Understanding the pathological features of focality, grade and tumour volume of early-stage prostate cancer as a foundation for parenchyma-sparing prostate cancer therapies: active surveillance and focal targeted therapy

Focal Boost in Prostate Cancer Radiotherapy: A Review of Planning Studies and Clinical Trials

BACKGROUND

Focal boost radiotherapy was developed to deliver elevated doses to functional sub-volumes within a target. Such a technique was hypothesized to improve treatment outcomes without increasing toxicity in prostate cancer treatment.

PURPOSE

To summarize and evaluate the efficacy and variability of focal boost radiotherapy by reviewing focal boost planning studies and clinical trials that have been published in the last ten years.

METHODS

Published reports of focal boost radiotherapy, that specifically incorporate dose escalation to intra-prostatic lesions (IPLs), were reviewed and summarized. Correlations between acute/late ≥G2 genitourinary (GU) or gastrointestinal (GI) toxicity and clinical factors were determined by a meta-analysis.

RESULTS

By reviewing and summarizing 34 planning studies and 35 trials, a significant dose escalation to the GTV and thus higher tumor control of focal boost radiotherapy were reported consistently by all reviewed studies. Reviewed trials reported a not significant difference in toxicity between focal boost and conventional radiotherapy. Acute ≥G2 GU and late ≥G2 GI toxicities were reported the most and least prevalent, respectively, and a negative correlation was found between the rate of toxicity and proportion of low-risk or intermediate-risk patients in the cohort.

CONCLUSION

Focal boost prostate cancer radiotherapy has the potential to be a new standard of care.

Focal HDR brachytherapy boost to stereotactic radiotherapy (fBTsRT) for prostate cancer: a phase II randomized controlled trial

BACKGROUND

For patients with a higher burden of localized prostate cancer, radiation dose escalation with brachytherapy boosts have improved cancer control outcomes at the cost of urinary toxicity. We hypothesize that a focal approach to brachytherapy boosts targeting only grossly visualized tumor volumes (GTV) combined with stereotactic radiotherapy will improve quality of life (QoL) outcomes without compromising cancer control.

METHODS

150 patients with intermediate or high-risk prostate cancer will be enrolled and randomized 1:1 in a cohort multiple randomized clinical trial phase 2 design. Patients are eligible if planned for standard-of-care (SOC) high dose rate (HDR) brachytherapy boost to radiotherapy (RT) with GTVs encompassing < 50% of the prostate gland. Those randomly selected will be offered the experimental treatment, consisting of focal HDR brachytherapy boost (fBT) of 13-15 Gy in 1 fraction followed by stereotactic radiotherapy (sRT) 36.25-40 Gy in 5 fractions to the prostate (+/- 25 Gy to the elective pelvis) delivered every other day. The primary endpoint is to determine if fBTsRT is superior to SOC by having fewer patients experience a minimally important decline (MID) in urinary function as measured by EPIC-26 at 1 and 2 years. Secondary endpoints include rates of toxicity measured by Common Terminology Criteria for Adverse Events (CTCAE), and failure-free survival outcomes.

DISCUSSION

This study will determine whether a novel approach for the treatment of localized prostate cancer, fBTsRT, improves QoL and merits further evaluation. Trial registration This trial was prospectively registered in ClinicalTrials.gov as NCT04100174 as a companion to registry NCT03378856 on September 24, 2019.

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.

Additional Value of PET Radiomic Features for the Initial Staging of Prostate Cancer: A Systematic Review from the Literature

Simple Summary

Prostate cancer (PCa) is one of the most frequent malignancies diagnosed in men and its prognosis depends on the stage at diagnosis. Molecular imaging, namely PET/CT or PET/MRI using prostate-specific radiotracers, has gained increasing application in accurately evaluating PCa at staging, especially in cases of high-risk disease, and it is now also recommended by international guidelines. Radiomic analysis is an emerging research field with a high potential to offer non-invasive and longitudinal biomarkers for personalized medicine, and several applications have been described in oncology patients. In this review, we discuss the available evidence on the role of radiomic analysis in PCa imaging at staging, exploring two different hybrid imaging modalities, such as PET/CT and PET/MRI, and the whole spectrum of radiotracers involved.

Abstract

We performed a systematic review of the literature to provide an overview of the application of PET radiomics for the prediction of the initial staging of prostate cancer (PCa), and to discuss the additional value of radiomic features over clinical data. The most relevant databases and web sources were interrogated by using the query “prostate AND radiomic* AND PET”. English-language original articles published before July 2021 were considered. A total of 28 studies were screened for eligibility and 6 of them met the inclusion criteria and were, therefore, included for further analysis. All studies were based on human patients. The average number of patients included in the studies was 72 (range 52–101), and the average number of high-order features calculated per study was 167 (range 50–480). The radiotracers used were [68Ga]Ga-PSMA-11 (in four out of six studies), [18F]DCFPyL (one out of six studies), and [11C]Choline (one out of six studies). Considering the imaging modality, three out of six studies used a PET/CT scanner and the other half a PET/MRI tomograph. Heterogeneous results were reported regarding radiomic methods (e.g., segmentation modality) and considered features. The studies reported several predictive markers including first-, second-, and high-order features, such as “kurtosis”, “grey-level uniformity”, and “HLL wavelet mean”, respectively, as well as PET-based metabolic parameters. The strengths and weaknesses of PET radiomics in this setting of disease will be largely discussed and a critical analysis of the available data will be reported. In our review, radiomic analysis proved to add useful information for lesion detection and the prediction of tumor grading of prostatic lesions, even when they were missed at visual qualitative assessment due to their small size; furthermore, PET radiomics could play a synergistic role with the mpMRI radiomic features in lesion evaluation. The most common limitations of the studies were the small sample size, retrospective design, lack of validation on external datasets, and unavailability of univocal cut-off values for the selected radiomic features.

Optimal Number of Systematic Biopsy Cores Used in Magnetic Resonance Imaging/Transrectal Ultrasound Fusion Targeted Prostate Biopsy

Background

In recent years, the effectiveness of magnetic resonance imaging (MRI)-ultrasound fusion targeted biopsy (MRF-TB) has been widely reported. In this study, we assessed the effect of reduction of the number of systematic biopsy (SB) cores on the cancer detection rate (CDR).

Methods

Patients with a high prostate-specific antigen (PSA) level underwent prostate MRI. The Prostate Imaging-Reporting and Data System version 2 (PI-RADS) was then used to rate the lesions. The inclusion criteria were as follows: (1) PSA level between 4.0 and 30.0 ng/mL and (2) patients with one or more lesions on MRI and a PI-RADS score of 3 or more. All enrolled patients were SB naïve or had a history of one or more prior negative SBs. A total of 104 Japanese met this selection criterion. We have traditionally performed 14-core SB following the MRF-TB. In this study, the CDRs of 10-core SB methods, excluding biopsy results at the center of the base and mid-level on both sides, were compared with those of the conventional biopsy method.

Results

We compared CDRs of the 14-core and 10-core SBs used in combination. The overall CDR was 55.8% for the former and 55.8% for the latter, thereby indicating that there was no significant difference (P = 1.00) between the two. In addition, the CDRs of csPCa were 51.9% for the former and 51.1% for the latter, which indicated that there was no significant difference (P = 0.317).

Conclusion

There was no significant difference in the CDR when the number of SB cores to be used in combination was 14 and 10.

Focal therapy for primary and salvage prostate cancer treatment: a narrative review

Despite innovations in surgical technology and advancements in radiation therapy, radical treatments for clinically localized prostate cancer are associated with significant patient morbidity, including both urinary and sexual dysfunction. This has created a vital need for therapies and management strategies that provide an acceptable degree of oncologic efficacy while mitigating these undesirable side effects. Successful developments in screening approaches and advances in prostate imaging have allowed clinicians to identify, localize, and more precisely target early cancers. This has afforded urologists with an important opportunity to develop and employ focal ablation techniques that selectively destroy tumors while preserving the remainder of the gland, thus avoiding detrimental treatment effects to surrounding sensitive structures. A lack of high-level evidence supporting such an approach had previously hindered widespread adoption of focal treatments, but there are now numerous published clinical trials which have sought to establish benchmarks for safety and efficacy. As the clinical evidence supporting a potential role in prostate cancer treatment begins to accumulate, there has been a growing acceptance of focal therapy in the urologic oncology community. In this narrative review article, we describe the techniques, advantages, and side effect profiles of the most commonly utilized focal ablative techniques and analyze published clinical trial data supporting their evolving role in the prostate cancer treatment paradigm.

Integration of functional imaging in brachytherapy

Functional imaging allows the evaluation of numerous biological properties that could be considered at all steps of the therapeutic management of patients treated with brachytherapy. Indeed, it enables better initial staging of the disease, and some parameters may also be used as predictive biomarkers for treatment response, allowing better selection of patients eligible for brachytherapy. It may also improve the definition of target volumes with the aim of dose escalations by dose-painting. Finally, it could be useful during the follow-up to assess response to treatment. In this review, we report how functional imaging is integrated at the present time during the brachytherapy procedure, and what are its potential future contributions in the main tumour locations where brachytherapy is recommended. Functional imaging has great potential in the contact of brachytherapy, but still, several issues remain to be resolved before integrating it into clinical practice, especially as a biomarker or in dose painting strategies.

High-grade tumours promote growth of other less-malignant tumours in the same prostate

Prostate cancer is a multifocal disease, but if and how individual prostate tumours influence each other is largely unknown. We therefore explored signs of direct or indirect tumour–tumour interactions in experimental models and patient samples. Low‐metastatic AT1 and high‐metastatic MatLyLu (MLL) Dunning rat prostate cancer cells were injected into separate lobes of the ventral prostate of immunocompetent rats. AT1 tumours growing in the same prostate as MLL tumours had increased tumour size and proliferation compared to AT1 tumours growing alone. In addition, the vasculature and macrophage density surrounding the AT1 tumours were increased by MLL tumour closeness. In patient prostatectomy samples, selected to contain an index tumour [tumour with the highest grade, International Society of Urological Pathology (ISUP) grade 1, 2, 3 or 4] and a low‐grade satellite tumour (ISUP grade 1), cell proliferation in low‐grade satellite tumours gradually increased with increasing histological grade of the index tumour. The density of blood vessels and CD68⁺ macrophages also increased around the low‐grade satellite tumour if a high‐grade index tumour was present. This suggests that high‐grade tumours, by changing the prostate microenvironment, may increase the aggressiveness of low‐grade lesions in the organ. Future studies are needed to explore the mechanisms behind tumour–tumour interactions and their clinical importance. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Uncovering the invisible-prevalence, characteristics, and radiomics feature-based detection of visually undetectable intraprostatic tumor lesions in 68GaPSMA-11 PET images of patients with primary prostate cancer

Introduction

Primary prostate cancer (PCa) can be visualized on prostate-specific membrane antigen positron emission tomography (PSMA-PET) with high accuracy. However, intraprostatic lesions may be missed by visual PSMA-PET interpretation. In this work, we quantified and characterized the intraprostatic lesions which have been missed by visual PSMA-PET image interpretation. In addition, we investigated whether PSMA-PET-derived radiomics features (RFs) could detect these lesions.

Methodology

This study consists of two cohorts of primary PCa patients: a prospective training cohort (n = 20) and an external validation cohort (n = 52). All patients underwent ⁶⁸Ga-PSMA-11 PET/CT and histology sections were obtained after surgery. PCa lesions missed by visual PET image interpretation were counted and their International Society of Urological Pathology score (ISUP) was obtained. Finally, 154 RFs were derived from the PET images and the discriminative power to differentiate between prostates with or without visually undetectable lesions was assessed and areas under the receiver-operating curve (ROC-AUC) as well as sensitivities/specificities were calculated.

Results

In the training cohort, visual PET image interpretation missed 134 tumor lesions in 60% (12/20) of the patients, and of these patients, 75% had clinically significant (ISUP > 1) PCa. The median diameter of the missed lesions was 2.2 mm (range: 1–6). Standard clinical parameters like the NCCN risk group were equally distributed between patients with and without visually missed lesions (p < 0.05). Two RFs (local binary pattern (LBP) size-zone non-uniformality normalized and LBP small-area emphasis) were found to perform excellently in visually unknown PCa detection (Mann-Whitney U: p < 0.01, ROC-AUC: ≥ 0.93). In the validation cohort, PCa was missed in 50% (26/52) of the patients and 77% of these patients possessed clinically significant PCa. The sensitivities of both RFs in the validation cohort were ≥ 0.8.

Conclusion

Visual PSMA-PET image interpretation may miss small but clinically significant PCa in a relevant number of patients and RFs can be implemented to uncover them. This could be used for guiding personalized treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-020-05111-3.

Suboptimal Prediction of Clinically Significant Prostate Cancer in Radical Prostatectomy Specimens by mpMRI-Targeted Biopsy

OBJECTIVE

To investigate the correlation of multiparametric magnetic resonance imaging targeted (TBx) and/or systematic prostate biopsy (SBx) in predicting the presence of clinically significant (cs) prostate cancer (PCa) in radical prostatectomy (RP) specimens. Concordance of mpMRI and RP specimen lesions was also investigated in terms of tumor localization and histopathological features.

METHODS

A total of 70 male patients with PCa and treated with robot-assisted RP were included in this study between January 2016 and December 2019. All patients underwent mpMRI-TBx and concomitant SBx. Suspicious lesions on mpMRI were scored according to Prostate Imaging-Reporting and Data System version 2 (PI-RADS) criteria. TBx was performed for all suspicious lesions with a PI-RADS score ≥3.

RESULTS

The median age was 67 (43-77) years. Presence of csPCa in prostatectomy specimens was missed by TBx and SBx specimens in 25.4% and 19.4% of the cases, respectively (P<.001, for each). Combination of both biopsy (CBx) results improved detection by missing only 4.5% of csPCa (P = .250). International Society of Urologic Pathology grade group concordance with RP specimens were 50%, 54.3% and 67.1% for SBx, TBx, and CBx, respectively. There was a statistically significant correlation in terms of tumor localization and histopathological features between prostatectomy specimens and the first 3 lesions, particularly for the index lesions.

CONCLUSIONS

CBx improved detection rate of csPCa. We propose TBx of 3 lesions with highest PI-RADS score(s) and a combination with SBx for the highest correlation with prostatectomy histopathology.

68Ga-PSMA PET/CT tumour intensity pre-operatively predicts adverse pathological outcomes and progression-free survival in localised prostate cancer

PURPOSE

Prostate-specific membrane antigen (PSMA) positron emission tomography (PSMA-PET) improves prostate cancer staging. Intraprostatic PSMA intensity may predict clinically relevant oncological outcomes. The aim of this study was to investigate the relationship between intraprostatic PSMA intensity and adverse pathology outcomes, including biochemical progression-free survival (PFS) after radical prostatectomy.

METHODS

This is a cohort study of 71 patients with MRI-guided, biopsy-proven prostate cancer and pre-operative ⁶⁸Ga-PSMA-11 PET/CT prior to radical prostatectomy (RP). Intraprostatic PSMA intensity was correlated to adverse pathology outcomes (Gleason score and upgrading from biopsy, pathological stage) and PFS using multivariate statistical analysis.

RESULTS

⁶⁸Ga-PSMA-11 PET/CT intensity in vivo predicted all of Gleason score on RP, upgrading from biopsy to RP histopathology, pathological stage, positive surgical margins and PFS. 74.6% (53/71) of patients were free from progression at a median follow-up of 19.5 months (0.4-48 months). Predictive accuracy was particularly enhanced by PSMA among patients with biopsy Gleason score ≤ 3 + 4 (n = 39) as the most significant predictor of PFS according to Cox-proportional hazards regression. Cox-regression adjusted survival analysis predicted a 5.48-fold increase in hazard for Gleason score ≤ 3 + 4 patients with high (SUVmax > 8) compared with low (SUVmax < 8) PSMA intensity.

CONCLUSION

Intraprostatic ⁶⁸Ga-PSMA-11 intensity is prognostic and may be a valuable new biomarker in localised prostate cancer, especially in men with biopsy-proven Gleason 3 + 4 disease considering an initial approach of active surveillance or focal therapy.

Voxel-based comparison of [68Ga]Ga-RM2-PET/CT and [68Ga]Ga-PSMA-11-PET/CT with histopathology for diagnosis of primary prostate cancer

BACKGROUND

Focal therapies or focally escalated therapies of primary prostate cancer are becoming more and more important. This increases the need to identify the exact extension of the intraprostatic tumor and possible dominant intraprostatic lesions by imaging techniques. While the prostate-specific membrane antigen (PSMA) is already a well-established target for imaging of prostate cancer cells, the gastrin-releasing peptide receptor (GRPR) seems to provide interesting additional information. Histopathology was used to examine the extent to which the single and combined image information of PET scans targeting GRPR and PSMA might lead to better tumor delineation.

METHODS

Eight patients with histologically proven primary prostate cancer underwent two positron emission tomography with computer tomography scans, [68Ga]Ga-RM2-PET/CT (RM2-PET) and [68Ga]Ga-PSMA-11-PET/CT (PSMA-PET), prior to radical prostatectomy. RM2-PET data were correlated voxel-wise to a voxel-based model of the histopathologic tumor volume information. The results were compared to, correlated to, and combined with the correlation of PSMA-PET data analyzed analogously.

RESULTS

In 4/8 patients, RM2-PET showed a higher signal in histologically proven tumor regions compared to PSMA. There were also tumor regions where PSMA-PET showed a higher signal than GRPR in 4/8 patients. A voxel-wise correlation of RM2-PET against histopathology yielded similar results compared to the correlation of PSMA-PET against histopathology, while PSMA-PET is the slightly better performing imaging technique. The combined information of both tracers yielded the best overall result, although this effect was not statistically significant compared to RM2-PET alone.

CONCLUSIONS

Qualitative and quantitative findings in this preliminary study with 8 patients indicate that RM2-PET and PSMA-PET partially show not only the same, but also distinct regions of prostate cancer. Patients with pPCa might profit from information given by tracers targeting GRPR and PSMA simultaneously, in terms of a better delineation of the gross tumor volume.

Analysis of outcomes after non-contour-based dose painting of dominant intra-epithelial lesion in intra-operative low-dose rate brachytherapy

Purpose

To compare the outcomes of patients with intermediate risk prostate cancer (IR-PCa) treated with low-dose rate I-125 seed brachytherapy (LDR-BT) and targeted dose painting of a histologic dominant intra-epithelial lesion (DIL) to those without a DIL.

Methods

455 patients with IR-PCa were treated at a single center with intra-operatively planned LDR-BT, each following the same in-house dose constraints. Patients with a DIL on pathology had hot spots localized to that region but no specific contouring during the procedure.

Results

396 (87%) patients had a DIL. Baseline tumor characteristics and overall prostate dosimetry were similar between patients with and without DIL except the median number of biopsy cores taken: 10 (10–12) vs 12 (10–12) (p = 0.002).

19 (5%) and 18 (5%) of patients with and 1 (2%) and 0 (0%) of those without DIL experienced CTCAE grade 2 and 3 toxicity respectively. Overall, toxicity grade did not significantly correlate with presence of DIL (p = 0.10).

Estimated 7-year freedom from biochemical failure (FFBF) was 84% (95% confidence interval: 79–89) and 70% (54–89) in patients with and without a DIL (log-rank p = 0.315). In DIL patients, cox regression revealed location of DIL (“Base” vs “Apex” HR: 1.03; 1.00–1.06; p = 0.03) and older age (70 vs 60 HR: 1.62; 1.06–2.49; p = 0.03) was associated with poor FFBF.

Conclusions

Targeting DIL through dose painting during intraoperatively planned LDR-BT provided no statistically significant change in FFBF. Patients with DILs in the prostate base had slightly lower FFBF despite DIL boost.

Progress towards Patient-Specific, Spatially-Continuous Radiobiological Dose Prescription and Planning in Prostate Cancer IMRT: An Overview

Advances in imaging have enabled the identification of prostate cancer foci with an initial application to focal dose escalation, with subvolumes created with image intensity thresholds. Through quantitative imaging techniques, correlations between image parameters and tumour characteristics have been identified. Mathematical functions are typically used to relate image parameters to prescription dose to improve the clinical relevance of the resulting dose distribution. However, these relationships have remained speculative or invalidated. In contrast, the use of radiobiological models during treatment planning optimisation, termed biological optimisation, has the advantage of directly considering the biological effect of the resulting dose distribution. This has led to an increased interest in the accurate derivation of radiobiological parameters from quantitative imaging to inform the models. This article reviews the progress in treatment planning using image-informed tumour biology, from focal dose escalation to the current trend of individualised biological treatment planning using image-derived radiobiological parameters, with the focus on prostate intensity-modulated radiotherapy (IMRT).

Dosimetric Evaluation of PSMA PET-Delineated Dominant Intraprostatic Lesion Simultaneous Infield Boosts

PURPOSE

Prostate cancer is multifocal. However, there often exists a single dominant focus in the gland responsible for driving the biology of the disease. Dose escalation to the dominant lesion is a proposed strategy to increase tumor control. We applied radiobiological modeling to evaluate the dosimetric feasibility and benefit of dominant intraprostatic lesion simultaneous in-field boosts (DIL-SIB) to the gross tumor volume (GTV), defined using a novel molecular positron emission tomography (PET) probe (18F-DCFPyL) directed against prostate specific membrane antigen (PSMA).

METHODS AND MATERIALS

Patients with clinically localized, biopsy-proven prostate cancer underwent preoperative [18F]-DCFPyL PET/computed tomography (CT). DIL-SIB plans were generated by importing the PET/CT into the RayStation treatment planning system. GTV-PET for the DIL-SIB was defined by the highest %SUVmax (percentage of maximum standardized uptake value) that generated a biologically plausible volume. Volumetric arc-based plans incorporating prostate plus DIL-SIB treatment were generated. Tumor control probability (TCP) and normal tissue complication probability (NTCP) with fractionation schemes and boost doses specified in the FLAME (Investigate the Benefit of a Focal Lesion Ablative Microboost in Prostate Cancer; NCT01168479), PROFIT (Prostate Fractionated Irradiation Trial; NCT00304759), PACE (Prostate Advances in Comparative Evidence; NCT01584258), and hypoFLAME (Hypofractionated Focal Lesion Ablative Microboost in prostatE Cancer 2.0; NCT02853110) protocols were compared.

RESULTS

Comparative DIL-SIB plans for 6 men were generated from preoperative [18F]-DCFPyL PET/CT. Median boost GTV volume was 1.015 cm3 (0.42-1.83 cm3). Median minimum (D99%) DIL-SIB dose for F35BS, F20BS, F5BS, and F5BSH were 97.3 Gy, 80.8 Gy, 46.5 Gy, and 51.5Gy. TCP within the GTV ranged from 84% to 88% for the standard plan and 95% to 96% for the DIL-SIB plans. Within the rest of the prostate, TCP ranged from 89% to 91% for the standard plans and 90% to 92% for the DIL-SIB plans. NTCP for the rectum NTCP was similar for the DIL-SIB plans (0.3%-2.7%) compared with standard plans (0.7%-2.6%). Overall, DIL-SIB plans yielded higher uncomplicated TCP (NTCP, 90%-94%) versus standard plans (NTCP, 83%-85%).

CONCLUSIONS

PSMA PET provides a novel approach to define GTV for SIB-DIL dose escalation. Work is ongoing to validate PSMA PET-delineated GTV through correlation to coregistered postprostatectomy digitized histopathology.

Current status and future prospective of focal therapy for localized prostate cancer: development of multiparametric MRI, MRI-TRUS fusion image-guided biopsy, and treatment modalities

Multiparametric magnetic resonance imaging (mpMRI) has been increasingly used to diagnose clinically significant prostate cancer (csPC) because of its usefulness in combination with anatomic and functional data. MRI-targeted biopsy, such as MRI-transrectal ultrasound (TRUS) fusion image-guided prostate biopsy, has high accuracy in the detection and localization of csPC. This novel diagnostic technique contributes to the development of tailor-made medicine as focal therapy, which cures the csPC while preserving the anatomical structures related to urinary and sexual function. In the early days of focal therapy, TRUS-guided systematic biopsy was used for patient selection, and treatment was performed for patients with low-risk PC. With the introduction of mpMRI and mapping biopsy, the treatment range is now determined based on individualized cancer localization. In recent prospective studies, 87.4% of treated patients had intermediate- and high-risk PC. However, focal therapy has two main limitations. First, a randomized controlled trial would be difficult to design because of the differences in pathological features between patients undergoing focal therapy and radical treatment. Therefore, pair-matched studies and/or historical controlled studies have been performed to compare focal therapy and radical treatment. Second, no long-term (≥ 10-year) follow-up study has been performed. However, recent prospective studies have encouraged the use of focal therapy as a treatment strategy for localized PC because it contributes to high preservation of continence and erectile function.

Focal high-dose-rate brachytherapy for localized prostate cancer: toxicity and preliminary biochemical results

BACKGROUND

This study aimed to evaluate the outcomes and the toxicity of focal high-dose-rate (HDR) brachytherapy in selected localized prostate cancer patients.

METHODS

Fifty patients were treated with focal high-dose-rate brachytherapy between March 2013 and November 2017, representing 5% of the cases treated by our group during this period. Only patients with very limited and localized tumors, according to strict criteria, were selected for the procedure. The prescribed dose for the focal volume was 24 Gy.

RESULTS

The treated volume corresponded to a mean value of 32% of the total prostatic volume. The mean focal D₉₀ in our series was 23 Gy (range 16-26 Gy). The mean initial IPSS was 8.2 (range 0-26), at 6 months 7.5 (range 0-23), and at 24 months 6.7 (range 0-18). No acute or late urinary retention was seen. When the ICIQ-SF score was 0 at the end of treatment, it remained nil thereafter at 1 and 2 years for all patients. No intraoperative or perioperative complications occurred. No rectal toxicity was reported after treatment. Of the total patients identified as potent, only three patients had a very slight decrease of the mean IIEF5. The mean initial PSA was 6.9 ng/mL (range 1.9-13.4). At the last follow-up visit, the mean PSA was 3 ng/ml (range 0.48-8.11).

CONCLUSION

HDR focal brachytherapy in selected patients with low intermediate-risk prostate cancer could achieve the same satisfactory results in terms of relapse-free survival as conventional whole prostate brachytherapy with less toxicity.

MRI targeted single fraction HDR Brachytherapy for localized Prostate Carcinoma: a feasibility study of focal radiation therapy (ProFocAL)

OBJECTIVES

The aim of the study was to establish the setup and workflow for delivering focal MRI-guided high-dose-rate (HDR) brachytherapy for prostate cancer (PCA) and to assess patient comfort and safety aspects of MRI-guided single-fraction HDR.

METHODS

Patients with histologically proven focal low- to intermediate-risk PCA with a single PIRADS 4/5 lesion were treated with percutaneous interstitial HDR brachytherapy in a single fraction with a minimum dose for the gross tumor volume of 20 Gy while sparing the organ at risk (OAR). Using a 3T-MRI, brachytherapy catheters were placed transgluteal in freehand technique. No antibiotic therapy or general analgesics were administered. Patient data, procedure time, patient discomfort, and complications were recorded. Quarterly PSA controls, biannual follow-up imaging, and annual re-biopsy were planned.

RESULTS

So far, 9 patients were successfully treated and followed for 6 months. Mean intervention time was 34 min. Using the VAS scale, the pain reported for the intervention ranged from 2 to 3. Short-term follow-up showed no acute genitourinary or gastrointestinal toxicity so far. None of the patients displayed signs of infection. PSA levels in all patients decreased significantly. On follow up no residual PCA was detected treated region so far. PSA levels in all patients decreased significantly. On follow-up, no residual PCA was detected so far.

CONCLUSIONS

MR-guided single-fraction focal HDR brachytherapy for localized PCA is feasible as well as safe for the individual patient. Catheters can be placed accurately and maximum therapeutic dose distribution can be restricted to the tumor. Countersigning the minimally invasive character of the procedure, no general anesthesia or antibiosis is necessary.

KEY POINTS

• MR-guided focal HDR brachytherapy allows an accurate placement of catheters with maximum therapeutic dose distribution restricted to the tumor. • No major anesthesia or antibiosis is necessary emphasizing the minimal invasive character of the procedure. • Patients with low- and intermediate-risk prostate carcinoma in particular may benefit to halt disease progression whereas treatment-related morbidity is reduced compared with radical therapy.

Transrectal ultrasound-guided prostate biopsy versus combined magnetic resonance imaging-ultrasound fusion and systematic biopsy for prostate cancer detection in routine clinical practice

PURPOSE

The goal of this study was to retrospectively compare systematic ultrasound-guided prostate biopsy (US-PB) and multiparametric magnetic resonance imaging-ultrasound fusion prostate biopsy (MRI-PB) in men undergoing primary or repeated biopsies.

METHODS

A population of 2,200 patients with a prostate-specific antigen (PSA) level >4.0 ng/ dL and/or an abnormal rectal examination was divided into two groups. All patients underwent US-PB (n=1,021) or MRI-PB (n=1,179) between April 2015 and April 2019. Population demographics, including age, PSA level, digital rectal examination results, prostate volume, number of previous negative biopsies, Prostate Imaging Reporting and Data System (PI-RADS) version 2 (V2) score, and biopsy results, were acquired and compared with respect to these variables. Univariate regression analysis of the risk factors for a higher Gleason score (GS) was performed.

RESULTS

The cancer detection rate (CDR) was 23.8% (243 of 1,021) in the US-PB group and 31.3% (399 of 1,179) in the MRI-PB group. Of those, 225 patients (22.0%) in the US-PB group and 374 patients (31.7%) in the MRI-PB group had clinically significant prostate cancer (csPCa). The patients with csPCa in the MRI-PB group included 10 (40%), 50 (62.5%), 184 (94.8%), and 32 (94.1%) patients with PI-RADS V2 scores of 2, 3, 4, and 5, respectively. Of the patients with csPCa, 155 (91.7%) in the US-PB group were diagnosed on the basis of the primary biopsy, compared to 308 (94.4%) in the MRI-PB group. We found the PI-RADS V2 score to be the best predictor of a higher GS.

CONCLUSION

MRI-PB showed a high CDR for csPCa. MRI-PB could be a reasonable approach in patients with high PI-RADS V2 scores at primary biopsy.

The Key Combined Value of Multiparametric Magnetic Resonance Imaging, and Magnetic Resonance Imaging-targeted and Concomitant Systematic Biopsies for the Prediction of Adverse Pathological Features in Prostate Cancer Patients Undergoing Radical Prostatectomy

BACKGROUND

The combined role of multiparametric magnetic resonance imaging (mp-MRI), and magnetic resonance imaging (MRI)-targeted and concomitant systematic biopsies in the identification of prostate cancer (PCa) patients at a higher risk of adverse pathology at radical prostatectomy (RP) is still unclear.

OBJECTIVE

To develop novel models to predict extracapsular extension (ECE), seminal vesicle invasion (SVI), or upgrading in patients diagnosed with MRI-targeted and concomitant systematic biopsies.

DESIGN, SETTING, AND PARTICIPANTS

We included 614 men with clinical stage≤T2 at digital rectal examination who underwent MRI-targeted biopsy with concomitant systematic biopsy.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSES

Logistic regression analyses predicting ECE, SVI, and upgrading (ie, a shift from biopsy International Society of Urological Pathology grade group to any higher grade at RP) based on clinical variables with or without mp-MRI features and systematic biopsy information (the percentage of cores with grade group ≥2 PCa) were developed and internally validated. The area under the curve (AUC) was used to identify the models with the highest discrimination. Decision-curve analyses (DCAs) determined the net benefit associated with their use.

RESULTS AND LIMITATIONS

Overall, 333 (54%), 88 (14%), and 169 (27%) patients had ECE, SVI, and upgrading at RP, respectively. The inclusion of mp-MRI data improved the discrimination of clinical models for ECE (67% vs 70%) and SVI (74% vs 76%). Models including mp-MRI, and MRI-targeted and concomitant systematic biopsy information achieved the highest AUC at internal validation for ECE (73%), SVI (81%), and upgrading (73%) and represented the basis for three risk calculators that yield the highest net benefit at DCA.

CONCLUSIONS

Not only mp-MRI and MRI-targeted sampling, but also concomitant systematic biopsies provide significant information to identify patients at a higher risk of adverse pathology. Although omitting systematic prostate sampling at the time of MRI-targeted biopsy might be associated with a reduced risk of detecting insignificant PCa and lower patient discomfort, it reduces the ability to accurately predict pathological features.

PATIENT SUMMARY

The combination of multiparametric magnetic resonance imaging (mp-MRI) with accurate biopsy information on MRI-targeted and systematic biopsies improves the accuracy of multivariable models based on clinical and mp-MRI data alone. Correct mp-MRI interpretation and proper extensive prostate sampling are both needed to predict adverse pathology accurately at radical prostatectomy.

Comparison of multiparametric MRI-based and transrectal ultrasound-based preplans with intraoperative ultrasound-based planning for low dose rate interstitial prostate seed implantation

PURPOSE

Transrectal ultrasound images are routinely acquired for low dose rate (LDR) prostate brachytherapy dosimetric preplanning (pTRUS), although diagnostic multiparametric magnetic resonance imaging (mpMRI) may serve this purpose as well. We compared the predictive abilities of TRUS vs MRI relative to intraoperative TRUS (iTRUS) to assess the role of mpMRI in brachytherapy preplanning.

MATERIALS AND METHODS

Retrospective analysis was performed on 32 patients who underwent iTRUS-guided prostate LDR brachytherapy as either mono- or combination therapy. 56.3% had pTRUS-only volume studies and 43.7% had both 3T-mpMRI and pTRUS preplanning. MRI was used for preplanning and its image fusion with iTRUS was also used for intraoperative guidance of seed placement. Differences in gland volume, seed number, and activity and procedure time were examined, as well as the identification of lesions suspicious for tumor foci. Pearson correlation coefficient and Fisher's Z test were used to estimate associations between continuous measures.

RESULTS

There was good correlation of planning volumes between iTRUS and either pTRUS or MRI (r = 0.89, r = 0.77), not impacted by the addition of hormonal therapy (P = 0.65, P = 0.33). Both consistently predicted intraoperative seed number (r = 0.87, r = 0.86). MRI/TRUS fusion did not significantly increase surgical or anesthesia time (P = 0.10, P = 0.46). mpMRI revealed suspicious focal lesions in 11 of 14 cases not visible on pTRUS, that when correlated with histopathology, were incorporated into the plan.

CONCLUSIONS

Relative to pTRUS, MRI yielded reliable preplanning measures, supporting the role of MRI-only LDR treatment planning. mpMRI carries numerous diagnostic, staging and preplanning advantages that facilitate better patient selection and delivery of novel dose escalation and targeted therapy, with no additional surgical or anesthesia time. Prospective studies assessing its impact on treatment planning and delivery can serve to establish mpMRI as the standard of care in LDR prostate brachytherapy planning.

Prostate cancer treatment with Irreversible Electroporation (IRE): Safety, efficacy and clinical experience in 471 treatments

Background

Irreversible Electroporation (IRE) is a novel image-guided tissue ablation technology that induces cell death via very short but strong pulsed electric fields. IRE has been shown to have preserving properties towards vessels and nerves and the extracellular matrix. This makes IRE an ideal candidate to treat prostate cancer (PCa) where other treatment modalities frequently unselectively destroy surrounding structures inducing severe side effects like incontinence or impotence. We report the retrospective assessment of 471 IRE treatments in 429 patients of all grades and stages of PCa with 6-year maximum follow-up time.

Material and findings

The patient cohort consisted of low (25), intermediate (88) and high-risk cancers (312). All had multi-parametric magnetic resonance imaging, and 199 men had additional 3D-mapping biopsy for diagnostic work-up prior to IRE. Patients were treated either focally (123), sub-whole-gland (154), whole-gland (134) or for recurrent disease (63) after previous radical prostatectomy, radiation therapy, etc. Adverse effects were mild (19.7%), moderate (3.7%) and severe (1.4%), never life-threatening. Urinary continence was preserved in all cases. IRE-induced erectile dysfunction persisted in 3% of the evaluated cases 12 months post treatment. Mean transient IIEF-5-Score reduction was 33% within 12-month post IRE follow-up and 15% after 12 months. Recurrences within the follow-up period occurred in 10% of the treated men, 23 in or adjacent to the treatment field and 18 outside the treatment field (residuals). Including residuals for worst case analysis, Kaplan Maier estimation on recurrence rate at 5 years resulted in 5.6% (CI95: 1.8–16.93) for Gleason 6, 14.6% (CI95: 8.8–23.7) for Gleason 7 and 39.5% (CI95: 23.5–61.4) for Gleason 8–10.

Conclusion

The results indicate comparable efficacy of IRE to standard radical prostatectomy in terms of 5-year recurrence rates and better preservation of urogenital function, proving the safety and suitability of IRE for PCa treatment. The data also shows that IRE, besides focal therapy of early PCa, can also be used for whole-gland ablations, in patients with recurrent PCa, and as a problem-solver for local tumor control in T4-cancers not amenable to surgery and radiation therapy anymore.

Dose to the dominant intraprostatic lesion using HDR vs. LDR monotherapy: A Phase II randomized trial

PURPOSE

To present the dosimetric results of a Phase II randomized trial comparing dose escalation to the MRI-defined dominant intraprostatic lesion (DIL) using either low-dose-rate (LDR) or high-dose-rate (HDR) prostate brachytherapy.

MATERIAL AND METHODS

Patients receiving prostate brachytherapy as monotherapy were randomized to LDR or HDR brachytherapy. Prostate and DILs were contoured on preoperative multiparametric MRI. These images were registered with transrectal ultrasound for treatment planning. LDR brachytherapy was preplanned using I-125 seeds. HDR brachytherapy used intraoperative transrectal ultrasound-based planning to deliver 27 Gy/2 fractions in separate implants. DIL location was classified as peripheral, central, or anterior. A student t-test compared DIL D₉₀ between modalities and DIL locations.

RESULTS

Of 60 patients, 31 underwent LDR and 29 HDR brachytherapy. Up to three DILs were identified per patient (100 total) with 74 peripheral, six central, and 20 anterior DILs. Mean DIL volume was 1.9 cc (SD: 1.7 cc) for LDR and 1.6 cc (SD 1.3 cc) for HDR (p = 0.279). Mean DIL D₉₀ was 151% (SD 30%) for LDR and 132% (SD 13%) for HDR. For LDR, mean peripheral DIL D₉₀ was 159% (SD 27%) and central or anterior 127% (SD 13%). HDR peripheral DILs received 137% (SD 12%) and central or anterior 119% (SD 7%). DIL D₉₀ for peripheral lesions was higher than anterior and central (p < 0.001).

CONCLUSIONS

DIL location affects dose escalation, particularly because of urethral proximity, such as for anterior and central DILs. HDR brachytherapy may dose escalate better when target DIL is close to critical organs.

Comparing outcomes of concurrent chemotherapy regimens in patients 65 years old or older with locally advanced oropharyngeal carcinoma

BACKGROUND

The comparative efficacy of cisplatin (CDDP), carboplatin, and cetuximab (CTX) delivered concurrently with radiation for locally advanced oropharyngeal squamous cell carcinoma continues to be evaluated.

METHODS

The linked Surveillance, Epidemiology, and End Results-Medicare database was used to identify and compare patient and disease profiles, mortality, toxicity, and overall cost for patients with oropharynx cancer undergoing definitive concurrent chemoradiation with CDDP, carboplatin, or CTX between 2006 and 2011. The human papillomavirus status was unknown. The primary outcome was 2-year overall survival (OS).

RESULTS

Four hundred nine patients receiving concurrent CDDP (n = 167), carboplatin (n = 69), or CTX (n = 173) were included. Those who were older, those who were nonwhite, and those with a Charlson Comorbidity Index ≥ 2 were less likely to receive CDDP. Two-year OS was inferior with CTX (hazard ratio [HR], 1.68; 95% confidence interval [CI], 1.08-2.60; P = .020) and no different with carboplatin (HR, 1.31; 95% CI, 0.73-2.35; P = .362) in a Cox proportional hazards model (reference CDDP). There was no statistically significant difference between carboplatin and CTX (HR, 1.28; 95% CI, 0.77-2.14; P = .891). Rates of antiemetic use and hospital visits for nausea/emesis/diarrhea or dehydration were statistically higher with CDDP. Pneumonia rates were higher with carboplatin. In the multivariate model, the corrected mean per-patient spending was significantly higher for CTX and carboplatin than CDDP ($61,133 and $65,721 vs $48,709).

CONCLUSIONS

Patients who received CDDP had improved OS. CDDP was also associated with slightly lower overall costs and higher antiemetic usage and hospital visit rates, although a strong selection bias was observed because those receiving CTX and carboplatin were older and had higher comorbidity scores.

Medium-term Follow-up of Vascular-targeted Photodynamic Therapy of Localized Prostate Cancer Using TOOKAD Soluble WST-11 (Phase II Trials)

BACKGROUND AND OBJECTIVE

To assess the medium-term tumor control in patients with localized prostate cancer (PCa) treated with vascular-targeted photodynamic (VTP) therapy with TOOKAD Soluble WST11 (VTP) and to assess the medium-term tolerability of the treatment.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

During the clinical phase II studies, 68 patients were treated with VTP under optimal treatment conditions (WST11 at 4mg/kg, light energy at 200J/cm, and a light density index ≥1) and have been included in a 3.5-yr follow-up.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Post-interventional visits were scheduled every 6 mo and conducted as per local standard practice in each study center. Cancer-free status was assessed by means of prostate-specific antigen kinetics, multiparametric magnetic resonance imaging and/or prostate biopsies.

RESULTS AND LIMITATIONS

At the end of the 3.5-yr follow-up, overall successful focal ablation was achieved for 51 patients (75%). Cancer was identified in the untreated lobe in 17 patients (25%). In total, 34 patients (50%) were cancer-free in both the prostate lobes. In case of recurrent/persistent malignancy, the Gleason score remained consistent or changed at the maximum by one point (upgrading by 1 Gleason point to 3+4 for eight patients and 4+3 for two patients). There were 64 related adverse events (AEs): 48% were Clavien grade I, 47% were grade II, and 5% were grade III. There were no Clavien grade IV and V AEs. Limitations included small sample size and heterogeneity in the follow-up for some centers.

CONCLUSIONS

VTP is a safe and efficient treatment and represents an alternative option for localized low-risk PCa management over the medium term. Precise diagnostic methods and imaging tools are thereby essential requirements to ensure safe and complete targeted therapy.

PATIENT SUMMARY

In this report, we looked at the medium-term outcomes of focal photodynamic therapy for early-stage prostate cancer. We found that this form of treatment is efficient and might have the potential to become a therapeutic option for low-risk cancer. Effectiveness depends on precise diagnostic methods, such as magnetic resonance imaging and accurate biopsy.

Validation of MRI to TRUS registration for high-dose-rate prostate brachytherapy

PURPOSE

The objective of this study was to develop and validate an open-source module for MRI to transrectal ultrasound (TRUS) registration to support tumor-targeted prostate brachytherapy.

METHODS AND MATERIALS

In this study, 15 patients with prostate cancer lesions visible on multiparametric MRI were selected for the validation. T2-weighted images with 1-mm isotropic voxel size and diffusion weighted images were acquired on a 1.5T Siemens imager. Three-dimensional (3D) TRUS images with 0.5-mm slice thickness were acquired. The investigated registration module was incorporated in the open-source 3D Slicer platform, which can compute rigid and deformable transformations. An extension of 3D Slicer, SlicerRT, allows import of and export to DICOM-RT formats. For validation, similarity indices, prostate volumes, and centroid positions were determined in addition to registration errors for common 3D points identified by an experienced radiation oncologist.

RESULTS

The average time to compute the registration was 35 ± 3 s. For the rigid and deformable registration, respectively, Dice similarity coefficients were 0.87 ± 0.05 and 0.93 ± 0.01 while the 95% Hausdorff distances were 4.2 ± 1.0 and 2.2 ± 0.3 mm. MRI volumes obtained after the rigid and deformable registration were not statistically different (p > 0.05) from reference TRUS volumes. For the rigid and deformable registration, respectively, 3D distance errors between reference and registered centroid positions were 2.1 ± 1.0 and 0.4 ± 0.1 mm while registration errors between common points were 3.5 ± 3.2 and 2.3 ± 1.1 mm. Deformable registration was found significantly better (p < 0.05) than rigid registration for all parameters.

CONCLUSIONS

An open-source MRI to TRUS registration platform was validated for integration in the brachytherapy workflow.

[Focal therapies: An alternative option for low-risk prostate cancer management?]

Recommended options for low-risk prostate cancer treatment are active surveillance, radical treatments or watchful waiting. Focal therapies are currently assessed for low risk prostate cancer treatment. Focal therapies can be performed in research protocols. Oncologic results of these focal treatments are encouraging and show excellent tolerance with few complications. Radical treatments are still possible after focal therapies failure. Focal therapies are a possible solution to over-treatment issue of low risk prostate cancers.

A novel biopsy-related parameter derived from location and relationship of positive cores on standard 12-core trans-rectal ultrasound-guided prostate biopsy: a useful parameter for predicting tumor volume compared to number of positive cores

PURPOSE

To develop a novel biopsy-related parameter, named overlapping line, defined as the line between the adjacent positive cores on 12-core trans-rectal ultrasound-guided prostate biopsy, and evaluated the value of overlapping line for predicting tumor volume in the final pathologic examination.

METHODS

Among patients with prostate cancer who underwent radical prostatectomy at Boramae Medical Center, 470 patients who underwent standard 12-core trans-rectal ultrasound-guided prostate biopsy were selected for the analysis. The number of overlapping line was determined in each patient, and its effects on tumor volume were evaluated after adjusting for other variables.

RESULTS

Median prostate specific antigen level was 9.1 ng/mL, and the maximum % cancer in positive cores was 42.8%. Median numbers of positive cores and overlapping lines were three and two, respectively. The pathologic stage was T2 or less, T3a, and T3b or greater in 297 (63.5%), 104 (22.2%), and 67 patients (14.3%), respectively. Median tumor volume in prostatectomy specimen was 3.4 mL. In multivariable analysis, the number of overlapping lines (B 0.750, p < 0.001) was a significant predictor for tumor volume, in addition to prostate specific antigen level and maximum % cancer in positive cores. In addition, the model with overlapping line showed superior accuracy compared to the model with positive core based adjusted r ² (0.467 vs. 0.456).

CONCLUSIONS

The number of overlapping lines, a novel prostate biopsy-related variable, is thought to be a more reliable predictor for tumor volume compared to the number of positive cores and could be easily applied to routine daily practice.

DNA repair deregulation in discrete prostate cancer lesions identified on multi-parametric MRI and targeted by MRI/ultrasound fusion-guided biopsy

Prostate cancer is histologically and molecularly heterogeneous. Clinically significant disease is often driven by dominant intra-prostatic lesions (IPLs). Prostate cancers cluster into molecular phenotypes with substantial genetic heterogeneity making pathway-based molecular analysis appealing. MRI/ultrasound fusion biopsy provides a unique opportunity to characterize tumor biology of discrete lesions at diagnosis. This study determined the feasibility of pathway-based gene expression analysis of prostate biopsies and characterized cancer pathway deregulation.

Thirteen patients had prostate cancer diagnosed by MRI/ultrasound fusion biopsy and either Gleason 6 or Gleason ≥8. Gene expression profiling was performed on 14 biopsies using >700 genes representing 13 cancer pathways. Pathway-based analysis compared gene expression among samples based on clinical, pathological, and radiographic characteristics. Pathway-based gene expression analysis was successful in 12 of 14 (86%) samples. Samples clustered based upon deregulation of DNA Repair and Notch, Chromatin Modification and Cell Cycle, or all other pathways, respectively. DNA Repair demonstrated the greatest differential deregulation. Lesions with Gleason ≥8, PSA ≥10, or intense dynamic contrast enhancement (DCE) had significantly higher DNA Repair deregulation than those with Gleason 6, PSA <10, or low to moderate DCE. Alterations in DNA Repair gene expression were diverse with upregulation of markers of DNA damage and down-regulation of DNA Repair proteins. This study demonstrates the feasibility of pathway-level gene expression analysis of discrete intra-prostatic lesions sampled by MRI/ultrasound fusion biopsy. IPLs cluster into distinct molecular phenotypes, the most significantly altered being DNA Repair.

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.

Multiparametric Magnetic Resonance/Ultrasound Fusion Prostate Biopsy: Number and Spatial Distribution of Cores for Better Index Tumor Detection and Characterization

PURPOSE

We evaluated the minimum core number for better index tumor detection to determine the best core site as well as biopsy Gleason score heterogeneity in the same index lesion. The aim was to optimize the highest Gleason score detection.

MATERIALS AND METHODS

A total of 327 patients with negative digital rectal examination underwent magnetic resonance imaging/transrectal ultrasound fusion targeted biopsy for elevated/rising prostate specific antigen and/or 1 or more detectable lesions on multiparametric magnetic resonance imaging after a previous negative standard biopsy. Depending on the diameter of each index lesion (8 or less, or greater than 8 mm) 4 or 6 cores, respectively, were taken according to a well determined sequence.

RESULTS

Of the patients 166 (50.7%) had prostate cancer, including 79 (47.6%) with an 8 mm or less index lesion and 87 (52.4%) with a greater than 8 mm index lesion. Of patients with an index tumor 8 mm or less 7 (8.9%) had 1, 31 (39.2%) had 2, 27 (34.2%) had 3 and 14 (17.7%) had 4 positive cores. Similarly, of patients with a lesion greater than 8 mm 8 (9.2%) had 1, 30 (34.5%) had 2, 13 (14.9%) had 3, 14 (16.1%) had 4, 12 (13.8%) had 5 and 10 (11.5%) had 6 positive cores. The major prevalence of positive cores was observed in the center of the target. Gleason score heterogeneity was found in 12.6% of those with an 8 mm or less target vs 26.4% with a target greater than 8 mm. In the center of the target there was a slight prevalence of Gleason pattern 4 or greater, or a lesser pattern.

CONCLUSIONS

Approaching magnetic resonance imaging/transrectal ultrasound fusion targeted biopsy with a single core might be inadequate. Rather, taking 2 cores in the center of the index lesion may provide more accurate cancer detection and optimize the chances of finding the highest Gleason pattern.

Advances in Prostate Cancer Magnetic Resonance Imaging and Positron Emission Tomography-Computed Tomography for Staging and Radiotherapy Treatment Planning

Conventional prostate cancer staging strategies have limited accuracy to define the location, grade, and burden of disease. Evaluations have historically relied upon prostate-specific antigen levels, digital rectal examinations, random systematic biopsies, computed tomography, pelvic lymphadenectomy, or ^99mtechnetium methylene diphosphonate bone scans. Today, risk-stratification tools incorporate these data in a weighted format to guide management. However, the limitations and potential consequences of their uncertainties are well known. Inaccurate information may contribute to understaging and undertreatment, or overstaging and overtreatment. Meanwhile, advances in multiparametric magnetic resonance imaging (MRI), whole-body MRI, lymphotropic nanoparticle-enhanced MRI, and positron emission tomography are now available to improve the accuracy of risk stratification to facilitate more informed medical decisions. They also guide radiation oncologists to develop more accurate treatment plans. This review provides a primer to incorporate these advances into routine clinical workflow.

(68)Ga-HBED-CC-PSMA PET/CT Versus Histopathology in Primary Localized Prostate Cancer: A Voxel-Wise Comparison

Purpose: We performed a voxel-wise comparison of ⁶⁸Ga-HBED-CC-PSMA PET/CT with prostate histopathology to evaluate the performance of ⁶⁸Ga-HBED-CC-PSMA for the detection and delineation of primary prostate cancer (PCa).

Methodology: Nine patients with histopathological proven primary PCa underwent ⁶⁸Ga-HBED-CC-PSMA PET/CT followed by radical prostatectomy. Resected prostates were scanned by ex-vivo CT in a special localizer and histopathologically prepared. Histopathological information was matched to ex-vivo CT. PCa volume (PCa-histo) and non-PCa tissue in the prostate (NPCa-histo) were processed to obtain a PCa-model, which was adjusted to PET-resolution (histo-PET). Each histo-PET was coregistered to in-vivo PSMA-PET/CT data.

Results: Analysis of spatial overlap between histo-PET and PSMA PET revealed highly significant correlations (p < 10^-5) in nine patients and moderate to high coefficients of determination (R²) from 42 to 82 % with an average of 60 ± 14 % in eight patients (in one patient R² = 7 %). Mean SUVmean in PCa-histo and NPCa-histo was 5.6 ± 6.1 and 3.3 ± 2.5 (p = 0.012). Voxel-wise receiver-operating characteristic (ROC) analyses comparing the prediction by PSMA-PET with the non-smoothed tumor distribution from histopathology yielded an average area under the curve of 0.83 ± 0.12. Absolute and relative SUV (normalized to SUVmax) thresholds for achieving at least 90 % sensitivity were 3.19 ± 3.35 and 0.28 ± 0.09, respectively.

Conclusions: Voxel-wise analyses revealed good correlations of ⁶⁸Ga-HBED-CC-PSMA PET/CT and histopathology in eight out of nine patients. Thus, PSMA-PET allows a reliable detection and delineation of PCa as basis for PET-guided focal therapies.

Pilot Study to Assess Safety and Clinical Outcomes of Irreversible Electroporation for Partial Gland Ablation in Men with Prostate Cancer

PURPOSE

Partial prostate gland ablation is a strategy to manage localized prostate cancer. Irreversible electroporation can ablate localized soft tissues. We describe 30 and 90-day complications and intermediate term functional outcomes in men undergoing prostate gland ablation using irreversible electroporation.

MATERIALS AND METHODS

We reviewed the charts of 25 patients with prostate cancer who underwent prostate gland ablation using irreversible electroporation as a primary procedure and who were followed for at least 6 months.

RESULTS

Median followup was 10.9 months. Grade 3 complications occurred in 2 patients including epididymitis (1) and urinary tract infection (1). Fourteen patients experienced grade 2 or lower complications, mainly transient urinary symptoms, hematuria and urinary tract infections. Of 25 patients 4 (16%) had cancer in the zone of ablation on routine followup biopsy at 6 months. Of those with normal urinary function at baseline 88% and 94% reported normal urinary function at 6 and 12 months after prostate gland ablation, respectively. By 12 months only 1 patient with normal erectile function at baseline reported new difficulty with potency and only 2 patients (8%) required a pad for urinary incontinence.

CONCLUSIONS

Prostate gland ablation with irreversible electroporation is feasible and safe in selected men with localized prostate cancer. Intermediate term urinary and erectile function outcomes appear reasonable. Irreversible electroporation is effective in the ablation of tumor bearing prostate tissue as a majority of men had no evidence of residual cancer on biopsy 6 months after prostate gland ablation.

Prostate Health Index and %p2PSA Predict Aggressive Prostate Cancer Pathology in Chinese Patients Undergoing Radical Prostatectomy

PURPOSE

To investigate the performance of prostate health index (PHI) and percentage prostate-specific antigen (PSA) isoform [-2]proPSA (%p2PSA) in predicting pathologic outcomes at radical prostatectomy (RP) in a Chinese population.

METHODS

We performed a prospective study of 135 prostate cancer patients with RP. The accuracy of preoperative %p2PSA (= p2PSA/free PSA) and PHI [= (p2PSA/free PSA) × √PSA] in predicting pathologic outcomes of RP including pT3 disease, pathologic Gleason score (pGS) ≥7, Gleason score (GS) upgrade at RP, tumor volume >0.5 ml, and Epstein criteria for significant tumor were calculated using multivariate analyses and area under the curve. The base model in multivariate analysis included age, PSA, abnormal digital rectal examination, and biopsy GS.

RESULTS

PHI was significantly higher in patients with pT3 or pGS ≥ 7 (p < 0.001), pT3 disease (p = 0.001), pGS ≥ 7 (p < 0.001), GS upgrade (p < 0.001), tumor volume >0.5 ml (p < 0.001), and Epstein criteria for significant tumor (p = 0.001). %p2PSA was also significantly higher in all the above outcomes. The risk of pT3 or pGS ≥ 7 was 16.1 % for PHI < 35 and 60.8 % for PHI > 35 (sensitivity 84.2 %, specificity of 60.3 %), and the risk of tumor volume >0.5 ml was 25.5 % for PHI < 35 and 72.6 % for PHI > 35 (sensitivity 79.1 %, specificity 67.2 %). In multivariate analysis, adding %p2PSA or PHI to the base model significantly improved the accuracy (area under the curve) in predicting pT3 or pGS ≥ 7 (by 7.2-7.9 %), tumor volume >0.5 ml (by 10.3-12.8 %), and Epstein criteria for significant tumor (by 13.9-15.9 %). Net clinical benefit was observed in decision curve analyses for prediction of both tumor volume >0.5 ml, and pT3 or pGS ≥ 7.

CONCLUSIONS

Both PHI and %p2PSA predict aggressive and significant pathologies in RP in Chinese men. This enabled identification of nonaggressive cancers for better counseling on active surveillance or treatment.

Prostate Radiotherapy in the Era of Advanced Imaging and Precision Medicine

Tremendous technological advancements in prostate radiotherapy have decreased treatment toxicity and improved clinical outcomes for men with prostate cancer. While these advances have allowed for significant treatment volume reduction and whole-organ dose escalation, further improvement in prostate radiotherapy has been limited by classic techniques for diagnosis and risk stratification. Developments in prostate imaging, image-guided targeted biopsy, next-generation gene expression profiling, and targeted molecular therapies now provide information to stratify patients and select treatments based on tumor biology. Image-guided targeted biopsy improves detection of clinically significant cases of prostate cancer and provides important information about the biological behavior of intraprostatic lesions which can further guide treatment decisions. We review the evolution of prostate magnetic resonance imaging (MRI) and MRI-ultrasound fusion-guided prostate biopsy. Recent advancements in radiation therapy including dose escalation, moderate and extreme hypofractionation, partial prostate radiation therapy, and finally dose escalation by simultaneous integrated boost are discussed. We also review next-generation sequencing and discuss developments in targeted molecular therapies. Last, we review ongoing clinical trials and future treatment paradigms that integrate targeted biopsy, molecular profiling and therapy, and prostate radiotherapy.

Dose escalation to dominant intraprostatic lesions with MRI-transrectal ultrasound fusion High-Dose-Rate prostate brachytherapy. Prospective phase II trial

BACKGROUND AND PURPOSE

To demonstrate the feasibility, safety and effectiveness of dose escalation to intraprostatic lesions with MRI-transrectal ultrasound fusion High-Dose-Rate (HDR) brachytherapy.

MATERIALS AND METHODS

15 patients with intermediate-high risk prostate cancer and visible dominant intra-prostatic nodule on mpMRI have been treated. The treatment consisted of combined MRI-TRUS fusion HDR-brachytherapy (1 fraction of 1500cGy) and hypofractionated external beam (3750cGy in 15 fractions). A dose of 1875Gy was delivered to at least 98% of the DIL volume.

RESULTS

Median prostate volume was 23.8cc; median number of needles was 16 (13-18). Dose escalation to DIL was feasible in 14/15 patients (93%) without violating dosimetric constraints and 1 patient presented a minimal deviation of dosimetric restrictions. With a median follow-up of 18months (17-24), none of the patients developed acute urinary retention or grade ⩾3 toxicity. In addition to standard PSA follow-up, response has been assessed by mpMRI at 12months. All patients presented adequate morphological responses on anatomical and functional sequences.

CONCLUSIONS

HDR brachytherapy using MRI-transrectal ultrasound fusion for image guidance is a suitable technique for partial prostate dose escalation. Tolerance and toxicity profiles are excellent and results are encouraging in terms of biochemical, morphological and functional response.

Preoperative prostate biopsy and multiparametric magnetic resonance imaging: reliability in detecting prostate cancer

Purpose

The aim of the study was to analyse and compare the ability of multiparametric magnetic resonance imaging (mp–MRI) and prostate biopsy (PB) to correctly identify tumor foci in patients undergoing radical prostatectomy (RP) for prostate cancer (PCa).

Materials and Methods

157 patients with clinically localised PCa with a PSA <10 ng/mL and a negative DRE diagnosed on the first (12 samples, Group A) or second (18 samples, Group B) PB were enrolled at our institution. All patients underwent mp-MRI with T2-weighted images, diffusion-weighted imaging, dynamic contrast enhanced-MRI prior to RP. A map of comparison describing each positive biopsy sample was created for each patient, with each tumor focus shown on the MRI and each lesion present on the definitive histological examination in order to compare tumor detection and location. The sensitivity of mp-MRI and PB for diagnosis was compared using Student’s t-test. The ability of the two exams to detect the prevalence of Gleason pattern 4 in the identified lesions was compared using a chi-square test.

Results

Overall sensitivity of PB and mp-MRI to identify tumor lesion was 59.4% and 78.9%, respectively (p<0.0001). PB missed 144/355 lesions, 59 of which (16.6%) were significant. mp-MRI missed 75/355 lesions, 12 of which (3.4%) were significant. No lesions with a GS≥8 were missed. Sensitivity of PB and mp-MRI to detect the prevalence of Gleason pattern 4 was 88.2% and 97.4%, respectively.

Conclusions

mp-MRI seems to identify more tumor lesions than PB and to provide more information concerning tumor characteristics.

Volumetric modulated arc therapy planning for primary prostate cancer with selective intraprostatic boost determined by 18F-choline PET/CT

PURPOSE

This study evaluated expected tumor control and normal tissue toxicity for prostate volumetric modulated arc therapy (VMAT) with and without radiation boosts to an intraprostatically dominant lesion (IDL), defined by (18)F-choline positron emission tomography/computed tomography (PET/CT).

METHODS AND MATERIALS

Thirty patients with localized prostate cancer underwent (18)F-choline PET/CT before treatment. Two VMAT plans, plan79 Gy and plan100-105 Gy, were compared for each patient. The whole-prostate planning target volume (PTVprostate) prescription was 79 Gy in both plans, but plan100-105 Gy added simultaneous boost doses of 100 Gy and 105 Gy to the IDL, defined by 60% and 70% of maximum prostatic uptake on (18)F-choline PET (IDLsuv60% and IDLsuv70%, respectively, with IDLsuv70% nested inside IDLsuv60% to potentially enhance tumor specificity of the maximum point dose). Plan evaluations included histopathological correspondence, isodose distributions, dose-volume histograms, tumor control probability (TCP), and normal tissue complication probability (NTCP).

RESULTS

Planning objectives and dose constraints proved feasible in 30 of 30 cases. Prostate sextant histopathology was available for 28 cases, confirming that IDLsuv60% adequately covered all tumor-bearing prostate sextants in 27 cases and provided partial coverage in 1 case. Plan100-105 Gy had significantly higher TCP than plan79 Gy across all prostate regions for α/β ratios ranging from 1.5 Gy to 10 Gy (P<.001 for each case). There were no significant differences in bladder and femoral head NTCP between plans and slightly lower rectal NTCP (endpoint: grade ≥ 2 late toxicity or rectal bleeding) was found for plan100-105 Gy.

CONCLUSIONS

VMAT can potentially increase the likelihood of tumor control in primary prostate cancer while observing normal tissue tolerances through simultaneous delivery of a steep radiation boost to a (18)F-choline PET-defined IDL.

Dose painting to treat single-lobe prostate cancer with hypofractionated high-dose radiation using targeted external beam radiation: Is it feasible?

Targeted focal therapy strategies for treating single-lobe prostate cancer are under investigation. In this planning study, we investigate the feasibility of treating a portion of the prostate to full-dose external beam radiation with reduced dose to the opposite lobe, compared with full-dose radiation delivered to the entire gland using hypofractionated radiation. For 10 consecutive patients with low- to intermediate-risk prostate cancer, 2 hypofractionated, single-arc volumetric-modulated arc therapy (VMAT) plans were designed. The first plan (standard hypofractionation regimen [STD]) included the entire prostate gland, treated to 70 Gy delivered in 28 fractions. The second dose painting plan (DP) encompassed the involved lobe treated to 70 Gy delivered in 28 fractions, whereas the opposing, uninvolved lobe received 50.4 Gy in 28 fractions. Mean dose to the opposing neurovascular bundle (NVB) was considerably lower for DP vs STD, with a mean dose of 53.9 vs 72.3 Gy (p < 0.001). Mean penile bulb dose was 18.6 Gy for DP vs 19.2 Gy for STD (p = 0.880). Mean rectal dose was 21.0 Gy for DP vs 22.8 Gy for STD (p = 0.356). Rectum V70 (the volume receiving ≥70 Gy) was 2.01% for DP vs 2.74% for STD (p = 0.328). Bladder V70 was 1.69% for DP vs 2.78% for STD (p = 0.232). Planning target volume (PTV) maximum dose points were 76.5 and 76.3 Gy for DP and STD, respectively (p = 0.760). This study demonstrates the feasibility of using VMAT for partial-lobe prostate radiation in patients with prostate cancer involving 1 lobe. Partial-lobe prostate plans appeared to spare adjacent critical structures including the opposite NVB.