Histological characteristics of the index lesion in whole-mount radical prostatectomy specimens: implications for focal therapy

Targeted biopsy of the prostate

Diagnostic multiparametric MRI of the prostate has steadily evolved over the last three decades and can now reliably depict the dominant tumor in most men with prostate cancer. In response, several methods of targeted biopsy to direct tissue sampling of suspected tumor foci seen at multiparametric MRI have been developed and successfully tested in recent years, including software-assisted MRI-ultrasound (US) fusion biopsy and direct MRI-guided in-bore biopsy. These advances are leading to a sea change in the approach to prostate cancer diagnosis, with the traditional approach of blind systematic biopsy increasingly being replaced by MRI directed targeted biopsy. This review aims to describe the current status of targeted biopsy, with an emphasis on the relative accuracy of different techniques. The results of several critical large multicenter trials are presented, while unanswered questions that require more research are highlighted.

Association of Pathological Features and Multiparametric MRI-Based Radiomics With TP53-Mutated Prostate Cancer

BACKGROUND

TP53 mutations are associated with prostate cancer (PCa) prognosis and therapy.

PURPOSE

To develop TP53 mutation classification models for PCa using MRI radiomics and clinicopathological features.

STUDY TYPE

Retrospective.

POPULATION

388 patients with PCa from two centers (Center 1: 281 patients; Center 2: 107 patients). Cases from Center 1 were randomly divided into training and internal validation sets (7:3). Cases from Center 2 were used for external validation.

FIELD STRENGTH/SEQUENCE

3.0T/T2-weighted imaging, dynamic contrast-enhanced imaging, diffusion-weighted imaging.

ASSESSMENT

Each patient's index tumor lesion was manually delineated on the above MRI images. Five clinicopathological and 428 radiomics features were obtained from each lesion. Radiomics features were selected by least absolute shrinkage and selection operator and binary logistic regression (LR) analysis, while clinicopathological features were selected using Mann-Whitney U test. Radiomics models were constructed using LR, support vector machine (SVM), and random forest (RF) classifiers. Clinicopathological-radiomics combined models were constructed using the selected radiomics and clinicopathological features with the aforementioned classifiers.

STATISTICAL TESTS

Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis and area under the curve (AUC). P value <0.05 indicates statistically significant.

RESULTS

In the internal validation set, the radiomics model had an AUC of 0.74 with the RF classifier, which was significantly higher than LR (AUC = 0.61), but similar to SVM (AUC = 0.69; P = 0.422). For the combined model, the AUC of RF model was 0.84, which was significantly higher than LR (0.64), but similar to SVM (0.80; P = 0.548). Both the combined RF and combined SVM models showed significantly higher AUCs than the radiomics models. In the external validation set, the combined RF and combined SVM models showed AUCs of 0.83 and 0.82.

DATA CONCLUSION

Pathological-radiomics combined models with RF, SVM show the association of TP53 mutations and pathological-radiomics features of PCa.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Focal therapy for prostate cancer

Traditional treatments for localized prostate cancer include radical prostatectomy or radiation therapy but pose challenges due to treatment related side effects, namely erectile dysfunction and urinary incontinence. In recent years, focal therapy has emerged as a viable treatment option for localized low-intermediate risk prostate cancer in carefully selected patients. Short and medium-term studies show acceptable cancer control outcomes and reduced morbidity when comparing focal therapy to whole gland treatment for prostate cancer, however there is paucity of long-term studies. Here we review focal ablative therapies commonly used, discuss the role of imaging in monitoring treatment, and summarize oncologic outcomes based on studies to date.

Focal therapy with high-intensity focused ultrasound for prostate cancer: 3-year outcomes from a prospective trial

OBJECTIVE

To assess the oncological and functional outcomes of focal high-intensity focused ultrasound (HIFU) in treating localised prostate cancer (PCa), a 3-year prospective study was undertaken using periodic post-ablation saturation biopsies.

PATIENTS AND METHODS

Men with two or fewer lesions of grade group (GG) ≤3 PCa were eligible for participation. Additional criteria included a prostate-specific antigen (PSA) level of ≤15 ng/mL, clinical T1c-T2, and a life expectancy of ≥10 years. The primary endpoint was failure-free survival (FFS), defined as absence of clinically significant PCa (csPCa) in- or out-of-field on protocol-mandated saturation biopsy, no whole-gland or systemic salvage treatment, PCa metastasis, or PCa-related death. Results are reported using two distinct definitions of csPCa: (i) the presence of any GG ≥2 and (ii) any GG ≥3 or core involvement of ≥6 mm. Secondary endpoints were functional patient-reported outcome measures addressing urinary, sexual, and bowel function.

RESULTS

A total of 91 patients were included: six (7%) with GG1 and 85 (93%) with GG ≥2. In all, 83 (91%) underwent at least one follow-up biopsy. Biopsy attendance at 6, 12, and 36 months was 84%, 67%, and 51%, respectively. The FFS at these time points for any GG ≥2 PCa was 79% (95% confidence interval [CI] 80-88%), 57% (95% CI 48-69%) and 44% (95% CI 34-56%), respectively. Using the second definition, FFS were 88% (95% CI 81-95%), 70% (95% CI 61-81%) and 65% (95% CI 55-77%), respectively. The 3-year cancer-specific survival was 100%, and freedom from metastasis was 99%. Magnetic resonance imaging (MRI) (negative predictive value of up to 89%, 95% CI 84-93%) and relative decrease of PSA values (P = 0.4) performed poorly in detecting residual disease. Urinary and bowel assessment returned to baseline questionnaire scores within 3 months. In all, 17 (21%) patients reported meaningful worsening in erectile function. A significant decrease of PCa related anxiety was observed.

CONCLUSIONS

Focal HIFU treatment for localised PCa shows excellent functional outcomes with half of the patients remaining cancer-free after 3 years. Whole-gland treatment was avoided in 81%. Early follow-up biopsies are crucial to change or continue the treatment modality at the right time, while the use of MRI and PSA in detecting PCa recurrence is uncertain.

Adaptation of a Clinical High-Frequency Transrectal Ultrasound System for Prostate Photoacoustic Imaging: Implementation and Pre-clinical Demonstration

OBJECTIVE

High-frequency, high-resolution transrectal micro-ultrasound (micro-US: ≥15 MHz) imaging of the prostate is emerging as a beneficial tool for scoring disease risk and accurately targeting biopsies. Adding photoacoustic (PA) imaging to visualize abnormal vascularization and accumulation of contrast agents in tumors has potential for guiding focal therapies. In this work, we describe a new imaging platform that combines a transrectal micro-US system with transurethral light delivery for PA imaging.

METHODS

A clinical transrectal micro-US system was adapted to acquire PA images synchronous to a tunable laser pulse. A transurethral side-firing optical fiber was developed for light delivery. A polyvinyl chloride (PVC)-plastisol phantom was developed and characterized to image PA contrast agents in wall-less channels. After resolution measurement in water, PA imaging was demonstrated in phantom channels with dyes and biodegradable nanoparticle contrast agents called porphysomes. In vivo imaging of a tumor model was performed, with porphysomes administered intravenously.

RESULTS

Photoacoustic imaging data were acquired at 5 Hz, and image reconstruction was performed offline. PA image resolution at a 14-mm depth was 74 and 261 μm in the axial and lateral directions, respectively. The speed of sound in PVC-plastisol was 1383 m/s, and the attenuation was 4 dB/mm at 20 MHz. PA signal from porphysomes was spectrally unmixed from blood signals in the tumor, and a signal increase was observed 3 h after porphysome injection.

CONCLUSION

A combined transrectal micro-US and PA imaging system was developed and characterized, and in vivo imaging demonstrated. High-resolution PA imaging may provide valuable additional information for diagnostic and therapeutic applications in the prostate.

Prostate cancer: Molecular aspects, consequences, and opportunities of the multifocal nature

Prostate cancer is unique compared to other major cancers due to the presence of multiple primary malignant foci in the majority of patients at the time of diagnosis. Each malignant focus has distinct somatic mutations and gene expression patterns, which represents a challenge for the development of prognostic tests for localized prostate cancer. Additionally, the molecular heterogeneity of advanced prostate cancer has important implications for management, particularly for patients with metastatic and locally recurrent cancer. Studies have shown that prostate cancers with mutations in DNA damage response genes are more sensitive to drugs inhibiting the poly ADP-ribose polymerase (PARP) enzyme. However, testing for such mutations should consider both spatial and temporal heterogeneity. Here, we summarize studies where multiregional genomics and transcriptomics analyses have been performed for primary prostate cancer. We further discuss the vast interfocal heterogeneity and how prognostic biomarkers and a molecular definition of the index tumor should be developed. The concept of focal treatments in prostate cancer has been evolving as a demand from patients and clinicians and is one example where there is a need for defining an index tumor. Here, biomarkers must have proven value for individual malignant foci. The potential discovery and implementation of biomarkers that are agnostic to heterogeneity are also explored as an alternative to multisample testing. Thus, deciding upon whole-organ treatment, such as radical prostatectomy, should depend on information from biomarkers which are informative for the whole organ.

Is imaging accurate enough to detect index lesion in prostate cancer? Analysis of the performance of MRI and other imaging modalities

Prostate imaging techniques have progressed across the years allowing for a better detection and characterization of prostate cancer (PCa) lesions. These advancements have led to the possibility to also improve and tailor the treatments on the most aggressive lesion, defined as Index Lesion (IL), to reduce morbidity. The IL is, indeed, considered as the entity which encompass the most aggressive features in prostate cancer disease. Multiparametric magnetic resonance imaging (mpMRI) has emerged as the suggested tool to detect the disease and plan treatments, including those under investigation such as focal therapy (FT). Our review aimed to query the literature on the ability of mpMRI in IL detection and to explore the future perspectives in PCa IL diagnosis. A review of the literature was performed from January 2010 to July 2023. All studies investigating the performance of mpMRI and other main imaging techniques able to detect the IL were assessed and evaluated. mpMRI performs well in the detection of IL with a sensitivity which reaches 71% to 94% among the different studies. However, mpMRI seems to have limited sensitivity in the detection of small tumours (<0.5 mL) and low-grade histology lesions. To overcome these limitations other diagnostic imaging techniques have been proposed. Multiparametric Ultrasound has shown results comparable to mpMRI while detecting 4.3% fewer clinically significant PCa (P=0.042). Positron emission tomography-based modalities using PSMA seems to have higher sensitivity than mpMRI, being able to yield from 13.5% to 18.2% additional cancers. MRI has emerged as the recommended tool since most of the IL can be easily identified, and is the imaging of choice while selecting patients for FT. Other imaging modalities has been proposed to improve PCa lesions detection, but results need to be confirmed by ongoing randomized controlled trial.

MRI-targeted biopsy cores from prostate index lesions: assessment and prediction of the number needed

BACKGROUND

Magnetic resonance imaging (MRI) is used to detect the prostate index lesion before targeted biopsy. However, the number of biopsy cores that should be obtained from the index lesion is unclear. The aim of this study is to analyze how many MRI-targeted biopsy cores are needed to establish the most relevant histopathologic diagnosis of the index lesion and to build a prediction model.

METHODS

We retrospectively included 451 patients who underwent 10-core systematic prostate biopsy and MRI-targeted biopsy with sampling of at least three cores from the index lesion. A total of 1587 biopsy cores were analyzed. The core sampling sequence was recorded, and the first biopsy core detecting the most relevant histopathologic diagnosis was identified. In a subgroup of 261 patients in whom exactly three MRI-targeted biopsy cores were obtained from the index lesion, we generated a prediction model. A nonparametric Bayes classifier was trained using the PI-RADS score, prostate-specific antigen (PSA) density, lesion size, zone, and location as covariates.

RESULTS

The most relevant histopathologic diagnosis of the index lesion was detected by the first biopsy core in 331 cases (73%), by the second in 66 cases (15%), and by the third in 39 cases (9%), by the fourth in 13 cases (3%), and by the fifth in two cases (<1%). The Bayes classifier correctly predicted which biopsy core yielded the most relevant histopathologic diagnosis in 79% of the subjects. PI-RADS score, PSA density, lesion size, zone, and location did not independently influence the prediction model.

CONCLUSION

The most relevant histopathologic diagnosis of the index lesion was made on the basis of three MRI-targeted biopsy cores in 97% of patients. Our classifier can help in predicting the first MRI-targeted biopsy core revealing the most relevant histopathologic diagnosis; however, at least three MRI-targeted biopsy cores should be obtained regardless of the preinterventionally assessed covariates.

Novel sampling scheme with reduced cores in men with multiparametric MRI-visible lesions undergoing prostate biopsy

PURPOSE

To investigate the effects of various prostate biopsy protocols with reduced cores on the detection of clinically significant prostate cancer (csPCa) in individuals with MRI-visible lesions (Prostate Imaging Reporting and Data System ≥ 3).

METHODS

A total of 464 patients with MRI-visible lesions were recruited. All patients underwent two or more targeted biopsies (TB) and systematic biopsies (SB). Several hypothetical biopsy schemes were set-up: TB alone, TB+ipsilateral SB, TB+contralateral SB, TB+SB of the targeted sector (TB+t-SB), and TB+SB of the non-targeted sector (TB+n-SB). A subgroup analysis of patients with multiple MRI-visible lesions was performed. The standard of reference was defined as TB+SB. McNemar test was used to compare csPCa detection rates between various sampling schemes.

RESULTS

The detection rates for prostate cancer and csPCa were 72.8% (338 of 464) and 62.1% (288 of 464), respectively. There were 8.0%, 0.3%, 6.3%, 1.0%, and 4.5% cases in which TB alone, TB+ipsilateral SB, TB+contralateral SB, TB+t-SB, and TB+n-SB would have missed csPCa, respectively. All hypothetical schemes, with the exception of TB+contralateral SB (p = 0.063), significantly outperformed TB alone in terms of csPCa detection (p < 0.05). As for the multi-focus cohort, which included 48 cases, none of the non-index lesions had a higher Gleason grade than the index lesions within the same patients.

CONCLUSION

TB+ipsilateral SB might be the optimal biopsy scheme for detecting csPCa. As for the multi-focus cohort, the biopsy of the non-index lesions provided limited pathological information.

P-score in preoperative biopsies accurately predicts P-score in final pathology at radical prostatectomy in patients with localized prostate cancer

BACKGROUND

Prostate cancer (PCa) is a highly heterogeneous, multifocal disease, and identification of clinically significant lesions is challenging, which complicates the choice of adequate treatment. The Prostatype® score (P-score) is intended to guide treatment decisions for newly diagnosed PCa patients based on a three-gene signature (IGFBP3, F3, and VGLL3) and clinicopathological information obtained at diagnosis. This study evaluated association of the P-score measured in preoperative magnetic resonance imaging/transrectal ultrasound fusion-guided core needle biopsies (CNBs) and the P-score measured in radical prostatectomy (RP) specimens of PCa patients. We also evaluated the P-score association with the pathology of RP specimens. Furthermore, concordance of the P-score in paired CNB and RP specimens, as well as in index versus concomitant nonindex tumor foci from the same RP was investigated.

METHODS

The study included 100 patients with localized PCa. All patients were diagnosed by CNB and underwent RP between 2015 and 2018. Gene expression was assessed with the Prostatype® real-time quantitative polymerase chain reaction kit and the P-score was calculated. Patients were categorized into three P-score risk groups according to previously defined cutoffs.

RESULTS

For 71 patients, sufficient CNB tumor material was available for comparison with the RP specimens. The CNB-based P-score was associated with the pathological T-stage in RP specimens (p = 0.02). Moreover, the CNB-based P-score groups were in substantial agreement with the RP-based P-score groups (weighted κ score: 0.76 [95% confidence interval, 95% CI: 0.60-0.92]; Spearman's rank correlation coefficient r = 0.83 [95% CI: 0.74-0.89]; p < 0.0001). Similarly, the P-score groups based on paired index tumor and concomitant nonindex tumor foci (n = 64) were also in substantial agreement (weighted κ score: 0.74 [95% CI: 0.57-0.91]; r = 0.83 [95% CI: 0.73-0.89], p < 0.0001).

CONCLUSIONS

Our findings suggest that the P-score based on preoperative CNB accurately reflects the pathology of the whole tumor, highlighting its value as a decision support tool for newly diagnosed PCa patients.

Evolving imaging methods of prostate cancer and the emergence of magnetic resonance imaging guided ablation techniques

Established therapies for prostate cancer (PCa), surgery and radiotherapy, treat the entire gland regardless of the location of the cancerous lesion within the prostate. Although effective, these methods include a significant risk of worsening genitourinary outcomes. Targeted image-guided cancer therapy has gained acceptance through improved PCa detection, localization, and characterization by magnetic resonance imaging (MRI). Minimally-invasive ablative techniques aim to achieve comparable oncological outcomes to radical treatment while preserving genitourinary function. Transurethral ultrasound ablation (TULSA) and next-generation transrectal high-intensity focused ultrasound (HIFU) utilize MRI guidance to thermally ablate prostate tissue under real-time MRI monitoring and active temperature feedback control. Previous trials performed by our group and others, including a large multicenter study in men with localized favorable-risk disease, have demonstrated that TULSA provides effective prostate ablation with a favorable safety profile and low impact on quality of life. Recently, MRI-guided HIFU focal therapy was also shown as a safe and effective treatment of intermediate-risk PCa. Here we review the current literature on ablative techniques in the treatment of localized PCa with a focus on TULSA and HIFU methods.

Detection of clinically significant index prostate cancer using micro-ultrasound: correlation with radical prostatectomy

OBJECTIVE

To determine the detection of clinically significant prostate cancer (csPCa) index lesion using high resolution transrectal micro-ultrasound (MicroUS) applying PRI-MUS (Prostate Risk Identification using Micro Ultrasound) score v1.0.

METHODS

Men who underwent radical prostatectomy following biopsy and MicroUS assessment were included. MicroUS dynamic cine loops of these patients were retrospectively reviewed by an experienced radiologist. The radiologist was aware that patients had undergone radical prostatectomy but was blinded to pathological data. Suspicious sites were assigned a PRI-MUS score. Radical prostatectomy specimens were examined with quarter mount technique. Detection rate of csPCa index lesion [Grade Group (GG) ≥2] by MicroUS was assessed at a patient level.

RESULTS

Twenty-five participants were included in the analysis. The median age was 65.5 years (range 56 - 74). Median PSA was 6.45 ng/dL (range 2 - 31.72). Two of 25 patients did not have csPCa (GG1 disease) on radical prostatectomy. MicroUS visualized 20/23 (87%) of the csPCa index lesions [median length 9 mm (range 1.5- 28.5)]. All identified lesions were categorized PRIMUS score 4 or 5. The 3 missed index lesions were in the transition zone [median length 10.5 mm (range 4.5-22.5)]. MicroUS missed 11 non index csPCa in 9 participants [median length 1.5 mm (range 1.5-10.5)]. Of these, 8 were GG2, two GG3 and one GG5. MicroUS identified the csPCa index lesion in all 9 of these men.

CONCLUSION

MicroUS showed high sensitivity (87%) in detecting index lesions in the prostate gland and identified 100% of index lesions in the peripheral zone.

Focal therapy: definition and rationale

PURPOSE OF REVIEW

The role of focal therapy for the treatment of prostate cancer is expanding in clinical practice. The aim of this review is to introduce readers to controversies in the use of focal therapy and its rationale.

RECENT FINDINGS

There is a growing body of literature regarding the short-term and medium-term cancer control parameters and quality of life outcomes. These are mostly observational studies without a comparative arm. There is a need for high-quality randomize control trials comparing these treatments to definitive standard of care interventions (e.g. surgery or radiotherapy) in appropriate patient populations.

SUMMARY

Focal therapy for prostate cancer has become an established therapeutic strategy. Evidence continues to accrue regarding its effectiveness. It is a useful treatment option for the appropriately selected patient, with the appeal of improved quality of life compared with standard therapies.

Focal prostate cancer therapy in the era of multiparametric MRI: a review of options and outcomes

BACKGROUND

The goal of prostate cancer focal therapy is to achieve oncologic control while reducing the rate of adverse events associated with whole-gland treatments. Numerous focal therapy modalities are currently available with early data demonstrating highly variable rates of cancer control and preservation of sexual/urinary function.

METHODS

All English language clinical trial publications evaluating various focal therapies for localized prostate cancer were reviewed. The literature search was limited to studies from the modern era of MRI-guided treatment, as MRI is hypothesized to improve tumor localization and targeting. Primary outcomes were post-treatment cancer-free rates, in-field/out-of-field recurrence rates, and rates of conversion to radical therapy. Secondary outcomes were related to functional status and adverse events.

RESULTS

Numerous focal therapies were identified with clinical data including high-intensity focused ultrasound, transurethral ultrasound ablation, focal laser ablation, focal cryotherapy, irreversible electroporation, and photodynamic therapy. Recurrence rates among all technologies were low to moderate (0-51%) and rates of freedom from radical treatment were highly variable (46-98%). Rates of erectile dysfunction and incontinence generally ranged from 0 to 44% and 0 to 12%, respectively, with variability between focal therapy modalities. Caution should be exercised when comparing studies as outcomes are strongly associated with patient selection. No individual focal therapy is currently recommended by society guidelines. Randomized controlled trials are ongoing in search of a standard of care.

CONCLUSION

For localized MRI-visible prostate cancer, early clinical trial data demonstrate that focal therapy can provide good to moderate cancer control while having preferable side effect profiles compared to whole-gland treatments. While current studies do not make head-to-head comparisons between technologies, early data suggest a potential for these technologies to provide adequate cancer control in a well-selected patient population. The oncologic outcomes of some focal therapies appear promising; however, longer-term follow-up data are needed to assess the durability of early outcomes.

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.

Short-duration dynamic [18F]DCFPyL PET and CT perfusion imaging to localize dominant intraprostatic lesions in prostate cancer: validation against digital histopathology and comparison to [18F]DCFPyL PET/MR at 120 minutes

Purpose

Localized prostate cancer (PCa) in patients is characterized by a dominant focus in the gland (dominant intraprostatic lesion, DIL). Accurate DIL identification may enable more accurate diagnosis and therapy through more precise targeting of biopsy, radiotherapy and focal ablative therapies. The goal of this study is to validate the performance of [¹⁸F]DCFPyL PET and CT perfusion (CTP) for detecting and localizing DIL against digital histopathological images.

Methods

Multi-modality image sets: in vivo T2-weighted (T2w)-MRI, 22-min dynamic [¹⁸F]DCFPyL PET/CT, CTP, and 2-h post-injection PET/MR were acquired in patients prior to radical prostatectomy. The explanted gland with implanted fiducial markers was imaged with T2w-MRI. All images were co-registered to the pathologist-annotated digital images of whole-mount mid-gland histology sections using fiducial markers and anatomical landmarks. Regions of interest encompassing DIL and non-DIL tissue were drawn on the digital histopathological images and superimposed on PET and CTP parametric maps. Logistic regression with backward elimination of parameters was used to select the most sensitive parameter set to distinguish DIL from non-DIL voxels. Leave-one-patient-out cross-validation was performed to determine diagnostic performance.

Results

[¹⁸F]DCFPyL PET and CTP parametric maps of 15 patients were analyzed. SUV_Late and a model combining K_i and k₄ of [¹⁸F]DCFPyL achieved the most accurate performance distinguishing DIL from non-DIL voxels. Both detection models achieved an AUC of 0.90 and an error rate of < 10%. Compared to digital histopathology, the detected DILs had a mean dice similarity coefficient of 0.8 for the K_i and k₄ model and 0.7 for SUV_Late.

Conclusions

We have validated using co-registered digital histopathological images that parameters from kinetic analysis of 22-min dynamic [¹⁸F]DCFPyL PET can accurately localize DILs in PCa for targeting of biopsy, radiotherapy, and focal ablative therapies. Short-duration dynamic [¹⁸F]DCFPyL PET was not inferior to SUV_Late in this diagnostic task.

Clinical trial registration number: NCT04009174 (ClinicalTrials.gov).

[Clinical aspects in the diagnosis and treatment of prostate cancer]

BACKGROUND

Diagnosis and treatment of primary prostate cancer (PCA) have undergone significant changes in the last few years due to modern imaging.

OBJECTIVES

Established and modern diagnostic and therapeutic modalities for detection and treatment of primary PCA are presented and discussed critically.

MATERIALS AND METHODS

Background knowledge and guideline recommendations on primary PCA are summarized and additional information from relevant publications is given.

RESULTS

Modern imaging, in particular multiparametric magnetic resonance imaging (mpMRI), has revolutionized the diagnostic work-up of primary PCA. Due to mpMRI, tumors are detected significantly better in both initial and re-biopsy with a significant reduction of overdiagnosis of clinically insignificant PCA. Therapeutic approaches such as active surveillance, radical prostatectomy and focal therapies are increasingly being planned and carried out relying on MR-imaging information concerning tumor extent and tumor aggressiveness. In addition, prostate-specific membrane antigen-positron emission tomography/computed tomography (PSMA-PET/CT) has shown superiority in assessing patients with suspected biochemical recurrence and in primary staging of PCA compared to conventional imaging in terms of detection of metastases.

CONCLUSIONS

Modern imaging, especially mpMRI and PSMA-PET/CT, has added substantial benefits in modern diagnosis and treatment of primary PCA. Moreover, multiparametric ultrasound is also a promising addition to the radiological armamentarium in the management of primary PCA.

Does PSA level affect the choice of prostate puncture methods among MRI-ultrasound fusion targeted biopsy, transrectal ultrasound systematic biopsy or the combination of both?

OBJECTIVES

To explore whether prostate-specific antigen (PSA) affects the choice of prostate puncture methods by comparing MRI-ultrasound fusion targeted biopsy (MRI-TBx) with transrectal ultrasound systematic biopsy (TRUS-SBx) in the detection of prostate cancer (PCa), clinically significant prostate cancer (csPCa) and non-clinically significant prostate cancer (nsPCa) in different PSA groups (<10.0,10.0-20.0 and>20.0 ng ml-1).

METHODS

A total of 190 patients with 215 lesions who underwent both MRI-TBx and TRUS-SBx were included in this retrospective study. PSA was measured pre-operatively and stratified to three levels. The detection rates of PCa, csPCa and nsPCa through different methods (MRI-TBx, TRUS-SBx, or MRI-TBx +TRUS SBx) were compared with stratification by PSA.

RESULTS

Among the 190 patients, the histopathological results revealed PCa in 126 cases, including 119 csPCa. In PSA <10.0 ng ml-1 group, although the detection rates of PCa and csPCa by MRI-TBx were higher than those of TRUS-SBx, no significant differences were observed (p = 0.741; p = 0.400). In PSA 10.0-20.0 ng ml-1 group, difference between the detection rate of csPCa with TRUS-SBx and the combined method was statistically significant (p = 0.044). As for PSA >20.0 ng ml-1, MRI-TBx had a higher csPCa rate than TRUS-SBx with no statistical significance noted (p = 0.600).

CONCLUSION

MRI-TBx combined with TRUS-SBx could be suitable as a standard detection approach for csPCa in patients with PSA 10.0-20.0 ng ml-1. As for PSA >20.0 and <10.0 ng ml-1, both MRI-TBx and TRUS-SBx might provide effective solutions for tumor detection.

ADVANCES IN KNOWLEDGE

This study gives an account of choosing appropriate prostate puncture methods through PSA level.

Performance of transgluteal CT-guided biopsy of prostate lesions in men without rectal access: A retrospective study

OBJECTIVE

To retrospectively study the performance of CT-guided biopsy of target prostate lesions at a single institution.

METHODS

Between May 2016 and February 2021, we retrospectively identified all men without rectal access who underwent transgluteal CT-guided biopsy of PIRADS 4 or 5 targets detected on multiparametric MRI (n = 9). Clinical, radiological, and pathological details were collected by review of the electronic medical record, and included age, pre-biopsy prostate specific antigen (PSA) value, prior biopsy history, biopsy targeting technique and procedural details, complications, and final histologic diagnosis. Two targeting techniques were used: Localizing with anatomic landmarks or localizing with contrast enhancement.

RESULTS

Mean patient age was 69 years (range, 49-74) and mean PSA was 14.6 ng/mL (range 7-23). Four lesions were targeted using anatomic landmarks and 5 were targeted using contrast enhancement. All biopsies were technically successful and all resulted as prostate cancer. Three biopsies showed Gleason 6 cancer and 6 biopsies showed clinically significant prostate cancers with Gleason 7 or above. There were no major complications. 7 patients went on to definitive treatment with surgery or radiation.

CONCLUSION

Transgluteal CT-guided biopsy of MRI detected prostate lesions diagnoses clinically significant prostate cancer without complication and therefore should be considered for patients without a rectum.

Diagnostic value of computed high b-value whole-body diffusion-weighted imaging for primary prostate cancer

PURPOSE

To investigate the utility of post-acquisition computed diffusion-weighted imaging (cDWI) for primary prostate cancer (PCa) evaluation in biparametric whole-body MRI (bpWB-MRI).

METHODS

Patients who underwent pelvic MRI for PCa screening and subsequent bpWB-MRI for staging were included. Two radiologists assessed the diagnostic performance of the following datasets for clinically significant PCa diagnosis (grade group ≥2 according to the Prostate Imaging-Reporting and Data System, version 2.1): bpMRI₂₀₀₀ (axial DWI scans with a b-value of 2,000 s/mm² + axial T2WI scans from pre-biopsy pelvic MRI), computed bpWB-MRI₂₀₀₀ (computed WB-DWI scans with a b-value of 2,000 s/mm² + axial WB-T2WI scans), and native bpWB-MRI₁₀₀₀ (native axial WB-DWI scans with a b-value of 1,000 s/mm² + axial WB-T2WI scans). Systemic biopsy was used as reference standard.

RESULTS

Fifty-one patients with PCa were included. The areas under the curve (AUCs) of bpMRI₂₀₀₀ (0.89 for reader 1 and 0.86 for reader 2) and computed bpWB-MRI₂₀₀₀ (0.86 for reader 1 and 0.83 for reader 2) were significantly higher (p < 0.001) than those of native bpWB-MRI₁₀₀₀ (0.67 for both readers). No significant difference was observed between the AUCs of bpMRI₂₀₀₀ and computed bpWB-MRI₂₀₀₀ (p = 0.10 for reader 1 and p = 0.25 for reader 2).

CONCLUSIONS

The diagnostic performance of computed bpWB-MRI₂₀₀₀ was similar to that of dedicated pelvic bpMRI₂₀₀₀ for primary PCa evaluation. cDWI can be recommended for implementation in standard WB-MRI protocols to facilitate a one-step evaluation for concurrent detection of primary and metastatic PCa.

MRI-guided Focused Ultrasound Ablation for Localized Intermediate-Risk Prostate Cancer: Early Results of a Phase II Trial

Background To reduce adverse effects of whole-gland therapy, participants with localized clinically significant prostate cancer can undergo MRI-guided focal therapy. Purpose To explore safety and early oncologic and functional outcomes of targeted focal high-intensity focused ultrasound performed under MRI-guided focused ultrasound for intermediate-risk clinically significant prostate cancer. Materials and Methods In this prospective phase II trial, between February 2016 and July 2019, men with unifocal clinically significant prostate cancer visible at MRI were treated with transrectal MRI-guided focused ultrasound. The primary end point was the 5-month biopsy (last recorded in December 2019) with continuation to the 24-month follow-up projected to December 2021. Real-time ablation monitoring was performed with MR thermography. Nonperfused volume was measured at treatment completion. Periprocedural complications were recorded. Follow-up included International Prostate Symptom Score (IPSS) and International Index of Erectile Function-15 (IIEF-15) score at 6 weeks and 5 months, and multiparametric MRI and targeted biopsy of the treated area at 5 months. The generalized estimating equation model was used for statistical analysis, and the Holm method was used to adjust P value. Results Treatment was successfully completed in all 44 men, 36 with grade group (GG) 2 and eight with GG 3 disease (median age, 67 years; interquartile range [IQR], 62-70 years). No major treatment-related adverse events occurred. Forty-one of 44 participants (93%; 95% CI: 82, 98) were free of clinically significant prostate cancer (≥6 mm GG 1 disease or any volume ≥GG 2 disease) at the treatment site at 5-month biopsy (median, seven cores). Median IIEF-15 and IPSS scores were similar at baseline and at 5 months (IIEF-15 score at baseline, 61 [IQR, 34-67] and at 5 months, 53 [IQR, 24-65.5], P = .18; IPSS score at baseline, 3.5 [IQR, 1.8-7] and at 5 months, 6 [IQR, 2-7.3], P = .43). Larger ablations (≥15 cm³) compared with smaller ones were associated with a decline in IIEF-15 scores at 6 weeks (adjusted P < .01) and at 5 months (adjusted P = .07). Conclusion Targeted focal therapy of intermediate-risk prostate cancer performed with MRI-guided focused ultrasound ablation was safe and had encouraging early oncologic and functional outcomes. © RSNA, 2021 Online supplemental material is available for this article See also the editorial by Tempany-Afdhal in this issue.

Role of MRI for the detection of prostate cancer

The use of multiparametric MRI has been hastened under expanding, novel indications for its use in the diagnostic and management pathway of men with prostate cancer. This has helped drive a large body of the literature describing its evolving role over the last decade. Despite this, prostate cancer remains the only solid organ malignancy routinely diagnosed with random sampling. Herein, we summarize the components of multiparametric MRI and interpretation, and present a critical review of the current literature supporting is use in prostate cancer detection, risk stratification, and management.

Should we perform systematic biopsies in case of suspicious MRI for prostate cancer in 2020? A review of literature

CONTEXT

Multiparametric magnetic resonance imaging (MRI) is now recommended before performing prostate biopsies, looking for suspicious lesions to perform targeted biopsies (TB). However, the association or exclusive performance of systematic biopsies (SB), criticized for its morbidity and for the detection of insignificant cancers, remains debated.

OBJECTIVE

To perform a literature review to answer three questions: (1) In the presence of a suspicious MRI lesion, should we always perform SB in addition to TB? (2) Can we avoid SB when considering focal treatment? (3) Is there an increase in adverse events when associating SB with TB?

SOURCES

A non-systematic literature review was carried out on Medline in April 2020 using the keywords "MRI", "PROSTATE CANCER", "SYSTEMATIC BIOPSY", "TARGETED BIOPSY", "ADVERSE EVENTS". The references of the selected articles were analyzed for additional articles. Selection of Studies published in the last five years were analyzed and retained if the available data made it possible to answer one of the three questions asked.

RESULTS

In biopsy-naive patients, the added value of SB to TB for detection of significative cancer varied from +5 to+7% and was reduced to +1 to +3% in the case of a previous series of negative biopsies. For patients under active surveillance, this added value was higher, ranging from +8% to +17%. MRI has a negative predictive value of 85 to 95%, but this value drops to 55% for the detection of secondary or tertiary foci. The use of SB is necessary if focal treatment is considered. Serious complications from biopsies requiring hospitalization range from 1.4 to 6.9% and are increased by the number of previous biopsy series performed more than by the number of biopsies per series.

CONCLUSION

In the presence of a suspicious MRI lesion, SB is indicated in addition to TB but can be discussed in patients with previous negative biopsies. They are necessary if focal treatment is considered to aid surgical planning. Severe complications from biopsies do not seem to increase when SB are associated to TB, but rather with the number of biopsy series performed.

Gold nanoshell-localized photothermal ablation of prostate tumors in a clinical pilot device study

Biocompatible gold nanoparticles designed to absorb light at wavelengths of high tissue transparency have been of particular interest for biomedical applications. The ability of such nanoparticles to convert absorbed near-infrared light to heat and induce highly localized hyperthermia has been shown to be highly effective for photothermal cancer therapy, resulting in cell death and tumor remission in a multitude of preclinical animal models. Here we report the initial results of a clinical trial in which laser-excited gold-silica nanoshells (GSNs) were used in combination with magnetic resonance-ultrasound fusion imaging to focally ablate low-intermediate-grade tumors within the prostate. The overall goal is to provide highly localized regional control of prostate cancer that also results in greatly reduced patient morbidity and improved functional outcomes. This pilot device study reports feasibility and safety data from 16 cases of patients diagnosed with low- or intermediate-risk localized prostate cancer. After GSN infusion and high-precision laser ablation, patients underwent multiparametric MRI of the prostate at 48 to 72 h, followed by postprocedure mpMRI/ultrasound targeted fusion biopsies at 3 and 12 mo, as well as a standard 12-core systematic biopsy at 12 mo. GSN-mediated focal laser ablation was successfully achieved in 94% (15/16) of patients, with no significant difference in International Prostate Symptom Score or Sexual Health Inventory for Men observed after treatment. This treatment protocol appears to be feasible and safe in men with low- or intermediate-risk localized prostate cancer without serious complications or deleterious changes in genitourinary function.

Prostate focal therapy: the rule or exception?

PURPOSE OF REVIEW

Prostate focal therapy has the potential to preserve urinary and sexual function while eliminating clinically significant cancer in a subset of men with low-volume, organ-confined prostate cancer. This systematic review aims to examine current evidence to determine the efficacy and safety of focal therapy for standard clinical application.

RECENT FINDINGS

Focal therapy reduces the rate of cancer progression and conversion to radical therapy in men on active surveillance for prostate cancer. As a strategy, success in focal therapy is heavily dependent on the use of imaging and targeted biopsies. Despite advances in these areas, there remains a small but significant risk of under-detecting clinically significant cancer. Similarly, under-estimation of tumor volume may contribute to infield recurrences and close attention must be paid to the ablation margin. Although long-term oncological outcomes remain lacking, focal therapy has a low complication rate, minimal impact on urinary continence and a moderate impact on erectile function.

SUMMARY

With the appropriate expertise in imaging, targeted biopsy and targeted ablation, focal therapy is a good option in men with low-intermediate risk cancer who are willing to maximize their urinary and sexual function. However, close posttreatment surveillance and the possibility of conversion to whole gland therapy must be accepted.

Detection and Localization of Prostate Cancer at 3-T Multiparametric MRI Using PI-RADS Segmentation

OBJECTIVE. The purpose of this study is to determine the overall and sector-based performance of 3-T multiparametric MRI for prostate cancer (PCa) detection and localization by using Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2) scoring and segmentation compared with whole-mount histopathologic analysis. MATERIALS AND METHODS. Multiparametric 3-T MRI examinations of 415 consecutive men were compared with thin-section whole-mount histopathologic analysis. A genitourinary radiologist and pathologist collectively determined concordance. Two radiologists assigned PI-RADSv2 categories and sectoral location to all detected foci by consensus. Tumor detection rates were calculated for clinical and pathologic (Gleason score) variables. Both rigid and adjusted sector-matching models were used to account for fixation-related issues. RESULTS. The 415 patients had 863 PCa foci (52.7% had a Gleason score ≥ 7, 61.9% were ≥ 1 cm, and 90.4% (375/415) of index lesions were ≥ 1 cm) and 16,185 prostate sectors. Multiparametric MRI enabled greater detection of PCa lesions 1 cm or larger (all lesions vs index lesions, 61.6% vs 81.6%), lesions with Gleason score greater than or equal to 7 (all lesions vs index lesions, 71.4% vs 80.9%), and index lesions with both Gleason score greater than or equal to 7 and size 1 cm or larger (83.3%). Higher sensitivity was obtained for adjusted versus rigid tumor localization for all lesions (56.0% vs 28.5%), index lesions (55.4% vs 34.3%), lesions with Gleason score greater than or equal to 7 (55.7% vs 36.0%), and index lesions 1 cm or larger (56.1% vs 35.0%). Multiparametric 3-T MRI had similarly high specificity (96.0-97.9%) for overall and index tumor localization with adjusted and rigid sector-matching approaches. CONCLUSION. Using 3-T multiparametric MRI and PI-RADSv2, we achieved the highest sensitivity (83.3%) for the detection of lesions 1 cm or larger with Gleason score greater than or equal to 7. Sectoral localization of PCa within the prostate was moderate and was better with an adjusted model than with a rigid model.

[Focal therapy for prostate cancer]

Focal therapy (FT) should have the same oncological efficacy as whole gland therapy with fewer side effects. Precise diagnosis with PI-RADS v2 standard multiparametric magnetic resonance imaging (MRI) and fusion or template biopsy is a basic prerequisite. Numerous ablation technologies and treatment strategies have been developed, including hemiablation. Treatment success is still inconsistently defined. The only large randomized study available compares one of the procedures to standard therapy. Therefore, even in 2019, FT must still be regarded as experimental and should only be carried out within the context of studies. Follow-up should correspond to active surveillance (AS), including MRI and fusion biopsy. Advantages and disadvantages of each ablation technique should be taken into consideration as well as the suitability of certain regions in the gland. Ideally, an individualized "à la carte" selection of various procedures should be offered. FT is well suited for patients with highly localized cancers at intermediate risk if standard therapies or AS is not possible or has been refused.

Histological characteristics of the largest and secondary tumors in radical prostatectomy specimens and implications for focal therapy

Background

Pathological features of prostate cancer in Korean men were analyzed to determine whether identification of tumor volume, Gleason score (GS), focality, and location using radical prostatectomy (RP) specimens can provide useful information for the application of focal therapy (hemiablation).

Methods

From January 2016 to December 2017, 913 patients who underwent RP at a single center were selected for analysis. Patients with prostate-specific antigen levels > 15 ng/mL or those who had received hormone therapy prior to surgery were excluded. Preoperative data and the number, volume, location, and GS of each tumor were recorded.

Results

Overall, 762 RP specimens were examined, and 1448 tumors were identified. The majority of the cases were multifocal (60.5%) and bilateral (82%) in nature. Among the 686 secondary tumors, 250 (36.4%) had a GS ≥7 and 122 (17.8%) had a tumor volume ≥ 0.5 mL. Among the 435 bilateral multifocal cases, secondary tumors on the lobes contralateral to the largest tumor were significant by volume (≥0.5 mL) in 91 (20.9%) cases and by grade (GS ≥7) in 179 (41.1%) cases. There were 102 (23.4%) tumors with a small tumor volume (< 0.5 mL) and Gleason pattern 4 on the lobe contralateral to the largest tumor.

Conclusions

Bilateral and multifocal tumors are a common feature and secondary tumors frequently exhibit clinically significant prostate cancer on RP specimens in Korea. In many cases, secondary tumors on the lobe contralateral to the largest tumor had a high GS and small tumor volume.

MRI-guided localization of the dominant intraprostatic lesion and dose analysis of volumetric modulated arc therapy planning for prostate cancer

PURPOSE

Primary radiation therapy is a curative treatment option for prostate cancer. The aim of this study was to evaluate the detection of the dominant intraprostatic lesion (DIL) with magnetic resonance imaging (MRI) for radiotherapy treatment planning, the comparison with transrectal ultrasound (TRUS)-guided biopsies and the examination of the dose distribution in relation to the DIL location.

MATERIALS AND METHODS

In all, 54 patients with treatment planning MRI for primary radiotherapy of prostate cancer from 03/2015 to 03/2017 at the Universitätsklinikum Würzburg were identified. The localization of the DIL was based on MRI with T2- and diffusion-weighted imaging. After registration of the MR image sets within Pinnacle³ (Philips Radiation Oncology Systems, Fitchburg, WI, USA), the dose distribution was analyzed. The location of the DIL was compared to the pathology reports in a side-based manner.

RESULTS

The DIL mean dose (Dmean) was 77.51 ± 0.77 Gy and in 50/51 cases within the tolerance range or exceeded the prescribed dose. There was a significant difference in Dmean between ventral (n = 21) and dorsal (n = 30) DIL (77.87 ± 0.67 vs. 77.26 ± 0.77 Gy; p = 0.005). MRI-guided localization showed an accuracy and sensitivity of up to 78.8% and 82.1% for inclusion of secondary lesions, respectively.

CONCLUSION

Up to 82.1% of histologically verified intraprostatic lesions were identified in the context of MRI-guided radiotherapy treatment planning. As expected, dorsal DIL tend to be minimally underdosed in comparison to ventral DIL. Adequate dose coverage was achieved in over 98% of patients.

New approach of ultra-focal brachytherapy for low- and intermediate-risk prostate cancer with custom-linked I-125 seeds: A feasibility study of optimal dose coverage

PURPOSE

To present the feasibility study of optimal dose coverage in ultra-focal brachytherapy (UFB) with multiparametric MRI for low- and intermediate-risk prostate cancer.

METHODS AND MATERIALS

UFB provisional dose plans for small target volumes (<7 cc) were calculated on a prostate training phantom to optimize the seeds number and strength. Clinical UFB consisted in a contour-based nonrigid registration (MRI/Ultrasound) to implant a fiducial marker at the location of the tumor focus. Dosimetry was performed with iodine-125 seeds and a prescribed dose of 160 Gy. On CT scans acquired at 1 month, dose coverage of 152 Gy to the ultra-focal gross tumor volume was evaluated. Registrations between magnetic resonance and CT scans were assessed on the first 8 patients with three software solutions: VariSeed, 3D Slicer, and Mirada, and quantitative evaluations of the registrations were performed. Impact of these registrations on the initial dose matrix was performed.

RESULTS

Mean differences between simulated dose plans and extrapolated Bard nomogram for UFB volumes were 36.3% (26-56) for the total activity, 18.3% (10-30) for seed strength, and 22.5% (16-38) for number of seeds. Registration method implemented in Mirada performed significantly better than VariSeed and 3D Slicer (p = 0.0117 and p = 0.0357, respectively). For dose plan evaluation between Mirada and VariSeed, D₁₀₀% (Gy) for ultra-focal gross tumor volume had a mean difference of 28.06 Gy, mean values being still above the objective of 152 Gy. D₉₀% for the prostate had a mean difference of 1.17 Gy. For urethra and rectum, dose limits were far below the recommendations.

CONCLUSIONS

This UFB study confirmed the possibility to treat with optimal dose coverage target volumes smaller than 7 cc.

Targeted Ablative Therapies for Prostate Cancer

Men diagnosed with low- to intermediate-risk, clinically localized prostate cancer (PCa) often face a daunting and difficult decision with respect to treatment: active surveillance (AS) or radical therapy. This decision is further confounded by the fact that many of these men diagnosed, by an elevated PSA, will have indolent disease and never require intervention. Radical treatments, including radical prostatectomy and whole-gland radiation, offer greater certainty for cancer control, but at the risk of significant urinary and/or sexual morbidity. Conversely, AS preserves genitourinary function and quality of life in exchange for burdensome surveillance and the psychological impact of living with cancer.

Prostatic adenocarcinoma in the setting of persistent müllerian duct syndrome: a case report

Persistent müllerian duct syndrome (PMDS) is a form of disordered sex development in which rudimentary müllerian structures are identified in phenotypically and genotypically normal males. It is caused by defects in the anti-müllerian hormone (AMH) system. Since patients with PMDS present with undescended testes, testosterone production by Leydig cells later in life is often decreased. The role of androgens in prostate cancerogenesis is well known. Cryptorchid testes and diminished testosterone levels in post-pubertal life in patients with PMDS play a protective role against prostate cancer, and hence, prostate cancer is a rare event in patients with PMDS. Herein, we present a patient who underwent prostatectomy for high-grade prostatic adenocarcinoma with persistent müllerian structures (such as rudimentary uterus, fallopian tubes, and cervix) identified during surgery. To our knowledge, this is the second case reported in the English language literature where PMDS was associated with prostate cancer.

Establishing the distribution of satellite lesions in intermediate- and high-risk prostate cancer: implications for focused radiotherapy

BACKGROUND

In focused radiotherapy for prostate cancer (PC), a full dose of radiation is delivered to the index lesion while reduced dose is delivered to the remaining prostate to reduce morbidity. As PC is commonly multifocal, we investigated whether baseline clinical characteristics or multiparametric magnetic resonance imaging (mpMRI) may be useful to predict the actual pathologic distribution of PC in men with intermediate- or high-risk PC, which may better inform how to deliver focused radiotherapy.

METHODS

A retrospective single-institutional study was performed on 71 consecutive men with clinically localized, intermediate- or high-risk PC who underwent mpMRI followed by radical prostatectomy (RP) from January 2012 to December 2012. Logistic regression analysis was performed to evaluate preoperative predictors for satellite lesions. Performance characteristics of mpMRI to detect satellite lesions and the extent of prostate disease (one hemi-gland vs both) were also evaluated.

RESULTS

In all, 50.7% had satellite lesions on mpMRI. On RP specimen analysis, 66.2% had satellite lesions and 55.3% of these satellite lesions had pathologic Gleason score (pGS)⩾3+4. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for mpMRI detecting a satellite lesion being present in the RP specimen were 59.6%, 66.7%, 77.8%, 45.7% and 62.0%, respectively. The presence of MRI satellite lesions was the only preoperative predictor significantly associated with finding satellite lesions on final pathology (hazard ratio (HR), 2.95, P=0.040). There was agreement in 76.1% of the entire cohort for unilateral vs bilateral disease when incorporating both biopsy and mpMRI information and comparing with the RP specimen.

CONCLUSIONS

In intermediate risk or greater PC, only the presence of mpMRI satellite lesions could predict for pathologic satellite lesions. While combining biopsy and mpMRI information may improve preoperative disease localization, the relatively high incidence of bilateral hemi-gland involvement with pGS ⩾7 satellite lesions makes it challenging to appropriately select men eligible for hemi-gland therapy.

Focal therapy in prostate cancer: A review of seven common controversies

Radical treatments such as prostatectomy and radiotherapy have demonstrated success in terms of biochemical and disease-specific survival for localised prostate cancer. However, whilst the end goal of any cancer treatment is to control or cure disease it must also do so by minimising any side effects that may be experienced by the patient. Focal therapy as a concept aims to redress this established therapeutic ratio by treating areas of the prostate affected by significant disease as opposed to treating the entire gland. However, there are a number of common criticisms of focal therapy - we deem the seven sins - that require further interrogation.

Hemi-gland focal low dose rate prostate brachytherapy: An analysis of dosimetric outcomes

BACKGROUND AND PURPOSE

Advances in magnetic resonance imaging (MRI) and prostate sampling enable early identification of men with low to intermediate risk prostate cancer who are candidates for focal therapies that minimise side effects. We report dosimetry data from a pilot study evaluating the effectiveness of hemi-gland low dose rate (HG-LDR) brachytherapy as a focal therapy approach to control unilateral localised disease.

MATERIAL AND METHODS

Twenty-two men underwent HG-LDR brachytherapy. Multi parametric MRI and transperineal template mapping biopsies were used to identify low volume unilateral disease. Whole gland therapy controls (n=120) were retrospectively obtained. All implants were performed with 4D Brachytherapy.

RESULTS

Intraoperative and postimplant dosimetry complied with established brachytherapy parameters. Mean (standard deviation) postoperative D90 for the target hemi-gland was 153.8 (11.3) Gy compared to 47.5 (12.7) Gy for the contralateral hemi-gland (P<0.001). Mean postoperative V100% was 93.1 (3.9) and 24.6 (10.5) for the target and contralateral hemi-glands respectively (P<0.001). Urethra D30 was 150.4 (19.8) Gy and 174.2 (15.0) Gy for hemi-gland and whole gland implants respectively (P<0.001). Significantly reduced dose was also observed for rectum and neurovascular bundles.

CONCLUSIONS

HG-LDR focal brachytherapy is feasible with significant reduction in dose to the contralateral hemi-gland and organs at risk.

Real-Time MRI-Guided Focused Ultrasound for Focal Therapy of Locally Confined Low-Risk Prostate Cancer: Feasibility and Preliminary Outcomes

OBJECTIVE

Focal therapy is an emerging approach to the treatment of localized prostate cancer. The purpose of this study was to report the 6-month follow-up oncologic and functional data of the initial phase 1 trial of patients treated with focal transrectal MRI-guided focused ultrasound in North America.

SUBJECTS AND METHODS

Four patients with a prostate-specific antigen (PSA) level of 10 ng/mL or less, tumor classification cT2a or less, and a Gleason score of 6 (3 + 3) were prospectively enrolled in the study and underwent multiparametric MRI and transrectal ultrasound-guided prostate systematic biopsy. Under MRI guidance and real-time monitoring with MR thermography, focused high-frequency ultrasound energy was delivered to ablate the target tissue. The incidence and severity of treatment-related adverse events were recorded along with responses to serial quality-of-life questionnaires for 6 months after treatment. Oncologic outcomes were evaluated with multiparametric MRI and repeat transrectal ultrasound-guided biopsy 6 months after treatment.

RESULTS

Four patients with a total of six target lesions were treated and had complications graded Clavien-Dindo I or less. Quality-of-life parameters were similar between baseline and 6-months. All four patients had normal MRI findings in the treated regions (100%), biopsy showed that three patients (75%) were clear of disease in the treated regions, representing complete ablation of five target lesions (83%). All patients had at least one Gleason 6-positive core outside of the treated zone.

CONCLUSION

MRI-guided focused ultrasound is a feasible method of noninvasively ablating low-risk prostate cancers with low morbidity. Further investigation and follow-up are warranted in a larger patient series with appropriate statistical analysis of oncologic and functional outcome measures.

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.

MRI-guided biopsies and minimally invasive therapy for prostate cancer

Recent advances in multiparametric magnetic resonance imaging (mp-MRI) have led to a paradigm shift in the diagnosis and management of prostate cancer (PCa). Its sensitivity in detecting clinically significant cancer and the ability to localize the tumor within the prostate gland has opened up discussion on targeted diagnosis and therapy in PCa. Use of mp-MRI in conjunction with prostate-specific antigen followed by targeted biopsy allows for a better diagnostic pathway than transrectal ultrasound (TRUS) biopsy and improves the diagnosis of PCa. Improved detection of PCa by mp-MRI has also opened up opportunities for focal therapy within the organ while reducing the incidence of side-effects associated with the radical treatment methods for PCa. This review discusses the evidence and techniques for in-bore MRI-guided prostate biopsy and provides an update on the status of MRI-guided targeted focal therapy in PCa.

1.5-T multiparametric MRI using PI-RADS: a region by region analysis to localize the index-tumor of prostate cancer in patients undergoing prostatectomy

BACKGROUND

The use of multiparametric magnetic resonance imaging (mpMRI) to detect and localize prostate cancer has increased in recent years. In 2010, the European Society of Urogenital Radiology (ESUR) published guidelines for mpMRI and introduced the Prostate Imaging Reporting and Data System (PI-RADS) for scoring the different parameters.

PURPOSE

To evaluate the reliability and diagnostic performance of endorectal 1.5-T mpMRI using the PI-RADS to localize the index tumor of prostate cancer in patients undergoing prostatectomy.

MATERIAL AND METHODS

This institutional review board IRB-approved, retrospective study included 63 patients (mean age, 60.7 years, median PSA, 8.0). Three observers read mpMRI parameters (T2W, DWI, and DCE) using the PI-RADS, which were compared with the results from whole-mount histopathology that analyzed 27 regions of interest. Inter-observer agreement was calculated as well as sensitivity, specificity, positive predictive value (PPV), and negative predicted value (NPV) by dichotomizing the PI-RADS criteria scores ≥3. A receiver-operating curve (ROC) analysis was performed for the different MR parameters and overall score.

RESULTS

Inter-observer agreement on the overall score was 0.41. The overall score in the peripheral zone achieved sensitivities of 0.41, 0.60, and 0.55 with an NPV of 0.80, 0.84, and 0.83, and in the transitional zone, sensitivities of 0.26, 0.15, and 0.19 with an NPV of 0.92, 0.91, and 0.92 for Observers 1, 2, and 3, respectively. The ROC analysis showed a significantly increased area under the curve (AUC) for the overall score when compared to T2W alone for two of the three observers.

CONCLUSION

1.5 T mpMRI using the PI-RADS to localize the index tumor achieved moderate reliability and diagnostic performance.

Role of transperineal template biopsy in prostate cancer

Prostate cancer is the most common neoplasm diagnosed in men. Whilst treatment modalities have progressed, diagnostic investigations in terms of biopsy methods have been assessed but there is no consensus of when the different diagnostic methods in terms of transrectal ultrasound (TRUS) or transperineal template (TPT) should be utilised. TPT biopsy has a higher diagnostic yield than TRUS in those with a primary biopsy, in those with previous negative biopsies with TRUS as well as those undergoing saturation biopsies. Despite the increased likelihood of diagnosing cancer with TPT than TRUS this maybe secondary to the increased number of biopsies being utilised. However there is no consensus regarding the ideal number of biopsies that should be utilised with TPT. Furthermore it is felt that the increased number of biopsies utilised with TPT is associated the higher complication rates with TPT. The role of TPT biopsy is recognised in those with previous negative biopsies with transrectal ultrasound but further work is required regarding the ideal number of biopsies. Furthermore, it is felt that TPT biopsy may have a role in primary biopsy.