality has further enabled the urologist to improve biopsy approaches using targeted biopsy via MRI-ultrasound fusion. From this foundation, an improved delineation of the location of disease has become possible, providing a critical foundation to the development of a focal therapy strategy. This chapter reviews the accuracy of mpMRI for detection of “aggressive“ disease, the accuracy of mpMRI in determining the tumor volume, and the ability of mpMRI to accurately identify the index lesion. While mpMRI provides a critical, first step in developing a strategy for focal therapy, considerable questions remain regarding the relationship between MR identified tumor volume and pathologic tumor volume, the accuracy and utility of mpMRI for treatment surveillance and the optimal role and timing of follow-up mpMRI.

Focal cryotherapy of localized prostate cancer: a systematic review of the literature

Radical/whole gland treatment for prostate cancer has significant side-effects. Therefore focal treatments such as cryotherapy have been used to treat localized lesions whilst aiming to provide adequate cancer control with minimal side-effects. We performed a systematic review of Pubmed/Medline and Cochrane databases' to yield 9 papers for primary focal prostate cryotherapy and 2 papers for focal salvage treatment (radio-recurrent). The results of 1582 primary patients showed biochemical disease-free survival between 71-93% at 9-70 months follow-up. Incontinence rates were 0-3.6% and ED 0-42%. Recto-urethral fistula occurred in only 2 patients. Salvage focal cryotherapy had biochemical disease-free survival of 50-68% at 3 years. ED occurred in 60-71%. Focal cryotherapy appears to be an effective treatment for primary localized prostate cancer and compares favorably to radical/whole gland treatments in medium-term oncological outcomes and side-effects. Although more studies are needed it is also effective for radio-recurrent cancer with a low complications rates.

Magnetic Resonance Imaging/Transrectal Ultrasonography Fusion Prostate Biopsy Significantly Outperforms Systematic 12-Core Biopsy for Prediction of Total Magnetic Resonance Imaging Tumor Volume in Active Surveillance Patients

OBJECTIVE

To correlate the highest percentage core involvement (HPCI) and corresponding tumor length (CTL) on systematic 12-core biopsy (SBx) and targeted magnetic resonance imaging/transrectal ultrasonography (MRI/TRUS) fusion biopsy (TBx), with total MRI prostate cancer (PCa) tumor volume (TV).

PATIENTS AND METHODS

Fifty patients meeting criteria for active surveillance (AS) based on outside SBx, who underwent 3.0T multiparametric prostate MRI (MP-MRI), followed by SBx and TBx during the same session at our institution were examined. PCa TVs were calculated using MP-MRI and then correlated using bivariate analysis with the HPCI and CTL for SBx and TBx.

RESULTS

For TBx, HPCI and CTL showed a positive correlation (R(2)=0.31, P<0.0001 and R(2)=0.37, P<0.0001, respectively) with total MRI PCa TV, whereas for SBx, these parameters showed a poor correlation (R(2)=0.00006, P=0.96 and R(2)=0.0004, P=0.89, respectively). For detection of patients with clinically significant MRI derived tumor burden greater than 500 mm(3), SBx was 25% sensitive, 90.9% specific (falsely elevated because of missed tumors and extremely low sensitivity), and 54% accurate in comparison with TBx, which was 53.6% sensitive, 86.4% specific, and 68% accurate.

CONCLUSIONS

HPCI and CTL on TBx positively correlates with total MRI PCa TV, whereas there was no correlation seen with SBx. TBx is superior to SBx for detecting tumor burden greater than 500 mm(3). When using biopsy positive MRI derived TVs, TBx better reflects overall disease burden, improving risk stratification among candidates for active surveillance.

Latent prostate cancer in Japanese men who die unnatural deaths: A forensic autopsy study

BACKGROUND

An accurate natural history of prostate cancer (PC) can be obtained from forensic autopsies of individuals who had performed their normal daily activities immediately before death and had not undergone long-term medical interventions. A retrospective analysis of such individuals was performed to understand the features of latent PC in Japan.

METHODS

The findings of forensic autopsies performed at Dokkyo Medical University from August 2002 to July 2005 on men without severely destroyed or severely decomposed tissues were collected. Two cross sections, at the base and apex of the prostate, were examined histopathologically. Data collected included basic history, cause of death, location of PC, and Gleason score.

RESULTS

Of 196 forensically autopsied males aged 0-90 years, 24 (12.7%) had latent PC. When analyzed by age group, PC was most prevalent among individuals in their eighties (33.3%). The prevalence of PC was similar in males who died of disease and of external causes. Most PCs were located at the base of the prostate, but were present on both the anterior and posterior sides. Nine of the 24 autopsied individuals also had other diseases, with three having cancers other than PC.

CONCLUSIONS

This is the first report of the features of latent PC in Asian men who died of unnatural causes. Forensic autopsies can clarify the natural history of PC and may help fill knowledge gaps regarding latent PC.

Histological outcomes after focal high-intensity focused ultrasound and cryotherapy

Introduction

Focal therapy has increasingly become an accepted treatment option for patients with localised prostate cancer. Most follow-up protocols use a mixture of protocol biopsies or “for cause” biopsies triggered by a rising PSA. In this paper, we discuss the histological outcomes from these biopsies and their use in guiding subsequent management and trial development.

Methods

We conducted a literature search and reviewed the post-treatment biopsy results from studies on focal HIFU and focal cryotherapy. We subsequently reviewed the results of three recently published consensus statements released discussing many of the issues concerning focal therapy.

Results

Research suggests that 1 in 5 of all post-treatment biopsies after focal therapy are positive. However, the majority of these seemed to be from the untreated portion of the gland or met criteria for clinically insignificant disease. The histological outcomes from focal therapy are promising and confirm its effectiveness in the short to medium term. Furthermore re-treatment is possible whilst maintaining a low-side-effect profile.

Conclusion

Debate is ongoing about the clinical significance of various levels of residual disease after focal therapy and the exact threshold at which to call failure within a patient who has had focal therapy.

[Diagnostic value of estimation of ERG expression in prostate adenocarcinoma and high-grade prostatic intraepithelial neoplasia]

OBJECTIVE

to estimate the diagnostic and prognostic value of analyzing the abnormal overexpression of the chimeric protein ERG, encoded by the chimeric gene TMPRSS2/ERG, in prostatic neoplasias.

MATERIAL AND METHODS

A total of 100 prostate adenocarcinoma samples were examined. The presence of tumor and high-grade prostatic intraepithelial neoplasia (hPIN) was verified by immunohistochemical tests using anti-P504S and anti-34βE12 antibodies in serial sections; RT-PCR was employed to analyze the chimeric transcript TMPRSS2/ERG in 30 prostate adenocarcinoma samples.

RESULTS

ERG expression was noted in 46% of the adenocarcinomas and in 21% of hPIN. Eight (8%) patients were observed to have heterogeneous ERG expression: the marked reaction in some tumor portions was concurrent with its complete absence in others. Furthermore, there was ERG expression in all cases of intraductal (noninvasive) carcinoma (the foci of intraductal carcinoma were assessed as atypical cribriform lesions by light microscopy). The prognostic value of ERG expression could not be determined at the current stage of the investigation.

CONCLUSION

The relatively low rate of ERG-positive hPIN counts in favor of the limited role of this marker in the differential diagnosis of hPIN. ERG in combination with P504S and 34βE12 is an informative marker for the differential diagnosis of hPIN with intraductal carcinoma.

Predicting the risk of non-organ-confined prostate cancer when perineural invasion is found on biopsy

OBJECTIVE

To more precisely define the risk of non-organ-confined (non-OC) prostate cancer among men with perineural invasion (PNI) identified on prostate biopsy.

MATERIALS AND METHODS

The Johns Hopkins radical prostatectomy database was queried for men with PNI reported on prostate biopsy. Patients with and without non-OC disease were compared for differences in preoperative clinical and pathologic characteristics, including three biopsy-based measures of tumor volume (number of cores with cancer, percentage of cores with cancer, and maximum percent core involvement with cancer). After evaluating the different preoperative variables in univariate analyses, a multivariable logistic regression model was generated, and bootstrap estimates of the risk of non-OC disease were calculated.

RESULTS

In total, 556 patients with PNI were analyzed, 279 (50.2%) of whom were found to have non-OC prostate cancer. In univariate analyses, preoperative prostate-specific antigen, clinical T stage, biopsy Gleason sum, and the three biopsy-based measures of tumor volume were significantly associated with non-OC disease. Of the three measures of tumor volume, the best fit to the data and highest degree of model discrimination were obtained using maximum percent core involvement with cancer. Incorporating this variable, preoperative prostate-specific antigen, clinical T stage, and biopsy Gleason sum into a multivariable model, the estimated risk of non-OC disease was found to range from 13.8% to 94.4% (bootstrap corrected c-index = 0.735).

CONCLUSION

Men with PNI on prostate biopsy are at a wide range of risk for non-OC disease. Preoperative estimation of this risk is improved by considering readily available biopsy estimates of tumor volume.

Gleason score 7 adenocarcinoma of the prostate with lymph node metastases: analysis of 184 radical prostatectomy specimens

CONTEXT

Prostate cancer (PC) with lymph node metastases (LN(+)) is relatively rare, whereas it is relatively common in disease with a Gleason score (GS) 8 to 10 and virtually never seen in PC with GS 6 or less. It is most variable in GS 7 PC.

OBJECTIVE

To determine clinicopathologic features associated with GS 7 PC with LN(+) compared with a control group without lymph node metastases (LN(-)).

DESIGN

We analyzed 184 GS 7 radical prostatectomies with LN(+) and the same number of LN(-) Gleason-matched controls. The LN(+) cases were GS 3 + 4 = 7 (n = 64; 34.8%), GS 4 + 3 = 7 (n = 66; 35.9%), GS 3 + 4 = 7 with tertiary 5 (n = 10; 5.4%), and GS 4 + 3 = 7 with tertiary 5 (n = 44; 23.9%).

RESULTS

The LN(+) cases demonstrated higher average values in preoperative prostate-specific antigen (12.2 versus 8.1 ng/mL), percentage of positive biopsy cores (59.1% versus 42.9%), prostate weight (54.4 versus 49.4 g), number of LNs submitted (12.7 versus 9.4), incidence of nonfocal extraprostatic extension (82.6% versus 63.6%), tumor volume (28.9% versus 14.8%), frequency of lymphovascular invasion (78.3% versus 38.6%), intraductal spread of carcinoma (42.4% versus 20.7%), incidence of satellite tumor foci (16.4% versus 4.3%), incidence of pT3b disease (49.5% versus 14.7%), and lymphovascular invasion in the seminal vesicles (52% versus 30%). There were differences in GS 4 patterns and cytology between LN(+) and LN(-) cases, with the former having higher volumes of cribriform and poorly formed patterns, larger nuclei and nucleoli, and more-frequent macronucleoli. All P ≤ .05.

CONCLUSION

Gleason score 7 PC with LN(+) has features highlighting a more-aggressive phenotype. These features can be assessed as prognostic markers in GS 7 disease on biopsy (eg, GS 4 pattern, intraductal spread, cytology) or at radical prostatectomies (all variables), even in men without LN dissection or LN(-) disease.

Diffusion-weighted imaging of the prostate: Comparison of b1000 and b2000 image sets for index lesion detection

PURPOSE

To compare tumor detection on acquired diffusion-weighted (DW) images and apparent diffusion coefficient (ADC) maps, obtained using b-values of 1000 s/mm(2) and 2000 s/mm(2) , using radical prostatectomy as the reference.

MATERIALS AND METHODS

In all, 29 prostate cancer patients who underwent 3T magnetic resonance imaging (MRI) including DW imaging using b-values of 1000 s/mm(2) and 2000 s/mm(2) were included. Two radiologists independently evaluated four image sets during different sessions and recorded the location and diameter of the dominant lesion: DW images acquired using b-values of 1000 s/mm(2) and 2000 s/mm(2) and ADC maps calculated using maximal b-values of 1000 s/mm(2) and 2000 s/mm(2) . Findings were correlated with the location and diameter of the dominant lesion at prostatectomy. Tumor-to-PZ contrast was also calculated, unblinded to pathology.

RESULTS

Both readers achieved significantly higher sensitivity for DW images obtained using a b-value of 2000 s/mm(2) than 1000 s/mm(2) (P < 0.001), although there was no difference in sensitivity between ADC maps calculated using the two b-values (P ≥ 0.309). Tumor-to-PZ contrast was higher for DW images using a b-value of 2000 s/mm(2) (P = 0.067), although it was not different between the two corresponding ADC maps (P = 0.544). For both readers, correlations with tumor diameters were higher for either ADC map (r = 0.59-0.73) than for either acquired DW image set (r = 0.03-0.57).

CONCLUSION

Use of a b-value of 2000 s/mm(2) compared with a b-value of 1000 s/mm(2) resulted in improved tumor sensitivity and higher tumor-to-PZ contrast on the acquired DW images, although performance of the ADC maps corresponding with the two b-values was similar. Correlation with tumor size was greater for either ADC map than for either acquired DW image set.

Development and Evaluation of an Actuated MRI-Compatible Robotic System for MRI-Guided Prostate Intervention

This paper reports the design, development, and magnetic resonance imaging (MRI) compatibility evaluation of an actuated transrectal prostate robot for MRI-guided needle intervention in the prostate. The robot performs actuated needle MRI-guidance with the goals of providing (i) MRI compatibility, (ii) MRI-guided needle placement with accuracy sufficient for targeting clinically significant prostate cancer foci, (iii) reducing interventional procedure times (thus increasing patient comfort and reducing opportunity for needle targeting error due to patient motion), (iv) enabling real-time MRI monitoring of interventional procedures, and (v) reducing the opportunities for error that arise in manually actuated needle placement. The design of the robot, employing piezo-ceramic-motor actuated needle guide positioning and manual needle insertion, is reported. Results of a MRI compatibility study show no reduction of MRI signal-to-noise-ratio (SNR) with the motors disabled. Enabling the motors reduces the SNR by 80% without RF shielding, but SNR is only reduced by 40% to 60% with RF shielding. The addition of radio-frequency shielding is shown to significantly reduce image SNR degradation caused by the presence of the robotic device. An accuracy study of MRI-guided biopsy needle placements in a prostate phantom is reported. The study shows an average in-plane targeting error of 2.4 mm with a maximum error of 3.7 mm. These data indicate the system's needle targeting accuracy is similar to that obtained with a previously reported manually actuated system, and is sufficient to reliably sample clinically significant prostate cancer foci under MRI-guidance.

The accuracy of different biopsy strategies for the detection of clinically important prostate cancer: a computer simulation

PURPOSE

The true accuracy of different biopsy strategies for detecting clinically significant prostate cancer is unknown, given the positive evaluation bias required for verification by radical prostatectomy. To evaluate how well different biopsy strategies perform at detecting clinically significant prostate cancer we used computer simulation in cystoprostatectomy cases with cancer.

MATERIALS AND METHODS

A computer simulation study was performed on prostates acquired at radical cystoprostatectomy. A total of 346 prostates were processed and examined for prostate cancer using 3 mm whole mount slices. The 96 prostates that contained cancer were digitally reconstructed. Biopsy simulations incorporating various degrees of random localization error were performed using the reconstructed 3-dimensional prostate computer model. Each biopsy strategy was simulated 500 times. Two definitions of clinically significant prostate cancer were used to define the reference standard, including definition 1--Gleason score 7 or greater, and/or lesion volume 0.5 ml or greater and definition 2--Gleason score 7 or greater, and/or lesion volume 0.2 ml or greater.

RESULTS

A total of 215 prostate cancer foci were present. The ROC AUC to detect and rule out definition 1 prostate cancer was 0.69, 0.75, 0.82 and 0.91 for 12-core transrectal ultrasound biopsy with a random localization error of 15 and 10 mm, 14-core transrectal ultrasound biopsy and template prostate mapping using a 5 mm sampling frame, respectively.

CONCLUSIONS

To our knowledge our biopsy simulation study is the first to evaluate the performance of different sampling strategies to detect clinically important prostate cancer in a population that better reflects the demographics of a screened cohort. Compared to other strategies standard transrectal ultrasound biopsy performs poorly for detecting clinically important cancer. Marginal improvement can be achieved using additional cores placed anterior but the performance attained by template prostate mapping is optimal.

Use of tumor dynamics to clarify the observed variability among biochemical recurrence nomograms for prostate cancer

BACKGROUND

Nomograms for biochemical recurrence (BCR) of prostate cancer (PC) after radical prostatectomy can yield very different prognoses for individual patients. Since the nomograms are optimized on different cohorts, the variations may be due to differences in patient risk-factor distributions. In addition, the nomograms assign different relative scores to the same PC risk factors and rarely stratify for tumor growth rate.

METHODS

We compared BCR-free probabilities from the GPSM model with a cell kinetics (CK) model that uses the individual's tumor state and growth rate. We first created a cohort of 143 patients that reproduced the GPSM patient distribution in Gleason score, Prostate specific antigen (PSA), Seminal vesicle involvement and Margin status since they form the GPSM score. We then performed 143 CK calculations to determine BCR-free probabilities for comparison with the GPSM results for all scores and with four other prominent nomograms for a high-risk patient.

RESULTS

The BCR-free probabilities from the CK model agree within 10% with those from the GPSM study for all scores once the CK model parameters are stratified in terms of the GPSM risk factors and the PSA doubling time (PSADT). However, the probabilities from widely used nomograms vary significantly.

CONCLUSIONS

The CK model reproduces the observed GPSM BCR-free probabilities with a broad stratification of model parameters for PC risk factors and can thus be used to describe PC progression for individual patients. The analysis suggests that nomograms should stratify for PSADT to be predictive.

Effect of Prostate Biopsy Hemorrhage on MRDW and MRS Imaging

Purpose

To retrospectively evaluate the effect of post-prostate-biopsy hemorrhage on the interpretation of magnetic resonance diffusion-weighted (MRDW) and magnetic resonance spectroscopic (MRS) imaging in the detection of prostate cancer. We also investigated the optimal timing for magnetic resonance examination after prostate biopsy.

Materials and Methods

We reviewed the records of 135 men. All patients underwent prostate magnetic resonance imaging (MRI). The prostate was divided into eight regions according to the biopsy site. Subsequently, we measured hemorrhage on apparent diffusion coefficient (ADC) values and (choline+creatinine)/citrate ([Cho+Cr]/Cit) ratios in the same regions on the MRI. We investigated the effect of hemorrhage at ADC values and (Cho+Cr)/Cit ratios on MRI and the relationship between prostate biopsy results and MRI findings.

Results

The mean patient age was 68.7 years and the mean time between biopsy and MRI was 23.5 days. The total hemorrhagic score demonstrated no significant associations with intervals from biopsy to MRI. Higher hemorrhagic scores were associated with higher ADC values, prostate cancer, and noncancer groups, respectively (p<0.001). ADC values were lower in tumors than in normal tissue (p<0.001), and ADC values were inversely correlated with tumor Gleason score in biopsy cores (p<0.001). However, (Cho+Cr)/Cit ratios did not exhibit any association with prostate biopsy results and hemorrhage.

Conclusions

Hemorrhage had no significant associations with the interval from biopsy to MRI. ADC values may help to detect prostate cancer and predict the aggressiveness of cancer; however, it is important to consider the bias effect of hemorrhage on the interpretation of MRDW imaging given that hemorrhage affects ADC values.

Comparison of real-time elastography with grey-scale ultrasonography for detection of organ-confined prostate cancer and extra capsular extension: a prospective analysis using whole mount sections after radical prostatectomy

OBJECTIVE

•To evaluate whether transrectal real-time elastography (RTE) improves the detection of intraprostatic prostate cancer (PCa) lesions and extracapsular extension (ECE) compared with conventional grey-scale ultrasonography (GSU).

PATIENTS AND METHODS

•In total, 229 patients with biopsy-proven PCa were prospectively screened for cancer-suspicious areas and ECE using GSU and RTE. •The largest tumour focus detected by RTE was defined as the index lesion. •The prostate gland was stratified into six sectors on GSU and RTE, which were compared with histopathological whole mount sections after radical prostatectomy.

RESULTS

•Histopathologically, PCa was confirmed in 894 out of 1374 (61.8%) evaluated sectors and ECE was identified in 47 (21%) patients. •Of these 894 sectors, RTE correctly detected 594 (66.4%) and GSU 215 (24.0%) cancer suspicious lesions. •Sensitivity was 51% and specificity 72% using RTE compared to 18% and 90% for GSU. •RTE identified the largest side specific tumour focus in 68% of patients. •ECE was identified with a sensitivity of 38% and specificity of 96% using RTE compared to 15% and 97% using GSU.

CONCLUSIONS

•Compared with GSU, RTE provides a statistically significant improvement in detection of PCa lesions and ECE. •RTE enhances GSU, although improvement is still needed to achieve a clinically meaningful sensitivity.

Computer-aided prognosis: predicting patient and disease outcome via quantitative fusion of multi-scale, multi-modal data

Computer-aided prognosis (CAP) is a new and exciting complement to the field of computer-aided diagnosis (CAD) and involves developing and applying computerized image analysis and multi-modal data fusion algorithms to digitized patient data (e.g. imaging, tissue, genomic) for helping physicians predict disease outcome and patient survival. While a number of data channels, ranging from the macro (e.g. MRI) to the nano-scales (proteins, genes) are now being routinely acquired for disease characterization, one of the challenges in predicting patient outcome and treatment response has been in our inability to quantitatively fuse these disparate, heterogeneous data sources. At the Laboratory for Computational Imaging and Bioinformatics (LCIB)(1) at Rutgers University, our team has been developing computerized algorithms for high dimensional data and image analysis for predicting disease outcome from multiple modalities including MRI, digital pathology, and protein expression. Additionally, we have been developing novel data fusion algorithms based on non-linear dimensionality reduction methods (such as Graph Embedding) to quantitatively integrate information from multiple data sources and modalities with the overarching goal of optimizing meta-classifiers for making prognostic predictions. In this paper, we briefly describe 4 representative and ongoing CAP projects at LCIB. These projects include (1) an Image-based Risk Score (IbRiS) algorithm for predicting outcome of Estrogen receptor positive breast cancer patients based on quantitative image analysis of digitized breast cancer biopsy specimens alone, (2) segmenting and determining extent of lymphocytic infiltration (identified as a possible prognostic marker for outcome in human epidermal growth factor amplified breast cancers) from digitized histopathology, (3) distinguishing patients with different Gleason grades of prostate cancer (grade being known to be correlated to outcome) from digitized needle biopsy specimens, and (4) integrating protein expression measurements obtained from mass spectrometry with quantitative image features derived from digitized histopathology for distinguishing between prostate cancer patients at low and high risk of disease recurrence following radical prostatectomy.

Role of endorectal magnetic resonance spectroscopic imaging in two different Gleason scores in prostate cancer

OBJECTIVE

The major goal of the work was to record three-dimensional magnetic resonance spectroscopic imaging (MRSI) and to compare metabolite ratios between different Gleason scores (GS).

MATERIALS AND METHODS

MRSI localized by endorectal coil-acquired point-resolved spectroscopy was performed in 14 men with prostate cancer of GS 6 (n = 7) and 7 (n = 7) using a 1.5-tesla MRI scanner.

RESULTS

The ratio of (choline + creatine)/citrate was increased with an increase of GS, i.e. 0.590 ± 0.171 in the target lesion and 0.321 ± 0.157 in the contralateral region of patients with a GS of 6 as opposed to 1.082 ± 0.432 in the target lesion and 0.360 ± 0.243 in the contralateral region of patients with a GS of 7.

CONCLUSION

Our pilot results demonstrated that MRSI was an additional biochemical tool which is complementary to the current imaging modalities for early diagnosis and therapeutic management of prostate cancer.

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.

Impact of prostate cancer multifocality on its biology and treatment

Any focal therapy requires correct localization of the lesion; consequently, much effort is now devoted to accurate characterization of the spatial distribution of the tumor within the prostate. One of the greatest difficulties in the localization of prostate cancer is its frequent multifocality, but prostate cancer is unifocal in 13% to 43.7% of cases and unilateral in 19.2%. In cases of multifocality, it seems that the index tumor is the biologic driving force behind the malignant potential of prostate cancer. Not only is the Gleason score of the secondary nodes lower than that of the index node, but 80% of the secondary nodes are smaller than 0.5 cc and almost all extraprostatic extensions are associated with the largest cancers. While current evaluation with 12 to 18 core biopsies may be adequate to determine the index lesion, transperineal three-dimensional mapping biopsy of the prostate should be undertaken if greater accuracy is needed.

Prostate tumor volume measurement with combined T2-weighted imaging and diffusion-weighted MR: correlation with pathologic tumor volume

PURPOSE

To retrospectively determine the accuracy of diffusion-weighted (DW) magnetic resonance (MR) imaging for identifying cancer in the prostate peripheral zone (PZ) and to assess the accuracy of tumor volume measurements made with T2-weighted imaging and combined T2-weighted and DW MR imaging by using surgical pathologic examination as the reference standard.

MATERIALS AND METHODS

The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Forty-two patients underwent endorectal MR at 1.5 T before undergoing radical prostatectomy for prostate cancer and had at least one PZ tumor larger than 0.1 cm(3) at surgical pathologic examination. On T2-weighted images, an experienced radiologist outlined suspected PZ tumors. Two apparent diffusion coefficient (ADC) cutoff values were identified by using the Youden index and published literature. Image cluster analysis was performed on voxels within the suspected tumor regions. Associations between volume measurements from imaging and from pathologic examination were assessed by using concordance correlation coefficients (CCCs). The sensitivity and specificity of ADCs for identifying malignant PZ voxels were calculated.

RESULTS

In identifying malignant voxels, respective ADC cutoff values of 0.0014 and 0.0016 mm(2)/sec yielded sensitivity of 82% and 95% and specificity of 85% and 65%, respectively. Sixty PZ cancer lesions larger than 0.1 cm(3) were found at pathologic examination; 43 were detected by the radiologist. CCCs between imaging and pathologic tumor volume measurements were 0.36 for T2-weighted imaging, and 0.46 and 0.60 for combined T2-weighted and DW MR imaging with ADC cutoffs of 0.0014 and 0.0016 mm(2)/sec, respectively; the CCC of combined T2-weighted and DW MR imaging (ADC cutoff, 0.0016 mm(2)/sec) was significantly higher (P = .006) than that of T2-weighted imaging alone.

CONCLUSION

Adding DW MR to T2-weighted imaging can significantly improve the accuracy of prostate PZ tumor volume measurement.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/252/2/449/DC1.

Peripheral zone prostate cancer. Pre-treatment evaluation with MR and 3D ¹H MR spectroscopic imaging: correlation with pathologic findings

The purpose of this study was to retrospectively characterize benign and malignant prostate peripheral zone tissue by using endorectal MRI and 3D ¹H MRS. Fifty-two men with untreated biopsy-proven prostate cancer underwent combined endorectal MRI and MRSI. Whole-mount step-section histopathologic analysis constituted the reference standard. Biopsy correctly detected 74 locations; MRI correctly detected 72 locations; MRS correctly detected 72 locations; MRI + MRS correctly detected 78 locations. Cohen's test showed that biopsy had a lower degree of agreement with histology than MRI + MRS combined. The ratio of [(Cho + Cr)]/Cit correlates with the pathologic Gleason score. The addition of 3D¹H MRSI to MRI can improve diagnosis of prostate cancer contributing indirectly to improve local staging. In addition, the correlation between metabolic 3D¹H MRSI data with pathological Gleason grade may offer a non-invasive means to better predict prostate cancer aggressiveness.

Pretreatment tumor volume estimation based on total serum psa in patients with localized prostate cancer

OBJECTIVES

To establish a formula that estimates tumor volume in localized prostate cancer based on serum prostate specific antigen levels. One of the main prognostic variables in localized prostate cancer is tumor volume, which can be precisely defined only after prostate extirpation. The present study defines a simple method that allows for estimation of tumor volume before treatment, which can help to establish a better therapeutic strategy for each patient.

METHODS

From 1997 to 2002, 735 patients with prostate cancer of stagesT1c-T2c without any previous treatment were submitted to radical prostatectomy. Surgical specimens were evaluated by the same pathologist and the total tumor volume (in cc) and the relative tumor volume (as the percent of the total prostate volume) were determined using the grid morphometric method. Pretreatment serum prostate specific antigen was correlated with tumor volume in each patient using a linear regression model.

RESULTS

There were positive correlations between the serum levels of prostate specific antigen and the total tumor volume in cc (p<0.001) and the relative tumor volume as a percentage (p<0.001). For each ng/ml unit increment of serum prostate specific antigen, there was a 0.302 cc increase in total tumor volume and a 0.7% increase in relative tumor volume. Total and percent tumor volume could be calculated, respectively, using the formulas Volume (cc) = 3.476 + 0.302 x PSA (ng/ml) and Volume (%) = 11.331 + 0.704 x prostate specific antigen (ng/ml).

CONCLUSIONS

Tumor volume in patients with prostate cancer can be determined before treatment based on the serum prostate specific antigen levels.

[Prostate MRI spectroscopy]

MRI spectroscopy is a non invasive method for detecting active metabolites used as markers. Chorine and citrate are used for analyzing prostate cancer. MRI spectroscopy combines morphologic imaging and metabolic cartography. This combination allows a new approach for the diagnosis of prostate cancer in patients with negative biopsy and high Levels of PSA. With MRI spectroscopy the Local staging of prostate cancer has a better accuracy than with MRI alone. It can also be used for the diagnosis of residual disease and recurrence in patients treated with conservative therapy.

[Prostate biopsy strategies. A review of the literature]

INTRODUCTION

In 1987 transrectal ultrasound was described like the technique for guiding prostate biopsy. Since that time different options of transrectal ultrasound guided prostate biopsy were described.

MATERIAL AND METHODS

We did a reviewed of the different techniques and cores distribution in the prostate biopsy, also we describes the patient preparation and the most important complications.

RESULTS

The majority of the reviewed showed an increase in the sensibility rates with the extended transrectal ultrasound guided prostate biopsies. These improvements generally are due to the most lateral zones.

CONCLUSION

Until now, due to a great experience and a low complications rate, the transrectal ultrasound guided prostate biopsy strategy should be extended respect the classical sextant biopsy with cores from the most lateral zones of the prostate.

Maximum tumor diameter is not an independent prognostic factor in high-risk localized prostate cancer

OBJECTIVES

Previous studies suggest that maximum tumor diameter (MTD) is a predictor of recurrence in prostate cancer (PC). This study investigates the prognostic value of MTD for biochemical recurrence (BCR) in patients with PC, after radical prostatectomy (RP), with emphasis on high-risk localized prostate cancer.

METHODS

RP specimens of 542 patients were evaluated with a median follow-up of 39.5 months (range 0.6-150 months). MTD was defined as the largest diameter of the largest tumor; high-risk as >or=T2c or PSA level>20 ng/ml or Gleason score>or=8 and BCR as two consecutive PSA levels>0.10 ng/ml. Proportional hazards multivariable regression models were composed to determine prognostic factors for BCR.

RESULTS

Overall, 114 patients developed BCR after RP. The overall 5-year risk of BCR was 25% (95% CI=20.4-29.6), and median MTD was 24 mm (range 1-65). MTD in the total and high-risk group was associated with total tumor volume, volume of the largest tumor, pre-operative PSA levels, and Gleason score. In a univariable analyses, MTD was weakly associated with risk of BCR (HR=1.02 per mm increase, 95% CI=1.002-1.035, P=0.024) in the total group; in the high-risk group this association was lost (HR=1.01, 95%CI=0.99-1.03, P=0.18). Multivariable analyses indicated that positive surgical margins, higher Gleason score, advanced pathological stage, and multiple tumors were the main prognostic factors for BCR irrespective of the risk profile. MTD did not provide additional information.

CONCLUSIONS

MTD is not an independent prognostic factor for BCR in patients treated with RP, irrespective of the risk profile.

Clinical implications of tumor size and local extent of primary prostatic lesions in prostate cancer patients with metastases: value of endorectal magnetic resonance imaging in patients with metastases

OBJECTIVES

To investigate the clinical significance of local assessment by endorectal magnetic resonance imaging (MRI) in prostate cancer patients with metastases.

METHODS

The local extent and tumor size were determined by endorectal MRI in 95 prostate cancer patients with metastases, and their clinical implications were assessed.

RESULTS

The maximum diameter and tumor volume significantly correlated with the local extent of disease but not with extent of disease (EOD) on bone scan. In univariate analyses, EOD, serum prostate-specific antigen level, serum alkaline phosphatase level, and hemoglobin level were significantly associated with disease-specific survival, whereas tumor size and local extent of primary lesions were not. In a multivariate analysis EOD on bone scan was a significant prognostic factor.

CONCLUSIONS

Tumor size and local extent of the primary lesion estimated by endorectal MRI were not associated with disease-specific survival. Assessment of the primary lesion by endorectal MRI is of limited value in predicting the prognosis of prostate cancer patients with metastases.

Positive-block ratio in radical prostatectomy specimens is an independent predictor of prostate-specific antigen recurrence

Tumor volume has been considered an important variable in determining the probability of prostate-specific antigen (PSA) recurrence in prostatic adenocarcinoma. There have been many studies that have tried to determine an appropriate method of calculating tumor volume, but no single methodology has been agreed upon. We tested the hypothesis that the ratio of tumor positive tissue blocks to the total number of blocks submitted (positive-block ratio) can be used as an independent prognostic indicator for PSA recurrence. We analyzed 504 patients who underwent total radical retropubic prostatectomy between 1990 and 1998. None of the patients had preoperative radiation or androgen-deprivation therapy. Clinical records were reviewed. The mean positive-block ratio was 0.44 (median, 0.43; range, 0.05 to 1.0). The positive block-ratio was significantly associated with Gleason score, pathologic stage, surgical margin status, extraprostatic extension, seminal vesical invasion, lymph node metastasis, perineural invasion, and preoperative serum PSA level (all P<0.001). Using a multivariate Cox regression model, controlling for pathologic stage, Gleason score, lymph node metastasis, and surgical margin status, positive-block ratio was an independent predictor of PSA recurrence (hazard ratio, 2.3; 95% confidence interval, 1.06-4.83; P=0.03). Five-year PSA recurrence-free survival was 67% for those patients with positive-block ratio <or=0.43, as compared with 42% those with positive-block ratio >0.43 (P<0.001). Positive-block ratio is an independent predictor of PSA recurrence and this simple method of tumor measurement seems to be promising for quantifying tumor volume if our findings are validated by subsequent reports.

Value of magnetic resonance imaging in prostate cancer diagnosis

MRI has shown its potential in prostate cancer (PCa) imaging. MRI is able to demonstrate zonal anatomy with excellent contrast resolution. Furthermore it can detect PCa dependent not only on tumor-size, histological grading, PSA levels, but also on technical equipment and reader's experience. Non-palpable PCas in the inner and outer gland can be detected by this technique. Another potential is that MRI is helpful for tumor staging and treatment planning as well as response evaluation. Besides the morphological information, MRI can give functional information based on metabolic evaluation with proton magnetic resonance spectroscopy and of tumor angiogenesis based on dynamic contrast-material enhanced MRI and diffusion-weighted imaging. In addition MRI can be used for targeted prostate biopsies; however, the clinical practicability is questionable. Furthermore many data about the value of MRI for PCa diagnosis are based on transrectal ultrasound (TRUS) biopsy findings. Since there is lack of accuracy in fusing MRI images with TRUS images these limit the results of MRI for cancer diagnosis. However, in the future MRI may play an additional role in planning and monitoring minimally invasive PCa therapies. Although, MRI of the prostate seems to be useful, nevertheless this method remains expensive and lacks availability regarding the oncoming requirements.

Diagnosis of Prostate Cancer in Patients with an Elevated Prostate-Specific Antigen Level: Role of Endorectal MRI and MR Spectroscopic Imaging

OBJECTIVE

The objective of our study was to determine the accuracy of endorectal MRI and MR spectroscopic imaging (MRSI) in the diagnosis of prostate cancer in patients with an elevated serum prostate-specific antigen (PSA) level.

MATERIALS AND METHODS

We retrospectively identified 40 patients with an elevated serum PSA level and without a histologic diagnosis of prostate cancer who underwent endorectal MRI and MRSI at our institution. On the basis of MRI findings alone and then combined MRI and MRSI findings, a single experienced observer rated the presence or absence of prostate cancer in each side of the prostate on a 5-point scale (1 = definitely absent, 5 = definitely present). Areas under the receiver operating characteristic (ROC) curve were calculated using the hemiprostate as the unit of analysis. The presence or absence of cancer on subsequent endorectal sonographically guided sextant biopsy was used as the standard of reference.

RESULTS

Biopsy revealed no cancer in 24 patients, bilateral cancer in 11, and unilateral cancer in five. The areas under the ROC curve for the diagnosis of prostate cancer by hemigland was 0.70 for MRI alone and 0.63 for combined MRI and MRSI (no significant difference, p = 0.32).

CONCLUSION

Endorectal MRI and MRSI are reasonably accurate for the diagnosis of prostate cancer in patients with an elevated serum PSA level, but the remaining limitations suggest that MRI and MRSI should be used as a supplement rather than a replacement for biopsy using the current technology and diagnostic criteria.

E-cadherin promoter polymorphisms are not associated with the aggressiveness of prostate cancer in Caucasian patients

BACKGROUND

-160C-->A and -347G-->GA polymorphisms in the promoter region decrease E-cadherin gene transcription. Decreased E-cadherin expression predicts poor outcome among patients with cancer. We sought to investigate whether -160C-->A and/or -347G-->GA polymorphisms were associated with the aggressiveness of prostate cancer.

METHODS

TaqMan single nucleotide polymorphism genotyping assay (Applied Biosystems, Foster City, CA) was used to detect -160C-->A and -347G-->GA polymorphisms in deoxyribonucleic acid from the paraffin-embedded prostate tissues of 98 Caucasian patients.

RESULTS

The genotype frequencies were -160C/C: 48% (47 of 98); -160C/A: 44% (43 of 98); -160A/A: 8% (8 of 98); -347G/G: 68% (67 of 98); -347G/GA: 28% (27 of 98); and -347GA/GA: 4% (4 of 98). Using the chi-square test, we found that the polymorphisms -160C-->A and -347G-->GA were not related to other clinical and pathologic parameters (i.e., age, prostate-specific antigen level, Gleason grade, and clinical stage) (P > 0.05). In combination analysis, there was no significant relationship between patients with both -160C/C and -347G/G, and these same parameters (P > 0.05). Using the log-rank test, we found no significant difference in relapse-free survival and overall survival between patients with -160C/C and those with -160A/C or -160A/A (P = 0.0764 and 0.2746, respectively), and also no significant difference between patients with -347G/G and those with -347GA/G or -347GA/GA (P = 0.9416 and 0.7367, respectively). There was also no significant difference in relapse-free survival and overall survival between patients with homozygosities of -160C/-347G and patients with other genotypes (P = 0.1418 and 0.2434, respectively).

CONCLUSION

We conclude that E-cadherin -160C-->A and/or -347G-->GA polymorphisms are not associated with the aggressiveness of prostate cancer in Caucasian patients.

Functional MR Imaging of Prostate Cancer

T2-weighted magnetic resonance (MR) imaging has been widely used for pretreatment work-up for prostate cancer, but its accuracy for the detection and localization of prostate cancer is unsatisfactory. To improve the utility of MR imaging for diagnostic evaluation, various other techniques may be used. Dynamic contrast material-enhanced MR imaging allows an assessment of parameters that are useful for differentiating cancer from normal tissue. The advantages of this technique include the direct depiction of tumor vascularity and, possibly, obviation of an endorectal coil; however, there also are disadvantages, such as limited visibility of cancer in the transitional zone. Diffusion-weighted imaging demonstrates the restriction of diffusion and the reduction of apparent diffusion coefficient values in cancerous tissue. This technique allows short acquisition time and provides high contrast resolution between cancer and normal tissue, but individual variability in apparent diffusion coefficient values may erode diagnostic performance. The accuracy of MR spectroscopy, which depicts a higher ratio of choline and creatine to citrate in cancerous tissue than in normal tissue, is generally accepted. The technique also allows detection of prostate cancer in the transitional zone. However, it requires a long acquisition time, does not directly depict the periprostatic area, and frequently is affected by artifacts. Thus, a comprehensive evaluation in which both functional and anatomic MR imaging techniques are used with an understanding of their particular advantages and disadvantages may help improve the accuracy of MR for detection and localization of prostate cancer.