Radiotherapy for recurrent prostate cancer: 2018 Recommendations of the Australian and New Zealand Radiation Oncology Genito-Urinary group

European association of urology risk stratification predicts outcome in patients receiving PSMA-PET-planned salvage radiotherapy for biochemical recurrence following radical prostatectomy

PURPOSE

The European Association of Urology (EAU) proposed a risk stratification (high vs. low risk) for patients with biochemical recurrence (BR) following radical prostatectomy (RP). Here we investigated whether this stratification accurately predicts outcome, particularly in patients staged with PSMA-PET.

METHODS

For this study, we used a retrospective database including 1222 PSMA-PET-staged prostate cancer patients who were treated with salvage radiotherapy (SRT) for BR, at 11 centers in 5 countries. Patients with lymph node metastases (pN1 or cN1) or unclear EAU risk group were excluded. The remaining cohort comprised 526 patients, including 132 low-risk and 394 high-risk patients.

RESULTS

The median follow-up time after SRT was 31.0 months. The 3-year biochemical progression-free survival (BPFS) was 85.7 % in EAU low-risk versus 69.4 % in high-risk patients (p = 0.002). The 3-year metastasis-free survival (MFS) was 94.4 % in low-risk versus 87.6 % in high-risk patients (p = 0.005). The 3-year overall survival (OS) was 99.0 % in low-risk versus 99.6 % in high-risk patients (p = 0.925). In multivariate analysis, EAU risk group remained a statistically significant predictor of BPFS (p = 0.003, HR 2.022, 95 % CI 1.262-3.239) and MFS (p = 0.013, HR 2.986, 95 % CI 1.262-7.058).

CONCLUSION

Our data support the EAU risk group definition. EAU risk grouping for BCR reliably predicted outcome in patients staged lymph node-negative after RP and with PSMA-PET before SRT. To our knowledge, this is the first study validating the EAU risk grouping in patients treated with PSMA-PET-planned SRT.

Feasibility and Acute Toxicity of Hypo-Fractionated Radiotherapy on 0.35T MR-LINAC: The First Prospective Study in Spain

This observational, descriptive, longitudinal, and prospective basket-type study (Registry #5289) prospectively evaluated the feasibility and acute toxicity of hypo-fractionated radiotherapy on the first 0.35T MR-LINAC in Spain. A total of 37 patients were included between August and December 2023, primarily with prostate tumors (59.46%), followed by pancreatic tumors (32.44%). Treatment regimens typically involved extreme hypo-fractionated radiotherapy, with precise dose delivery verified through quality assurance measures. Acute toxicity assessment at treatment completion revealed manageable cystitis, with one case persisting at the three-month follow-up. Gastrointestinal toxicity was minimal. For pancreatic tumors, daily adaptation of organ-at-risk (OAR) and gross tumor volume (GTV) was practiced, with median doses to OAR within acceptable limits. Three patients experienced gastrointestinal toxicity, mainly nausea. Overall, the study demonstrates the feasibility and safety of extreme hypo-fractionated radiotherapy on a 0.35T MR-LINAC, especially for challenging anatomical sites like prostate and pancreatic tumors. These findings support the feasibility of MR-LINAC-based radiotherapy in delivering precise treatments with minimal toxicity, highlighting its potential for optimizing cancer treatment strategies.

The Dedicated Imaging Post-Prostatectomy for Enhanced Radiotherapy outcomes (DIPPER) trial protocol: a multicentre, randomised trial of salvage radiotherapy versus surveillance for low-risk biochemical recurrence after radical prostatectomy

BACKGROUND

Salvage radiation therapy (SRT) and surveillance for low-risk prostate-specific antigen (PSA) recurrence have competing risks and benefits. The efficacy of early SRT to the prostate bed with or without pelvic lymph nodes compared to surveillance in patients with PSA recurrence after radical prostatectomy and no identifiable recurrent disease evident on prostate specific membrane antigen-positron emission tomography/computer tomography (PSMA-PET/CT) is unknown.

STUDY DESIGN

The Dedicated Imaging Post-Prostatectomy for Enhanced Radiotherapy outcomes (DIPPER) is an open-label, multicentre, randomised Phase II trial.

ENDPOINTS

The primary endpoint is 3-year event-free survival, with events comprising one of PSA recurrence (PSA ≥0.2 ng/mL higher than baseline), radiological evidence of metastatic disease, or initiation of systemic or other salvage treatments. Secondary endpoints include patient-reported outcomes, treatment patterns, participant perceptions, and cost-effectiveness.

ELIGIBILITY CRITERIA

Eligible participants have PSA recurrence of prostate cancer after radical prostatectomy, defined by serum PSA level of 0.2-0.5 ng/mL, deemed low risk according to modified European Association of Urology biochemical recurrence risk criteria (International Society for Urological Pathology Grade Group ≤2, PSA doubling time >12 months), with no definite/probable recurrent prostate cancer on PSMA-PET/CT.

PATIENTS AND METHODS

A total of 100 participants will be recruited from five Australian centres and randomised 1:1 to SRT or surveillance. Participants will undergo 6-monthly clinical evaluation for up to 36 months. Androgen-deprivation therapy is not permissible. Enrolment commenced May 2023.

TRIAL REGISTRATION

This trial has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN: ACTRN12622001478707).

How to Report PSMA PET

Prostate cancer (PCa) is the most common cancer diagnosed in men in most developed countries and a leading cause of cancer-related morbidity and mortality. Prostate-specific membrane antigen positron emission tomography (PSMA-PET) has become a valuable tool in the staging and assessment of disease recurrence in PCa, and more recently for assessment for treatment eligibility to PSMA radioligand therapy (RLT). Harmonization of PSMA-PET interpretation and synoptic reports are needed to communicate concisely and reproducibly PSMA-PET/CT to referring physicians and to support clinician therapeutic management decisions in various stages of the disease. Uniform image interpretation is also important to provide comparable data between clinical trials and to translate such data from research to daily practice. This review provides an overview of the value of PSMA-PET across the different clinical stages of PCa, discusses published reporting criteria for PSMA-PET, identifies pitfalls in reporting PSMA, and provides recommendations for synoptic reports.

Stereotactic Body Radiation Therapy Salvage for Lymph Node Recurrent Prostate Cancer in the Era of PSMA PET Imaging

PURPOSE OF REVIEW

Our understanding of patterns of prostate cancer recurrence after primary treatment of localized disease has significantly evolved since the development of positron emission tomography (PET) agents targeting prostate cancer. Previously, most biochemical recurrences were not associated with imaging correlates when restaging with computed tomography (CT), magnetic resonance imaging (MRI), or bone scintigraphy and, hence, were typically assumed to represent occult metastases. A rising prostate specific antigen (PSA) after previous local therapy prompting a PET scan showing uptake limited to regional lymph nodes is an increasingly common clinical scenario as advanced prostate cancer imaging becomes more widely utilized. The optimal management strategy for patients who have lymph node recurrent prostate cancer is both unclear and evolving, particularly in terms of local and regionally directed therapies. Stereotactic body radiation therapy (SBRT) utilizes ablative radiation doses with steep gradients to achieve local tumor control while sparing nearby normal tissues. SBRT is an attractive therapeutic modality due to its efficacy, favorable toxicity profile, and flexibility to administer elective doses to areas of potential occult involvement. The purpose of this review is to briefly describe how SBRT is being implemented in the era of PSMA PET for the management of solely lymph node recurrent prostate cancer.

RECENT FINDINGS

SBRT has been shown to effectively control individual lymph node tumor deposits within the pelvis and retroperitoneum for prostate cancer and is well-tolerated with a favorable toxicity profile. However, a major limitation thus far has been the lack of prospective trials supporting the use of SBRT for oligometastatic nodal recurrent prostate cancer. As further trials are conducted, its exact role in the treatment paradigm of recurrent prostate cancer will be better established. Although PET-guided SBRT appears feasible and potentially beneficial, there is still considerable uncertainty about the use of elective nodal radiotherapy (ENRT) in patients with nodal recurrent oligometastatic prostate cancer. PSMA PET has undoubtedly advanced imaging of recurrent prostate cancer, revealing anatomic correlates for disease recurrence that previously went undetected. At the same time, SBRT continues to be explored in prostate cancer with feasibility, a favorable risk profile, and satisfactory oncologic outcomes. However, much of the existing literature comes from the pre-PSMA PET era and integration of this novel imaging approach has led to greater focus on new and ongoing clinical trials to rigorously evaluate this approach and compare to other established treatment modalities utilized for oligometastatic, nodal recurrence of prostate cancer.

Salvage radiotherapy is effective in patients with PSMA-PET-negative biochemical recurrence- results of a retrospective study

BACKGROUND

/Purpose: The present study aimed to assess whether SRT to the prostatic fossa should be initiated in a timely manner after detecting biochemical recurrence (BR) in patients with prostate cancer, when no correlate was identified with prostate-specific membrane antigen positron emission tomography (PSMA-PET).

MATERIALS AND METHODS

This retrospective, multicenter analysis included 1222 patients referred for PSMA-PET after a radical prostatectomy due to BR. Exclusion criteria were: pathological lymph node metastases, prostate-specific antigen (PSA) persistence, distant or lymph node metastases, nodal irradiation, and androgen deprivation therapy (ADT). This led to a cohort of 341 patients. Biochemical progression-free survival (BPFS) was the primary study endpoint.

RESULTS

The median follow-up was 28.0 months. The 3-year BPFS was 71.6% in PET-negative cases and 80.8% in locally PET-positive cases. This difference was significant in univariate (p=0.019), but not multivariate analyses (p=0.366, HR: 1.46, 95%CI: 0.64-3.32). The 3-year BPFS in PET-negative cases was significantly influenced by age (p=0.005), initial pT3/4 (p<0.001), pathology scores (ISUP) ≥3 (p=0.026), and doses to fossa >70 Gy (p=0.027) in univariate analyses. In multivariate analyses, only age (HR: 1.096, 95%CI: 1.023-1.175, p=0.009) and PSA-doubling time (HR: 0.339, 95%CI: 0.139-0.826, p=0.017) remained significant.

CONCLUSION

To our best knowledge, this study provided the largest SRT analysis in patients without ADT that were lymph node-negative on PSMA-PET. A multivariate analysis showed no significant difference in BPFS between locally PET-positive and PET-negative cases. These results supported the current EAU recommendation to initiate SRT in a timely manner after detecting BR in PET negative patients.

PSMA-PET-guided dose-escalated volumetric arc therapy for newly diagnosed lymph node-positive prostate cancer: 5 Year outcomes following the FROGG and EviQ node-positive guidelines

INTRODUCTION

The Royal Australian and New Zealand College of Radiologists (RANZCR) Faculty of Radiation Oncology Genitourinary Group (FROGG) guidelines and online EviQ protocols incorporate prostate-specific membrane antigen (PSMA) positron emission tomography (PET)-guided dose-escalated intensity-modulated radiation therapy (DE-IMRT) for newly diagnosed lymph node (LN) positive prostate cancer. We evaluated late toxicity and efficacy outcomes following the FROGG and EviQ approach.

METHODS

Patients with LN-positive-only metastases on PSMA-PET imaging were offered curative therapy with 3 months neoadjuvant androgen deprivation therapy (ADT) followed by DE-IMRT and 3 years adjuvant ADT. IMRT was delivered via volumetric arc therapy (VMAT). We aimed to deliver 81 Gy in 45 fractions (Fx) to the prostate and PET-positive LNs, and 60 Gy in 45 Fx to elective pelvic nodes, contoured using the PIVOTAL guidelines.

RESULTS

Forty-five patients were included. The median number of PET-positive nodes boosted was 2 (range 1-6) and median boost volume 1.16 cc (range 0.15-4.14). Seventeen (38%) patients had PET-positive nodes outside of PIVOTAL contouring guidelines. With 60 months median follow-up, disease-free, metastasis-free, prostate cancer-specific and overall survival were 88.1%, 95.3%, 100% and 91.5%. There were no in-field nodal failures. Late grade 1, 2 and 3 gastrointestinal toxicities occurred in 4%, 2% and 0% of patients, and genitourinary toxicity in 18%, 18% and 4%. Lower limb grade 2 lymphoedema occurred in three patients (7%).

CONCLUSION

Outcomes following FROGG guidelines and EviQ are promising, with high long-term disease control and low toxicity. Contouring guidelines require modification due to the high rate of PET-positive nodes demonstrated beyond recommended coverage.

Using PSMA imaging for prognostication in localized and advanced prostate cancer

The use of prostate-specific membrane antigen (PSMA)-directed applications in modern prostate cancer management has evolved rapidly over the past few years, helping to establish new treatment pathways and provide further insights into prostate cancer biology. However, the prognostic implications of PSMA-PET have not been studied systematically, owing to rapid clinical implementation without long follow-up periods to determine intermediate-term and long-term oncological outcomes. Currently available data suggest that traditional prognostic factors and survival outcomes are associated with high PSMA expression (both according to immunohistochemistry and PET uptake) in men with localized and biochemically recurrent disease. Treatment with curative intent (primary and/or salvage) often fails when PSMA-positive metastases are present; however, the sensitivity of PSMA-PET in detecting all metastases is poor. Low PSMA-PET uptake in recurrent disease is a favourable prognostic factor; however, it can be associated with poor prognosis in conjunction with high ¹⁸F-fluorodeoxyglucose uptake in metastatic castration-resistant prostate cancer. Clinical trials embedding PSMA-PET for guiding management with reliable oncological outcomes are needed to support ongoing clinical use.

Event-free survival after radical prostatectomy according to prostate-specific membrane antigen-positron emission tomography and European Association of Urology biochemical recurrence risk groups

OBJECTIVE

To assess European Association of Urology (EAU) risk groups for biochemical recurrence (BCR) of prostate cancer relative to prostate-specific membrane antigen-positron emission tomography (PSMA-PET) status and oncological outcomes.

PATIENTS AND METHODS

A retrospective analysis of a study that incorporated PSMA-PET for men with BCR after radical prostatectomy (RP) was undertaken. EAU risk groups were considered relative to clinical variables, PSMA-PET findings, and deployment of salvage radiotherapy (SRT). The primary oncological outcome was event-free survival (EFS) and this was analysed relative to clinical and imaging variables. An 'event' occurred if prostate-specific antigen (PSA) level rose >0.2 ng/mL above nadir or additional therapies were introduced.

RESULTS

A total of 137 patients were included, most of whom had EAU high-risk disease (76%) and/or low PSA levels (80% <0.5 ng/mL) at the time of PSMA-PET. EAU risk group was not associated with regional nodal/distant metastasis on PSMA-PET. Regional nodal/distant metastasis on PSMA PET (compared to negative/local recurrence: hazard ratio [HR] 2.2; P = 0.002) and SRT use (vs no SRT: HR 0.44; P = 0.004) were associated with EFS. EAU high-risk status was not significantly associated with worse EFS (HR 1.7, P = 0.12) compared to EAU low-risk status. Among patients who received SRT, both regional/distant metastasis on PSMA-PET (HR 3.1; P < 0.001) and EAU high-risk status (HR 2.9; P = 0.04) were independently associated with worse EFS, which was driven by patients in the EAU high-risk group with regional/distant metastases (38%; HR 3.1, P = 0.001).

CONCLUSIONS

In patients with post-RP BCR, PSMA-PET findings and receipt of SRT predicted EFS. In patients receiving SRT, PSMA status combined with EAU risk grouping was most predictive of EFS. These findings suggest that the EAU risk groups could be improved with the addition of PSMA-PET.

1.5T MR-Guided Daily Adaptive Stereotactic Body Radiotherapy for Prostate Re-Irradiation: A Preliminary Report of Toxicity and Clinical Outcomes

Background

Prostate re-irradiation is an attractive treatment option in the case of local relapse after previous radiotherapy, either in the definitive or in the post-operative setting. In this scenario, the introduction of MR-linacs may represent a helpful tool to improve the accuracy and precision of the treatment.

Methods

This study reports the preliminary data of a cohort of 22 patients treated with 1.5T MR-Linacs for prostate or prostate bed re-irradiation. Toxicity was prospectively assessed and collected according to CTCAE v5.0. Survival endpoints were measured using Kaplan-Meier method.

Results

From October 2019 to October 2021, 22 patients received 1.5T MR-guided stereotactic body radiotherapy for prostate or prostate-bed re-irradiation. In 12 cases SBRT was delivered to the prostate, in 10 to the prostate bed. The median time to re-RT was 72 months (range, 12-1460). SBRT was delivered concurrently with ADT in 4 cases. Acute toxicity was: for GU G1 in 11/22 and G2 in 4/22; for GI G1 in 7/22, G2 in 4/22. With a median follow-up of 8 months (3-21), late G1 and G2 GU events were respectively 11/22 and 4/22. Regarding GI toxicity, G1 were 6/22, while G2 3/22. No acute/late G≥3 GI/GU events occurred. All patients are alive. The median PSA-nadir was 0.49 ng/ml (0.08-5.26 ng/ml), for 1-year BRFS and DPFS rates of 85.9%. Twenty patients remained free from ADT with 1-year ADT-free survival rates of 91.3%.

Conclusions

Our experience supports the use of MR-linacs for prostate or prostate bed re-irradiation as a feasible and safe treatment option with minimal toxicity and encouraging results in terms of clinical outcomes.

Recommendations on Weight Loss and Healthy Lifestyle in Prostate Cancer Clinical Guidelines: A Systematic Review

Obesity is associated with negative prostate cancer outcomes (e.g., specific mortality, all-cause mortality, biochemical recurrence, etc.), according to the current scientific literature. Nevertheless, recommendations on weight loss and healthy lifestyles are poorly covered by clinicians. We aimed at identifying these recommendations from clinical practice guidelines (CPGs) for prostate cancer. We systematically searched MEDLINE, EMBASE, Web of Science, Scopus, guideline databases and online sources for CPGs updated from January 2015 to August 2021. The searches were independently conducted by two researchers, without language restrictions. A total of 97 prostate cancer guidelines, including 84 (86.6%) CPGs and 13 (13.4%) consensus statements, were included. Recommendations on reaching and maintaining a healthy weight or healthy lifestyles were provided by 7 (7.2%) and 13 (13.4%) documents, respectively. No differences regarding recommendations were found by type of document, year of publication or country. Our results suggest that professional societies and governments should update prostate cancer guidelines to include these recommendations for improving prostate cancer prognosis.

External radiotherapy for prostatic cancers

We present the update of the recommendations of the French society of oncological radiotherapy on external radiotherapy of prostate cancer. External radiotherapy is intended for all localized prostate cancers, and more recently for oligometastatic prostate cancers. The irradiation techniques are detailed. Intensity-modulated radiotherapy combined with prostate image-guided radiotherapy is the recommended technique. A total dose of 74 to 80Gy is recommended in case of standard fractionation (2Gy per fraction). Moderate hypofractionation (total dose of 60Gy at a rate of 3Gy per fraction over 4 weeks) in the prostate has become a standard of therapy. Simultaneous integrated boost techniques can be used to treat lymph node areas. Extreme hypofractionation (35 to 40Gy in five fractions) using stereotactic body radiotherapy can be considered a therapeutic option to treat exclusively the prostate. The postoperative irradiation technique, indicated mainly in case of biological recurrence and lymph node involvement, is detailed.

Evaluation of the reporting quality of clinical practice guidelines on prostate cancer using the RIGHT checklist

Background

The International Reporting Items for Practice Guidelines in Healthcare (RIGHT) statement is a set of recommendations for reporting in clinical practice guidelines (CPGs). We aimed to use RIGHT to evaluate the reporting quality of CPGs on prostate cancer.

Methods

We systematically searched literature databases and websites from January 1, 2018 to December 1, 2020 to identify CPGs on prostate cancer. Two investigators reviewed the identified articles and assessed the reporting quality independently by using the RIGHT checklist. We reported the proportions of guidelines that complied with each of the 35 RIGHT checklist item and the mean reporting compliance percentages for each of the seven domains of RIGHT.

Results

A total of 38 CPGs were included. The mean overall reporting rate over the included CPGs was 51.6%. Eighteen items were reported by more than half of the guidelines four items (1a 3, 7a and 13a) were reported by all guidelines. Items 7b (10.5%), 13b (10.5%), 14c (13.2%), and 18b (7.9%) had the lowest reporting proportions. The mean reporting rates in each RIGHT domain were 74.6% for “Basic Information”, 26.3% for “Review and quality assurance”, 59.9% for “Background”, 43.7% for “Evidence”, 43.2% for “Recommendations”, 43.4% for “Funding and declaration and management of interests”, and 43.0% for “Other information”.

Conclusions

The overall adherence of CPGs on prostate cancer to RIGHT checklist is poor. Following the RIGHT checklist during the development of the guideline could improve the quality of reporting in the future.

Feasibility and Outcome of PSMA-PET-Based Dose-Escalated Salvage Radiotherapy Versus Conventional Salvage Radiotherapy for Patients With Recurrent Prostate Cancer

Introduction

Prostate-specific membrane antigen-positron emission tomography-(PSMA-PET) imaging facilitates dose-escalated salvage radiotherapy (DE-SRT) with simultaneous-integrated boost (SIB) for PET-positive lesions in patients with prostate cancer (PC). Therefore, we aimed to compare toxicity rates of DE-SRT with SIB to conventional SRT (C-SRT) without SIB and to report outcome.

Materials and Methods

We evaluated 199 patients who were treated with SRT between June 2014 and June 2020. 101 patients received DE-SRT with SIB for PET-positive local recurrence and/or PET-positive lymph nodes. 98 patients were treated with C-SRT to the prostate bed +/− elective pelvic lymphatic pathways without SIB. All patients received PSMA-PET imaging prior to DE-SRT ([68Ga]PSMA-11: 45.5%; [18F]-labeled PSMA: 54.5%). Toxicity rates for early (<6 months) and late (>6 months) gastrointestinal (GI) toxicities rectal bleeding, proctitis, stool incontinence, and genitourinary (GU) toxicities hematuria, cystitis, urine incontinence, urinary obstruction, and erectile dysfunction were assessed. Further, we analyzed the outcome with disease-free survival (DFS) and prostate-specific antigen (PSA) response.

Results

The overall toxicity rates for early GI (C-SRT: 2.1%, DE-SRT: 1.0%) and late GI (C-SRT: 1.4%, DE-SRT: 5.3%) toxicities ≥ grade 2 were similar. Early GU (C-SRT: 2.1%, DE-SRT: 3.0%) and late GU (C-SRT: 11.0%, DE-SRT: 14.7%) toxicities ≥ grade 2 were comparable, as well. Early and late toxicity rates did not differ significantly between DE-SRT versus C-SRT in all subcategories (p>0.05). PSA response (PSA ≤0.2 ng/ml) in the overall group of patients with DE-SRT was 75.0% and 86.4% at first and last follow-up, respectively.

Conclusion

DE-SRT showed no significantly increased toxicity rates compared with C-SRT and thus is feasible. The outcome of DE-SRT showed good results. Therefore, DE-SRT with a PSMA-PET-based SIB can be considered for the personalized treatment in patients with recurrent PC.

A survey among German-speaking radiation oncologists on PET-based radiotherapy of prostate cancer

Background

Positron emission tomography-(PET) has evolved as a powerful tool to guide treatment for prostate cancer (PC). The aim of this survey was to evaluate the acceptance and use of PET—especially with prostate-specific membrane antigen (PSMA) targeting tracers—in clinical routine for radiotherapy (RT) and the impact on target volume definition and dose prescription.

Methods

We developed an online survey, which we distributed via e-mail to members of the German Society of Radiation Oncology (DEGRO). The survey included questions on patterns of care of RT for PC with/without PET. For evaluation of doses we used the equivalent dose at fractionation of 2 Gy with α/β = 1.5 Gy [EQD2(1.5 Gy)].

Results

From 109 participants, 78.9% have the possibility to use PET for RT planning. Most centers use PSMA-targeting tracers (98.8%). In 39.5%, PSMA-PET for biochemical relapse after prior surgery is initiated at PSA ≥ 0.5 ng/mL, while 30.2% will perform PET at ≥ 0.2 ng/mL (≥ 1.0 ng/mL: 16.3%, ≥ 2.0 ng/mL: 2.3%, regardless of PSA: 11.7%). In case of PET-positive local recurrence (LR) and pelvic lymph nodes (LNs), 97.7% and 96.5% of the participants will apply an escalated dose. The median total dose in EQD2(1.5 Gy) was 70.00 Gy (range: 56.89–85.71) for LR and 62.00 Gy (range: 52.61–80.00) for LNs. A total number of ≤ 3 (22.0%) or ≤ 5 (20.2%) distant lesions was most often described as applicable for the definition as oligometastatic PC.

Conclusion

PSMA-PET is widely used among German radiation oncologists. However, specific implications on treatment planning differ among physicians. Therefore, further trials and guidelines for PET-based RT are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-021-01811-8.

MR-Guided Hypofractionated Radiotherapy: Current Emerging Data and Promising Perspectives for Localized Prostate Cancer

Simple Summary

The biological features of prostate cancer as a tumor with a low alpha beta ratio have led clinicians to consider the use of higher doses per fraction, thus gaining an advantage both in terms of clinical outcomes and of logistic opportunities. To date, moderate hypofractionated schedules are supported by several international clinical guidelines. The subsequent step was represented by the adoption of extreme hypofractionated schedules, for which recent literature data report non-inferiority results for the five-fractions regimens. In this scenario, the recent introduction of MR-guided daily adaptive radiotherapy is a potential paradigm shift, given the ability to increase the resolution of the pelvis anatomy and to take into account of the daily variations in shape and size of the nearby healthy structures.

Abstract

In this review we summarize the currently available evidence about the role of hybrid machines for MR-guided radiotherapy for prostate stereotactic body radiotherapy. Given the novelty of this technology, to date few data are accessible, but they all report very promising results in terms of tolerability and preliminary clinical outcomes. Most of the studies highlight the favorable impact of on-board magnetic resonance imaging as a means to improve target and organs at risk identification with a consequent advantage in terms of dosimetric results, which is expected to relate to a more favorable toxicity pattern. Still, the longer treatment time per session may potentially affect the patient’s compliance to the treatment, although first quality of life assessment studies have reported substantial tolerability and no major impact on quality of life. Finally, in this review we hypothesize some future scenarios of further investigation, based on the possibility to explore the superior anatomy visualization and the role of daily adapted treatments provided by hybrid MR-Linacs.

Radiotherapy treatment volumes for oligorecurrent nodal prostate cancer: a systematic review

BACKGROUND

Radiotherapy is an emerging treatment strategy for nodal oligorecurrent prostate cancer (PCa) patients. However, large heterogeneities exist in the RT regimens used, with series reporting the use of elective nodal radiotherapy (ENRT) strategies and others the delivery of focal treatments to the relapsing nodes with Stereotactic Body Radiotherapy (SBRT). In this systematic review of the literature we compared the oncological outcomes and toxicity of the different RT regimens for nodal oligorecurrent PCa patients, with the aim of defining the optimal RT target volume in this setting.

METHODS

We performed a systemic search on the Pubmed database to identify articles reporting on the use of ENRT or SBRT for oligometastatic PCa with nodal recurrence.

RESULTS

Twenty-two articles were analyzed, including four prospective phase II trials (3 with SBRT and 1 with ENRT). Focal SBRT, delivered with an involved node, involved site, and involved field modality, was the most commonly used strategy with 2-year progression-free survival (PFS) rates ranging from 16 to 58% and a very low toxicity profile. Improved PFS rates were observed with ENRT strategies (52-80% at 3 years) compared to focal SBRT, despite a slightly higher toxicity rate. One ongoing randomized phase II trial is comparing both modalities in patients with nodal oligorecurrent PCa.

CONCLUSIONS

With a large variability in patterns of practice, the optimal RT strategy remains to be determined in the setting of nodal oligorecurrent PCa. Ongoing randomized trials and advances in translational research will help to shed light on the best management for these patients. .

Prostate re-irradiation: current concerns and future perspectives

INTRODUCTION

To date, the optimal management of locally relapsed prostate cancer patients after an initial course of radiotherapy remains a matter of debate. In recent years, local approaches have been proposed as a therapeutic option, which may potentially delay the initiation of hormone therapy. In the case of external beam radiotherapy (EBRT), re-irradiation has been supported by growing evidence in the literature, mostly represented by extreme hypofractionated schedules delivered with stereotactic body radiotherapy (SBRT).

AREAS COVERED

We performed a systematic review of the literature using the PICO methodology to explore the available evidence regarding the use of EBRT in the setting of locally relapsed prostate cancer, both in terms of safety, tolerability and preliminary clinical outcomes.

EXPERT OPINION

Current literature data report the use of EBRT and particularly of SBRT for the safe and feasible re-treatment of locally recurrent prostate cancer after an initial treatment course of radiotherapy. When extreme hypofractionation is adopted, only occasional grade ≥3 late adverse events are reported. Despite the current lack of high-level evidence and the short follow-up, preliminary clinical outcomes are promising and allow clinicians to hypothesize further prospective studies to evaluate SBRT as an alternative to the early initiation of androgen-deprivation therapy.

Single‐fraction image‐guided robotic radiosurgery efficiently controls local prostate cancer recurrence after radical prostatectomy

Purpose

To assess the therapeutic potential of single‐fraction robotic stereotactic ablative body radiotherapy (SABR) in patients with locally recurrent prostate cancer (PC) after radical prostatectomy (RP).

Materials and methods

We included 35 patients with biochemical failure after RP with single‐site local recurrence in the prostate bed diagnosed by PSMA PET/CT. About 20/35 pts had previously received post‐surgical adjuvant radiation therapy.

High‐resolution multiparametric magnetic resonance imaging (mpMRI) for exact visualization of tumor tissue was performed at 1.5 (n = 23; Siemens Magnetom Aera) or 3 Tesla (n = 12; Siemens Magnetom VIDA, Siemens Healthineers, Erlangen, Germany). Using the MRI and PET/CT dataset for planning, SABR was carried out after ultrasound‐guided placement of a single gold fiducial marker at the site of tumor recurrence using a CyberKnife M6 unit (Accuray Inc., Sunnyvale, USA). Due to the high diagnostic accuracy of PSMA PET/CT and mpMRI, pre‐SABR biopsy of tumor tissue was not deemed necessary. PSMA PET/CT performed in median 88 days before SABR confirmed the absence of distant metastases. MpMRI was performed at a median of 22 days prior to the intervention. SABR was performed in a single fraction with a dose of 20 (5/35), 21 (27/35) or 22 (3/35) Gy. Follow‐up serum PSA was measured every 3 months thereafter.

Results

Median patient age was 72 years (57‐80 years) and median time from RP to SABR was 96.8 months (IQR, 69.3‐160.2). Median serum PSA before SABR was 1.38 ng/mL (IQR 0.75‐2.72). At 3 months, median PSA had dropped significantly in 27/35 patients to a median of 0.35 ng/mL (IQR 0.25‐0.68). At 6 months, 30/35 patients showed biochemical response to SABR, while five patients were progressing: three had systemic disease on PSMA PET/CT, while two patients had rising PSA values without a visible correlate on PET/CT. The median follow‐up time was 16 months. Grade 1 genitourinary (GU) toxicity was reported in 3/35 patients (9%) and grade 1 gastrointestinal (GI) toxicity in 2/35 patients (6%), respectively.

Conclusion

SABR is an efficient new treatment option in the management of single‐site local recurrent PC without the evidence of systemic disease; due to its very low toxicity, it is an alternative to surgical re‐treatment or other focal therapies. It can significantly delay the onset of androgen deprivation therapy (ADT) in biochemical failure after radical prostatectomy.

Clinical impact of PET imaging in prostate cancer management

PURPOSE OF REVIEW

Imaging of prostate cancer has been a rapidly evolving field in recent years with the introduction of multiple new PET tracer agents. Introduction of novel imaging techniques into clinical practice requires careful evaluation, with the ultimate aims of improved patient outcomes, better sequencing of treatments, and cost effectiveness. The increased sensitivity and specificity of these new PET agents present both challenges and opportunities. We know they frequently change management, but are these effective management changes, and is it always in the best interests of the patients?

RECENT FINDINGS

This review will focus on recent publications that provide high-level evidence for the use of PET in prostate cancer. It will discuss studies that have evaluated the clinical impact of PET imaging in prostate cancer and will review a number of trials that demonstrate the potential of PET to change current standard of care, from diagnosis, to prognostic capabilities in men with metastatic prostate cancer.

SUMMARY

Evidence for the use of PET in prostate cancer is building with studies evaluating diagnostic accuracy of PET at all stages of prostate cancer. We review the evidence available, focusing on prospective trials that are measuring the impact of new technology on patient outcomes.

Changing the Goal Posts: Prostate-specific Membrane Antigen Targeted Theranostics in Prostate Cancer

OBJECTIVE

Prostate-specific membrane antigen (PSMA) theranostics is changing the face of prostate cancer diagnosis and therapy. PSMA, a transmembrane protein over-expressed in many prostate cancers, is a promising target for theranostics. Theranostics is the concept of small molecule proteins that are labelled to different radionuclides and can be used for either diagnosis or therapy, dependent on whether they are labelled with an imaging or therapy radionuclide. By directly targeting the cancer cells with imaging and then for therapy, this approach embodies the philosophy of precision medicine - right drug, right time, right dose. The question is how to best utilise these new imaging and therapy agents in clinical practice. This review will evaluate the importance of PSMA in prostate cancer, its role in diagnostic imaging, and its potential as a therapy of advanced prostate cancer.

DATA SOURCES

Electronic databases including MEDLINE, Scopus, professional websites were searched.

CONCLUSION

PSMA-directed theranostics has an expanding role in prostate cancer because of its utility as a sensitive diagnostic tool that can be coupled with efficacious and low-toxicity therapeutic options. Ongoing research is required to determine how to use this effective tool for best patient care.

IMPLICATIONS FOR NURSING PRACTICE

PSMA theranostics is rapidly being incorporated into the routine care of men with prostate cancer. Understanding its strengths, its limitations, and where it may be valuable in clinical care is important in undertaking best patient practice.

Early salvage radiotherapy in patients with biochemical recurrence after radical prostatectomy: Its impact and optimal candidate

AIM

We aimed to identify the optimal candidates for early salvage radiotherapy (SRT) among patients with biochemical recurrence (BCR) after radical prostatectomy (RP).

METHODS

This multi-institutional retrospective study included 371 patients treated using SRT after RP. The median (range) PSA level at BCR was 0.36 (0.10-2.00) ng/mL. The association between early SRT (ie, starting PSA level < 0.50) and BCR after SRT was tested in each subgroup according to our own risk stratification.

RESULTS

The median follow-up time was 51 months. By multivariate analysis, pT3b, Gleason score ≥ 8, negative surgical margins, PSA doubling time < 6 months, and non-early SRT were associated with BCR after SRT. Patients were stratified by four risk factors other than non-early SRT: (1) low risk (0 risk factor), (2) intermediate risk (1 risk factor), and (3) high risk (≥2 risk factors). The BCR-free survival was higher in the early SRT group than the nonearly SRT group in the high-risk subgroup (P = 0.020), whereas that was similar between two groups in the low-risk and intermediate-risk subgroups (P = .79 and .18, respectively). Multivariate analysis revealed that early SRT was beneficial for the high-risk subgroup (P = .032), whereas early SRT was not associated with improved outcomes in the low-risk and intermediate-risk subgroups (P = .92 and 1.0, respectively).

CONCLUSIONS

This study suggested that early SRT seemed to contribute to better biochemical control for patients with more adverse features, whereas no benefit was observed in men with no adverse features.

Imaging Biochemical Recurrence After Prostatectomy: Where Are We Headed?

OBJECTIVE. In this article, we discuss the evolving roles of imaging modalities in patients presenting with biochemical recurrence after prostatectomy. CONCLUSION. Multiple imaging modalities are currently available to evaluate patients with prostate cancer presenting with biochemical recurrence after prostatectomy. Multiparametric MRI (mpMRI) focuses on the postsurgical bed as well as regional lymph nodes and bones. PET/CT studies using ¹⁸F-fluciclovine, ¹¹C-choline, and prostate-specific membrane antigen (PSMA) ligands are useful in detecting locoregional and distant metastasis. Multiparametric MRI is preferred for patients with low risk of metastasis for localizing recurrence in prostate bed as well as pelvic lymph node and bone recurrence. Moreover, mpMRI aids in guiding biopsy and additional salvage treatments. For patients with high risk of metastatic disease, both mpMRI and whole-body PET/CT may be performed. PET/MRI using ⁶⁸Ga-PSMA has potential to enable a one-stop shop for local recurrence and metastatic disease evaluation, and clinical trials of PET/MRI are ongoing.

Are all prostate cancer patients "fit" for salvage radiotherapy?

The indication for salvage radiotherapy (RT) (SRT) in patients with biochemically-recurrent prostate cancer after surgery is based on prostate-specific antigen (PSA) levels at the time of biochemical recurrence. Although there are clear criteria (pT3-pT4 disease and/or positive margins) for the use of adjuvant radiotherapy, no specific clinical or tumour-related criteria have yet been defined for SRT. In retrospective series, 5-year biochemical progression-free survival (PFS) ranges from 35%-85%, depending on the PSA level at the start of RT. Two phase 3 trials have compared SRT with and without androgen deprivation therapy (ADT), finding that combined treatment (SRT+ADT) improves both PFS and overall survival. Similar to adjuvant RT, the indication for ADT is based on tumour-related factors such as PSA levels, tumour stage, and surgical margins. The number of patients referred to radiation oncology departments for SRT continues to rise. In the present article, we define the clinical, therapeutic, and tumour-related factors that we believe should be evaluated before prescribing SRT. In addition, we propose a decision algorithm to determine whether the patient is fit for SRT. This algorithm will help to identify patients in whom radiotherapy is likely to improve survival without significantly worsening quality of life.

Impact of advanced radiotherapy techniques and dose intensification on toxicity of salvage radiotherapy after radical prostatectomy

The safety and efficacy of dose-escalated radiotherapy with intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT) remain unclear in salvage radiotherapy (SRT) after radical prostatectomy. We examined the impact of these advanced radiotherapy techniques and dose intensification on the toxicity of SRT. This multi-institutional retrospective study included 421 patients who underwent SRT at the median dose of 66 Gy in 2-Gy fractions. IMRT and IGRT were used for 225 (53%) and 321 (76%) patients, respectively. At the median follow-up of 50 months, the cumulative incidence of late grade 2 or higher gastrointestinal (GI) and genitourinary (GU) toxicities was 4.8% and 24%, respectively. Multivariate analysis revealed that the non-use of either IMRT or IGRT, or both (hazard ratio [HR] 3.1, 95% confidence interval [CI] 1.8-5.4, p < 0.001) and use of whole-pelvic radiotherapy (HR 7.6, CI 1.0-56, p = 0.048) were associated with late GI toxicity, whereas a higher dose ≥68 Gy was the only factor associated with GU toxicities (HR 3.1, CI 1.3-7.4, p = 0.012). This study suggested that the incidence of GI toxicities can be reduced by IMRT and IGRT in SRT, whereas dose intensification may increase GU toxicity even with these advanced techniques.

PSMA-PET guided dose-escalated volumetric arc therapy (VMAT) for newly diagnosed lymph node positive prostate cancer: Efficacy and toxicity outcomes at two years

PURPOSE/OBJECTIVES

There are no published reports of prostate specific membrane antigen (PSMA) positron emission tomography (PET) guided dose-escalated intensity-modulated radiation therapy (DE-IMRT) in newly diagnosed lymph node (LN) positive prostate cancer. We report early toxicity and efficacy outcomes with this approach.

MATERIALS/METHODS

Patients with newly diagnosed high-risk prostate cancer were staged using PSMA PET, computed tomography (CT) and bone scans. Patients with LN positive-only metastases were offered curative therapy using 3 months androgen deprivation therapy (ADT) followed by DE-IMRT (using volumetric arc therapy), and 3 years adjuvant ADT. All patients had fiducial marker insertion, with privately insured patients having spacer hydrogel insertion. PET and prostate magnetic resonance imaging were fused with the planning CT. We aimed to deliver 81 Gy in 45 fractions (Fx) to the prostate and PET-positive LNs, and 60 Gy in 45Fx to bilateral elective pelvic LNs.

RESULTS

In all, 46 patients were treated, with 83% Gleason 8-10, 67% T3/T4, median number of LNs 2 (range 1-6), and median PET-positive LN volume 1.14 cc (range 0.15-4.14). LNs were outside of standard contouring guidelines in 37% of patients. The mean PET-positive LN clinical target volume dose ranged from 73.3 to 85.9 Gy (median 83.6 Gy). With 24 months median follow-up, two year failure-free survival was 100%, and 2 year overall survival 95.7%. Acute grade 1 and 2 GI toxicity occurred in 48 and 11% of patients, and GU toxicity in 72 and 24%. Late grade 1, 2 and 3 GI toxicity occurred in 13, 2 and 0%, and GU toxicity 28, 13 and 4%. No toxicity was attributable to the high dose LN boost.

CONCLUSIONS

PSMA PET-guided DE-IMRT up to 81 Gy to the prostate and involved LNs, and long term ADT, is a promising approach for newly diagnosed LN positive prostate cancer. LN contouring guidelines require re-evaluation in the era of PSMA PET imaging.

Radiotherapy for pelvic nodal recurrences after radical prostatectomy: patient selection in clinical practice

Aim

There is no general consensus on the optimal treatment for prostate cancer (PC) patients with intrapelvic nodal oligorecurrences after radical prostatectomy. Besides androgen deprivation therapy (ADT) as standard of care, both elective nodal radiotherapy (ENRT) and stereotactic body radiotherapy (SBRT) as well as salvage lymph node dissection (sLND) are common treatment options. The aim of our study was to assess decision making and practice patterns for salvage radiotherapy (RT) in this setting.

Methods

Treatment recommendations from 14 Swiss radiation oncology centers were collected and converted into decision trees. An iterative process using the objective consensus methodology was applied to assess differences and consensus.

Results

PSMA PET/CT was recommended by 93% of the centers as restaging modality. For unfit patients defined by age, comorbidities or low performance status, androgen deprivation therapy (ADT) alone was recommended by more than 70%. For fit patients with unfavorable tumor characteristics such as short prostate-specific antigen (PSA) doubling time or initial high-risk disease, the majority of the centers (57–71%) recommended ENRT + ADT for 1–4 lesions. For fit patients with favorable tumor characteristics, there were low levels of consensus and a wide variety of recommendations. For 1–4 nodal lesions, focal SBRT was offered by 64% of the centers, most commonly as a 5-fraction course.

Conclusions

As an alternative to ADT, ENRT or SBRT for pelvic nodal oligorecurrences of PC are commonly offered to selected patients, with large treatment variations between centers. The exact number of lymph nodes had a major impact on treatment selection.

Salvage reirradiation for local prostate cancer recurrence after radiation therapy. For who? When? How?

PURPOSE

Literature review reporting results of salvage brachytherapy and stereotactic body radiotherapy for prostate recurrence only after radiotherapy for prostate cancer.

MATERIALS AND METHODS

A total of 38 studies (including at least 15 patients per study) were analysed: 19 using low-dose-rate brachytherapy, nine high-dose-rate brachytherapy and ten stereotactic body radiotherapy. Only five studies were prospective. The median numbers of patients were 30 for low-dose-rate brachytherapy, 34 for high-dose-rate brachytherapy, and 30 for stereotactic body radiotherapy. The median follow-up were 47months for low-dose-rate brachytherapy, 36months for high-dose-rate brachytherapy and 21months for stereotactic body radiotherapy.

RESULTS

Late genitourinary toxicity rates ranged, for grade 2: from 4 to 42% for low-dose-rate brachytherapy, from 7 to 54% for high-dose-rate brachytherapy and from 3 to 20% for stereotactic body radiotherapy, and for grade 3 or above: from 0 to 24% for low-dose-rate brachytherapy, from 0 to 13% for high-dose-rate brachytherapy and from 0 to 3% for grade 3 or above (except 12% in one study) for stereotactic body radiotherapy. Late gastrointestinal toxicity rates ranged, for grade 2: from 0 to 6% for low-dose-rate brachytherapy, from 0 to 14% for high-dose-rate brachytherapy and from 0 to 11% for stereotactic body radiotherapy, and for grade 3 or above: from 0 to 6% for low-dose-rate brachytherapy, and from 0 to 1% for high-dose-rate brachytherapy and stereotactic body radiotherapy. The 5-year biochemical disease-free survival rates ranged from 20 to 77% for low-dose-rate brachytherapy and from 51 to 68% for high-dose-rate brachytherapy. The 2- and 3-year disease-free survival rates ranged from 40 to 82% for stereotactic body radiotherapy. Prognostic factors of biochemical recurrence have been identified.

CONCLUSION

Despite a lack of prospective data, salvage reirradiation for prostate cancer recurrence can be proposed to highly selected patients and tumours. Prospective comparative studies are needed.

11C-Choline PET Guided Salvage Radiation Therapy for Isolated Pelvic and Paraortic Nodal Recurrence of Prostate Cancer After Radical Prostatectomy: Rationale and Early Genitourinary or Gastrointestinal Toxicities

Purpose

To assess gastrointestinal (GI) and genitourinary (GU) adverse events (AEs) of ¹¹C-choline-positron emission tomography (CholPET) guided lymph node (LN) radiation therapy (RT) in patients who experience biochemical failure after radical prostatectomy.

Methods and Materials

From 2013 to 2016, 107 patients experienced biochemical failure of prostate cancer, had CholPET-detected pelvic and/or paraortic LN recurrence, and were referred for RT. Patients received androgen suppression and CholPET guided LN RT (median dose, 45 Gy) with a simultaneous integrated boost to CholPET-avid sites (median dose, 56.25 Gy), all in 25 fractions. RT-naïve patients had the prostatic fossa included in the initial treatment volumes followed by a sequential boost (median dose, 68 Gy). GI and GU AEs were reported per Common Terminology Criteria for Adverse Events (version 4.0) with data gathered retrospectively. Differences in maximum GI and GU AEs at baseline, immediately post-RT, and at early (median, 4 months) and late (median, 14 months) follow-up were assessed.

Results

Median follow-up was 16 months (interquartile range [IQR], 11-25). Median prostate-specific antigen at time of positive CholPET was 2.3 ng/mL (IQR, 1.3-4.8), with a median of 2 (IQR, 1-4) choline-avid LNs per patient. Most recurrences were within the pelvis (53%) or pelvis + paraortic (40%). Baseline rates of grade 1 to 2 GI AEs were 8.4% compared with 51.9% (4.7% grade 2) of patients post-RT (P < .01). These differences resolved by 4-month (12.2%, P = .65) and 14-month AE assessments (9.1%, P = .87). There was no significant change in grade 1 to 2 GU AEs post-RT (64.1%) relative to baseline (56.0%, P = .21), although differences did arise at 4-month (72.2%, P = .01) and 14-month (74.3%, P = .01) AE assessments.

Conclusions

Salvage CholPET guided nodal RT has acceptably low rates of acute GI and GU AEs and no significant detriment in 14-month GI AEs. These data are of value in counseling patients and designing prospective trials evaluating the oncologic efficacy of this treatment strategy.

Prospective, Multisite, International Comparison of 18F-Fluoromethylcholine PET/CT, Multiparametric MRI, and 68Ga-HBED-CC PSMA-11 PET/CT in Men with High-Risk Features and Biochemical Failure After Radical Prostatectomy: Clinical Performance and Patient Outcomes

A significant proportion of men with rising prostate-specific antigen (PSA) levels after radical prostatectomy (RP) fail prostate fossa (PF) salvage radiation treatment (SRT). This study was done to assess the ability of 18F-fluoromethylcholine (18F-FCH) PET/CT (hereafter referred to as 18F-FCH), 68Ga-HBED-CC PSMA-11 PET/CT (hereafter referred to as PSMA), and pelvic multiparametric MRI (hereafter referred to as pelvic MRI) to identify men who will best benefit from SRT. Methods: Prospective, multisite imaging studies were carried out in men who had rising PSA levels after RP, high-risk features, and negative/equivocal conventional imaging results and who were being considered for SRT. 18F-FCH (91/91), pelvic MRI (88/91), and PSMA (31/91) (Australia) were all performed within 2 wk. Imaging was interpreted by experienced local/central interpreters who were masked with regard to other imaging results, with consensus being reached for discordant interpretations. Expected management was documented before and after imaging, and data about all treatments and PSA levels were collected for 3 y. The treatment response to SRT was defined as a reduction in PSA levels of >50% without androgen deprivation therapy. Results: The median Gleason score, PSA level at imaging, and PSA doubling time were 8, 0.42 (interquartile range, 0.29-0.93) ng/mL, and 5.0 (interquartile range, 3.3-7.6) months. Recurrent prostate cancer was detected in 28% (25/88) by pelvic MRI, 32% (29/91) by 18F-FCH, and 42% (13/31) by PSMA. This recurrence was found within the PF in 21.5% (19/88), 13% (12/91), and 19% (6/31) and at sites outside the PF (extra-PF) in 8% (7/88), 19% (17/91), and 32% (10/31) by MRI, 18F-FCH, and PSMA, respectively (P < 0.004). A total of 94% (16/17) of extra-PF sites on 18F-FCH were within the pelvic MRI field. Intrapelvic extra-PF disease was detected in 90% (9/10) by PSMA and in 31% (5/16) by MRI. 18F-FCH changed management in 46% (42/91), and MRI changed management in 24% (21/88). PSMA provided additional management changes over 18F-FCH in 23% (7/31). The treatment response to SRT was higher in men with negative results or disease confined to the PF than in men with extra-PF disease (18F-FCH 73% [32/44] versus 33% [3/9] [P < 0.02], pelvic MRI 70% [32/46] versus 50% [2/4] [P was not significant], and PSMA 88% [7/8] versus 14% [1/7] [P < 0.005]). Men with negative imaging results (MRI, 18F-FCH, or PSMA) had high (78%) SRT response rates. Conclusion:18F-FCH and PSMA had high detection rates for extra-PF disease in men with negative/equivocal conventional imaging results and rising PSA levels after RP. These findings affected management and treatment responses, suggesting an important role for PET in triaging men being considered for curative SRT.

Oligometastases in prostate cancer: Ablative treatment

Technological advances in radiotherapy have led to the introduction of techniques such as stereotactic body radiation therapy (SBRT), allowing the administration of ablative doses. The hypothesis that oligometastatic disease may be cured through local eradication therapies has led to the increasing use of SBRT in patients with this type of disease. At the same time, scientific advances are being made to allow the confirmation of clinically suspected oligometastatic status at molecular level. There is growing interest in identifying patients with oligometastatic prostate cancer (PCa) who may benefit from curative intent metastasis-directed therapy, including SBRT. The aim is to complement, replace or delay the introduction of hormone therapy or other systemic therapies. The present review aims to compile the evidence from the main ongoing studies and results on SBRT in relation to oligometastatic PCa; examine aspects where gaps in knowledge or a lack of consensus persist (e.g., optimum schemes, response assessment, identification and diagnosis of oligometastatic patients); and document the lack of first-level evidence supporting the use of such techniques.

Reirradiation for isolated local recurrence of prostate cancer: Mono-institutional series of 64 patients treated with salvage stereotactic body radiotherapy (SBRT)

OBJECTIVE:

To evaluate high-precision external beam reirradiation (re-EBRT) for local relapse of prostate cancer (PCa) after radiotherapy.

METHODS:

This retrospective study included patients with biochemical failure and evidence of isolated local recurrence of PCa after radical/salvage EBRT or brachytherapy that received salvage stereotactic body radiation therapy (SBRT, re-EBRT). Biopsy was not mandatory if all diagnostic elements were univocal (prostate specific antigen evolution, choline-positron emission tomography or magnetic resonance imaging). Salvage SBRT (re-EBRT) was delivered with image-guided radiation therapy (RapidArc®, VERO® and CyberKnife®).

RESULTS:

Data of 64 patients were included, median age at salvage SBRT was 73.2 years, median pre-salvage SBRT prostate specific antigen was 3.89  ng ml^-1 . Median total dose was 30  Gy in five fractions, biologically effective dose (BED) of 150  Gy. One acute G3 genitourinary event and one late G3 genitourinary event were observed. No G ≥ 3 bowel toxicity was registered. At the median follow-up of 26.1 months, tumor progression was observed in 41 patients (64%). 18 patients (28%) experienced local relapse. 2-year local control, biochemical and clinical relapse free survival rates were 75, 40 and 53%, respectively. With BED ≥130  Gy 1-year biochemical and clinical progression-free survival rate were 85 and 90%, respectively.

CONCLUSIONS:

Salvage SBRT (re-EBRT) for isolated local PCa recurrence is a safe, feasible and noninvasive salvage treatment. Further investigation is warranted to define the optimal patient selection, dose and volume parameters.

ADVANCES IN KNOWLEDGE:

Salvage SBRT reirradiation for the locally recurrent PCa offer a satisfactory tumor control and excellent toxicity profile, if BED ≥130 Gy is administered.