This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for RAD 1801: Pilot Study of Intra-Urethral Radiotransponder Beacon Guided Focal Prostate Stereotactic Body Radiotherapy (NCT03458234), a na na study. The primary outcome is Confirm the Feasibility of Focal Prostate Stereotactic Body Radiotherapy (SBRT) With Real Time Guidance by Intra-urethral Radiotransponder Beacons..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03458234 |
| Phase | NA |
| Condition | Prostate Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 5 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Alabama at Birmingham |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned patients with prostate cancer. The arm description refers to patients with confirmed histology, while the primary-outcome record states that 5 patients signed consent and 1 withdrew consent before treatment began. The record does not report further characteristics of the enrolled patients.
Intervention
The planned approach was focal prostate stereotactic body radiotherapy (SBRT) using real-time guidance from intra-urethral radiotransponder beacons. The listed device intervention is a 16 French Foley Catheter. The registry description refers to imaging and treatment-planning steps, but the study did not proceed to data collection.
Comparator
There was no separate comparator group. The study is recorded as a single-group design, with no allocation to treatment groups. It therefore cannot estimate a treatment contrast against traditional treatment or another control condition.
Primary question
The primary question was whether focal prostate SBRT with real-time intra-urethral beacon guidance was technically feasible. Feasibility was defined as the ability for treatment to take place as planned, with a timeframe of 2 years. The registry record states that no data were collected, so it does not report whether that criterion was met.
3. Trial Design
This was a pilot study recorded as single-group, with allocation listed as NA and masking listed as NONE. The registry record lists an enrollment of 5 and identifies prostate cancer as the condition. The study was sponsored by University of Alabama at Birmingham. Its recorded start date was 2020-01-28, and its primary completion date was 2023-04-20. The study status is TERMINATED.
The planned intervention combined focal prostate stereotactic body radiotherapy with real-time guidance from intra-urethral radiotransponder beacons. The intervention list names a 16 French Foley Catheter. The arm description outlines imaging and simulation with a catheter containing dummy beacons for planning, followed by focal SBRT; however, the description is truncated in the registry record, and the study did not proceed to data collection.
The primary objective was technical feasibility, defined as treatment taking place as planned. The record gives a 2 years timeframe. Other stated aims were to assess early efficacy, late toxicity, and quality of life. These aims describe intended outcome domains; they are not evidence that outcomes were measured.
The primary-outcome record says 5 patients signed consent, 1 withdrew consent before treatment, and the funding source informed the investigators that it was no longer manufacturing the radiotransponder. It also states that there was no similar product, that the study would not proceed, and that no data were collected. The record does not report a statistical analysis plan, a sample-size justification, or a protocol for handling the study’s termination.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Focal SBRT With Intra-urethral Radiotransponder |
|---|---|
| STARTED | 5 |
| COMPLETED | 4 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Focal SBRT With Intra-urethral Radiotransponder |
|---|---|
| Withdrawal by Subject | 1 |
Analysis population for the primary outcome, as defined in the registry: 5 patients signed consent, 1 patient withdrew consent prior to start of treatment. The funding source informed they are no longer manufacturing radiotransponder. No similar product. Therefore, no longer proceeding with study and no data collected.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Focal SBRT With Intra-urethral Radiotransponder |
|---|---|---|
| Participants analysed | 5 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 2 |
| Age, Categorical: >=65 years | Participants | 3 |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 5 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 5 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Confirm the Feasibility of Focal Prostate Stereotactic Body Radiotherapy (SBRT) With Real Time Guidance by Intra-urethral Radiotransponder Beacons., measured over 2 years.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was intended to confirm the feasibility of focal prostate stereotactic body radiotherapy with real-time guidance by intra-urethral radiotransponder beacons. The registry defines feasibility as the ability for treatment to take place as planned and assigns a timeframe of 2 years. This is a process-oriented endpoint: it asks whether the planned treatment procedure could be carried out, rather than estimating a comparative treatment effect.
Feasibility endpoints can be useful in pilot research because they address whether a technical approach can be implemented before a larger evaluation is considered. The meaning of such an endpoint depends on a clear operational definition and on recording whether each participant reached the intended treatment step. The registry record gives a definition but does not report participant-level feasibility outcomes or a summary result.
Instead, the primary-outcome record explains that the study was stopped after the funding source reported that the radiotransponder was no longer being manufactured and no similar product was available. It states that no data were collected. Consequently, the registry record cannot establish whether treatment was delivered as planned, how often it might have been feasible, or how precisely feasibility could have been estimated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive point is that the registry record contains no primary-outcome result. It describes a planned feasibility study but states that the study did not proceed to data collection. Accordingly, there is no observed estimate of the proportion of participants for whom treatment took place as planned, and no estimate of uncertainty around such a proportion. The endpoint’s definition and timeframe are recorded, but they do not substitute for outcome observations.
The record lists enrollment of 5, and the primary-outcome text says 5 patients signed consent. It also says 1 patient withdrew before treatment began. Those enrollment details do not establish that participants received SBRT, completed treatment, or were assessed for feasibility. The same text explicitly states that no data were collected. Enrollment, consent, treatment exposure, and endpoint ascertainment are distinct stages; the record should not be read as if enrollment alone represented a completed feasibility assessment.
The study was not a randomized comparison. It is recorded as single-group, with allocation listed as NA, so it has no concurrent comparator from which to estimate a between-group difference. Even if treatment outcomes had been recorded, a single-group feasibility result would address implementation in the study participants, not establish a comparative benefit or effect relative to another approach. The registry record reports no analysis results.
The serious-adverse-event listing gives 5 at risk and 0 affected, with 0 deaths. However, the primary-outcome record states that no data were collected and that a patient withdrew before treatment. The adverse-event counts therefore require cautious reading: they are registry entries, but the record does not explain how the risk set was defined or how those entries were generated in relation to the statement that no data were collected. They do not resolve the absence of outcome data.
Four outcome measures are listed and no analyses are reported. The stated secondary domains include early efficacy, late toxicity, and quality of life. No corresponding results are described in the registry record. The record also does not report a statistical analysis plan, missing-data procedures, or a prespecified method for combining feasibility outcomes. The appropriate conclusion is limited to the study’s status and documentation: the trial was terminated, and the planned primary question remains unanswered in the posted record.
9. Statistical Methods Explained
Statistical methods should be interpreted in light of the study question and the data actually recorded. In this case, the primary question concerned technical feasibility, and the registry defines feasibility as treatment taking place as planned. A feasibility analysis would ordinarily require a clear account of who was assessed, who reached the planned treatment procedure, and how the endpoint was classified. The record states that no data were collected, so it does not report those observations or an analysis based on them.
What a single-group design can estimate
In a single-group study, participants follow the same planned intervention pathway rather than being allocated between intervention and control groups. If outcomes are recorded, the design can describe what happened among the participants studied. It does not create a direct treatment contrast with an alternative group. Because this study is listed as single-group and allocation is NA, there is no randomized comparison to interpret. The absence of a comparator is not a statistical defect for every feasibility question, but it limits what can be inferred about relative effects.
A feasibility endpoint often has a binary form, such as whether treatment was carried out as planned, though the registry does not report the precise participant-level coding method used for this study. A proportion and an uncertainty interval could describe the observed feasibility experience if the relevant outcomes were collected. A confidence interval is a statistical range reflecting uncertainty around an estimate under stated assumptions; it is not a guarantee that the true value lies within that range. No feasibility estimate or confidence interval is reported in the registry record.
Why the record does not support an effect estimate
Outcome analysis begins with observed data. A planned endpoint, a study enrollment figure, or a stated objective does not supply the outcome values needed to estimate an effect. Here, the primary-outcome narrative explicitly says that no data were collected. The registry also reports 0 analyses. There is therefore no basis in the record for interpreting a treatment effect, estimating its precision, or assessing whether a result is compatible with a particular hypothesis.
General statistical explanation: precision describes how much uncertainty surrounds an estimate. Larger amounts of usable information can often produce more precise estimates, while small or incomplete datasets can leave substantial uncertainty. That general principle does not create an estimate where no outcome data are reported. No observed effect size, variance, event rate, or endpoint distribution is available in the registry record for this study.
Planning illustrations are not study results
The planning assumptions associated with sample-size illustrations describe a hypothetical calculation using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They also describe the effect to detect as a stated fraction of an observed effect. These are planning assumptions, not evidence of the trial’s actual design or its results. They do not match the recorded single-group design, which has no two-arm allocation.
The record does not report a sample-size justification for this pilot study, nor does it report an observed primary effect from which a study-specific planning value could be interpreted. Any sample-size illustration should therefore be understood as hypothetical rather than as the trial’s planned enrollment target or an assessment of the study’s performance. Sample-size calculations concern prospective planning under assumptions; they are not observed power and do not determine whether a study result is valid.
General statistical explanation: power is a design-stage probability tied to a specified effect, variability, test, and significance level. It is not a property that can be recovered from a study merely by looking at its observed result. In a terminated study with no outcome data, the record cannot support an observed treatment-effect analysis or an empirical assessment of the probability of detecting one.
Over-dispersion and model choice
General statistical explanation: over-dispersion arises when observed variability is greater than a statistical model expects. It can make standard errors too small if a model assumes less variability than the data contain. Whether over-dispersion matters depends on the outcome type, the model, and the observed data. The registry record does not report a fitted model, an analysis of dispersion, or outcome data for assessing this issue. It would therefore be inappropriate to claim that over-dispersion was present or that a particular correction was used.
More generally, selecting an analysis requires knowing the endpoint’s scale, the number and timing of observations, the treatment or follow-up structure, and the estimand—the precise quantity the analysis is intended to describe. The registry lists a feasibility endpoint and several secondary domains, but does not report the detailed analysis procedures. The record does not state whether any planned analysis would have used a proportion, time-to-event method, repeated-measures model, or another approach. These details are not reported in the registry record.
Statistical interpretation must therefore remain descriptive. The registry documents the intended technical question, the single-group design, the termination, and the explicit statement that data were not collected. It does not provide a numerical efficacy or feasibility result that can be reanalysed. No conclusion about treatment effects, safety rates, or quality-of-life change can be drawn from the absence of outcome measurements.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 4 outcome measures and names secondary aims concerning early efficacy, late toxicity, and quality of life. It reports 0 analyses. The record does not describe how multiple outcomes would have been prioritized or whether any adjustment for multiple statistical tests was planned. Multiplicity arises when several outcomes or comparisons are examined: without an appropriate plan, the chance of at least one apparently unusual result can increase. That general concern does not imply that any such analysis occurred in this study.
The record does not report a statistical analysis plan, interim analyses, or criteria for stopping based on outcomes. The stated reason the study did not proceed was that the funding source was no longer manufacturing the radiotransponder and no similar product was available. This is a documented operational reason, not a reported statistical stopping boundary.
Missing-data methods are also not reported in the registry record. The primary-outcome narrative states that 1 patient withdrew consent before treatment and that no data were collected. This is not a conventional pattern of partial outcome follow-up that can be repaired through an imputation method using the information in the record. No individual outcome data or analysis population definitions are available.
The registry does not report whether any analysis population would have been defined by consent, treatment initiation, completion, or endpoint availability. Nor does it explain how the adverse-event risk set of 5 relates to the withdrawal and the statement that no data were collected. These details are not reported in the registry record, so the listed counts cannot be used to reconstruct a population-level analysis.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Focal SBRT With Intra-urethral Radiotransponder | 0 | 5 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Focal SBRT With Intra-urethral Radiotransponder | 0 of 5 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Focal SBRT With Intra-urethral Radiotransponder | 0 of 5 |
The adverse-event listing records 5 participants at risk for serious events and 0 affected; it also records 5 at risk for other events and 0 affected, with 0 deaths. These are registry counts, not a detailed safety analysis. The record does not provide event terms, follow-up duration, participant-level information, or an explanation of how the risk set was determined.
Most importantly, the primary-outcome narrative states that 1 patient withdrew before treatment and that no data were collected. That statement is difficult to reconcile with an adverse-event group listing 5 at risk and no events. The registry does not explain the relationship between these entries. The zeros should therefore be read as reported counts, not as proof that no adverse events occurred during treatment or follow-up.
General statistical explanation: a zero count does not by itself establish that an event is impossible or that a treatment is free of risk. Interpretation depends on who was observed, for how long, and how events were collected. Those details are not reported in the registry record. No safety rate or uncertainty estimate can be derived from the information described in the record.
12. What the Result Does, and Does Not, Mean
The registry record documents a planned pilot investigation of focal prostate SBRT using real-time guidance by intra-urethral radiotransponder beacons. Its primary question was whether treatment could take place as planned, with feasibility defined in that way and assessed over a timeframe of 2 years. The record also lists aims involving early efficacy, late toxicity, and quality of life.
The main result is not a measured feasibility outcome. The record says that 5 patients signed consent, 1 withdrew before treatment, and the funding source reported that it was no longer manufacturing the radiotransponder. It further says that no similar product was available, the study would not proceed, and no data were collected. The status is TERMINATED. These registry entries explain why the planned question is not answered by the registry record.
This record does not show that the planned procedure was feasible or infeasible. It does not provide an estimate of efficacy, a quality-of-life change, or a treatment-related toxicity rate. The single-group design would not have provided a randomized comparison with another treatment, even if the study had collected outcomes. No analysis result is reported.
The listed zero adverse-event counts should not be interpreted as evidence of an absence of harms because the record does not explain their relationship to the explicit statement that no data were collected. Likewise, the enrollment figure is not a substitute for treatment or follow-up observations. The information supports a description of study intent, design, termination, and the lack of collected data; it does not support conclusions about clinical benefit or harm.
13. Why This Trial Matters Statistically
This trial is statistically important as an example of the distinction between a well-defined research question and an answerable one. The registry describes a specific technical feasibility question: whether focal prostate SBRT with real-time intra-urethral beacon guidance could take place as planned. It also supplies an operational definition of feasibility. Yet a clear endpoint cannot be estimated without observations of the endpoint, and the record states that none were collected.
The case also illustrates the difference between enrollment and evaluable outcome data. The registry lists enrollment of 5, while the primary-outcome narrative says 5 patients signed consent and 1 withdrew before treatment. Those counts describe participation and withdrawal, not whether treatment was delivered or whether feasibility was demonstrated. Statistical summaries must follow the actual measurement process rather than treating enrollment as an outcome.
Study design shapes the questions that can be answered. A single-group pilot can be suited to describing whether a technical procedure can be implemented, but it does not offer a concurrent randomized comparator for estimating a relative treatment effect. That limitation matters independently of the trial’s termination. In this record, the absence of collected data is more fundamental: there is no observed feasibility or clinical outcome to summarize.
Finally, the adverse-event listing alongside the statement that no data were collected shows why registry fields need to be interpreted together. Counts require context about the risk set and data collection. The record does not reconcile these entries, so careful statistical reading distinguishes what is listed from what can be inferred.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The primary limitation is explicit: the registry record states that no data were collected. The planned feasibility endpoint therefore has no reported outcome, and the listed secondary aims have no reported results. This prevents estimation of feasibility, efficacy, toxicity, or quality-of-life outcomes.
The study was terminated after the funding source informed the investigators that it was no longer manufacturing the radiotransponder, with no similar product available. As a result, the intended treatment pathway could not proceed as described in the record. The registry does not report whether any participant received a study procedure before termination, beyond stating that 1 patient withdrew consent prior to treatment and that no data were collected.
The small listed enrollment of 5 and the withdrawal further limit what could have been learned even if some observations had been available. However, the record does not support calculations about precision or likely statistical power, and no such inference should be made from enrollment alone.
Other details needed to assess the study are not reported in the registry record. These include a detailed statistical analysis plan, endpoint-level data, definitions for analysis populations, missing-data procedures, interim analyses, and the method used to assign the adverse-event risk set. The arm description is also truncated. These omissions make it impossible to reconstruct the intended analytic workflow or reconcile the adverse-event counts with the statement that no data were collected.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: RAD 1801: Pilot Study of Intra-Urethral Radiotransponder Beacon Guided Focal Prostate Stereotactic Body Radiotherapy — NCT03458234.
- Registry record last updated 2024-05-20; status last verified 2024-05.
- Results first posted 2024-05-20.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry record describes a single-group pilot study of focal prostate SBRT with real-time guidance by intra-urethral radiotransponder beacons. It lists a 16 French Foley Catheter as the device intervention and defines the primary feasibility endpoint as treatment taking place as planned, with a timeframe of 2 years.
The study lists enrollment of 5, with 5 patients signing consent and 1 withdrawing before treatment, according to the primary-outcome narrative. The record says the funding source stopped manufacturing the radiotransponder, no similar product was available, the study would not proceed, and no data were collected. Its status is TERMINATED.
Four outcome measures are listed, but the registry reports 0 analyses and no primary or secondary outcome results. Serious and other adverse-event entries list 0 affected, but their relationship to the statement that no data were collected is not explained.