Therapy In Oligometastatic Prostate Cancer Research Articles

Systemic and tumor-directed therapy for oligometastatic prostate cancer (SOLAR): A phase II trial for veterans with de novo oligometastatic prostate cancer.

163 Background: Treatment paradigms for oligometastatic castration-sensitive prostate cancer patients are evolving. Molecular imaging improves staging, intensified systemic and primary tumor directed therapy improves survival, metastasis-directed therapy improves local control. The impact of combining these imaging and therapeutic approaches into a planned multimodal treatment strategy is unknown. Here we report a prospective phase II single-arm trial combining local, metastasis-directed, and intensified systemic therapies of limited duration with the objective to durably render Veterans free of progression off therapy. Methods: Veterans with de novo M1a/b prostate cancer and 1-5 radiographically visible M1 lesions underwent radical local treatment, intensified systemic therapy for six months (leuprolide, abiraterone acetate with prednisone, apalutamide), and metastasis-directed stereotactic ablative radiotherapy (SBRT). Radical local therapy was either radical prostatectomy (n=12) with lymph node dissection and post-operative radiotherapy (pT≥3a, N1, or positive margins) or radical radiotherapy (n=12) directed to the prostate, SVs, and pelvic LNs. The primary endpoint was the percentage of patients achieving an undetectable serum PSA (for radical prostatectomy) or <2 ng/mL (for radical radiotherapy) six months after recovery of testosterone to ≥150 ng/dL. Secondary endpoints included time to biochemical progression, time to radiographic progression, time to initiation of alternative antineoplastic therapy, prostate cancer specific survival, health related quality-of-life, safety and tolerability. Results: Twenty-eight patients enrolled and 4 dropped out (3 prior to start of treatment). All were staged by PSMA PET/CT except two (one by Fluciclovine PET/CT, and one by NaF PET/CT, CT, MRI). Twenty-nine percent were M1a, seventy-one percent were M1b. Median follow-up was 30 months (range 20 - 61 months). Mean and median number of M1 metastases were both two. Sixty-two percent completed all planned systemic therapy without dose modification. One did not recover testosterone after 29 months. Twenty-two had >6 months follow-up after testosterone recovery, 19 of 22 (86%) remain free of any progression (primary endpoint). Three had metastatic progression, one poly nodal M1a progression, one multiple bone metastases, one multiple bone and nodal metastases. Grade 2 and 3 toxicities for primary tumor therapy were 46% and 4%; SBRT 0% and 0%; systemic therapy 42% and 4%. There was one Grade 4 toxicity. Conclusions: Although a small trial, a majority of patients with molecular imaging defined de novo oligometastatic prostate cancer treated with primary and metastasis-directed therapy with intensified systemic therapy of limited duration remained free of progression with a recovered testosterone off all active therapy. Clinical trial information: NCT03298087 .

Clinical Outcomes with Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer: Results from a Prospective Registry Trial

Metastasis-directed radiation therapy using stereotactic body radiation therapy (SBRT) in oligometastatic prostate cancer (Oligo PCa) has a demonstrated benefit for local control and biochemical recurrence free survival for men with oligorecurrent PCa; however, the impact of SBRT within other oligometastatic states and in the context of systemic therapy remains poorly characterized. In this study, we investigate prognostic factors for clinical outcomes in a prospective cohort of Oligo PCa patients treated with metastasis-directed SBRT. Using a single-institution registry trial, we analyzed a prospective cohort of 86 patients with Oligo PCa (≤5 metastatic lesions) and treated with metastasis-directed SBRT between 2017- 2022. Patients were classified as synchronous, metachronous, or induced oligometastatic disease as per the ESTRO guidelines. We evaluated the time to radiographic progression (TTRP), defined as the time from SBRT start date to radiographic progression, as well as time to initiation of new treatment (TTNT), defined as the time from SBRT end date to initiation of new therapy (systemic or radiation therapy). Time to event (TTE) was defined as the time from SBRT start date to radiographic progression or initiation of new therapy, whichever occurred first. Patients without documented events were censored at the date of last disease assessment. Comparative analyses were performed using Kaplan-Meier and Cox proportional hazards regression methods. Eighty-six men with Oligo PCa treated with SBRT were followed for a median of 16.4 months with M0 (73%), Oligo PCa (21%) or polymetastatic PCa (6%) GS > = 8 (63%) at initial diagnosis. At the time of treatment with initial SBRT, 21% had synchronous oligometastatic disease, 63% had metachronous or repeat oligorecurrence or oligoprogression, and 16% had induced oligometastatic disease. Most patients were treated to 1-3 sites (94%), which predominantly included bone (86%), and the median dose was 35 Gy/5F. Concurrent systemic therapy during SBRT was seen in 85% of patients, including (60.5% with new generation androgen receptor signaling inhibitors). Overall survival at 1-year and 2-years was 96.9% [95% CI, 88.2-99.2%] and 94.4% [95% CI, 83.2-98.2%]. Using univariable analysis, those who did not receive systemic treatment during SBRT had significantly shorter TTRP (HR 3.67, [95% CI, 1.62-8.32], p = 0.002), TTNT (HR 3.24, 95% CI [1.49-7.06], p = 0.003), and TTE (HR 3.05, [95% CI, 1.44-6.45], p = 0.004). Additionally, patients treated with SBRT for metachronous (HR 2.89, [95% CI 0.68-12.30]) and induced metastatic disease (HR 8.96, [95% CI 1.85-43.37]) had significantly shorter TTE compared to synchronous oligometastatic disease (p = 0.006). Using a prospective registry cohort of men with Oligo PCa treated with SBRT, we identify an association of oligometastatic state and the use of concurrent systemic therapy with improved TTRP and TTNT. Further prospective studies are warranted.

Addition of Metastasis-Directed Therapy to Intermittent Hormone Therapy for Oligometastatic Prostate Cancer

Despite evidence demonstrating an overall survival benefit with up-front hormone therapy in addition to established synergy between hormone therapy and radiation, the addition of metastasis-directed therapy (MDT) to hormone therapy for oligometastatic prostate cancer, to date, has not been evaluated in a randomized clinical trial. To determine in men with oligometastatic prostate cancer whether the addition of MDT to intermittent hormone therapy improves oncologic outcomes and preserves time with eugonadal testosterone compared with intermittent hormone therapy alone. The External Beam Radiation to Eliminate Nominal Metastatic Disease (EXTEND) trial is a phase 2, basket randomized clinical trial for multiple solid tumors testing the addition of MDT to standard-of-care systemic therapy. Men aged 18 years or older with oligometastatic prostate cancer who had 5 or fewer metastases and were treated with hormone therapy for 2 or more months were enrolled to the prostate intermittent hormone therapy basket at multicenter tertiary cancer centers from September 2018 to November 2020. The cutoff date for the primary analysis was January 7, 2022. Patients were randomized 1:1 to MDT, consisting of definitive radiation therapy to all sites of disease and intermittent hormone therapy (combined therapy arm; n = 43) or to hormone therapy only (n = 44). A planned break in hormone therapy occurred 6 months after enrollment, after which hormone therapy was withheld until progression. The primary end point was disease progression, defined as death or radiographic, clinical, or biochemical progression. A key predefined secondary end point was eugonadal progression-free survival (PFS), defined as the time from achieving a eugonadal testosterone level (≥150 ng/dL; to convert to nanomoles per liter, multiply by 0.0347) until progression. Exploratory measures included quality of life and systemic immune evaluation using flow cytometry and T-cell receptor sequencing. The study included 87 men (median age, 67 years [IQR, 63-72 years]). Median follow-up was 22.0 months (range, 11.6-39.2 months). Progression-free survival was improved in the combined therapy arm (median not reached) compared with the hormone therapy only arm (median, 15.8 months; 95% CI, 13.6-21.2 months) (hazard ratio, 0.25; 95% CI, 0.12-0.55; P < .001). Eugonadal PFS was also improved with MDT (median not reached) compared with the hormone therapy only (6.1 months; 95% CI, 3.7 months to not estimable) (hazard ratio, 0.32; 95% CI, 0.11-0.91; P = .03). Flow cytometry and T-cell receptor sequencing demonstrated increased markers of T-cell activation, proliferation, and clonal expansion limited to the combined therapy arm. In this randomized clinical trial, PFS and eugonadal PFS were significantly improved with combination treatment compared with hormone treatment only in men with oligometastatic prostate cancer. Combination of MDT with intermittent hormone therapy may allow for excellent disease control while facilitating prolonged eugonadal testosterone intervals. ClinicalTrials.gov Identifier: NCT03599765.

A phase II randomized trial of metastasis-directed therapy with alpha emitter radium-223 in men with oligometastatic castration-resistant prostate cancer (MEDAL)

BackgroundThe significance of metastasis-directed therapy for oligometastatic prostate cancer has been widely discussed, and targeted therapy for progressive sites is a feasible option as a multidisciplinary treatment for castration-resistant prostate cancer (CRPC). When oligometastatic CRPC with only bone metastases progresses after targeted therapy, it tends to progress as multiple bone metastases. The progression of oligometastatic CRPC after targeted therapy may be due in part to the presence of micrometastatic lesions that, though undetected on imaging, were present prior to targeted therapy. Thus the systemic treatment of micrometastases in combination with targeted therapy for progressive sites is expected to enhance the therapeutic effect. Radium-223 dichloride (radium-223) is a radiopharmaceutical that selectively binds to sites of increased bone turnover and inhibits the growth of adjacent tumor cells by emitting alpha rays. Therefore, for oligometastatic CRPC with only bone metastases, radium-223 may enhance the therapeutic effect of radiotherapy for active metastases.MethodsThis phase II, randomized trial of Metastasis-Directed therapy with ALpha emitter radium-223 in men with oligometastatic CRPC (MEDAL) is designed to assess the utility of radium-223 in combination with metastasis-directed radiotherapy in patients with oligometastatic CRPC confined to bone. In this trial, patients with oligometastatic CRPC with three or fewer bone metastases on whole-body MRI with diffusion-weighted MRI (WB-DWI) will be randomized in a 1:1 ratio to receive radiotherapy for active metastases plus radium-223 or radiotherapy for active metastases alone. The prior use of androgen receptor axis-targeted therapy and prostate-specific antigen doubling time will be used as allocation factors. The primary endpoint will be radiological progression-free survival against progression of bone metastases on WB-DWI.DiscussionThis will be the first randomized trial to evaluate the effect of radium-223 in combination with targeted therapy in oligometastatic CRPC patients. The combination of targeted therapy for macroscopic metastases with radiopharmaceuticals targeting micrometastasis is expected to be a promising new therapeutic strategy for patients with oligometastatic CRPC confined to bone.Trial registration Japan Registry of Clinical Trials (jRCT) (jRCTs031200358); Registered on March 1, 2021, https://jrct.niph.go.jp/latest-detail/jRCTs031200358

Difficulties in Defining Oligometastatic Prostate Cancer: Implications for Clinical Trial Accrual and Community Practice Adoption of Metastasis-Directed Therapy Approaches

Metastasis-directed therapy is widely utilized for oligometastatic prostate cancer patients, but standard imaging does not always identify metastases definitively and, even with PSMA PET, there may be equivocal findings. Not all clinicians have access to detailed imaging review, particularly outside of academic cancer centers, and PET scan access is also limited. We sought to understand how imaging interpretation impacted recruitment to a clinical trial for oligometastatic prostate cancer. IRB approval was obtained to review medical records from all patients screened for the institutional IRB-approved clinical trial for men with oligometastatic prostate cancer involving androgen deprivation plus stereotactic radiation to all metastatic sites, as well as radium223 (NCT03361735). Clinical trial inclusion required at least one bone metastatic lesion and no more than five total sites of metastasis, including soft tissue sites. Tumor board discussion records were reviewed, along with results from additional radiology studies ordered or confirmatory biopsies performed. Clinical characteristics such as PSA level and Gleason score were studied for association with likelihood of oligometastatic disease confirmation. At the time of data analysis, 18 subjects were deemed eligible and 20 were not eligible. The most common reasons for ineligibility were no confirmed bone metastasis in 16 patients (59%) and too many metastatic sites in 3 (11%). The median PSA of eligible subjects was 3.28 (range 0.4-45.5), whereas the median PSA of those found to be ineligible was 10.45 (range 3.7-26.3) when there were too many metastases identified, and 2.7 (range 0.2-34.5) when metastases were unconfirmed. PET imaging (PSMA or fluciclovine PET) increased the number of metastases, while MRI resulted in downstaging to non-metastatic disease. This research suggests that additional imaging (i.e., at least two independent imaging modalities of a possible metastatic lesion) or tumor board adjudication of imaging findings may be critical to correctly identify patients appropriate for enrollment in oligometastatic protocols. This should be considered as trials of metastasis-directed therapy for oligometastatic prostate cancer accrue and results are translated to broader oncology practice.

Serial stereotactic body radiation therapy for oligometastatic prostate cancer detected by novel PET-based radiotracers.

Radiopharmaceuticals, including Ga-68-prostate specific membrane antigen (PSMA)-11 and F-18-Fluciclovine, are increasingly used to inform therapies for prostate cancer (CaP). Stereotactic body radiation therapy (SBRT) to PET-detected oligometastatic CaP has been shown to improve progression free survival (PFS) and delay androgen deprivation therapy (ADT) compared to observation. For men who subsequently develop oligorecurrent CaP, outcomes following second SBRT are unknown. A retrospective cohort study was conducted. Eligibility criteria included patients with oligometastatic (1-5 lesions) CaP detected on PSMA or Fluciclovine PET who underwent 2 consecutive SBRT courses to tracer-avid sites. Data on stage, tracer type, concurrent systemic therapy, and prostate-specific antigen (PSA) responses for first SBRT (SBRT1) and second SBRT (SBRT2) were collected. Outcomes included PSA decline ≥50% (PSA50), PFS after SBRT2, and ADT initiation or intensification-free survival after SBRT2. Factors potentially associated with PSA50 after SBRT2 was evaluated with multivariable logistic regression. Factors potentially associated with PFS and ADT initiation/intensification-free survival after SBRT2 were evaluated with separate multivariable Cox proportional-hazards models. Twenty-five patients were identified. At SBRT2, oligorecurrence was detected on PSMA and Fluciclovine PET in 17 (68%) and 8 (32%) patients, respectively. Fifteen (60%) patients had castration-sensitive disease and 10 (40%) had castration-resistant disease. After SBRT2, 16 (64%) achieved a PSA50 response, median PFS was 11.0mo, and median ADT initiation/intensification-free survival was 23.2mo. On multivariable analysis, maximum percent change in PSA after SBRT1 (OR 0.94, 95%CI 0.88-0.99, P = 0.046) and concurrent change in systemic therapy (OR 21.61, 95%CI 1.12-417.9, P = 0.042) were associated with PSA50 responses after SBRT2. PSA50 response after SBRT1 was associated with improved PFS (HR 0.36, 95%CI 0.00-0.42, P = 0.008) and ADT initiation/intensification-free survival (HR 0.07, 95%CI 0.01-0.68, P = 0.021) after SBRT2. From SBRT1 to last follow-up (median 48 months), 7 (28%) patients remained ADT-free. Serial SBRT for oligometastatic CaP detected on PSMA or Fluciclovine PET is feasible and can achieve PSA declines, with or without systemic therapy. Degree of biochemical response to first SBRT warrants further study as a potential predictor of PSA response, PFS, and ADT initiation/intensification-free survival following a subsequent SBRT course. This preliminary evidence provides rationale for larger, prospective studies of this strategy.

NRG-GU011: A phase II double-blinded, placebo-controlled trial of prostate oligometastatic radiotherapy with or without androgen deprivation therapy in oligometastatic prostate cancer (NRG PROMETHEAN).

TPS283 Background: There is no clear standard of care for biochemically recurrent prostate cancer (PCa) with positron emission tomography (PET)-detected oligometastases and normal conventional imaging (CIM). Phase II trials show that stereotactic ablative body radiotherapy (SABR) to oligometastases may delay cancer progression and initiation of androgen deprivation therapy (ADT) and its untoward effects. ADT with radiation prolongs survival in locally advanced PCa and in CIM metastatic PCa. However, there is a knowledge gap about timing and benefit vs toxicity of ADT with SABR in early oligometastatic PCa. NRG GU011 (PROMETHEAN) is a randomized phase II trial of SABR with or without relugolix for early PET-detected recurrent oligometastatic PCa. This study aims to evaluate the impact of relugolix, a novel oral gonadotropin-releasing hormone receptor antagonist, when combined with SABR to oligometastases. Relugolix allows for rapid testosterone recovery and is associated with fewer cardiovascular events when compared to leuprolide and is hypothesized to have low late ADT toxicity. GU011 will provide patients and their physicians data on the relative risks and benefits of early or delayed ADT in this setting. Methods: NRG-GU011 NCT# 05053152 is a randomized phase II double-blinded, placebo-controlled trial with randomization to SABR + 6 months placebo vs SABR + 6 months relugolix. Eligible patients have biochemical recurrence after prior curative intent radiation or surgery for localized PCa, PSA &lt; 10 ng/mL, negative CIM and 1-5 PET-evident metastases (≥1 extrapelvic). SABR is delivered in 1-5 fractions to BED &gt;100 Gy1.5, followed by placebo or relugolix 120mg daily for 6 months. Patients will then be followed with imaging at time of biochemical recurrence. The planned sample size of 260 patients (130 per arm) will provide 85% power to detect a hazard ratio of 0.65 for radiographic progression-free survival (rPFS), based on a one-sided test at alpha 0.10. Planned enrollment is predicted at 8 patients per month with an estimated study completion date of late 2026. The primary endpoint is CIM rPFS. Secondary endpoints include PET-based rPFS, sexual and hormonal quality of life (QoL) assessed by EPIC-26, other QoL measures from EQ5D-5L, EORTC QLQ-30 and PROMIS Fatigue, and between-group comparisons of time to salvage therapy, castration-resistance, local progression (SABR-targeted lesion), biochemical progression, distant metastases, prostate cancer-specific mortality, metastasis-free survival, and overall survival. We also aim to determine adverse event rates for both treatment arms and evaluate genomic and blood markers of treatment response. This study opened in December 2021. Clinical trial information: NCT05053152 .

Addition of Metastasis-Directed Therapy to Intermittent Hormone Therapy for Oligometastatic Prostate Cancer (EXTEND): A Multicenter, Randomized Phase II Trial

<h3>Purpose/Objective(s)</h3> There has been increased utilization of metastasis directed therapy (MDT) for oligometastatic prostate cancer. Despite data demonstrating the benefit of upfront hormone therapy (HT) and synergy between radiation and HT, there exists no randomized trials testing their combination. As it is accepted by most clinicians and men with prostate cancer that time off HT holds intrinsic value, we evaluated whether the addition of metastasis directed therapy (MDT) to intermittent HT in men with oligometastatic prostate cancer facilities time off HT by improving PFS and eugonad PFS. <h3>Materials/Methods</h3> EXTEND (NCT03599765) is a phase II randomized basket trial for multiple solid tumors testing whether the addition of MDT improves PFS. The primary endpoint was pre-specified to be independently assessed and reported for the prostate intermittent HT basket at 41 events. Men with ≤5 metastases were randomized after ≥2 months of HT to continuing HT with or without MDT. HT consisted of a luteinizing hormone-releasing hormone agonist/antagonist with or without a 2^nd generation androgen-receptor targeting agent (SART). The primary endpoint was progression, defined as death or radiographic, clinical, or biochemical progression. A planned HT break occurred 6 months after enrollment, after which HT was withheld until progression. The study was designed to have 80% power to detect an improvement in median PFS from 18 to 36 months, with a type I error of 0.1. Exploratory analysis included flow cytometry and TCR sequencing from peripheral blood at baseline and 3 months follow up. <h3>Results</h3> Between Sept 2018 to Nov 2020, 87 men were randomized, 43 combined therapy and 44 to HT-only. Arms were well balanced. At a median follow-up of 22.1 months (range 13.0 to 39.3 months), 41 events were observed. PFS was improved by the receipt of MDT (median not reached vs 15.8 months for HT-only, P<0.001; HR=0.25 [95% CI, 0.12 to 0.55]). Among secondary endpoints, time from eugonad testosterone levels (>150 ng/dL) to progression was improved by MDT (median not reached vs 6.1 months, P=0.03), as was time to appearance of new lesions (2-year rate 33% vs 41%, P=0.04). Three grade 3 toxicities were observed in each arm. Subgroup analysis identified PFS improvement with MDT in patients who received (HR=0.24 [95% CI, 0.08 to 0.71]) or did not receive a SART (HR=0.36 [95% CI, 0.15 to 0.83]). Flow cytometry and TCR sequencing demonstrated increases in markers of T cell activation, proliferation, and clonal expansion limited to the combined therapy arm. <h3>Conclusion</h3> EXTEND represents the first randomized study to evaluate MDT with HT in oligometastatic prostate cancer and demonstrated improvement in PFS and eugonad PFS. Combination of MDT with intermittent HT may allow for both excellent disease control while facilitating prolonged eugonad testosterone intervals.

Systemic Therapy Postponement after Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer

<h3>Purpose/Objective(s)</h3> To evaluate the oncological outcome after stereotactic body radiation therapy (SBRT) for oligometastatic (OM) prostate cancer (PC) patients. <h3>Materials/Methods</h3> In this retrospective observational multi-institutional study (Health-data-hub N°F20210402112942), patients with OM (≤ 5) PC underwent SBRT. While patients were enrolled irrespective of PC initial treatment, castration sensitive (CS)/resistant (CR) and synchronous (SM)/metachronous (MM) metastatic disease status were taken into account. Primary endpoint was systemic therapy postponement (STP) after SBRT. Oncological outcome was assessed by post-SBRT biochemical response, local (LR; in SBRT field), metastatic (MR), prostatic (PR) and isolated biochemical (iBR) relapses. PSA kinetic (PSAdt; velocity) and prognostic factors for STP were investigated. Toxicity was reported (CTCAE v5). <h3>Results</h3> From 01/07 to 09/19, 169 pts (median age 71.4 y [48.7 – 100.1]) underwent SBRT. At the time of SBRT, 151 pts (89.3%) and 18 pts (10.7%) were MM and SM respectively and 119 pts (70.4%) and 50 pts (29.6%) were CS and CR respectively. Median PSA, PSAdt and velocity were 2.4 ng/ml [0.01 – 277], 5.2 months [0.9 – 45.2] and 2.3 ng/ml/an [0.1 – 25.9] respectively. Median time between initial PC/metastatic disease (TPCMD) and metastatic disease/SBRT were 68.9 months [1.9 – 273.4] and 3.1 months [0.1 – 97.9]. Metastatic anatomic sites were pelvic (PLN) and extra-pelvic lymph nodes (EPLN), bone and brain for 58 pts (34.4%), 15 pts (8.9%), 92 pts (54.4%) and 4 pts (2.4%) respectively. SBRT regimens were 27 Gy/3f (29%), 35 Gy/5f (24.3%), 36 Gy/6f (18.3%) and other (28.4%). With a MFU of 27.5 months [1 – 100.5], median time between SBRT/1^st PSA control was 2 months [0.5 – 29]. PSA decreased in 67.4%, was stable in 9.4% and increased in 23.2%. Eighty-eight pts (52.1%) underwent post-SBRT systemic therapy after a median STP of 15.4 months [2.6 – 86.9]. One hundred and thirty events (LR, MR, PR, iBR) were observed in 106 pts (62.7%), among whom 13 (12.3%) relapsed in the irradiated area (local control rate: 92.3%). MR, PR, iBR were observed in 82 pts (77.4%), 33 pts (31.1 %) and 2 pts (1.9 %) respectively. Prognostic factors for STP after SBRT were: hormonal status (CS vs CR: 20.9 vs 10.8 months; p < 0.001), post-SBRT biochemical response ([declined + stable] PSA vs increased PSA: 21 vs 11 months; p = 0.004) and TPCMD (< 42 vs ≥ 42 months; p < 0.001). G≥3 toxicity occurred in 4 pts: 2 pts with G3 post-SBRT fracture (1 surgery), 1 pt with G3 radiation pneumonitis and 1 pt with G4 intracranial hypertension (emergency surgery). <h3>Conclusion</h3> SBRT for oligometastatic prostate cancer is an option to postpone systemic therapy, mainly for CS and MM patients with an acceptable toxicity profile. Patient selection criteria remain a crucial goal in order to refine SBRT indications, while the impact of combination with systemic therapy remains under investigation.

Recommendations for radiation therapy in oligometastatic prostate cancer: An ESTRO-ACROP Delphi consensus

Background and purposeOligometastatic prostate cancer is a new and emerging treatment field with only few prospective randomized studies published so far. Despite the lack of strong level I evidence, metastasis-directed therapies (MDT) are widely used in clinical practice, mainly based on retrospective and small phase 2 studies and with a large difference across centers. Pending results of ongoing prospective randomized trials, there is a clear need for more consistent treatment indications and radiotherapy practices. Material and methodsA European Society for Radiotherapy and Oncology (ESTRO) Guidelines Committee consisting of radiation oncologists’ experts in prostate cancer was asked to answer a dedicated questionnaire, including 41 questions on the main controversial issues with regard to oligometastatic prostate cancer. ResultsThe panel achieved consensus on patient selection and routine use of prostate-specific membrane antigen positron emission tomography (PSMA PET) imaging as preferred staging and restaging imaging. MDT strategies are recommended in the de novo oligometastatic, oligorecurrent and oligoprogressive disease setting for nodal, bone and visceral metastases. Radiation therapy doses, volumes and techniques were discussed and commented. ConclusionThese recommendations have the purpose of providing standardization and consensus to optimize the radiotherapy treatment of oligometastatic prostate cancer until mature results of randomized trials are available.

PO-1376 The role of Stereotactic Body Radiation Therapy in Oligometastatic Prostate Cancer

PO-1376 The role of Stereotactic Body Radiation Therapy in Oligometastatic Prostate Cancer

The Promise of Metastasis-Directed Therapy for Oligometastatic Prostate Cancer: Going Beneath the Surface with Molecular Imaging.

Historically, metastatic disease was thought to represent an all-or-nothing incurable state, distinct from curable localized disease and necessitating treatment with systemic therapy alone. The role for life-prolonging local therapy was known to be futile. This dogma was challenged in the 1990s with

Multimodal therapy for oligometastatic prostate cancer: results from a single-centre study

Introduction. In recent years, interest in the use of radical prostatectomy (RPE) as one of the components of a multimodal approach in patients with lymphogenous disseminated and metastatic prostate cancer (PCa) has grown significantly. At the same time, the dearth of large randomized trials does not make it possible to use this technique in wide clinical practice outside of clinical trials.Purpose of the study. To evaluate the effectiveness of multimodal therapy using combined chemo-hormonal, surgical and radiation therapy in patients with primary oligometastatic hormone-sensitive PCa.Material and methods. The study included 48 patients with primary oligometastatic prostate cancer who received combination treatment within the internal one-research-center protocol. At the first stage, all patients underwent combined drug therapy with docetaxel (75 mg/m2 intravenously every 3 weeks for 6 courses) and degarelix. Patients who had a decrease in PSA level ≤ 2 ng/ml and registered stabilization of the disease according to radiological examination were treated surgically through RPE with extended pelvic and retroperitoneal lymph node dissection. Radiation therapy was performed only in patients with the presence of bone lesions at a dose of 50-70 Gy to the location of bone metastases in the stage 3 plan of combined multimodal therapy.Results. PCa biochemical relapse was verified in 27 (56.3%) patients during the median follow-up of 10 months. The average time to PSA increase was 9.0 ± 5.7 months (from 1 to 24 months), median — 7 months, Six-month PSA relapse-free survival (PSA-RFS) was 61.2 ± 7.5%; 1-year PSA-RFS — 38.0 ± 8.6%. The average duration before the initiation of hormonal therapy was 12 ± 6.1 months (from 3 to 27 months), median: 10 months. Six-month survival before the drug administration was 72.6 ± 6.8%; twelve-month survival: 40.9 ± 8.7%. About 40% of patients with oligometastatic PCa had no signs of progression and did not receive any other drug therapy for 12 months after completion of protocol treatment.Conclusions. Analysis of the study results demonstrates satisfactory oncological outcomes of the studied treatment option in patients with newly diagnosed oligometastatic hormone-sensitive PCa, as well as a low likelihood of side effects and complications. Nevertheless, it is necessary to continue conducting larger and more structured randomized trials to determine the possibility of applying this therapeutic approach in clinical practice.

Long-term clinical outcomes of external beam radiation therapy for oligometastatic prostate cancer: A combination of prostate-targeted treatment and metastasis-directed therapy.

To assess the efficacy of combination of prostate-targeted treatment and metastasis-directed therapy for oligometastatic prostate cancer. We retrospectively evaluated the clinical outcomes of synchronously diagnosed oligometastatic prostate cancer patients treated with external beam radiation therapy for the prostate and all metastatic lesions (≤3 lesions) at Kyoto University Hospital between January 2004 and April 2019. The prescribed dose was basically ≥70Gy for the prostate with or without whole pelvic irradiation, and ≥45Gy for the metastatic lesions. Clinical outcomes were compared with a contemporary cohort of 55 synchronous oligometastatic prostate cancer patients treated with the standard of care. In total, 16 consecutive patients with synchronous oligometastatic prostate cancer were analyzed. The median follow-up period was 7.4years. The 8-year overall survival, prostate cancer-specific survival, biochemical failure-free, clinical failure-free and castration-resistant prostate cancer-free rates were 64.8%, 71.3%, 38.5%, 47.3% and 67.3%, respectively. No grade3 or higher radiation-induced late toxicities occurred. Patients with prostate-targeted treatment plus metastasis-directed therapy had a significantly higher castration-resistant prostate cancer-free rate than those without prostate-targeted treatment plus metastasis-directed therapy (P=0.00741). Prostate-targeted treatment plus metastasis-directed therapy through external beam radiation therapy can result in favorable long-term disease-free and survival outcomes with acceptable morbidities among synchronous oligometastatic prostate cancer patients. Therefore, this approach may represent a promising treatment strategy for this population. Further investigation is required.

Local and metastasis-directed therapy for oligometastatic prostate cancer

New developments of systemic therapy concepts for metastatic prostate carcinoma have led to a significant improvement in the prognosis in the recent past. It has long been unclear to what extent local and/or metastasis-directed therapies have an additional oncologic benefit in addition to palliation, local control and functional maintenance. For local therapy of the prostate, the highest evidence currently exists for radiotherapy and shows a significantly increased overall survival in "low- burden" oligometastatic patients. Metastasis-directed surgical or radio-oncological concepts may also improve prognosis but have not yet been sufficiently investigated and should therefore be discussed, documented and established on an individual and interdisciplinary basis.

Current topics in radiotherapy for genitourinary cancers: Consensus statements of the Genitourinary Radiation Oncologists of Canada

The biennial meeting of the Genitourinary Radiation Oncologists of Canada (GUROC) took place November 22-23, 2019. A consensus-building session was held during the meeting addressing topics of emerging interest or controversy in the management of genitourinary malignancies. Draft statements were debated among all meeting attendees in an open forum with anonymous live voting. Statements for which there was at least 75% agreement among attendees were adopted as GUROC consensus. Four evidence-based consensus statements were developed. First, the use of prostate radiotherapy is recommended in the setting of de novo low-volume metastatic hormone-sensitive prostate cancer to improve overall survival. Second, the support of ongoing randomized trials evaluating metastasis-directed ablative local therapy in oligometastatic prostate cancer is recommended; where such trials are available, off-trial use of oligometastasis-directed ablative radiotherapy at this time is strongly discouraged. Third, routine use of prostate-rectal hydrogel spacer devices in patients with localized prostate cancer planned to receive external beam radiotherapy is not recommended; instead, selective use in patients at highest risk of rectal toxicity may be considered. Finally, multidisciplinary consultation is recommended for all patients with newly diagnosed localized muscle-invasive bladder cancer. The GUROC consensus statements provide practical guidance to clinicians in areas of current controversy in the management of prostate and bladder cancer, and it is hoped that their implementation will contribute to improved outcomes in real-world practice and greater support of clinical trials.

Metastasis-directed therapy and prostate-targeted therapy in oligometastatic prostate cancer: a systematic review.

The aim of this review was to summarize the available evidence on the role of metastasis-directed therapy (MDT) and/or prostate-targeted therapy (PTT) in the setting of oligometastatic prostate cancer (PCa). We searched PubMed, the Web of Science, and the Cochrane Library databases. The following keywords were used: ("prostate cancer" OR "prostate carcinoma" OR "prostate neoplasm" OR "prostate tumor") AND ("oligometastatic" OR "oligometastasis" OR "PSMA") AND ("surgery" OR "prostatectomy" OR "radical prostatectomy" OR "cytoreductive" OR "local treatment" OR "radiotherapy" OR "stereotactic" OR "stereotaxic") AND ("survival" OR "mortality"). After evaluating the selection criteria, 81 studies were evaluated for our endpoints. We included 22 studies for PTT of synchronous mPCa. There have been no randomized studies on cytoreductive prostatectomy (cRP). Four prospective studies showed that cRP was feasible but did not contribute to a positive effect on overall survival (OS). Regarding PTT-radiotherapy, two randomized controlled phase 3 trials showed that OS was improved in men with a low metastatic burden. Regarding MDT of metachronous lymph node recurrence, we included 29 retrospective studies. For MDT of oligometastases, we included 30 studies. One randomized phase 2 trial showed that androgen deprivation therapy-free survival improved with stereotactic body radiation therapy compared to that with surveillance; however, benefits on OS remain unclear. We performed a comprehensive overview of the current literature on MDT and PTT. The feasibility of MDT and PTT is supported by several retrospective studies. Nevertheless, there remains a lack of high-quality trials to prove its survival benefits. Results from ongoing prospective trials data are awaited.

Surveillance or metastasis-directed therapy for oligometastatic prostate cancer recurrence (STOMP): Five-year results of a randomized phase II trial.

10 Background: Multiple randomized phase II trials suggest that metastasis-directed therapy (MDT) for oligometastatic prostate cancer (PCa) improves progression-free survival, but the majority of trials lack longer follow-up. We present the updated 5-year results from the STOMP-trial. Methods: In this multicentre, randomised, phase II study, asymptomatic PCa patients were eligible in case of a biochemical recurrence following primary PCa treatment with curative intent and presenting with up to 3 extracranial on choline PET-CT and a serum testosterone levels &gt; 50 ng/ml. Patients were randomly assigned (1:1) to either surveillance or MDT of all detected lesions. Randomisation was balanced dynamically on two factors: PSA doubling time (≤3 vs. &gt; 3 months) and nodal vs non-nodal metastases. The primary endpoint was androgen deprivation therapy (ADT)-free survival. Castrate resistant prostate cancer-free survival (CRPC) was a secondary endpoint. Tests were performed two-sided; p values less than 0.20 were deemed significant. Results: The 5-year ADT-free survival was 8% for the surveillance group and 34% for the MDT group (Figure 1, hazard ratio 0.57 [80% CI: 0.38-0.84], log-rank p = 0.06). There was no significant difference in effect for the different stratification factors (interaction test). The 5-year CRPC-free survival was 53% for the surveillance group and 76% for the MDT group (hazard ratio 0.62 [80% CI: 0.35−1.09]; log−rank p = 0.27). At a median follow for survival of 5.3 years (IQR 4.3-6.3), the 5-year overall survival was 85%, with 6 out of 14 deaths attributed to prostate cancer. Conclusions: The updated STOMP trial outcomes confirm the earlier reported significant difference in ADT free survival in favor of the MDT group compared to surveillance. Prostate-cancer related mortality is low within the first 5 years of diagnosis of oligorecurrent prostate cancer. Clinical trial information: NCT01558427.

Online Prostate-Specific Membrane Antigen and Positron Emission Tomography–Guided Radiation Therapy for Oligometastatic Prostate Cancer

PurposeStereotactic ablative radiation therapy (SABR) for oligometastatic prostate cancer (OMPC) may improve clinical outcomes, but current challenges in intrafraction tracking of multiple small targets limits treatment accuracy. A biology-guided radiation therapy (BgRT) delivery system incorporating positron emission tomography (PET) detectors is being developed to use radiotracer uptake as a biologic fiducial for intrafraction tumor tracking to improve geometric accuracy. This study simulates prostate-specific membrane antigen (PSMA)-directed BgRT using a cohort from our phase II randomized trial of SABR in men with recurrent hormone sensitive OMPC and compares dose distributions to clinical SABR (CSABR). Methods and MaterialsA research treatment planning system (RTPS) was used to replan 15 patients imaged with PSMA-targeted 18F-DCFPyL PET/computed tomography and previously treated with CSABR using conventional linear accelerators (linacs). The RTPS models a prototype ring-mounted linac incorporating PET and kilo-voltage computed tomography imaging subsystems and can be used to optimize BgRT plans, as well as research SABR (RSABR) plans, which use the prototype linac without radiotracer guidance. CSABR, RSABR, and BgRT plans were compared in terms of maximum planning target volume (PTV) dose (Dmax), mean dose to proximal organs at risk (DOAR), conformity index, as well as voxel-wise correlation of dose with PET specific uptake values to investigate possible dose-painting effects. ResultsRSABR and BgRT plans resulted in mean ± standard deviation increases in Dmax of 4 ± 11% (P = .21) and 18 ± 15% (P < .001) and reductions in DOAR of –20 ± 19% (P <.001) and –10 ± 19% (P = .02) compared with CSABR. Similar target coverage was maintained with conformity indices of 0.81 ± 0.04 (P < .001) and 0.72 ± 0.08 (P = .44) for RSABR and BgRT compared with 0.74 ± 0.08 for CSABR. Dose and log (specific uptake values) had Pearson correlation coefficients of 0.10 (CSABR), 0.16 (RSABR), and 0.31 (BgRT). ConclusionsBgRT plans provided similar PTV coverage and conformity compared with CSABR while incorporating underlying PET activity. These results demonstrate feasibility of BgRT optimization enabling online PSMA-targeted, PET-based tracked dose delivery for OMPC.

Single Dose Radiotherapy (SDRT) With or Without Adjuvant Systemic Therapy for Oligometastatic Prostate Cancer

Single Dose Radiotherapy (SDRT) With or Without Adjuvant Systemic Therapy for Oligometastatic Prostate Cancer