Transrectal Ultrasound in Prostate Cancer: Current Utilization, Integration with mpMRI, HIFU and Other Emerging Applications

Transrectal ultrasound (TRUS) has been an invaluable tool in the assessment of prostate size, anatomy and aiding in prostate cancer (PCa) diagnosis for decades. Emerging techniques warrant an investigation into the efficacy of TRUS, how it compares to new techniques, and options to increase the accuracy of prostate cancer diagnosis. Currently, TRUS is used to guide both transrectal and transperineal biopsy approaches with similar cancer detection rates, but lower rates of infection have been reported with the transperineal approach, while lower rates of urinary retention are often reported with the transrectal approach. Multiparametric MRI has substantial benefits for prostate cancer diagnosis and triage such as lesion location, grading, and can be combined with TRUS to perform fusion biopsies targeting specific lesions. Micro-ultrasound generates higher resolution images that traditional ultrasound and has been shown effective at diagnosing PCa, giving it the potential to become a future standard of care. Finally, high-intensity focused ultrasound focal therapy administered via TRUS has been shown to offer safe and effective short-term oncological control for localized disease with low morbidity, and the precise nature makes it a viable option for salvage and repeat therapy.

Focal therapy compared to radical prostatectomy for non-metastatic prostate cancer: a propensity score-matched study

INTRODUCTION

Focal therapy (FT) ablates areas of prostate cancer rather than treating the whole gland. We compared oncological outcomes of FT to radical prostatectomy (RP).

METHODS

Using prospective multicentre databases of 761 FT and 572 RP cases (November/2005-September/2018), patients with PSA < 20 ng/ml, Gleason </= 4 + 3 and stage </= T2c were 1-1 propensity score-matched for treatment year, age, PSA, Gleason, T-stage, cancer core length and use of neoadjuvant hormones. FT included 1-2 sessions. Primary outcome was failure-free survival (FFS) defined by need for salvage local or systemic therapy or metastases. Differences in FFS were determined using Kaplan-Meier analysis with log-rank test.

RESULTS

335 radical prostatectomy and 501 focal therapy patients were eligible for matching. For focal therapy, 420 had HIFU and 81 cryotherapy. Cryotherapy was used predominantly for anterior cancer. After matching, 246 RP and 246 FT cases were identified. For radical prostatectomy, mean (SD) age was 63.4 (5.6) years, median (IQR) PSA 7.9 g/ml (6-10) and median (IQR) follow-up 64 (30-89) months. For focal therapy, these were 63.3 (6.9) years, 7.9 ng/ml (5.5-10.6) and 49 [34-67] months, respectively. At 3, 5 and 8 years, FFS (95%CI) was 86% (81-91%), 82% (77-88%) and 79% (73-86%) for radical prostatectomy compared to 91% (87-95%), 86% (81-92%) and 83% (76-90%) following focal therapy (p = 0.12).

CONCLUSIONS

In patients with non-metastatic low- intermediate prostate cancer, oncological outcomes over 8 years were similar between focal therapy and radical prostatectomy.

Focal therapy, time to join the multi-disciplinary team discussion?

Organ preserving management is common place in renal cancer, breast cancer and many other solid organ tumours. Current strategies in managing intermediate risk prostate cancer include either whole gland treatment, in the form of radical radiotherapy or radical prostatectomy, or active surveillance. The former is associated with significant post-treatment functional morbidity, whilst the latter associated with the burden of surveillance activity and patient anxiety. Focal therapy would logically fit as a middle ground for suitable patients in whom treatment would be recommended, but where much better functional outcomes may be possible. Ideally this comes without restricting the successful prevention of harm from the cancer. Historically limitations in developing tissue preserving focal therapy strategies in prostate cancer, were due to inaccuracies in tumour characterisation prior to treatment and during follow up. Consequently for example many patients undergoing an active surveillance strategy were being upgraded and upstaged within a short period. Recently high level evidence supporting the use of MRI and targeted biopsies, in particular the PROMIS and PRECISION trials have strengthened clinician confidence in accurate disease characterisation, thus making focal therapy to become a more feasible management option. With improved diagnostic strategies and the publication of reassuring medium term oncological and functional outcomes after focal therapy for intermediate risk prostate cancer, has the time come to require consideration of focal therapy within our multi-disciplinary team (MDT) meetings and with patients? In this review we will consider patient selection and the evidence for the various focal ablation options as well as the surveillance of these patients after treatment. The forthcoming trials to determine comparative effectiveness will be discussed.

Histotripsy: The Next Generation of High-Intensity Focused Ultrasound for Focal Prostate Cancer Therapy

This article reviews the most current methods and technological aspects of high-intensity focused ultrasound (HIFU), which is termed histotripsy. The rationale for focal therapy for prostate carcinoma rather than prostatectomy, which is being used extensively throughout Europe and Asia, is presented, and an argument for why HIFU is the modality of choice for primary therapy and recurrent disease is offered. The article presents a review of the technical advances including higher ultrasound beam energy than current thermal HIFU which allows for more accurate tissue targeting, less collateral tissue damage, and faster treatment times. Finally, the article presents a discussion about the advantage of ultrasound guidance for histotripsy in preference to magnetic resonance imaging guidance primarily based on cost, ease of application, and portability.

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.

Experimental assessment of phase aberration correction for breast MRgFUS therapy

PURPOSE

This study validates that phase aberrations in breast magnetic resonance-guided focussed ultrasound (MRgFUS) therapies can be corrected in a clinically relevant time frame to generate more intense, smaller and more spatially accurate foci.

MATERIALS AND METHODS

Hybrid angular spectrum (HAS) ultrasound calculations in an magnetic resonance imaging (MRI)-based tissue model, were used to compute phase aberration corrections for improved experimental MRgFUS heating in four heterogeneous breast-mimicking phantoms (n = 18 total locations). Magnetic resonance(MR) temperature imaging was used to evaluate the maximum temperature rise, focus volume and focus accuracy for uncorrected and phase aberration-corrected sonications. Thermal simulations assessed the effectiveness of the phase aberration correction implementation.

RESULTS

In 13 of 18 locations, the maximum temperature rise increased by an average of 30%, focus volume was reduced by 40% and focus accuracy improved from 4.6 to 3.6 mm. Mixed results were observed in five of the 18 locations, with focus accuracy improving from 6.1 to 2.5 mm and the maximum temperature rise decreasing by 8% and focus volume increasing by 10%. Overall, the study demonstrated significant improvements (p < 0.005) in maximum temperature rise, focus volume and focus accuracy. Simulations predicted greater improvements than observed experimentally, suggesting potential for improvement in implementing the technique. The complete phase aberration correction procedure, including model generation, segmentation and phase aberration computations, required less than 45 min per sonication location.

CONCLUSION

The significant improvements demonstrated in this study i.e., focus intensity, size and accuracy from phase aberration correction have the potential to improve the efficacy, time-efficiency and safety of breast MRgFUS therapies.

High-intensity focused ultrasonic ablation of sacral chordoma is feasible: a series of four cases and details of a national clinical trial

High-intensity focused ultrasound describes the use of high-intensity focused ultrasound (HIFU) to ablate tumours without requiring an incision or other invasive procedure. This technique has been trialled on a range of tumours including uterine fibroids, prostate, liver and renal cancer. We describe our experience of using HIFU to ablate sacral chordoma in four patients with advanced tumours. Patients were treated under general anaesthetic or sedation using an ultrasound-guided HIFU device. HIFU therapy was associated with a reduction in tumour volume over time in three patients for whom follow up scans were available. Tumour necrosis was reliably demonstrated in two of the three patients. We have established a national trial to assess if HIFU may improve long-term outcome from sacral chordoma, details are given.

Magnetic resonance-guided high-intensity focused ultrasound combined with radiotherapy for palliation of head and neck cancer-a pilot study

Background

Radiotherapy is a critical component of the multidisciplinary management of cancers of the head and neck. It may comprise the primary curative treatment modality or is used in an adjuvant setting to improve local control and survival by preventing seeding and reseeding of distant metastases from persistent reservoirs of locoregional disease. Although considerable advances have been made recently in the fields of radiotherapy, systemic treatment and surgery for head and neck tumours, locoregional recurrence rates remain high and treatment side effects may have severe impact on patients’ quality of life.

Magnetic resonance-guided high-intensity focused ultrasound (MRg-HIFU) is a novel technique in the treatment of cancer that has the potential to improve tumour cure rates and decrease treatment-related toxicity. Clinical applications of HIFU are being used increasingly for the treatment of several tumour sites, for example uterine leiomyomas and prostate cancer.

Methods/Design

The pilot study presented here is an initial step toward utilizing MRg-HIFU for head and neck cancer treatment. The rationale for novel treatment options in head and neck cancer is reviewed as well as emerging evidence that support the increasing clinical utilization of MRg-HIFU.

Discussion

This pilot study aims to assess safety, toxicity and feasibility of MRg-HIFU treatments to the head and neck region and to evaluate changes caused by MRg-HIFU within the treated tumour regions based on post-treatment MRI.

The Effect of Radiotherapy on Ultrasound-Guided Fine Needle Aspiration Biopsy and the Ultrasound Characteristics of Neck Lymph Nodes in Oral Cancer Patients after Primary Treatment

Objectives

To investigate the effect of radiotherapy (RT) on ultrasound-guided fine needle aspiration (USgFNA) and sonographic characteristics in the assessment of cervical lymph nodes (LNs) in oral squamous cell carcinoma (OSCC) patients after primary treatment.

Materials and Methods

88 treated OSCC patients underwent 111 USgFNAs of the neck LNs after US evaluation. Among them, 48 USgFNAs were performed on 40 patients following RT and 63 USgFNAs on 48 patients without previous RT. The results of USgFNA and the US characteristics were compared between these two groups.

Results

USgFNA had a sensitivity of 88.0%, specificity of 91.4%, positive predictive value (PPV) of 88.0%, negative predictive value (NPV) of 91.4% and accuracy of 90.0% in patients without previous RT, and a sensitivity of 97.1%, specificity of 83.3%, PPV of 94.3%, NPV of 90.9% and accuracy of 93.5% in those with previous neck RT. The ranges of the short-axis and long-axis length were 13.3 ± 8.0 mm (mean ± SD) versus 17.8 ± 9.1 mm, and 18.6 ± 9.0 mm versus 24.4 ± 10.9 mm for recurrent LNs from patients with, versus without, previous RT (both ps < 0.05), respectively. 76.5% (26/34) of the recurrent nodes after RT and 48% (12/25) of the recurrent nodes without previous RT exhibited an irregular margin (p < 0.05). Additionally, irradiated recurrent LNs had a significantly decreased percentage of discernable calcification compared with non-irradiated recurrent nodes (48% versus 20.6%, p < 0.05).

Conclusions

RT had influence on sonographic characteristics but no influence on USgFNA in diagnosing recurrent LNs in treated OSCC patients.