A Phase 2 interventional study of Next generation Stereotactic Ablative Radiotherapy (SABR) in Prostate Adenocarcinoma, sponsored by Cancer Trials Ireland. Recruiting at 4 sites in 2 countries. Open to male participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-07-06.
Sponsored by Cancer Trials Ireland · Phase 2, Interventional, and Treatment
This is a Phase II, single arm, multi-centre, prospective clinical trial evaluating next generation Stereotactic Ablative Radiotherapy (SABR) for low, intermediate, and eligible high-risk prostate cancer. Eligible patients will receive next generation prostate SABR incorporating toxicity reduction strategies
This is a Phase II, single arm, multi-centre, prospective clinical trial evaluating next generation Stereotactic Ablative Radiotherapy (SABR) for low, intermediate, and eligible high-risk prostate cancer. Eligible patients will receive next generation prostate SABR incorporating toxicity reduction strategies: urethral/trigone sparing, rectal hydrogel spacer, and neurovascular bundle preservation [as per Desai POTEN-C trial, Desai et al., 2025].
Treatment will prioritise the dominant intraprostatic lesion (DIL) while sparing surrounding organs at risk (OARs). Planned doses are: DIL 40-50 Gy in 5 fractions delivered on alternate days, prostate CTV 35 Gy, PTV 33.25 Gy, and urethral PRV 32.5 Gy. Eligible high-risk and some intermediate-risk patients may receive 6-12 months of androgen deprivation therapy (ADT)/hormonal therapy at the physician's discretion, provided they have not received >14 weeks prior to registration.
Radiotherapy planning will include advanced image-guided verification with fiducial markers, pre-treatment dosimetry to minimise dose to OARs, and adherence to protocol-defined constraints for urethra, rectum, and neurovascular bundles. Peri-rectal spacers will be inserted 7-10 days prior to CT-simulation to reduce rectal dose. Dose prioritisation allows full coverage of the DIL while sparing urethra, bladder trigone, and neurovascular bundles to minimise genitourinary, rectal, and sexual toxicity.
Follow-up assessments will include clinical evaluation, toxicity reporting using v5 NCI CTCAE, and patient-reported outcome measures (PRO/QoL) at 2-, 4-, 8-, and 12-weeks post-treatment, 6 and 9 months, and annually up to 5 years. Data on biochemical/clinical failure, progression-free survival, and initiation or re-initiation of ADT will also be collected.
A total of 136 patients will be enrolled to achieve 122 evaluable participants, allowing detection of a statistically significant reduction in Grade ≥2 late genitourinary toxicity compared to historical SABR controls.
Patients belonging to one of the following risk groups:
Low risk - patients meeting all of the following criteria:
Intermediate risk - patients meeting any of the following criteria, assuming no high-risk features apply:
High risk - patients with tumours that meet a maximum of one of the following criteria:
Exclusion Criteria:
Eligible patients will receive next generation prostate SABR incorporating toxicity reduction strategies: urethral/trigone sparing, rectal hydrogel spacer, and neurovascular bundle preservation.
Radiation: Next generation Stereotactic Ablative Radiotherapy (SABR)
Treatment will prioritise the dominant intraprostatic lesion (DIL) while sparing surrounding organs at risk (OARs).
Late GU toxicity
Rate of ≥ Grade 2 version 5 (v5) NCI CTCAE late GU toxicity in next-generation prostate SABR at 2 years.
Time frame: 2 years after last fraction
Acute GU Toxicity
Acute Grade ≥ 2 GU toxicity ≤12 weeks, using v5 NCI CTCAE
Time frame: ≤12 weeks after last fraction
Acute GI Toxicity
Acute Grade ≥ 2 GI toxicity ≤12 weeks, using v5 NCI CTCAE
Time frame: ≤12 weeks after last fraction
Late GU toxicity at 5 years
Late Grade ≥ 2 GU toxicity at 5 years, using v5 NCI CTCAE
Time frame: 5 years after last fraction
Late GI toxicity at 5 years
Late Grade ≥ 2 GI toxicity at 5 years, using v5 NCI CTCAE
Time frame: 5 years after last fraction
Patient-Reported Outcomes (PRO) / Quality of Life (QoL) assessments for all patients via Expanded Prostate Cancer Index Composite Short Form (EPIC-26).
EPIC-26 will be reported at 4 weeks, 12 weeks, 6, 9, and 12 months following treatment and yearly thereafter (until year 5). Response options for each EPIC item form a Likert scale, and multi- scores are transformed linearly to a 0-100 scale with higher scores representing better HRQOL.
Time frame: 4 weeks, 12 weeks, 6, 9, and 12 months, 24 months, 36 months, 48 months, 60 months after treatment
Patient-Reported Outcomes (PRO) / Quality of Life (QoL) assessments for all patients via International Index of Erectile Function (IIEF-5).
IIEF-5 will be reported at 12 weeks, 6 and 12 months following treatment and yearly thereafter (until year 5). IIEF-5 is reported on a scale of 5 to 25 with higher scores representing better function.
Time frame: 12 weeks, 6 and 12 months, 24 months, 36 months, 48 months, 60 months after treatment
Patient-Reported Outcomes (PRO) / Quality of Life (QoL) assessments for all patients via International Prostate Symptom Score (IPSS).
IPSS will be reported at 4 weeks, 12 weeks, 6, 9, and 12 months following treatment and yearly thereafter (until year 5). The total symptom score of IPSS ranges from 0 to 35 where 0 indicates no symptoms and 35 indicates the patient is severely symptomatic.
Time frame: 4 weeks, 12 weeks, 6, 9, and 12 months, 24 months, 36 months, 48 months, 60 months after treatment
Freedom from biochemical or clinical failure.
Freedom from biochemical (Phoenix definition) or clinical (commencement or re-commencement of androgen deprivation therapy \>12 weeks after completing the neoadjuvant/adjuvant course of ADT, local recurrence, nodal recurrence and distant metastases) failure.
Time frame: The primary timepoint of interest is 5 years from registration.
Disease specific survival and overall survival
Disease specific survival and overall survival
Time frame: 5 years from registration.
Progression-free survival (PFS)
Progression-free survival (PFS) - radiographic, clinical or biochemical evidence of local or distant failure.
Time frame: 5 years from registration
To assess commencement or re-commencement of androgen deprivation therapy (ADT)
Eligible high-risk patients and some intermediate risk patients may be planned to receive (or may have already commenced) 6-12 months ADT/hormonal therapy at physician's discretion.
Time frame: Up to five years post last fraction.
Patient-Reported Outcomes (PRO) / Quality of Life (QoL) assessments for all patients via Penile Shortening and well being questionnaire (PSW E9).
PSW E9 will be reported at baseline, 6 months and 2 years post treatment. PSW E9 is a 9 item questionnaire using a Likert scale 0-4 where higher scores indicate lower satisfaction.
Time frame: Baseline, 6 months and 2 years post treatment.
Plan to share: Undecided
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