Systematic review of the efficacy and safety of high-intensity focussed ultrasound for the primary and salvage treatment of prostate cancer

Interventional oncology: new techniques and new devices

Interventional oncology is a rapidly emerging field in the treatment of cancer. Minimally invasive techniques such as transarterial embolization with chemotherapeutic and radioactive agents are established therapies and are found in multiple guidelines for the management of primary and metastatic liver lesions. Percutaneous ablation is also an alternative to surgery for small liver, renal, and pancreatic tumors. Recent research in the niche of interventional oncology has focused on improving outcomes of established techniques in addition to the development of novel therapies. In this review, we address the recent and current advancements in devices, technologies, and techniques of chemoembolization and ablation: thermal ablation, histotripsy, high-intensity focused ultrasound, embolization strategies, liquid embolic agents, and local immunotherapy/antiviral therapies.

Comparing the toxicity and disease control rate of radiotherapy for prostate cancer between salvage settings after high-intensity focused ultrasound therapy and initial settings

The purpose of this retrospective study was to compare the toxicity and disease control rate of radiotherapy for prostate cancer in salvage settings after high-intensity focused ultrasound (HIFU) therapy (HIFU cohort) with those in radical settings (non-HIFU cohort). From 2012 to 2020, 215 patients were identified for this study and 17 were treated in the salvage settings after HIFU. The median follow-up time was 34.5 months (range: 7-102 months, inter-quartile range [IQR]: 16-64 months). Genitourinary (GU) and gastrointestinal (GI) adverse events were evaluated in acute and late periods with Common Terminology Criteria for Adverse Events version 5, and the rates of biochemical-clinical failure free survival (BCFS) and overall survival (OS) were estimated. The cumulative incidence of late GU Grade 2 or greater toxicity after five years was significantly different between the non-HIFU and HIFU cohorts with rates of 7.3% and 26.2%, respectively (P = 0.03). Regarding GI Grade 2 or greater toxicity, there was no significant difference between the two cohorts. The 5y-BCFS was 84.2% in the non-HIFU cohort and 69.5% in the HIFU cohort with no significant difference (P = 0.10) and the 5y-OS was 95.9% and 92.3%, respectively (P = 0.47). We concluded that the possibility of increased late GU Grade 2 or greater should be considered when applying salvage radiotherapy for local recurrence after HIFU.

Factores de riesgo y estrategias de prevención para el desarrollo de estrechez uretral de origen iatrogénico: Papel del urólogo

La estrechez uretral constituye una patología con morbilidad importante en el sexo masculino. Se evidencia en la actualidad un cambio en la frecuencia de las etiologías, con la disminución de causas inflamatorias y una transición hacia la iatrogenia como la más común. Mediante la búsqueda del estado del arte en cuanto a los procedimientos diagnósticos y terapéuticos conocidos como factores asociados a la estrechez uretral iatrogénica, se realizó una revisión narrativa de la literatura con el fin de describir y generar estrategias para su prevención. De los procedimientos terapéuticos que originan la estrechez uretral como complicación, el sondaje vesical es la mayor causa (hasta 34,3%), seguido de la prostatectomía radical (29,9%). Una buena técnica de sondaje vesical orientada desde el adecuado entrenamiento del personal disminuye de forma considerable su incidencia. Por otra parte, la adecuada selección de tratamientos y aspectos técnicos en pacientes que requieren el manejo de patologías obstructivas del tracto urinario como la hiperplasia prostática y litiasis u oncológicas como el cáncer de próstata, son unas de las recomendaciones para la prevención de ese trastorno. El entendimiento de los factores de riesgo y la adherencia a las estrategias de prevención descritas buscan disminuir la incidencia de la estrechez uretral de origen iatrogénico.

Peri-operative, functional and early oncologic outcomes of salvage robotic-assisted radical prostatectomy after high-intensity focused ultrasound partial ablation

BACKGROUND

Partial ablation of the prostate using high-intensity focussed ultrasound (HIFU-PA) is a treatment option for localised prostate cancer. When local recurrence occurs, salvage robot-assisted radical prostatectomy is a treatment option for selected patients, but there is a paucity of data on the peri-operative safety, functional and oncologic outcomes of sRARP.. The objective of this study was therefore to describe peri-operative safety, functional and early oncologic outcomes following salvage robot-assisted radical prostatectomy (sRARP) for local recurrence after HIFU-PA.

METHODS

Retrospective analysis of a prospective database of 53 consecutive men who underwent sRARP after HIFU-PA from 2012 to 2018. Continence and erectile-function were reported pre-HIFU, pre-sRARP, 3-months post-sRARP and 12-months post-sRARP. Complications, PSMs and need for subsequent ADT/radiotherapy were assessed.

RESULTS

45 men were suitable for inclusion and had sufficient data for analyses. Median duration from HIFU to sRARP was 30.0 months and median follow-up post-sRARP was 17.7 months. Median age, PSA and ISUP group were 63.0 yrs., 7.2 ng/mL and 2; 88.9% were cT2. Median operative-console time, blood loss and hospital stay were 140 min, 200 ml and 1 day respectively. Clavien-Dindo grade 1, 2 and 3 complications < 90 days occurred in 8.9, 6.7 and 2.2%; late (>90d) complications occurred in 13.2%. At sRARP pathology, ISUP 3-5 occurred in 51.1%, pT3a/b in 64.5%, and PSMs in 44.4% (37.5% for pT2, 48.3% for pT3). Of men with > 3-months follow-up after sRARP, 26.3% underwent adjuvant radiotherapy/ADT for residual disease or adverse pathologic features; 5.3% experienced BCR requiring salvage ADT/radiotherapy. Freedom from ADT/radiotherapy was 66.7% at 12-months. Pad-free rates were 100% pre-HIFU, 95.3% post-HIFU, 29.4% 3-months post-sRARP, and 65.5% 12-months post-sRARP. Median IIEF-5 scores pre-HIFU, post-HIFU, 3- and 12-months post-sRARP were 23.5, 16, 5 and 5, respectively. Potency rates were 81.8, 65.5, 0 and 0%, respectively. Bilateral/unilateral nerve sparing were feasible in 7%/22%.

CONCLUSION

Salvage RARP was safe with acceptable but sub-optimal continence and poor sexual-function and poor oncologic outcomes. One in three men required additional treatment within 12-months. This information may aid men and urologists with treatment selection and counselling regarding primary HIFU-PA vs primary RARP and when considering salvage RARP.

Survival and quality of life outcomes of high-intensity focused ultrasound treatment of localized prostate cancer

BACKGROUND

To evaluate the survival and quality of life (QoL) outcomes of high-intensity focused ultrasound (HIFU) whole-gland ablation for localized prostate cancer.

METHODS

Over 8 years, men with localized prostate cancer treated with whole-gland HIFU were prospectively followed. Transrectal prostate ablation was performed under general anesthesia with Sonablate-500® (Sonacare Medical©, Charlotte, North Carolina, USA). The primary outcome was failure-free survival defined as no transition to any of the following: (1) local salvage therapy (surgery or radiotherapy), (2) systemic therapy, (3) metastases, or (4) prostate cancer-specific mortality. Secondary outcomes included both survival outcomes and QoL measures.

RESULTS

Of 70 men, 29.7% had International Society of Urological Pathology (ISUP) grade 1, 43.8% ISUP 2, 10.9% ISUP 3, and 15.6% ISUP 4 disease. At median follow-up of 83.4 months, overall mortality was 8.6% and prostate cancer-specific mortality 0%. Failure-free survival was 78.2% at 5 years and 71.2% at 7 years. Of all men, 7.1% of men developed metastases, with median metastasis-free survival of 75.4 months. There was negligible post-HIFU urinary incontinence or lower urinary tract symptom with a median Male Urogenital Distress Inventory score of 32 at 6 months and 33 at 12 months and median IPSS of 4 at 6 months and 3 at 12 months. Median Radiation Therapy Oncology Group rectal toxicity score was 0 throughout. In men who had mild or no erectile dysfunction at baseline (International Index of Erectile Function ≥17), the mean International Index of Erectile Function score declined to 37% from 23.5 at baseline to 14.7 at 12 months.

CONCLUSION

At median follow-up of 7 years, whole-gland HIFU appears to have comparable survival outcomes with other cohort studies involving radical prostatectomy and radiotherapy patient. It has low impact on QoL, preserved urinary continence, and erectile function approximate to nerve-sparing prostatectomy. Whole-gland HIFU presents a potential alternative minimally invasive and safe option for the treatment of localized prostate cancer.

Oncologic outcome, side effects and comorbidity of high-intensity focused ultrasound (HIFU) for localized prostate cancer. A review

Introduction

Prostate cancer is considered one of the most important health problems. Due to the increased number of diagnosed patients and the inability to distinguish aggressive tumors, minimally-invasive procedures have become increasingly interesting. High-intensity focused ultrasound (HIFU) is an alternative option to radical surgery to treat prostate cancer. To date, however, data on side effects and comorbidities of this technique are still not conclusive.

Methods and results

We reviewed the literature to concentrate on side effects and comorbidities of HIFU treatment of prostate cancer with the following key words: hifu, high intensity focused ultrasound, ultrasonic therapy, transrectal hifu, prostate ablation, side effects, comorbidities. MedLine and Embase via Ovid database were searched. Selection criteria were: English language, articles published between 2001 and 2015, case series including at least 100 participants and reported data on side effects and comorbidities. Sixteen uncontrolled studies were identified. No randomized controlled trials (RCT) were found in the literature comparing side effects and comorbidities of HIFU to other routine approaches to prostate cancer treatment.

Conclusion

HIFU seems to be a promising minimally-invasive treatment for low- and intermediate-risk prostate cancer, especially for patients who are unfit for radical surgery. Prospective studies with longer follow-up periods and RCT are required to properly assess the impact of side effects and comobidities related to the HIFU technique in comparison with other therapies to treat prostate cancer.

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HIFU is a promising minimally-invasive treatment for prostate cancer, especially in patients with low- and intermediate-risk disease.

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To date, the most proper indication to HIFU is for patients who are not fit for, or are unwilling to undergo, radical surgery.

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The most common complications are impotence, urinary incontinence, acute urinary retention and urethral fistula.

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High-intensity focused ultrasound is a safe and effective procedure.

Thermal Therapy With a Fully Electronically Steerable HIFU Phased Array Using Ultrasound Guidance and Local Harmonic Motion Monitoring

The method of localized harmonic motion (LHM) monitoring has been proposed as an ultrasound-based monitoring technique for in vivo real-time ultrasound-guidance during thermal surgery.

OBJECTIVE

The focus of this paper is to study the performance of LHM monitoring in vivo in order to assess the tissue coagulation during ultrasound surgery of bone metastases. This is done through a pre-clinical study on large scale animals (pigs) as well as a first-in-human pilot study, using a hand held ultrasound-guided HIFU phased array.

METHODS

A flat, fully steerable HIFU phased array system (1024 elements, 100 mm diameter, 516 kHz), in combination with a co-aligned 64 element imaging system, is used to perform thermal surgery and monitor tissue coagulation using the LHM technique. The in vivo experiments are conducted using thirteen animals, followed by a first-in-human pilot study in which nine patients are enrolled.

RESULTS

The pre-clinical results show that the LHM monitoring method is able to detect about 80% of the observed coagulated tissue volumes visible in dissection. In the pilot study, six out of nine patients have durable pain reduction with good correlation observed from LHM detections.

CONCLUSION

In general, the results suggest that the LHM monitoring performance is promising in detecting thermal tissue coagulation during focused ultrasound surgery in tissues close to the bone.

SIGNIFICANCE

The LHM technique can offer a very accessible and cost-efficient monitoring solution during ultrasound surgery within a clinical setting.

Partial ablation versus radical prostatectomy in intermediate-risk prostate cancer: the PART feasibility RCT

BACKGROUND

Prostate cancer (PCa) is the most common cancer in men in the UK. Patients with intermediate-risk, clinically localised disease are offered radical treatments such as surgery or radiotherapy, which can result in severe side effects. A number of alternative partial ablation (PA) technologies that may reduce treatment burden are available; however the comparative effectiveness of these techniques has never been evaluated in a randomised controlled trial (RCT).

OBJECTIVES

To assess the feasibility of a RCT of PA using high-intensity focused ultrasound (HIFU) versus radical prostatectomy (RP) for intermediate-risk PCa and to test and optimise methods of data capture.

DESIGN

We carried out a prospective, multicentre, open-label feasibility study to inform the design and conduct of a future RCT, involving a QuinteT Recruitment Intervention (QRI) to understand barriers to participation.

SETTING

Five NHS hospitals in England.

PARTICIPANTS

Men with unilateral, intermediate-risk, clinically localised PCa.

INTERVENTIONS

Radical prostatectomy compared with HIFU.

PRIMARY OUTCOME MEASURE

The randomisation of 80 men.

SECONDARY OUTCOME MEASURES

Findings of the QRI and assessment of data capture methods.

RESULTS

Eighty-seven patients consented to participate by 31 March 2017 and 82 men were randomised by 4 May 2017 (41 men to the RP arm and 41 to the HIFU arm). The QRI was conducted in two iterative phases: phase I identified a number of barriers to recruitment, including organisational challenges, lack of recruiter equipoise and difficulties communicating with patients about the study, and phase II comprised the development and delivery of tailored strategies to optimise recruitment, including group training, individual feedback and 'tips' documents. At the time of data extraction, on 10 October 2017, treatment data were available for 71 patients. Patient characteristics were similar at baseline and the rate of return of all clinical case report forms (CRFs) was 95%; the return rate of the patient-reported outcome measures (PROMs) questionnaire pack was 90.5%. Centres with specific long-standing expertise in offering HIFU as a routine NHS treatment option had lower recruitment rates (Basingstoke and Southampton) - with University College Hospital failing to enrol any participants - than centres offering HIFU in the trial context only.

CONCLUSIONS

Randomisation of men to a RCT comparing PA with radical treatments of the prostate is feasible. The QRI provided insights into the complexities of recruiting to this surgical trial and has highlighted a number of key lessons that are likely to be important if the study progresses to a main trial. A full RCT comparing clinical effectiveness, cost-effectiveness and quality-of-life outcomes between radical treatments and PA is now warranted.

FUTURE WORK

Men recruited to the feasibility study will be followed up for 36 months in accordance with the protocol. We will design a full RCT, taking into account the lessons learnt from this study. CRFs will be streamlined, and the length and frequency of PROMs and resource use diaries will be reviewed to reduce the burden on patients and research nurses and to optimise data completeness.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN99760303.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 52. See the NIHR Journals Library website for further project information.

Short-Term Observation of Ultrasonic Cyclocoagulation in Chinese Patients with End-Stage Refractory Glaucoma: A Retrospective Study

Purpose

To assess the efficacy and safety of HIFU-based ultrasonic cyclocoagulation in Chinese patients with end-stage refractory glaucoma.

Method

Patients were recruited consecutively from May 2016 to May 2017 in the Zhongshan Ophthalmic Center. Ultrasonic cyclocoagulation was performed on every patient, using the EyeOP1 ultrasound emitting device. Return visits were set at 1 day, 7 days, 1 month, and 3 months after the treatment. An intraocular pressure (IOP) reduction of ≥20% while IOP ≥ 5 mmHg was deemed as success. Mean IOP change was assessed. Efficacy of two modes (6 sectors and 8 sectors) was also compared. Complications were recorded for safety evaluation.

Results

61 eyes were treated in this study. The baseline IOP (mean ± SD) was 41.11 ± 10.65 mmHg. The percentage of IOP reduction after treatment was 29.2%, 43.2%, 34.8%, and 23.1% at 1 day, 7 days, 1 month, and 3 months, respectively. Overall success rate at 3 months was 50.0% (26/52). No significant difference was found between the 6 sectors group and the 8 sectors group in terms of the success rate (48.6% vs. 52.9%, p=0.768) as well as IOP reduction (p=0.417) at 3 months. Primary angle-closure glaucoma (PACG) had the highest success rate (80.0%, 12/15). Scleral thinning existed in 12 eyes, among which 2 developed hypotony (2 mmHg and 3 mmHg). Average pain score decreased massively compared with baseline data.

Conclusion

With high percentage of IOP reduction and a good safety profile observed in our study, HIFU-based ultrasonic cyclocoagulation might become a promising alternative to cyclodestructive methods. Long-term efficacy and safety need further assessment. The study was registered with Chinese Clinical Trial Registry (http://www.chictr.org.cn; Registration number: ChiCTR-OOC-17014028).

High-intensity focused ultrasound therapy for the treatment of prostate cancer: Medium-term experience

INTRODUCTION

The treatment of localised prostate cancer seeks to minimise the impact on sexual function and urinary continence. In this respect, therapy with high-intensity focused ultrasound offers important results. We present our experience with this technique in 2 Spanish centres.

MATERIAL AND METHODS

We conducted a retrospective review of 75 patients with localised prostate cancer treated with high-intensity focused ultrasound between March 2007 and July 2016. The oncological results and perioperative complications were assessed, as well as the impact on sexual function and continence.

RESULTS

A total of 67 patients were analysed. The mean follow-up was 7.2 years. The PSA nadir was 0.2ng/mL (0-3), 24 patients (35.5%) presented biochemical recurrence, and 18 underwent a further biopsy, with 10 cases (55.5%) presenting disease recurrence. The overall biochemical relapse-free survival at 5 and 8 years was 93.2 and 80.5%, respectively. The cancer-specific survival at 5 and 8 years was 96% in both cases. In the postoperative period, 50 patients (74.6%) were continent, 16 (23.9%) reported mild incontinence, and one (1.5%) reported moderate incontinence. The median International Index of Erectile Function-5 before and after the surgery was 17 (5-25) and 16 (2-23) points, respectively. Nine patients reported de novo erectile dysfunction (13.5%).

CONCLUSION

High-intensity focused ultrasound appears to be a safe alternative for the treatment of localised prostate cancer, especially for low-risk localised prostate cancer. In our experience, this technique offers advantages in preserving urinary continence, and the medium-term oncological results are encouraging. Given the natural progression of prostate cancer, long-term studies with a larger number of cases are needed to corroborate these results.

[Morphological changes in tumor and nontumor tissue in the treatment of prostate adenocarcinoma with high-intensity focused ultrasound in combination with androgen deprivation]

OBJECTIVE

To investigate structural changes in the tumor and nontumor tissues of the prostate in patients with its cancer (PC) after treatment with high-intensity focused ultrasound (HIFU) in combination with androgen deprivation to clarify criteria for evaluating the efficiency of treatment.

SUBJECT AND METHODS

Comparative morphological, immunohistochemical, and morphometric analyses were carried out to examine 253 pre- and postoperative biopsy specimens, as well as transurethral resection specimens from 32 patients with localized PC and with or without a local recurrence within 3 years after a HIFU session.

RESULTS

HIFU ablation was accompanied by coagulation necrosis and progressive pancreatic fibrosis with complete tumor regression or by a reduction in the number of positive columns (by an average of 58%) in cases with recurrence. An inverse relationship was found between the degree of a reduction in the nontumor parenchyma in the control specimens and the probability of a recurrence - a less than 20% reduction in the non-tumor glands corresponded to a 3.4-fold increased risk of tumor progression. The development of recurrence was associated with less differentiated PC (GS ≥4+3) and the presence of cribriform structures in the pretreatment samples. Combined androgen deprivation as the maximum blockade was associated with the most pronounced signs of therapeutic pathomorphism, with a reduction of the microcirculatory bed in the focus of residual tumor, and a decrease in the frequency of local progression.

CONCLUSION

Neoadjuvant hormone therapy contributes to the enhanced efficiency of HIFU treatment for PC. A less than 20% reduction in nontumor parenchyma volumes in the control biopsy specimens may indicate insufficient ablation in pancreatic tissue and serve as a marker for increased risk of local progression.

Treatment effects in prostate cancer

Nonsurgical treatments for prostate cancer include androgen-deprivation therapy (ADT), radiation therapy (RT), ablative therapies, chemotherapy, and newly emerging immunotherapies. These approaches can be used alone or in combination depending on the clinical scenario. ADT is typically reserved for high-risk locally or systemically advanced disease that is not amenable to curative surgery. Radiation therapy can be used instead of surgery as primary therapy with curative intent for low-intermediate-risk disease as well as for control of locally advanced disease not suitable for surgery. Ablative therapies can be used as primary therapy for low-intermediate-risk disease or as salvage therapy for clinically localized disease where RT has failed. Chemotherapy and immune-based therapies are currently used for androgen-independent disease, although the indications for these approaches may well change as new data from clinical trials accrue. Pathologists should be able to recognize tissue changes associated with these treatments to provide information that will optimize patient management. This is particularly true in situations where clinical history of recent or remote nonsurgical treatment is not provided with the specimen. In the absence of this information, pathologists encountering the features described herein are encouraged to review patient records or communicate directly with clinical colleagues to determine how a given patient was treated and when.

Oncological and functional outcomes of elderly men treated with HIFU vs. minimally invasive radical prostatectomy: A propensity score analysis

AIM

To assess outcomes of whole gland high-intensity focused ultrasound (HIFU) as compared with minimally-invasive radical prostatectomy (MIRP) in elderly patients.

MATERIALS & METHODS

Patients aged ≥70 years with, cT1-cT2 disease, biopsy Gleason score (GS) 3 + 3 or 3 + 4 and preoperative PSA ≤10 ng/mL were submitted to either whole-gland HIFU or MIRP. Propensity-score matching analysis was performed to ensure the baseline equivalence of groups. Follow-up visits were routinely performed assessing PSA and urinary function according to the International Continence Score (ICS) and the International Prostatic Symptoms Score (IPSS) questionnaires. Estimated rates of salvage-treatment free survival (SFS) overall-survival (OS), cancer-specific survival (CSS) and metastasis-free survival (MTS) were assessed and compared.

RESULTS

Overall, 84 (33.3%) and 168 (66.7%) patients were treated with HIFU and MIRP, respectively. MIRP was associated with a 5-yrs SFS of 93.4% compared to 74.8% for HIFU (p < 0.01). The two groups did not differ in terms of OS and MTS. No cancer-related deaths were registered. Patients treated with HIFU showed better short-term (6-mos) continence outcomes [mean-ICS: 1.7 vs. 4.8; p = 0.005] but higher IPSS mean scores at 12-mos assessment. A comparable rate of patients experiencing post-treatment Clavien-Dindo grade ≥III complications was observed within the two groups.

CONCLUSIONS

Whole-gland HIFU is a feasible treatment in elderly men with low-to intermediate-risk PCa and could be considered for patients either unfit for surgery, or willing a non-invasive treatment with a low morbidity burden, although a non-negligible risk of requiring subsequent treatment for recurrence should be expected.

Multimodality Image Fusion with PSMA PET/CT and High-Intensity Focused Ultrasound Focal Therapy for Primary Diagnosis and Management of Prostate Cancer: A Planned Research Initiative

Recent developments in diagnostic imaging herald a new approach to diagnosis and management of prostate cancer. Multimodality fusion that combines anatomic with functional imaging data has surpassed either of the two alone. This opens up the possibility to "find and fix" malignancy with greater accuracy than ever before. This is particularly important for prostate cancer because it is the most common male cancer in most developed countries. This article describes technical advances under investigation at our institution and others using multimodality image fusion of magnetic resonance imaging (MRI), transrectal ultrasound (TRUS), and PSMA PET/CT (defined as the combination of prostate-specific membrane antigen [PSMA], positron emission tomography [PET], and computed tomography [CT]) for personalized medicine in the diagnosis and focal therapy of prostate cancer with high-intensity focused ultrasound (HiFUS).

[Prospective: How will renal, prostatic and urothelial tumours be treated in 10 years?]

Forward thinking does not seek to predict the future, to unveil it as if it were already in existence, rather, its aim is to help us to construct it. Although today's epidemiological and therapeutic situations for urogenital tumours can evolve over the next 10 years, diagnostic and therapeutic methods, as well as the treatment and implementation of innovations, are already rapidly changing. Rather than reducing our prospective thinking to the therapeutic treatment of cancer only, we will aim at proposing a global sanitary vision that includes diagnosis, therapies, prevention, routine utilisation of technomedicine, genomics and even nanomedicine. This journey into the near future of tomorrow's cancerology holds the promise of being better adapted to the evolution of the medical thinking process. Imagining the way we will be treating renal, prostatic and urothelial tumours in 10 years' time is as much an introspection into our present day treatment system as a projection into its hoped for future evolution.

An Ultrasound Imaging-Guided Robotic HIFU Ablation Experimental System and Accuracy Evaluations

In recent years, noninvasive thermal treatment by using high-intensity focused ultrasound (HIFU) has high potential in tumor treatment. The goal of this research is to develop an ultrasound imaging-guided robotic HIFU ablation system for tumor treatment. The system integrates the technologies of ultrasound image-assisted guidance, robotic positioning control, and HIFU treatment planning. With the assistance of ultrasound image guidance technology, the tumor size and location can be determined from ultrasound images as well as the robotic arm can be controlled to position the HIFU transducer to focus on the target tumor. After the development of the system, several experiments were conducted to measure the positioning accuracy of this system. The results show that the average positioning error is 1.01 mm with a standard deviation 0.34, and HIFU ablation accuracy is 1.32 mm with a standard deviation 0.58, which means this system is confirmed with its possibility and accuracy.

Fast lesion mapping during HIFU treatment using harmonic motion imaging guided focused ultrasound (HMIgFUS) in vitro and in vivo

The successful clinical application of high intensity focused ultrasound (HIFU) ablation depends on reliable monitoring of the lesion formation. Harmonic motion imaging guided focused ultrasound (HMIgFUS) is an ultrasound-based elasticity imaging technique, which monitors HIFU ablation based on the stiffness change of the tissue instead of the echo intensity change in conventional B-mode monitoring, rendering it potentially more sensitive to lesion development. Our group has shown that predicting the lesion location based on the radiation force-excited region is feasible during HMIgFUS. In this study, the feasibility of a fast lesion mapping method is explored to directly monitor the lesion map during HIFU. The harmonic motion imaging (HMI) lesion map was generated by subtracting the reference HMI image from the present HMI peak-to-peak displacement map, as streamed on the computer display. The dimensions of the HMIgFUS lesions were compared against gross pathology. Excellent agreement was found between the lesion depth (r ²  =  0.81, slope  =  0.90), width (r ²  =  0.85, slope  =  1.12) and area (r ²  =  0.58, slope  =  0.75). In vivo feasibility was assessed in a mouse with a pancreatic tumor. These findings demonstrate that HMIgFUS can successfully map thermal lesions and monitor lesion development in real time in vitro and in vivo. The HMIgFUS technique may therefore constitute a novel clinical tool for HIFU treatment monitoring.

Vascular Targeted Photodynamic Therapy with Padeliporfin for Low Risk Prostate Cancer Treatment: Midterm Oncologic Outcomes

PURPOSE

We assessed the midterm oncologic outcomes of vascular targeted photodynamic therapy with padeliporfin for low risk prostate cancer treatment.

MATERIALS AND METHODS

We prospectively assessed all patients treated with vascular targeted photodynamic therapy for low risk prostate cancer at our center. Patients were followed every 6 months. All patients underwent prostate biopsies 6 months after treatment or when there was biological or clinical progression. The primary end point was progression-free survival. Secondary end points were absent clinically significant cancer in the treated lobes, radical therapy and the prostate specific antigen rate. Variables were compared with the chi-square, Mann-Whitney or Wilcoxon test. Progression-free survival is reported with Kaplan-Meier curves.

RESULTS

A total of 82 men were treated with vascular targeted photodynamic therapy. Median followup was 68 months (range 6 to 89). Median progression-free survival was 86 months (95% CI 82-90). Median prostate specific antigen decreased significantly by 41% 6 months after treatment and it remained stable during followup (p <0.001). A total of 115 lobes were treated and absent clinically significant cancer was achieved in 94 (82%). Of the 82 patients 20 (24%) underwent radical therapy, including radical prostatectomy in 18 and brachytherapy in 2, at a median of 22 months (range 6 to 86). Study limitations include a single arm design, small population size and midterm followup.

CONCLUSIONS

Padeliporfin vascular targeted photodynamic therapy for low risk prostate cancer achieved an 82% rate of absent clinically significant cancer in treated lobes and 76% of patients avoided radical therapy at a median followup of 68 months. However, longer followup is required to determine long-term outcomes.

Quality of life and functional outcome after infravesical desobstruction and HIFU treatment for localized prostate cancer

Background

To evaluate quality of life, functional and oncological outcome after infravesical desobstruction and HIFU treatment for localized prostate cancer.

Methods

One hundred thirty-one patients, treated with TURP and HIFU in a single institution were followed up for oncological and functional outcome. Oncological outcome was quantified by biochemical recurrence free survival using the Stuttgart and Phoenix criteria. Quality of life was assessed by usage of standardized QLQ-C30 and QLQ-PR25 questionnaires. In addition, functional questionnaires such as IPSS and IIEF-5 were used. Complications were assessed by the Clavien-Dindo classification.

Results

One hundred thirty-one patients with a mean age of 72.8 years (SD: 6.0) underwent HIFU for prostate cancer (29.0% low risk, 58.8% intermediate risk, 12.2% high risk). PSA nadir was 0.6 ng/ml (SD: 1.2) after a mean of 4.6 months (SD: 5.7). Biochemical recurrence free survival defined by Stuttgart criteria was 73.7%, 84.4% and 62.5% for low-, intermediate- and high-risk patients after 22.2 months. Complications were grouped according to Clavien-Dindo and occurred in 10.7% (grade II) and 11.5% (grade IIIa) of cases. 35.1% of patients needed further treatment for bladder neck stricture. Regarding incontinence, 14.3%, 2.9% and 0% of patients had de novo urinary incontinence grade I°, II° and III° and 3.8% urge incontinence due to HIFU treatment. Patients were asked for the ability to have intercourse: 15.8%, 58.6% and 66.7% of patients after non-, onesided and bothsided nervesparing procedure were able to obtain sufficient erection for intercourse, respectively. Regarding quality of life, mean global health score according to QLQ-C30 was 69.4%.

Conclusion

HIFU treatment for localized prostate cancer shows acceptable oncological safety. Quality of life after HIFU is better than in the general population and ranges within those of standard treatment options compared to literature. HIFU seems a safe valuable treatment alternative for patients not suitable for standard treatment.

Beam distortion due to gold fiducial markers during salvage high-intensity focused ultrasound in the prostate

PURPOSE

High intensity focused ultrasound (HIFU) provides a non-invasive salvage treatment option for patients with recurrence after external beam radiation therapy (EBRT). As part of EBRT the prostate is frequently implanted with permanent fiducial markers. To date, the impact of these markers on subsequent HIFU treatment is unknown. The objective of this work was to systematically investigate, using computational simulations, how these fiducial markers affect the delivery of HIFU treatment.

METHODS

A series of simulations was performed modelling the propagation of ultrasound pressure waves in the prostate with a single spherical or cylindrical gold marker at different positions and orientations. For each marker configuration, a set of metrics (spatial-peak temporal-average intensity, focus shift, focal volume) was evaluated to quantify the distortion introduced at the focus. An analytical model was also developed describing the marker effect on the intensity at the focus. The model was used to examine the marker's impact in a clinical setting through case studies.

RESULTS

The simulations show that the presence of the marker in the pre-focal region causes reflections which induce a decrease in the focal intensity and focal volume, and a shift of the maximum pressure point away from the transducer's focus. These effects depend on the shape and orientation of the marker and become more pronounced as its distance from the transducer's focus decreases, with the distortion introduced by the marker greatly increasing when placed within 5 mm of the focus. The analytical model approximates the marker's effect and can be used as an alternative method to the computationally intensive and time consuming simulations for quickly estimating the intensity at the focus. A retrospective review of a small patient cohort selected for focal HIFU after failed EBRT indicates that the presence of the marker may affect HIFU treatment delivery.

CONCLUSIONS

The distortion introduced by the marker to the HIFU beam when positioned close to the focus may result in an undertreated region beyond the marker due to less energy arriving at the focus, and an overtreated region due to reflections. Further work is necessary to investigate whether the results presented here justify the revision of the patient selection criteria or the markers' placement protocol.

Levator Ani Necrosis: An Exceptional Complication Occurring after "High Intensity Focused Ultrasound" of the Prostate

High intensity focused ultrasound (HIFU) is a minimally invasive treatment option that might be considered in the management of localized prostate cancer. It is a well-tolerated treatment with few minor urologic complications and no major toxicities. In this paper, we report to our knowledge the first case of levator ani necrosis in a patient treated with HIFU, manifesting as sturdy perineal pain, which took years of NSAID intake and serial MRIs to demonstrate partial improvement. Therefore, we regard HIFU as a serious potential treatment option that still requires longer follow-up data before its approval in the personalized treatment panel of prostate cancer.

Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy

Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.

Emerging minimally invasive procedures for focal treatment of organ-confined prostate cancer

Prostate cancer is the most common malignancy amongst American men. However, the majority of prostate cancer diagnoses are of low risk, organ-confined disease. Many men elect to undergo definitive treatment, but may benefit from focal therapy to maintain continence and potency. This review reports the mechanism of action and outcomes of emerging focal therapies for prostate cancer. We report the mechanism of action of focal cryotherapy, high intensity focused ultrasound, focal laser ablation, and irreversible electroporation. In addition, we reviewed the largest studies available reporting rates of urinary incontinence, erectile dysfunction, biochemical recurrence-free survival (ASTRO), and post-operative adverse events for each procedure. Each treatment modality stated has a unique mechanism in the ablation of cancerous cells. Genito-urinary symptoms following these studies report incontinence and erectile dysfunction rates ranging from 0-15% and 0-53%, respectively. Biochemical disease-free survival was reported using the ASTRO definition. Some treatment modalities lack the necessary follow-up to determine effectiveness in cancer control. No focal therapy studies reported serious adverse events. These minimally invasive procedures are feasible in a clinical setting and show promising functional and disease control results with short to medium-term follow-up. However, each treatment requires additional robust prospective studies as well as its own unique domain to determine biochemical recurrence free survival to properly determine their role in treatment of organ-confined prostate cancer.

Frequency considerations for deep ablation with high-intensity focused ultrasound: A simulation study

PURPOSE

The objective of this study was to explore frequency considerations for large-volume, deep thermal ablations with focused ultrasound. Though focal patterns, focal steering rate, and the size of focal clusters have all been explored in this context, frequency studies have generally explored shallower depths and hyperthermia applications. This study examines both treatment efficiency and near-field heating rate as functions of frequency and depth.

METHODS

Flat, 150 mm transducer arrays were simulated to operate at frequencies of 250, 500, 750, 1000, 1250, and 1500 kHz. Each array had λ2 interelement spacing yielding arrays of 2000-70 000 piston-shaped elements arranged in concentric rings. Depths of 50, 100, and 150 mm were explored, with attenuation (α) values of 2.5-10 (Np/m)/MHz. Ultrasound propagation was simulated with the Rayleigh-Sommerfeld integral over a volume of homogeneous simulated tissue. Absorbed power density was determined from the acoustic pressure which, in turn, was modeled with the Pennes bioheat transfer equation. Using this knowledge of temperature over time, thermal dose function of Sapareto and Dewey was used to model the resulting bioeffect of each simulated sonication. Initially, single foci at each depth, frequency, and α were examined with either fixed peak temperatures or fixed powers. Based on the size of the resulting, single foci lesions, larger compound sonications were designed with foci packed together in multiple layers and rings. For each depth, focal patterns were chosen to produce a similar total ablated volume for each frequency. These compound sonications were performed with a fixed peak temperature at each focus. The resulting energy efficiency (volume ablated per acoustic energy applied), near-field heating rate (temperature increase in the anterior third of the simulation space per unit volume ablated), and near- and far-field margins were assessed.

RESULTS

Lesions of comparable volume were created with different frequencies at different depths. The results reflect the interconnected nature of frequency as it effects focal size (decreasing with frequency), peak pressure (generally increasing with frequency), and attenuation (also increasing with frequency). The ablation efficiency was the highest for α = 5 (Np/m)/MHz at a frequency of 750 kHz at each depth. For α = 10 (Np/m)/MHz, efficiency was the highest at 750 kHz for a depth of 50 mm, and 500 kHz at depths of 100 and 150 mm. At all sonication depths, near-field heating was minimized with lower frequencies of 250 and 500 kHz.

CONCLUSIONS

Large-volume ablations are most efficient at frequencies of 500-750 kHz at depths of 100-150 mm. When one considers that near-field heat accumulation tends to be the rate limiting factor in large-volume ablations like uterine fibroid surgery, the results show that frequencies as low as 500 kHz are favored for their ability to reduce heating in the near-field.

Robotic transmural ablation of bladder tumors using high-intensity focused ultrasound: Experimental study

OBJECTIVES

To evaluate the feasibility of robot-assisted laparoscopic high-intensity focused ultrasound for targeted, extravesical, transmural, full-thickness ablation of intact bladder wall and tumor.

METHODS

In three fresh cadavers and one acute porcine model, the transperitoneal robotic approach was used to mobilize the bladder and create a midline cystotomy. "Mimic" bladder tumors (2 tumors/case) were created by robotically suturing a piece of striated muscle (2.5 × 2.5 cm) to the luminal, urothelial surface of the bladder wall. The cystotomy was suture-repaired and bladder distended with 250 mL saline. A laparoscopic high-intensity focused ultrasound probe was robotically placed extravesically in direct contact with the serosal surface of the bladder wall to image the "mimic" tumor. Targeted, transmural, full-thickness high-intensity focus ultrasound ablation of the "mimic" tumor and adjacent bladder was carried out under real-time ultrasound and robotic monitoring. Untreated areas of the bladder served as a comparison. Post-procedure, gross and microscopic examinations were carried out.

RESULTS

Laparoscopic high-intensity focused ultrasound ablation was feasible for all "mimic" tumors (100%). Real-time ultrasound clearly visualized the "mimic" tumor. Simultaneous display of the pre-planning and real-time treatment ultrasound images confirmed targeting precision. Mean operative room times for ultrasound localization, laparoscopic high-intensity focused ultrasound probe coupling, high-intensity focus ultrasound ablation, and total procedure were 3, 5, 6 and 60 min, respectively. On necropsy, no thermal/mechanical injuries occurred to the untreated bladder wall, adjacent organs or ureters. Gross inspection distinguished the treated from untreated areas. Histopathology confirmed sharply demarcated thermal coagulative necrosis and shrinkage effects between the treated and untreated areas.

CONCLUSIONS

Laparoscopic extravesical high-intensity focus ultrasound for transmural, full-thickness targeted ablation of intact bladder wall and tumor is feasible. This has implications for bladder-sparing surgery in select patients with solitary muscle-invasive bladder cancer.

Medium-term Outcomes after Whole-gland High-intensity Focused Ultrasound for the Treatment of Nonmetastatic Prostate Cancer from a Multicentre Registry Cohort

BACKGROUND

High-intensity focused ultrasound (HIFU) is a minimally-invasive treatment for nonmetastatic prostate cancer.

OBJECTIVE

To report medium-term outcomes in men receiving primary whole-gland HIFU from a national multi-centre registry cohort.

DESIGN, SETTING, AND PARTICIPANTS

Five-hundred and sixty-nine patients at eight hospitals were entered into an academic registry.

INTERVENTION

Whole-gland HIFU (Sonablate 500) for primary nonmetastatic prostate cancer. Redo-HIFU was permitted as part of the intervention.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Our primary failure-free survival outcome incorporated no transition to any of the following: (1) local salvage therapy (surgery or radiotherapy), (2) systemic therapy, (3) metastases, or (4) prostate cancer-specific mortality. Secondary outcomes included adverse events and genitourinary function.

RESULTS AND LIMITATIONS

Mean age was 65 yr (47-87 yr). Median prostate-specific antigen was 7.0 ng/ml (interquartile range 4.4-10.2). National Comprehensive Cancer Network low-, intermediate-, and high-risk disease was 161 (28%), 321 (56%), and 81 (14%), respectively. One hundred and sixty three of 569 (29%) required a total of 185 redo-HIFU procedures. Median follow-up was 46 (interquartile range 23-61) mo. Failure-free survival at 5 yr after first HIFU was 70% (95% confidence interval [CI]: 64-74). This was 87% (95% CI: 78-93), 63% (95% CI: 56-70), and 58% (95% CI: 32-77) for National Comprehensive Cancer Network low-, intermediate-, and high-risk groups, respectively. Fifty eight of 754 (7.7%) had one urinary tract infection, 22/574 (2.9%) a recurrent urinary tract infection, 22/754 (3%) epididymo-orchitis, 227/754 (30%) endoscopic interventions, 1/754 (0.13%) recto-urethral fistula, and 1/754 (0.13%) osteitis pubis. Of 206 known to be pad-free pre-HIFU, 183/206 (88%) remained pad free, and of 236 with good baseline erectile function, 91/236 (39%) maintained good function. The main limitation is lack of long-term data.

CONCLUSIONS

Whole-gland HIFU is a repeatable day-case treatment that confers low rates of urinary incontinence. Disease control at a median of just under 5 yr of follow-up demonstrates its potential as a treatment for nonmetastatic prostate cancer. Endoscopic interventions and erectile dysfunction rates are similar to other whole-gland treatments.

PATIENT SUMMARY

In this report we looked at the 5-yr outcomes following whole-gland high-intensity focused ultrasound treatment for prostate cancer and found that cancer control was acceptable with a low risk of urine leakage. However, risk of erectile dysfunction and further operations was similar to other whole-gland treatments like surgery and radiotherapy.

Clinical Application of High-intensity Focused Ultrasound in Cancer Therapy

The treatment of cancer is an important issue in both developing and developed countries. Clinical use of ultrasound in cancer is not only for the diagnosis but also for the treatment. Focused ultrasound surgery (FUS) is a noninvasive technique. By using the combination of high-intensity focused ultrasound (HIFU) and imaging method, FUS has the potential to ablate tumor lesions precisely. The main mechanisms of HIFU ablation involve mechanical and thermal effects. Recent advances in HIFU have increased its popularity. Some promising results were achieved in managing various malignancies, including pancreas, prostate, liver, kidney, breast and bone. Other applications include brain tumor ablation and disruption of the blood-brain barrier. We aim at briefly outlining the clinical utility of FUS as a noninvasive technique for a variety of types of cancer treatment.

Update on Clinical Magnetic Resonance-Guided Focused Ultrasound Applications

In this review, several clinical applications of magnetic resonance (MR)-guided focused ultrasound (FUS) are updated. MR-guided FUS is used clinically for thermal ablation of uterine fibroids and bone metastases. Thousands of patients have successfully been treated. Transcranial MR-guided FUS has received CE certification for ablation of deep, central locations in the brain. Thermal ablation of specific parts of the thalamus can result in relief of the symptoms in a number of neurological disorders. Several approaches have been proposed for ablation of prostate and breast cancer and clinical trials should show the potential of MR-guided FUS for these and other applications.

Low-Energy Ultrasound Treatment Improves Regional Tumor Vessel Infarction by Retargeted Tissue Factor

OBJECTIVES

To enhance the regional antitumor activity of the vascular-targeting agent truncated tissue factor (tTF)-NGR by combining the therapy with low-energy ultrasound (US) treatment.

METHODS

For the in vitro US exposure of human umbilical vein endothelial cells (HUVECs), cells were put in the focus of a US transducer. For analysis of the US-induced phosphatidylserine (PS) surface concentration on HUVECs, flow cytometry was used. To demonstrate the differences in the procoagulatory efficacy of TF-derivative tTF-NGR on binding to HUVECs with a low versus high surface concentration of PS, we performed factor X activation assays. For low-energy US pretreatment, HT1080 fibrosarcoma xenotransplant-bearing nude mice were treated by tumor-regional US-mediated stimulation (ie, destruction) of microbubbles. The therapy cohorts received the tumor vessel-infarcting tTF-NGR protein with or without US pretreatment (5 minutes after US stimulation via intraperitoneal injection on 3 consecutive days).

RESULTS

Combination therapy experiments with xenotransplant-bearing nude mice significantly increased the antitumor activity of tTF-NGR by regional low-energy US destruction of vascular microbubbles in tumor vessels shortly before application of tTF-NGR (P < .05). Mechanistic studies proved the upregulation of anionic PS on the outer leaflet of the lipid bilayer of endothelial cell membranes by low-energy US and a consecutive higher potential of these preapoptotic endothelial cells to activate coagulation via tTF-NGR and coagulation factor X as being a basis for this synergistic activity.

CONCLUSIONS

Combining retargeted tTF to tumor vessels with proapoptotic stimuli for the tumor vascular endothelium increases the antitumor effects of tumor vascular infarction. Ultrasound treatment may thus be useful in this respect for regional tumor therapy.

Systematic Review of the Efficacy and Safety of High-intensity Focussed Ultrasound for Localised Prostate Cancer

CONTEXT

High-intensity focussed ultrasound (HIFU) has been used for 10 yr to treat localised prostate cancer (PCa).

OBJECTIVE

To evaluate systematically the evidence on the efficacy and side effects of HIFU in the primary treatment of localised PCa.

EVIDENCE ACQUISITION

We performed a critical review and appraisal of Medline (Ovid), PreMedline, Embase, and Cochrane Database of Systematic Reviews publications on HIFU up to May 2013. One systematic review and 18 primary studies, all case series, were eligible.

EVIDENCE SYNTHESIS

Outcomes were summarised and evidence was evaluated using Grading of Recommendations, Assessment, Development and Evaluation methodology. Low-quality evidence suggests an overall survival rate after Ablatherm HIFU ranging from 80% to 89% for >5 yr. The PCa survival rate ranges from 97% to 99% for >5 yr. Effect of HIFU on quality of life remains undetermined. Erectile dysfunction was the most frequent adverse event reported from zero but up to 74% of patients. Adverse events affecting the urinary tract occurred in 0.7-31% of patients, bladder outlet obstruction in 4-51.5%, and they were more frequent in patients who had transurethral resection of the prostate the same day or within 2 d of HIFU. Outcomes vary for low- and high-risk categories.

CONCLUSIONS

Good quality evidence on the efficacy of HIFU treatment for localised PCa is lacking.

PATIENT SUMMARY

We reviewed all the data on treatment with high-intensity focussed ultrasound (HIFU) for localised prostate cancer (PCa). The quality of the evidence is very low because the information is based on a series of patients who received HIFU treatment with no comparison with active surveillance or radical treatment. Case series suggest an overall survival rate up to 89% and a PCa survival rate up to 99% after 5 yr, but these numbers vary according to the patient's risk category. Longer term and effects on quality of life are unknown.

Focal therapy for prostate cancer: The current status

Purpose

In an era of increasing prostate cancer incidence and earlier detection, the assessment of clinical significance of prostate cancer is critical. Minimally invasive therapies are increasingly being investigated in localized prostate cancer.

Methods and results

In this review, we discuss the current status of magnetic resonance imaging targeted fusion prostate biopsy and focal therapy for prostate cancer, its rationale, and techniques.

Conclusion

Focal therapy offers a promising outlook for prostate cancer treatment, with the goal of effectively achieving cancer control while minimizing morbidity. Long term studies are needed.

High-Intensity Focused Ultrasound (HIFU) in Localized Prostate Cancer Treatment

Background

High-intensity focused ultrasound (HIFU) applies high-intensity focused ultrasound energy to locally heat and destroy diseased or damaged tissue through ablation. This study intended to review HIFU to explain the fundamentals of HIFU, evaluate the evidence concerning the role of HIFU in the treatment of prostate cancer (PC), review the technologies used to perform HIFU and the published clinical literature regarding the procedure as a primary treatment for PC.

Material/Methods

Studies addressing HIFU in localized PC were identified in a search of internet scientific databases. The analysis of outcomes was limited to journal articles written in English and published between 2000 and 2013.

Results

HIFU is a non-invasive approach that uses a precisely delivered ultrasound energy to achieve tumor cell necrosis without radiation or surgical excision. In current urological oncology, HIFU is used clinically in the treatment of PC. Clinical research on HIFU therapy for localized PC began in the 1990s, and the majority of PC patients were treated with the Ablatherm device.

Conclusions

HIFU treatment for localized PC can be considered as an alternative minimally invasive therapeutic modality for patients who are not candidates for radical prostatectomy. Patients with lower pre-HIFU PSA level and favourable pathologic Gleason score seem to present better oncologic outcomes. Future advances in technology and safety will undoubtedly expand the HIFU role in this indication as more of patient series are published, with a longer follow-up period.

Urethral strictures and the cancer survivor

PURPOSE OF REVIEW

Urethral stricture disease is poorly understood in prostate cancer survivors who have undergone radiation or ablative treatments. We review the cause and incidence of urethral strictures (excluding bladder neck contracture) in this setting, as well as risk factors and treatment options.

RECENT FINDINGS

Stricture rates differ for various modalities of radiation therapy, with the highest rate in high-dose-rate brachytherapy. Risk factors include higher dose of radiation delivered to prostate apex, radiation delivered per treatment, and prior transurethral resection of prostate. Cryoablation and high-intensity focused ultrasound of the prostate also carry high risk of urethral stricture formation, particularly in the salvage setting. Dilation or direct vision incision of the urethra can be utilized as a temporizing technique, with frequent recurrence. Urethral stenting is also an option; however, this is associated with a high rate of incontinence. Urethroplasty has durable outcomes for radiation-induced strictures, with a preference for excision and primary anastomosis because of the bulbomembranous location and relatively short length of these strictures. Salvage radical prostatectomy has been described in a small series as treatment for posterior urethral strictures and bladder neck contractures resulting from ablative therapies.

SUMMARY

Prostate cancer survivors treated with radiation or ablative therapies are at risk for urethral stricture formation. Urethroplasty is a feasible and durable treatment option and should be considered in the appropriate patient.

High-intensity focused ultrasound for the treatment of prostate cancer: A prospective trial with long-term follow-up

OBJECTIVE

High-intensity focused ultrasound (HIFU) is a minimally invasive treatment for prostate cancer. Data from the literature show promising oncological outcomes with a favourable side-effect profile. The aim of this study was to re-evaluate and bring up to date the follow-up of a previously published, prospective trial on HIFU as the primary treatment for prostate cancer.

MATERIALS AND METHODS

Between 2004 and 2007, 163 consecutive men with T1-T3N0M0 prostate cancer underwent HIFU with the Sonablate 500. Follow-up included prostate-specific antigen (PSA) tests every 3 months after treatment and a random prostate biopsy at 6 months. Failure was defined according to positive findings at the 6 month biopsy and biochemical failure was defined according to the Phoenix criteria. Biochemical-free survival, metastasis-free survival and cancer-specific survival were calculated by Kaplan-Meier curves.

RESULTS

Median follow-up was 72.0 months. Of the 160 evaluable patients, 104 (65%) were biochemically disease free; in low- to intermediate-risk disease, on Kaplan-Meier analysis the 8 year biochemical-non-evidence of disease (bNED), metastasis-free survival and cancer-specific survival rates were 69.6%, 81.3%, 100% and 40.5%, 60.6%, 100%, respectively. A PSA nadir below 0.40 ng/ml and risk stratification have an independent predictive value for bNED and metastasis-free survival.

CONCLUSIONS

A long-term favourable outcome of HIFU is associated with careful patient selection, with low- to intermediate-risk disease being the ideal case. A low postoperative PSA nadir is a predictor of long-term bNED.

MR-guided focused ultrasound surgery, present and future

MR-guided focused ultrasound surgery (MRgFUS) is a quickly developing technology with potential applications across a spectrum of indications traditionally within the domain of radiation oncology. Especially for applications where focal treatment is the preferred technique (for example, radiosurgery), MRgFUS has the potential to be a disruptive technology that could shift traditional patterns of care. While currently cleared in the United States for the noninvasive treatment of uterine fibroids and bone metastases, a wide range of clinical trials are currently underway, and the number of publications describing advances in MRgFUS is increasing. However, for MRgFUS to make the transition from a research curiosity to a clinical standard of care, a variety of challenges, technical, financial, clinical, and practical, must be overcome. This installment of the Vision 20∕20 series examines the current status of MRgFUS, focusing on the hurdles the technology faces before it can cross over from a research technique to a standard fixture in the clinic. It then reviews current and near-term technical developments which may overcome these hurdles and allow MRgFUS to break through into clinical practice.