Proton Therapy as Salvage Treatment for Local Relapse of Prostate Cancer Following Cryosurgery or High-Intensity Focused Ultrasound

Salvage Radiotherapy Following Nonradiotherapy Ablative Techniques for Primary Prostate Cancer: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

The treatment landscape for localized prostate cancer has evolved with the increasing use of nonradiotherapy ablative interventions (NRAIs) such as high-intensity focused ultrasound (HIFU) and cryotherapy. These minimally invasive therapies promise fewer side effects and quicker recovery but come with a higher risk of recurrence, often necessitating salvage treatments. Salvage radiotherapy (SRT) is a potential option, but its efficacy and safety following NRAIs remain uncertain. Our aim was to conduct a systematic review and meta-analysis of the safety and efficacy of SRT in patients with recurrent prostate cancer after NRAI. The primary objective was SRT safety in terms of acute and late gastrointestinal (GI) and genitourinary (GU) toxicities. The secondary objectives were SRT efficacy in terms of biochemical relapse rates according to prior NRAI type (HIFU vs cryotherapy).

METHODS

A comprehensive literature search was conducted in PubMed, Web of Science, Scopus, and the Cochrane Library up to August 2023. Studies were included if they assessed SRT outcomes in patients with prostate cancer recurrence after NRAI, focusing on GI and GU toxicities and biochemical relapse. Data were extracted and pooled using a random-effects meta-analysis model to estimate the incidence of acute and late toxicities and biochemical recurrence rates. Statistical analysis included assessments of heterogeneity and publication bias.

KEY FINDINGS AND LIMITATIONS

Twenty-one studies involving 817 patients were included. The pooled rate for acute SRT grade 1-2 GI toxicity was 22% (95% confidence interval [CI] 10-34%; p < 0.01) and was higher for prior HIFU versus cryotherapy. The pooled rate for acute SRT grade 1-2 GU toxicity was 37% (95% CI 22-52%) and was higher for prior HIFU. The incidence of late grade 1-2 toxicity was 12% (95% CI 5-19%; p < 0.01) for GI and 26% (95% CI 12-39%; p < 0.01) for GU toxicity. Grade ≥3 toxicities were rare, occurring in less than 5% of patients. The biochemical relapse rate after SRT was ∼20% (95% CI 14-26%; p < 0.01) for both HIFU and cryotherapy, indicating similar efficacy. The odds ratio for biochemical relapse was 0.19 (95% CI 0.12-0.26; p < 0.01) for HIFU and 0.22 (95% CI 0.10-0.35; p < 0.01) for cryotherapy. There was evidence of publication bias and high heterogeneity.

CONCLUSIONS AND CLINICAL IMPLICATIONS

SRT following NRAI for localized prostate cancer has low toxicity rates, particularly following cryotherapy, and reasonable biochemical control. Despite these findings, short follow-up and variability in treatments for patients with varying risk profiles highlight the need for further studies to refine SRT protocols and establish more definitive long-term outcomes.

Salvage local treatment for recurrent prostate cancer after focal therapy: A systematic review and meta-analysis

OBJECTIVES

To evaluate the role of salvage local treatment in managing recurrent PCa following FT, focusing on oncological and functional outcomes.

METHODS

A systematic review and meta-analysis were performed following the PRISMA framework. A comprehensive literature search using the PubMed/MEDLINE and EMBASE databases was performed until July 2023. Eligible studies included patients with clinically localised PCa initially treated with FT, who experienced relapse during surveillance and subsequently underwent salvage radical prostatectomy (sRP), salvage external beam radiation therapy (sEBRT) or salvage focal therapy (sFT). The primary endpoint was the biochemical recurrence rate post-salvage treatment. The secondary endpoints were functional outcomes, including urinary incontinence and erectile dysfunction rates.

RESULTS

In 26 retrospective studies including 990 patients, the overall pooled biochemical recurrence rate postsalvage treatment was 26%. The subgroup analysis revealed a biochemical recurrence rate of 20%, 22%, and 42% after sRP, sEBRT, and sFT, respectively. The overall pooled rate of urinary incontinence was 20%. Salvage FT had the lowest prevalence of urinary incontinence, followed by sRP and sEBRT. The overall pooled rate of erectile dysfunction was 43%. Salvage RP had the highest prevalence of erectile dysfunction, followed by sFT and sEBRT. Substantial heterogeneity was observed among the studies, primarily due to different sample sizes. Meta-regression analysis revealed no to low contributions of salvage treatment modalities, extent of ablation, age, prostatic specific antigen level before salvage treatment, proportion of patients with Gleason score ≥7 at recurrence, and time between the primary and salvage therapies to heterogeneity.

CONCLUSION

Salvage local treatment for recurrent PCa after FT is feasible, and it provides acceptable oncological and functional outcomes. Among all treatment modalities, sRP and sEBRT appeared to have the lowest biochemical recurrence rates, whereas sFT was associated with improved functional outcomes.

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.

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.

Quality of Life and Patient-Reported Outcomes Following Proton Radiation Therapy: A Systematic Review

Background

As costs of cancer care rise, the importance of documenting value in oncology increases. Proton beam radiotherapy (PBT) has the potential to reduce toxicities in cancer patients, but is relatively expensive and unproven. Evaluating quality of life (QOL) and patient-reported outcomes (PROs) is essential to establishing PBT's "value" in oncologic therapy. The goal of this systematic review was to assess QOL and PROs in patients treated with PBT.

Methods

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic searches were conducted. The PubMed search engine was the primary data source, along with publications found from references of selected articles, and articles known to the authors published through 2017. Seventeen original investigations were found to have sufficient focus and relevance to be incorporated into the systematic review.

Results

Studies of skull base (n = 1), brain (n = 1), head/neck (n = 1), lung (n = 1), breast (n = 2), prostate (n = 8), and pediatric (n = 3) malignancies treated with PBT that met eligibility criteria were included. QOL did not deteriorate during PBT for skull base and after PBT for brain tumors, respectively. PROs were higher for PBT than photon-based radiotherapy for both head/neck and lung cancer. Patient-reported breast cosmesis was appropriate after PBT and comparable to photon modalities. PBT in various settings of prostate cancer displayed an expected post-therapy decline; one study showed improved PROs (rectal urgency, bowel frequency) for PBT, and two others showed PROs/QOL comparable with other modalities. Pediatric studies demonstrated improvements in QOL during therapy, with additional increases thereafter.

Conclusions

Based on limited data, PBT provides favorable QOL/PRO profiles for select brain, head/neck, lung, and pediatric cancers; measures for prostate and breast cancers were more modest. These results have implications for cost-effective cancer care and prudently designed QOL evaluation in ongoing trials, which are discussed. Future data could substantially change the conclusions of this review.

[Management of ablative therapies in prostate cancer]

OBJECTIVES

To describe the specific modalities of ablative therapies management in prostate cancer.

MATERIALS AND METHODS

A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of keywords. Publications obtained were selected based on methodology, language and relevance. After selection, 61 articles were analysed.

RESULTS

Development of innovations such as ablative therapies in prostate cancer induces specific modalities in their management, during pre-, per- and post-procedure. More than for classical and well-known treatments, the decision to propose an ablative therapy requires analysis and consensus of medical staff and patient's agreement. Patient's specificities and economical aspects must also be considered. Procedures and follow-up must be realized by referents actors.

CONCLUSION

Indication, procedure and follow-up of ablative therapies in prostate cancer require specific modalities. They must be respected in order to optimize the results and to obtain a precise and objective evaluation for defining future indications.

Emerging Technologies and Techniques in Radiation Therapy

The past decade has brought an improved ability to precisely target and deliver radiation as well as other focal prostate-directed therapy. Stereotactic body radiotherapy (SBRT), proton beam radiation, high-dose-rate (HDR) brachytherapy, as well as nonradiotherapy treatments such as cryoablation and high-intensity focused ultrasound are several therapeutic modalities that have been investigated for the treatment of prostate cancer in an attempt to reduce toxicity while improving cancer control. However, high-risk prostate cancer requires a comprehensive treatment of the prostate as well as areas at risk for cancer spread. Therefore, most new radiation treatment (SBRT, HDR, and proton beam radiation) modalities have been largely investigated in combination with regional radiation therapy. Though the evidence is evolving, the use of SBRT, HDR, and proton beam radiation is promising. Nonradiation focal therapy has been proposed mainly for partial gland treatment in men with low-risk disease, and its use in high-risk prostate cancer patients remains experimental.