Prostate Cancer AdenocarcinomaPhase 2POTEN-CNCT03525262
Prostate Oncologic Therapy While Ensuring Neurovascular Conservation (POTEN-C)
A Phase 2 study testing 30Gy (Gray) planning target volume (PTV) in people with Prostate Cancer Adenocarcinoma, run by University of Texas Southwestern Medical Center at 8 sites in United States.
Trial summary
Reduction of dose to or 'sparing' of neurovascular structures during stereotactic ablative body radiotherapy (SAbR) for localized prostate cancer will improve retention of sexual potency, while retaining excellent oncologic control and other secondary health-related quality of life (HRQOL) endpoints. Read more about this study
- Who is it for?
- Ages 18 years and older, men only
- Conditions the study is for
- Prostate Cancer Adenocarcinoma
- What is being tested?
- 30Gy (Gray) planning target volume (PTV)
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 124 participants
- Where
- 8 sitesUnited States
- Study dates
- 24 Apr 2018to Apr 2029
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- Men only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age ≥ 18 years.
- Appropriate staging studies identifying patient as AJCC 7th edition clinical stage T1 (a, b, or c) or T2 (a, b, or c) adenocarcinoma of the prostate gland. The patient should not have direct evidence of regional or distant metastases after appropriate staging studies. See Appendix I for details on AJCC 7th Edition staging criteria. Histologic confirmation of cancer will be required by biopsy performed within 12 months of registration. T-staging may be assessed by multi-parametric imaging alone if digital rectal examination was deferred.
- The patient's Zubrod performance status must be 0-2 (see Appendix II for definition).
- The Gleason summary score should be less than or equal to 7 [Grade group 1 (Gleason 3+3=6), group 2 (Gleason 3+4=7), and group 3 (Gleason 4+3=7) are allowed]. See Appendix III for details on definitions. While a template biopsy is recommended, it is not required in the case of MRI fusion biopsy performed on all dominant MR lesions (defined as PIRADS v2 4-5).
- Baseline AUA symptom score ≤19 (see Appendix IV for questionnaire) without need for maximum medical therapy (specifically, not on tamsulosin 0.8mg daily).
- EPIC sexual domain composite score 60-100 (see Appendix V).
Show all 11Show fewer
- Multi-parametric MRI evaluation of the prostate is required for this study within 12 months of registration. Gross radiographic disease on MRI (defined as PIRADS v2 score 3-5) must be > 5mm at minimum distance from at least one side's neurovascular bundle, which is typically the closest of the neurovascular elements to the prostate.
- The serum PSA should be less than or equal to 20 ng/ml within 90 days of registration.
- -Study entry PSA must not be obtained during the following time frames: (1) 10-day period following prostate biopsy; (2) following initiation of ADT or anti-androgen therapy; (3) within 30 days after discontinuation of finasteride; (4) within 90 days after discontinuation of dutasteride; (5) within 5 days of a digital rectal examination (which is not a required exam on the protocol).
- Ultrasound or MRI based volume estimation of prostate gland ≤ 80 grams. Cytoreduction therapy (finasteride or dutasteride only) may be considered for those with >60 gram size.
- All patients must be willing and capable to provide informed consent to participate in the protocol within the 30 days prior to registration.
Who cannot join
- Subjects with clinical (digital rectal examination) evidence of extraprostatic extension (T3a) or seminal vesicle involvement (T3b). MRI evidence of equivocal/potential but not definite extraprostatic extension is allowed, as long as it is unilateral and not on the side of the gland proposed for neurovascular element sparing. In equivocal cases of potential extracapsular extension on MRI only, discretion is left to the treating physician.
- MRI evidence of gross disease (defined as PIRADS v2 score 3-5 lesions) ≤5mm of BOTH neurovascular bundles, which are the most proximate of the neurovascular elements planned for sparing on this protocol.
- Patients with all three intermediate risk factors (PSA >10 and ≤ 20, Gleason 7, clinical stage T2b-T2c) who ALSO have ≥50% of the number of their template biopsy cores positive for cancer are ineligible.
- Inability to undergo multi-parametric MRI.
- Evidence of metastatic disease. Note bone scan is not required for this study given the low-intermediate NCCN risk cohort to be enrolled.
- Evidence of clinical nodal involvement of the pelvis. Biopsy is required for lymph nodes over ≥1.5cm in short-axis measured size.
Show all 24Show fewer
- No currently active ADT or anti-androgen therapy at time of registration is allowed. Further, no more than 3 cumulative months of prior ADT or anti-androgen therapy is allowed. If either has been used by the patient, there must be a demonstration of testosterone recovery (>50ng/dL serum blood level), EPIC sexual domain score ≥60, and at least 1 month between demonstration of testosterone recovery and study registration (any one measurement of testosterone recovery suffices).
- Testosterone ≤ 50 ng/dL (any one measurement >50 ng/dL suffices for inclusion) within 90 days of study entry.
- Subjects who have had previous pelvic radiotherapy or have had chemotherapy or surgery for prostate cancer.
- Subjects who have plans to receive other concomitant or post treatment adjuvant antineoplastic therapy while on this protocol including surgery, cryotherapy, conventionally fractionated radiotherapy, hormonal therapy, or chemotherapy given as part of the treatment of prostate cancer.
- Subjects who have undergone previous transurethral resection of the prostate (TURP) within 1 year of enrollment or ablative procedures to the prostate for benign prostatic hyperplasia or other conditions (i.e. cryotherapy, HIFU).
- Subjects who have baseline severe urinary symptoms, as defined by AUA symptom score >19 (alpha-blocker medication allowed except if taking tamsulosin 0.8mg daily at baseline which indicates compensated severe symptoms and also can affect sexual function).
- Subjects who have a history of significant psychiatric illness that would confound informed consent.
- Severe, active co-morbidity, defined as follows:
- Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months
- Myocardial infarction within the last 6 months
- Acute bacterial or fungal infection requiring intravenous antibiotics at time of registration
- Patients with active inflammatory colitis (including Crohn's Disease and ulcerative colitis) currently requiring systemic steroids and/or systemic immunosuppression are not eligible.
- Subjects with a known allergy to polyethylene glycol hydrogel (rectal spacer material) or contraindication to spacer products (SpaceOAR).
- Subjects with uncontrolled coagulation disorder which cannot be controlled with anticoagulants.
- Men active with partners of reproductive potential who do not agree that they will use an effective contraceptive method during treatment and 6 months after treatment.
- Men who require erectile function medication or aid to achieve an erection sufficient for intercourse. Ability to achieve erection sufficient for intercourse without medication or aid at least once time in the month prior to registration is sufficient for inclusion.
- Men who have clinically significant penile malformation (i.e. Peyronie's disease) or history of penile implantation are excluded.
- If DRE is performed, patient may not have palpable disease on side of gland to be planned for neurovascular sparing. Given the poor accuracy of DRE, such a finding should be confirmed by MRI and/or biopsy to harbor actual disease before excluding a patient on this basis.
Trial locations and contacts
8 sites in 1 country.
8 sites in 1 country
United States8 sites
University of Michigan- Michigan Medicine
Ann Arbor, Michigan, 48109
University of Colorado Hospital
Aurora, Colorado, 80045
Cleveland Clinic
Cleveland, Ohio, 44195
Penrose Hospital
Colorado Springs, Colorado, 80907
UT Southwestern Cancer Center
Dallas, Texas, 75235
Penn Medicine Radiation Oncology
Philadelphia, Pennsylvania, 19104
UCSF ( Department of Radiation Oncology University of California San Francisco)
San Francisco, California, 94143
Stony Brook University Cancer Center
Stony Brook, New York, 11794
About this study
Official title: A Phase II Randomized Controlled Trial of Stereotactic Ablative Body Radiotherapy (SAbR) With or Without Neurovascular Sparing for Erectile Function Preservation in Localized Prostate Cancer
Reduction of dose to or 'sparing' of neurovascular structures during stereotactic ablative body radiotherapy (SAbR) for localized prostate cancer will improve retention of sexual potency, while retaining excellent oncologic control and other secondary health-related quality of life (HRQOL) endpoints.
Primary Objectives:
Read more
- To compare the decline in patient health-related quality of life (HRQOL) instrument-defined erectile dysfunction following stereotactic ablative body radiotherapy (SAbR) with or without neurovascular sparing
Secondary Objectives:
- Assess acute (within 3 months of treatment) and chronic (>3 months after treatment) SAbR related GU and GI toxicities, as well as serial impact on HRQOL metrics over time
- Assess biochemical progression free survival, local recurrence, distant recurrence, and survival
- Evaluate simplified 'practical' secondary HRQOL sexual potency endpoints that can be compared to prior literature.
Exploratory Objectives:
- Evaluate feasibility of MRI BOLD/TOLD to be integrated as hypoxia monitoring sequences to standard already planned diagnostic and/or treatment planning MRI on the study in five patient pilot.
- Evaluate quality of spacer placement and its effect on dose to neurovascular structures
- Evaluate rate local recurrence in the area of sparing adjacent to the neurovascular elements by biopsy in those with biochemical progression.
Read the detailed description
This is a phase II randomized, multi-institution, open-label, patient and HRQOL endpoint assessor blinded study evaluating the ability of neurovascular element sparing SAbR to decrease erectile dysfunction. The study procedure is to reduce 2-year Expanded prostate cancer index composite (EPIC) sexual domain score decline by 50% (-20 to -10), there by improving potency preservation. This reduction is usually expected to observe in patients undergoing the treatment stereotactic ablative body radiotherapy (SAbR) to 40-45 Gy with rectal spacer +/- sparing of at least one side's neurovascular structures using dose-painting.
Primary Endpoint:
- The Expanded prostate cancer index composite (EPIC) health-related quality of life (HRQOL) instrument includes a sexual function domain, which is used to produce a composite score of 0-100 from 9 questions related to ability to achieve an erection with or without aids and participate in intercourse. The primary endpoint will be the mean 24-month decline in EPIC sexual function domain composite score.
Secondary Endpoints:
- Acute Genitourinary (GU) and Gastrointestinal (GI) toxicity is defined as grade 1-5 toxicity occurring prior to 270 days from the start of protocol treatment. It is graded based on CTCAE v4.0.
- Delayed GU and GI toxicity is defined as grade 1-5 toxicity occurring prior to 270 days from the start of protocol treatment. It is graded based on CTCAE v4.0.
- Non GU and GI toxicity up to six months post treatment.
- Biochemical failure Radiation therapy oncology group-American Society for Therapeutic Radiology and Oncology (RTOG-ASTRO) definition (also known as Phoenix definition) - Thus, when the Prostate Specific Antigen (PSA) rises by more than 2 ng/ml above the lowest level (nadir) achieved after treatment, biochemical failure has occurred and the date of the failure is recorded at the time the nadir plus 2 ng/ml level is reached. Patients should be followed for a minimum of 5 years on this study to evaluate this endpoint.
- Overall survival
- Disease-specific survival
- Clinical progression including local/regional and distant relapse
- HRQOL questionnaires (EPIC and SF-12)
- Erectile function medication and device aids tracked before and after therapy longitudinally
- Feasibility of MRI BOLD/TOLD in evaluating tumor hypoxia in no more than five patient pilot
Sample Size: To enroll 120 patients (60 patients in each treatment arm).
The sample size is estimated, first, assuming that neurovascular element sparing SAbR (experimental arm intervention) will result in a mean 24 month decline in EPIC (HRQOL instrument) sexual domain composite score of -20, as compared to a decline of -10 in a standard SAbR without neurovascular element sparing. A total sample size of 102 patients (51 patients in each treatment group) achieves 80% power to detect this difference of 10 in EPIC sexual domain composite score decline at 24 months after treatment, with an equal standard deviation of 20 in both groups and at a two-sided significance level of 0.10, using a two-sample t-test (effect size 0.50).
An attrition rate of EPIC sexual domain questionnaire completion at 2-years of 15% is anticipated, based upon yields from multi-center prospective trials in prostate cancer radiotherapy with EPIC HRQOL endpoints. A total of 120 patients will be accrued to account for this 15% attrition rate.
Statistical Analysis: For the primary endpoint, a two-sided two-sample t-test will be used to compare EPIC sexual function domain score composite declines at 24 months from treatment between experimental SAbR arms with and without neurovascular sparing. Our sample size of 60 patients in each arm gives a calculated 80% power to detect a difference of 10 (considered the minimally important difference for sexual domain) at a two-sided significance level 0.10, assuming an equal standard deviation of 20 in both groups and allowing for 15% attrition in survey completion. Secondary endpoints and their analysis methodology is further specified in the protocol.
- Conditions
- Prostate Cancer Adenocarcinoma
- Being tested
- 30Gy (Gray) planning target volume (PTV)
- Keywords
- Erectile dysfunction, Neurovascular, Prostate, Rectal spacer, Radiotherapy
- Medical subject headings
- Erectile Dysfunction
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
30Gy (Gray) planning target volume (PTV)Radiation
PTV1_30Gy represents a 3mm expansion on the prostate (and proximal seminal vesicle per physician discretion), excluding the neurovascular structures on the side to be spared (left or right). PTV1 will receive 6 Gy per fraction for 5 fractions (30 Gy).
| Study group | Role | What they receive |
|---|---|---|
| SAbR WITHOUT Neurovascular sparing | No intervention | * GTV represents MR defined dominant radiographic disease, if identifiable. * CTV encompasses the full prostate. At physician's discretion, the insertion of the seminal vesicle upon the prostate on slices containing prostate may be included. * PTV1_30Gy will not be used or created on this arm * PTV2_SAbR40Gy OR PTV2_SAbR45Gy will be generated by a 3mm expansion on the CTV. PTV2_SAbR will receive 8-9 Gy per fraction for 5 fractions (40-45 Gy). |
| SAbR WITH Neurovascular sparing | Experimental | * GTV represents MR defined dominant radiographic disease, if identifiable.
* CTV encompasses the full prostate. At physician's discretion, the insertion of the seminal vesicle upon the prostate on slices containing prostate may be included.
* PTV1_30Gy represents a 3mm expansion on the CTV, excluding the neurovascular structures on the side to be spared (left or right). PTV1 will receive 6 Gy per fraction for 5 fractions (30 Gy).
* PTV2_SAbR40Gy OR PTV2_SAbR45Gy will be generated by subtracting a 5mm expansion around the neurovascular elements to be spared (at least one side, left or right) from PTV1. These neurovascular structures consist of the neurovascular bundle, penile bulb, and internal pudendal arteries (see 4.1.5.2.16). PTV2 will receive 8-9 Gy per fraction for 5 fractions (40-45 Gy). Receives: Radiation: 30Gy (Gray) planning target volume (PTV) |
What is being measured
The primary outcome is the main question the study is designed to answer.
To compare the decline in patient health-related quality of life.
To compare the decline in patient health-related quality of life (HRQOL) instrument-defined erectile dysfunction following stereotactic ablative body radiotherapy (SAbR) with or without neurovascular sparing. The Expanded Prostate Cancer Index Composite (EPIC) health-related quality of life (HRQOL) instrument includes four sub-scales like urinary function, bowel habits, sexual function, and hormonal function. The primary outcome (sexual function) which has a range score of 0-100 from 9 questions related to ability to achieve an erection with or without aids and participate in intercourse. Higher the score represents the better outcome. Individual responses are summed for a total score of sexual function.
Measured: Mean 24-Months
Secondary outcomes (6)
Acute & Chronic Genitourinary (GU) and Gastrointestinal (GI) toxicity
Assess acute (within 3 months of treatment) and chronic (>3 months after treatment) SAbR related GU and GI toxicities, as well as serial impact on HRQOL metrics over time. Severity or Toxicity will be assessed according to the National Cancer Institute (NCI) Common Toxicity Criteria for Adverse Events (CTCAE), version 4.0. The consequences of gastointestinal/renal/genitourinary/sexual and reproductive toxicity should all be graded 1-5 according to the Common Terminology Criteria For Adverse Events (CTCAE), version 4.0 occurring prior to 270 days from the start of protocol treatment. Other treatment related toxicity attributed to the therapy will be captured, recorded and the consequences of should all be graded 1-5 according to the Common Terminology Criteria For Adverse Events (CTCAE). CTCAE V4.0 along with grades 1-5 is provided in the link for reference (https://evs.nci.nih.gov/ftp1/CTCAE/CTCAE_4.03/CTCAE_4.03_2010-06-14_QuickReference_8.5x11.pdf).
Measured: Mean 24-Months
Biochemical progression free survival.
Assess biochemical progression free survival. Biochemical failure RTOG-ASTRO definition - when the PSA rises by more than 2 ng/ml above the lowest level (nadir) achieved after treatment, biochemical failure has occurred and the date of the failure is recorded at the time the nadir plus 2 ng/ml level is reached.
Measured: 60 Months
Time to local recurrence.
The time to progression will be measured from the date of study entry to the date of documented local progression as determined by clinical exam and/or MRI. Local progression is defined by progression within the prostate, seminal vesicles or immediately adjacent extracapsular soft tissue. Biopsy confirmation is not required but is encouraged.
Measured: 60 Months
Time to distant recurrence.
The time to distant failure will be measured from the date of study entry to the date of documented regional nodal recurrence or distant disease relapse. Patients with evidence of biochemical failure, but a negative prostate biopsy, will be considered as distant failure only.
Measured: 60 Months
Overall survival.
The survival time will be measured from the date of accession to the date of death. All patients will be followed for survival. Every effort should be made to document the cause of death.
Measured: 60 Months
Evaluate simplified 'practical' secondary HRQOL sexual potency endpoints.
Evaluate simplified 'practical' secondary HRQOL sexual potency endpoints that can be compared to prior literature. The Expanded Prostate Cancer Index Composite (EPIC) health-related quality of life (HRQOL) instrument includes four sub-scales like urinary function, bowel habits, sexual function, and hormonal function. The primary outcome (sexual function) which has a range score of 0-100 from 9 questions related to ability to achieve an erection with or without aids and participate in intercourse. Higher the score represents the better outcome. Individual responses are summed for a total score of sexual function.
Measured: Mean 24-Months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 May 2018
- Study start24 Apr 2018
- Primary completionApr 2027 (estimated)
- Study completionApr 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Prostate Cancer AdenocarcinomaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 124 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Collaborators
- Boston Scientific Corporation
- Responsible party
- Principal investigator, Neil Desai, University of Texas Southwestern Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03525262
- Sponsor's protocol ID
- STU 092017-018
- Acronym
- POTEN-C
- Status last verified
- Jun 2026
- First submitted
- 23 Apr 2018
- Last updated
- 5 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 5 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase II Randomized Controlled Trial of Stereotactic Ablative Body Radiotherapy (SAbR) With or Without Neurovascular Sparing for Erectile Function Preservation in Localized Prostate Cancer
- ClinicalTrials.gov ID
- NCT03525262
- Acronym / sponsor ID
- POTEN-C / STU 092017-018
- Conditions
- Prostate Cancer Adenocarcinoma
- Keywords
- Erectile dysfunction, Neurovascular, Prostate, Rectal spacer, Radiotherapy
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 124 participants (actual)
- Lead sponsor
- University of Texas Southwestern Medical CenterUniversity, hospital or other
- Collaborators
- Boston Scientific Corporation
- Study start
- 24 Apr 2018 (actual)
- Primary completion
- Apr 2027 (estimated)
- Study completion
- Apr 2029 (estimated)
- First posted
- 15 May 2018 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Reduction of dose to or 'sparing' of neurovascular structures during stereotactic ablative body radiotherapy (SAbR) for localized prostate cancer will improve retention of sexual potency, while retaining excellent oncologic control and other secondary health-related quality of life (HRQOL) endpoints.
Primary Objectives:
- To compare the decline in patient health-related quality of life (HRQOL) instrument-defined erectile dysfunction following stereotactic ablative body radiotherapy (SAbR) with or without neurovascular sparing
Secondary Objectives:
- Assess acute (within 3 months of treatment) and chronic (>3 months after treatment) SAbR related GU and GI toxicities, as well as serial impact on HRQOL metrics over time
- Assess biochemical progression free survival, local recurrence, distant recurrence, and survival
- Evaluate simplified 'practical' secondary HRQOL sexual potency endpoints that can be compared to prior literature.
Exploratory Objectives:
- Evaluate feasibility of MRI BOLD/TOLD to be integrated as hypoxia monitoring sequences to standard already planned diagnostic and/or treatment planning MRI on the study in five patient pilot.
- Evaluate quality of spacer placement and its effect on dose to neurovascular structures
- Evaluate rate local recurrence in the area of sparing adjacent to the neurovascular elements by biopsy in those with biochemical progression.
Detailed description
This is a phase II randomized, multi-institution, open-label, patient and HRQOL endpoint assessor blinded study evaluating the ability of neurovascular element sparing SAbR to decrease erectile dysfunction. The study procedure is to reduce 2-year Expanded prostate cancer index composite (EPIC) sexual domain score decline by 50% (-20 to -10), there by improving potency preservation. This reduction is usually expected to observe in patients undergoing the treatment stereotactic ablative body radiotherapy (SAbR) to 40-45 Gy with rectal spacer +/- sparing of at least one side's neurovascular structures using dose-painting.
Primary Endpoint:
- The Expanded prostate cancer index composite (EPIC) health-related quality of life (HRQOL) instrument includes a sexual function domain, which is used to produce a composite score of 0-100 from 9 questions related to ability to achieve an erection with or without aids and participate in intercourse. The primary endpoint will be the mean 24-month decline in EPIC sexual function domain composite score.
Secondary Endpoints:
- Acute Genitourinary (GU) and Gastrointestinal (GI) toxicity is defined as grade 1-5 toxicity occurring prior to 270 days from the start of protocol treatment. It is graded based on CTCAE v4.0.
- Delayed GU and GI toxicity is defined as grade 1-5 toxicity occurring prior to 270 days from the start of protocol treatment. It is graded based on CTCAE v4.0.
- Non GU and GI toxicity up to six months post treatment.
- Biochemical failure Radiation therapy oncology group-American Society for Therapeutic Radiology and Oncology (RTOG-ASTRO) definition (also known as Phoenix definition) - Thus, when the Prostate Specific Antigen (PSA) rises by more than 2 ng/ml above the lowest level (nadir) achieved after treatment, biochemical failure has occurred and the date of the failure is recorded at the time the nadir plus 2 ng/ml level is reached. Patients should be followed for a minimum of 5 years on this study to evaluate this endpoint.
- Overall survival
- Disease-specific survival
- Clinical progression including local/regional and distant relapse
- HRQOL questionnaires (EPIC and SF-12)
- Erectile function medication and device aids tracked before and after therapy longitudinally
- Feasibility of MRI BOLD/TOLD in evaluating tumor hypoxia in no more than five patient pilot
Sample Size: To enroll 120 patients (60 patients in each treatment arm).
The sample size is estimated, first, assuming that neurovascular element sparing SAbR (experimental arm intervention) will result in a mean 24 month decline in EPIC (HRQOL instrument) sexual domain composite score of -20, as compared to a decline of -10 in a standard SAbR without neurovascular element sparing. A total sample size of 102 patients (51 patients in each treatment group) achieves 80% power to detect this difference of 10 in EPIC sexual domain composite score decline at 24 months after treatment, with an equal standard deviation of 20 in both groups and at a two-sided significance level of 0.10, using a two-sample t-test (effect size 0.50).
An attrition rate of EPIC sexual domain questionnaire completion at 2-years of 15% is anticipated, based upon yields from multi-center prospective trials in prostate cancer radiotherapy with EPIC HRQOL endpoints. A total of 120 patients will be accrued to account for this 15% attrition rate.
Statistical Analysis: For the primary endpoint, a two-sided two-sample t-test will be used to compare EPIC sexual function domain score composite declines at 24 months from treatment between experimental SAbR arms with and without neurovascular sparing. Our sample size of 60 patients in each arm gives a calculated 80% power to detect a difference of 10 (considered the minimally important difference for sexual domain) at a two-sided significance level 0.10, assuming an equal standard deviation of 20 in both groups and allowing for 15% attrition in survey completion. Secondary endpoints and their analysis methodology is further specified in the protocol.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| SAbR WITHOUT Neurovascular sparing | No intervention | –* GTV represents MR defined dominant radiographic disease, if identifiable. * CTV encompasses the full prostate. At physician's discretion, the insertion of the seminal vesicle upon the prostate on slices containing prostate may be included. * PTV1_30Gy will not be used or created on this arm * PTV2_SAbR40Gy OR PTV2_SAbR45Gy will be generated by a 3mm expansion on the CTV. PTV2_SAbR will receive 8-9 Gy per fraction for 5 fractions (40-45 Gy). |
| SAbR WITH Neurovascular sparing | Experimental | Radiation: 30Gy (Gray) planning target volume (PTV)* GTV represents MR defined dominant radiographic disease, if identifiable. * CTV encompasses the full prostate. At physician's discretion, the insertion of the seminal vesicle upon the prostate on slices containing prostate may be included. * PTV1_30Gy represents a 3mm expansion on the CTV, excluding the neurovascular structures on the side to be spared (left or right). PTV1 will receive 6 Gy per fraction for 5 fractions (30 Gy). * PTV2_SAbR40Gy OR PTV2_SAbR45Gy will be generated by subtracting a 5mm expansion around the neurovascular elements to be spared (at least one side, left or right) from PTV1. These neurovascular structures consist of the neurovascular bundle, penile bulb, and internal pudendal arteries (see 4.1.5.2.16). PTV2 will receive 8-9 Gy per fraction for 5 fractions (40-45 Gy). |
Who may qualify
- Ages
- 18 years and older
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Age ≥ 18 years.
- Appropriate staging studies identifying patient as AJCC 7th edition clinical stage T1 (a, b, or c) or T2 (a, b, or c) adenocarcinoma of the prostate gland. The patient should not have direct evidence of regional or distant metastases after appropriate staging studies. See Appendix I for details on AJCC 7th Edition staging criteria. Histologic confirmation of cancer will be required by biopsy performed within 12 months of registration. T-staging may be assessed by multi-parametric imaging alone if digital rectal examination was deferred.
- The patient's Zubrod performance status must be 0-2 (see Appendix II for definition).
- The Gleason summary score should be less than or equal to 7 [Grade group 1 (Gleason 3+3=6), group 2 (Gleason 3+4=7), and group 3 (Gleason 4+3=7) are allowed]. See Appendix III for details on definitions. While a template biopsy is recommended, it is not required in the case of MRI fusion biopsy performed on all dominant MR lesions (defined as PIRADS v2 4-5).
- Baseline AUA symptom score ≤19 (see Appendix IV for questionnaire) without need for maximum medical therapy (specifically, not on tamsulosin 0.8mg daily).
Key exclusion criteria (24 listed)
- Subjects with clinical (digital rectal examination) evidence of extraprostatic extension (T3a) or seminal vesicle involvement (T3b). MRI evidence of equivocal/potential but not definite extraprostatic extension is allowed, as long as it is unilateral and not on the side of the gland proposed for neurovascular element sparing. In equivocal cases of potential extracapsular extension on MRI only, discretion is left to the treating physician.
- MRI evidence of gross disease (defined as PIRADS v2 score 3-5 lesions) ≤5mm of BOTH neurovascular bundles, which are the most proximate of the neurovascular elements planned for sparing on this protocol.
- Patients with all three intermediate risk factors (PSA >10 and ≤ 20, Gleason 7, clinical stage T2b-T2c) who ALSO have ≥50% of the number of their template biopsy cores positive for cancer are ineligible.
- Inability to undergo multi-parametric MRI.
- Evidence of metastatic disease. Note bone scan is not required for this study given the low-intermediate NCCN risk cohort to be enrolled.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| 30Gy (Gray) planning target volume (PTV)PTV1_30Gy represents a 3mm expansion on the prostate (and proximal seminal vesicle per physician discretion), excluding the neurovascular structures on the side to be spared (left or right). PTV1 will receive 6 Gy per fraction for 5 fractions (30 Gy). | Radiation | SAbR WITH Neurovascular sparing |
Primary outcome
To compare the decline in patient health-related quality of life.
Time frame: Mean 24-Months
To compare the decline in patient health-related quality of life (HRQOL) instrument-defined erectile dysfunction following stereotactic ablative body radiotherapy (SAbR) with or without neurovascular sparing. The Expanded Prostate Cancer Index Composite (EPIC) health-related quality of life (HRQOL) instrument includes four sub-scales like urinary function, bowel habits, sexual function, and hormonal function. The primary outcome (sexual function) which has a range score of 0-100 from 9 questions related to ability to achieve an erection with or without aids and participate in intercourse. Higher the score represents the better outcome. Individual responses are summed for a total score of sexual function.
6 secondary outcomes
Acute & Chronic Genitourinary (GU) and Gastrointestinal (GI) toxicity
Time frame: Mean 24-Months
Biochemical progression free survival.
Time frame: 60 Months
Time to local recurrence.
Time frame: 60 Months
Time to distant recurrence.
Time frame: 60 Months
Overall survival.
Time frame: 60 Months
Evaluate simplified 'practical' secondary HRQOL sexual potency endpoints.
Time frame: Mean 24-Months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
8 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing 30Gy (Gray) planning target volume (PTV) in people with Prostate Cancer Adenocarcinoma, run by University of Texas Southwestern Medical Center at 8 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 24 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 5 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 8 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To compare the decline in patient health-related quality of life. (time frame: Mean 24-Months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Jun 2026; AzTrials last refreshed its copy on 28 Oct 2026.