Prostate Radiotherapy and Metastasis-Directed Therapy in Synchronous Oligometastatic Prostate Cancer (SynSABR-PC)

Outcomes and Patterns of Failure After Definitive Prostate-Directed Radiotherapy and Metastasis-Directed Therapy in Patients With Synchronous De Novo Prostate Cancer and Up to 10 Metastases: An Ambispective Multicenter Real-World Evidence Registry

This is an ambispective, multicenter, observational real-world registry of patients with synchronous de novo oligometastatic prostate cancer, defined as prostate cancer with up to 10 extraregional metastatic lesions diagnosed at initial presentation or within 6 months of the primary diagnosis.

The study will evaluate outcomes after comprehensive local and metastasis-directed treatment. Eligible patients receive definitive prostate-directed radiotherapy, which may include external-beam radiotherapy, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients, together with stereotactic body radiotherapy to all identified extraregional metastatic lesions. Systemic therapy is given according to routine clinical practice and local multidisciplinary decisions.

The registry is non-interventional. Participants are not assigned to treatment by the study protocol, and no experimental treatment, randomization, or protocol-mandated imaging schedule is used. The study collects de-identified data from routine medical records, including baseline disease characteristics, imaging, radiotherapy details, systemic therapy, radiographic progression, patterns of failure, subsequent treatments, adverse events, and survival.

The study includes historical retrospective data, prospective follow-up of previously treated eligible patients, and prospective enrollment of newly eligible patients from the registry activation date. The main goal is to describe where and when prostate cancer progresses after comprehensive treatment of the prostate and all visible metastatic lesions, and to identify clinical and treatment-related factors associated with disease control and adverse events.

Study Overview

• Status: Recruiting
• Conditions: Prostate Cancer; Metastatic Prostate Cancer; Oligometastatic Prostate Cancer; Synchronous Oligometastatic Prostate Cancer
• Intervention / Treatment: Radiation: Definitive Prostate-Directed Radiotherapy; Radiation: Metastasis-Directed Stereotactic Body Radiotherapy; Radiation: Pelvic Lymph Node Irradiation; Radiation: Prostate Brachytherapy

Detailed Description

SynSABR-PC is a multicenter, observational, ambispective real-world evidence registry designed to evaluate outcomes and patterns of failure in patients with synchronous de novo oligometastatic prostate cancer treated with comprehensive local and metastasis-directed radiotherapy.

Synchronous de novo oligometastatic prostate cancer represents an intermediate clinical state between localized prostate cancer and widely disseminated metastatic disease. In this study, eligible patients have up to 10 extraregional metastatic lesions detected at baseline staging, with metastatic disease diagnosed at initial presentation or within 6 months of the primary prostate cancer diagnosis. Baseline staging may include prostate-specific membrane antigen positron emission tomography/computed tomography, prostate-specific membrane antigen positron emission tomography/magnetic resonance imaging, conventional imaging, choline positron emission tomography, or other imaging used for routine clinical decision-making.

The central concept of the registry is comprehensive treatment of all visible disease. Included patients are treated with definitive prostate-directed radiotherapy and stereotactic body radiotherapy to all identified extraregional metastatic lesions. Prostate-directed radiotherapy may consist of external-beam radiotherapy, moderately hypofractionated radiotherapy, ultra-hypofractionated prostate radiotherapy, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients according to institutional practice. Elective or definitive pelvic lymph node irradiation and dose escalation to involved pelvic lymph nodes may be used according to local standards. Metastasis-directed therapy is delivered with ablative intent to all baseline extraregional metastatic lesions. Treatment of selected metastatic lesions only, while leaving other baseline metastatic sites untreated, is not consistent with the comprehensive treatment strategy of this registry. This study is non-interventional. The registry does not assign radiotherapy, brachytherapy, metastasis-directed therapy, systemic therapy, imaging, or follow-up schedules. All clinical decisions are made by the treating physicians and multidisciplinary teams according to institutional standards, available imaging, patient characteristics, and routine clinical practice. Systemic therapy, including androgen deprivation therapy, androgen receptor pathway inhibitors, docetaxel, or other systemic treatments, is recorded as part of real-world care and will be analyzed as a treatment-related covariate rather than as a protocol-assigned intervention. The study has an ambispective design. The historical retrospective cohort includes eligible patients treated before registry activation, with baseline, treatment, follow-up, outcome, and adverse event data abstracted from available medical records. The ambispective follow-up cohort includes eligible patients treated before registry activation who remain under follow-up, with retrospective baseline and treatment data and prospective updates of follow-up, imaging, progression, subsequent treatment, adverse events, and survival. The prospective enrollment cohort includes newly eligible patients identified from the registry activation date onward and entered prospectively before, during, or shortly after routine clinical decision-making for definitive prostate-directed radiotherapy and metastasis-directed therapy.

The primary objective is to characterize radiographic outcomes and patterns of first disease progression after definitive prostate-directed radiotherapy and stereotactic body radiotherapy to all visible metastatic lesions. The registry will evaluate the timing of first radiographic progression and the anatomical pattern of first failure, including local recurrence in the prostate or seminal vesicles, regional pelvic nodal recurrence, progression at previously treated metastatic sites, distant extraregional recurrence, and combined patterns of recurrence.

Secondary and exploratory objectives include evaluation of time to first radiographic progression, time to polymetastatic progression, time to initiation of the next line of systemic therapy, overall survival, and treatment-related adverse events graded according to the Common Terminology Criteria for Adverse Events version 5.0. The registry will also explore whether outcomes differ according to baseline metastatic burden, imaging modality, anatomical distribution of metastatic disease, prostate-directed radiotherapy modality, use of brachytherapy boost or brachytherapy monotherapy, pelvic lymph node irradiation, nodal boost, metastasis-directed radiotherapy dose and fractionation, systemic therapy intensity, and treatment sequence.

For time-to-event analyses, time zero is defined as the start date of the first radiotherapy course, corresponding to the earliest initiation date of metastasis-directed stereotactic body radiotherapy, prostate external-beam radiotherapy, or prostate brachytherapy delivered as boost or monotherapy. This approach is intended to provide a consistent time origin across patients and to minimize immortal time bias in a real-world setting where treatment sequencing may vary. Adverse events will be assessed using CTCAE version 5.0. Acute adverse events are defined as events occurring within 90 days from the start date of the first radiotherapy course. Late adverse events are defined as events occurring more than 90 days after the start date of the first radiotherapy course. Genitourinary and gastrointestinal adverse events will be summarized separately, and grade 3 or higher adverse events will be recorded with event date and clinical description where available.

Data will be collected in a centralized, de-identified registry. No direct patient identifiers will be transferred to the coordinating center. Data elements include baseline demographic and clinical characteristics, staging and imaging modality, prostate-directed radiotherapy details, brachytherapy details where applicable, pelvic lymph node irradiation, metastasis-directed stereotactic body radiotherapy, systemic therapy, radiographic progression, pattern of failure, repeat oligoprogression, transition to polymetastatic disease, subsequent metastasis-directed therapy, systemic therapy escalation, adverse events, vital status, and date of last known follow-up. Because this is an observational real-world registry, analyses will be primarily descriptive and exploratory. The registry is intended to improve understanding of outcomes after comprehensive treatment of synchronous de novo oligometastatic prostate cancer and to generate hypotheses for future prospective trials.

• Study Type: Observational
• Enrollment (Estimated): 700

Contacts and Locations

• Study Contact: Name: Mateusz Bilski, MD, PhD; Phone Number: +48 81 536 04 50; Email: mateusz.bilski@affidea.com
• Study Contact Backup: Name: Paulina Kleban; Phone Number: +48 81 536 04 50; Email: paulina.kleban@affidea.com

Study Locations

• Poland
  • Lublin Voivodeship
    • Zamość, Lublin Voivodeship, Poland, 22-400
      • Recruiting
      • Affidea Nu-med Center of Oncological Diagnostics and Therapy
      • Contact: Mateusz Bilski, MD, PhD; Phone Number: +48 81 536 04 50; Email: mateusz.bilski@affidea.com
      • Contact: Paulina Kleban; Phone Number: +48 81 536 04 50; Email: paulina.kleban@affidea.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients with synchronous de novo oligometastatic prostate cancer, defined as metastatic prostate adenocarcinoma diagnosed at initial presentation or within 6 months of primary diagnosis, with up to 10 extraregional metastatic lesions. Patients are treated in routine clinical practice with definitive prostate-directed radiotherapy, which may include external-beam radiotherapy, brachytherapy boost, or definitive brachytherapy monotherapy, and metastasis-directed radiotherapy to all identified extraregional metastatic lesions.

Description

Inclusion Criteria:

• Histologically confirmed adenocarcinoma of the prostate.
• Male sex.
• Age 18 years or older.
• Synchronous de novo metastatic prostate cancer diagnosed at initial presentation or within 6 months of primary prostate cancer diagnosis.
• Up to 10 extraregional metastatic lesions on staging imaging used for clinical decision-making.
• Treatment with definitive prostate-directed radiotherapy, including external-beam radiotherapy alone, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients.
• Treatment with SBRT or another ablative metastasis-directed radiotherapy approach to all identified extraregional metastatic lesions.
• Availability of sufficient clinical, imaging, radiotherapy, systemic therapy, follow-up, adverse event, and survival data for outcome assessment.
• For prospectively enrolled patients, ability to provide informed consent where required by local ethics and regulatory procedures.

Exclusion Criteria:

• More than 10 extraregional metastatic lesions at baseline staging.
• Incomplete metastasis-directed therapy, defined as treatment of selected metastatic lesions only while leaving other known baseline extraregional metastatic sites untreated.
• Prostate-directed radiotherapy delivered with palliative rather than definitive intent.
• Missing key dates preventing outcome determination, including prostate-directed radiotherapy, brachytherapy, metastasis-directed SBRT dates, or follow-up information.
• Prior definitive treatment of prostate cancer before diagnosis of synchronous metastatic disease.
• Histology other than adenocarcinoma of the prostate.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Historical Retrospective Cohort; Eligible patients treated before registry activation. Baseline disease characteristics, imaging, treatment details, follow-up, radiographic progression, adverse events, subsequent therapy, and survival data are abstracted retrospectively from available medical records.	Radiation: Definitive Prostate-Directed Radiotherapy; Definitive radiotherapy to the prostate delivered as part of routine clinical practice. Techniques may include external-beam radiotherapy, moderately hypofractionated radiotherapy, ultra-hypofractionated prostate radiotherapy, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients.; Radiation: Metastasis-Directed Stereotactic Body Radiotherapy; Stereotactic body radiotherapy delivered with ablative intent to all identified extraregional metastatic lesions at baseline. Dose, fractionation, target site, number of treated lesions, and treatment sequence are determined by routine institutional practice and recorded in the registry.; Radiation: Pelvic Lymph Node Irradiation; Elective or definitive pelvic lymph node irradiation, with or without dose escalation to involved pelvic lymph nodes, delivered according to institutional standards. This treatment is permitted but not mandatory and is recorded as a treatment-related variable.; Radiation: Prostate Brachytherapy; High-dose-rate or low-dose-rate prostate brachytherapy delivered either as a boost after external-beam radiotherapy or as definitive brachytherapy monotherapy in selected patients, according to institutional practice.
Ambispective Follow-Up Cohort; Eligible patients treated before registry activation who remain under follow-up. Baseline and treatment data are collected retrospectively, while follow-up updates after registry activation, including imaging, progression, subsequent therapy, adverse events, and survival, are collected prospectively where permitted.	Radiation: Definitive Prostate-Directed Radiotherapy; Definitive radiotherapy to the prostate delivered as part of routine clinical practice. Techniques may include external-beam radiotherapy, moderately hypofractionated radiotherapy, ultra-hypofractionated prostate radiotherapy, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients.; Radiation: Metastasis-Directed Stereotactic Body Radiotherapy; Stereotactic body radiotherapy delivered with ablative intent to all identified extraregional metastatic lesions at baseline. Dose, fractionation, target site, number of treated lesions, and treatment sequence are determined by routine institutional practice and recorded in the registry.; Radiation: Pelvic Lymph Node Irradiation; Elective or definitive pelvic lymph node irradiation, with or without dose escalation to involved pelvic lymph nodes, delivered according to institutional standards. This treatment is permitted but not mandatory and is recorded as a treatment-related variable.; Radiation: Prostate Brachytherapy; High-dose-rate or low-dose-rate prostate brachytherapy delivered either as a boost after external-beam radiotherapy or as definitive brachytherapy monotherapy in selected patients, according to institutional practice.
Prospective Enrollment Cohort; Newly eligible patients identified from registry activation onward and entered prospectively before, during, or shortly after routine clinical decision-making for definitive prostate-directed radiotherapy and metastasis-directed therapy. Treatment is not assigned by the registry.	Radiation: Definitive Prostate-Directed Radiotherapy; Definitive radiotherapy to the prostate delivered as part of routine clinical practice. Techniques may include external-beam radiotherapy, moderately hypofractionated radiotherapy, ultra-hypofractionated prostate radiotherapy, external-beam radiotherapy with brachytherapy boost, or definitive prostate brachytherapy monotherapy in selected patients.; Radiation: Metastasis-Directed Stereotactic Body Radiotherapy; Stereotactic body radiotherapy delivered with ablative intent to all identified extraregional metastatic lesions at baseline. Dose, fractionation, target site, number of treated lesions, and treatment sequence are determined by routine institutional practice and recorded in the registry.; Radiation: Pelvic Lymph Node Irradiation; Elective or definitive pelvic lymph node irradiation, with or without dose escalation to involved pelvic lymph nodes, delivered according to institutional standards. This treatment is permitted but not mandatory and is recorded as a treatment-related variable.; Radiation: Prostate Brachytherapy; High-dose-rate or low-dose-rate prostate brachytherapy delivered either as a boost after external-beam radiotherapy or as definitive brachytherapy monotherapy in selected patients, according to institutional practice.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to First Radiographic Progression	Time from the start date of the first radiotherapy course to the date of first radiographic progression documented on routine follow-up imaging. Radiographic progression includes new extraregional metastatic lesions, local recurrence, regional nodal recurrence, or unequivocal progression at previously treated metastatic sites.	From start of first radiotherapy course to first radiographic progression or last follow-up, up to 36 months
Number of Participants by First Radiographic Failure Pattern	Number of participants classified according to the first radiographic failure pattern after comprehensive prostate-directed radiotherapy and metastasis-directed therapy. Each participant with radiographic progression will be assigned to one prespecified first-failure category based on investigator assessment of routine follow-up imaging and clinical documentation. Categories include local prostate or prostate-bed recurrence, regional nodal recurrence, progression at previously treated metastatic sites, new distant metastatic lesions, combined recurrence, oligometastatic progression, polymetastatic progression, or death without documented radiographic progression.	At first documented radiographic progression or death, assessed up to 36 months.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to Polymetastatic Progression	Time from the start date of the first radiotherapy course to development of polymetastatic progression, defined as more than five new and/or regrowing extraregional metastatic lesions.	From start of first radiotherapy course to polymetastatic progression or last follow-up, up to 36 months
Time to Next-Line Systemic Therapy	Time from the start date of the first radiotherapy course to initiation or escalation of the next line of systemic therapy following radiographic progression or a documented clinical decision to intensify treatment.	From start of first radiotherapy course to next-line systemic therapy or last follow-up, up to 36 months
Overall Survival	Time from the start date of the first radiotherapy course to death from any cause. Patients alive at last available follow-up will be censored at the date of last known vital status.	From start of first radiotherapy course to death or last known follow-up, up to 60 months
Treatment-Related Adverse Events	Frequency and severity of treatment-related adverse events recorded during routine care and graded according to CTCAE version 5.0 where available. Genitourinary and gastrointestinal adverse events will be summarized separately, including grade 3 or higher adverse events.	From start of first radiotherapy course to last follow-up, up to 36 months

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Exploratory Associations Between Treatment Factors and Outcomes	Exploratory analyses will evaluate associations between outcomes and baseline metastatic burden, imaging modality, metastatic site distribution, prostate radiotherapy modality, brachytherapy boost or monotherapy, pelvic lymph node irradiation, metastasis-directed radiotherapy dose and fractionation, systemic therapy intensity, and treatment sequence.	From start of first radiotherapy course to last follow-up, up to 36 months

Collaborators and Investigators

• Sponsor: Affidea Nu-med Center of Oncological DIagnostics and Therapy
• Investigators: Principal Investigator: Mateusz Bilski, MD, PhD, Affidea Nu-med Center of Oncological Diagnostics and Therapy

Study record dates

Study Major Dates

• Study Start (Actual): June 26, 2026
• Primary Completion (Estimated): December 30, 2028
• Study Completion (Estimated): December 30, 2029

Study Registration Dates

• First Submitted: June 28, 2026
• First Submitted That Met QC Criteria: July 2, 2026
• First Posted (Actual): July 6, 2026

Study Record Updates

• Last Update Posted (Actual): July 6, 2026
• Last Update Submitted That Met QC Criteria: July 2, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: stereotactic body radiotherapy; adverse events; SBRT; prospective registry; PSMA PET; metastasis-directed therapy; real-world evidence; brachytherapy boost; prostate brachytherapy; synchronous de novo oligometastatic prostate cancer; definitive prostate radiotherapy; up to 10 metastases; patterns of failure; radiographic progression; polymetastatic progression; ambispective registry
• Additional Relevant MeSH Terms: Urogenital Diseases; Genital Diseases; Genital Neoplasms, Male; Urogenital Neoplasms; Neoplasms by Site; Neoplasms; Genital Diseases, Male; Prostatic Diseases; Male Urogenital Diseases; Prostatic Neoplasms
• Other Study ID Numbers: SynSABR-PC

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data underlying the main published analyses may be shared after publication. The shared dataset may include baseline clinical characteristics, staging and imaging modality, metastatic burden and location, prostate-directed radiotherapy details including brachytherapy where applicable, metastasis-directed radiotherapy details, systemic therapy, follow-up, radiographic progression, pattern of failure, subsequent treatments, adverse events, survival status, and censoring information. Direct identifiers, free-text clinical notes, raw imaging files, and exact calendar dates that could enable re-identification will not be shared.
• IPD Sharing Time Frame: Data will become available beginning 12 months after publication of the primary registry analysis and will remain available for 5 years.
• IPD Sharing Access Criteria: Data will be available to qualified researchers who submit a scientifically sound proposal approved by the study steering group. Data sharing will require a signed data use agreement and, where applicable, documentation of ethics or institutional approval. Shared data may be used only for the approved research purpose and may not be used to attempt participant re-identification.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No