Radium Ra 223 Dichloride, Hormone Therapy and Stereotactic Body Radiation Therapy in Treating Patients With Metastatic Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Radium Ra 223 Dichloride, Hormone Therapy and Stereotactic Body Radiation Therapy in Treating Patients With Metastatic Prostate Cancer (NCT03361735), a na phase 2 study. The primary outcome is Time to Treatment Failure.

2. Clinical Question

3. Trial Design

This is a phase 2 clinical trial with a single-group model. The registry lists enrollment of 25 and allocation as NA. Its status is active, not recruiting. The start date is 2018-08-29 and the primary completion date is 2024-03-21. Those record dates and status describe the study’s registration, not the timing or completeness of every participant’s follow-up.

The intervention combines ADT, SBRT and radium Ra 223 dichloride for patients with oligometastatic castration-sensitive prostate cancer. Leuprolide acetate or goserelin acetate is described as hormone therapy. The treatment description says it begins 4 weeks (28 days) before radiation therapy and may continue for up to 32 weeks. SBRT is described as 3-5 fractions, delivered every 40 hours over 7-21 days, beginning on day 1 of course 1. The radium schedule in the record is incomplete, so its full timing cannot be described from this entry.

The record lists no masking. With no separate comparator arm, the study is not a randomized comparison of the combined regimen against another treatment. Outcomes observed in a single group can describe what happened to participants receiving the regimen, but they do not by themselves separate treatment effects from other explanations, such as the natural course of disease or selection of participants. The registry record does not report a protocol-level statistical analysis plan, a sample-size justification, or further details of the analysis population. It also does not report whether any interim analyses were planned or conducted.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Time to Treatment Failure, measured over Assessed up to 5 years.

The primary endpoint is time to treatment failure, expressed as a median in months with a 95% confidence interval, and assessed up to 5 years. The clock starts at initiation of ADT for metastatic disease. Failure is defined by the earliest of the specified events: PSA increase to above the pre-ADT level or PSA above 10, whichever is smaller; radiographic or clinical progression; or resumption of ADT at the physician's choice.

Time-to-event endpoints are used when the outcome is the time until an event occurs. They can account for participants whose event has not been observed by the end of their available follow-up, provided the analysis method and censoring rules are specified and appropriately applied. A median time-to-event estimate marks the point at which the estimated event-free proportion reaches the median threshold; it is not an average time and does not mean every participant experienced failure at that time. These are general statistical descriptions, not claims about the analysis actually used in this trial.

The registry record gives the endpoint definition and planned timeframe but does not report the median or its confidence interval. It also does not report how the PSA criteria were operationalized, how events were adjudicated, or how censoring and participants with incomplete follow-up were handled. Without a posted estimate and interval, the endpoint’s magnitude and precision cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a median time-to-event estimate represent?

Time-to-event analysis concerns the elapsed time until a defined event. In this trial, the specified starting point is initiation of ADT for metastatic disease, and the endpoint combines PSA, progression and treatment-resumption criteria. A median time-to-event estimate is the time at which the estimated probability of remaining free of the event reaches the median threshold. It does not describe the time experienced by every participant and is not an arithmetic average.

Some participants may not have a recorded event before their follow-up ends. General time-to-event methods can retain information from such participants up to the point they are last known to be event-free through censoring. The validity of that approach depends on the analysis rules and assumptions, including how censoring relates to the chance of the event. The registry record does not report the censoring rules or the specific estimator used, so it is not possible to confirm how these issues were handled.

What does the confidence interval add?

A confidence interval expresses uncertainty around an estimate under the statistical model and its assumptions. It helps readers assess precision rather than treating a single point estimate as exact. The primary endpoint is designated to include a 95% confidence interval, but neither the median nor the interval limits are reported in the registry record. Consequently, the estimate’s precision cannot be evaluated from this entry.

Confidence intervals do not remove design limitations. A precise estimate from a single-group study would still describe the observed group and would not create a randomized comparison. Statistical precision and causal evidence answer different questions: the former concerns uncertainty around an estimate, while the latter concerns whether the design supports attributing an outcome difference to treatment.

How should the single-group design be understood?

In a randomized comparison, treatment groups are assigned according to a defined allocation process, allowing a direct comparison that can help address differences between groups. This record lists a single-group model and allocation as NA, with no masking. There is no separate control group described. Results from the treated group could characterize outcomes under the combined regimen, but they could not, on their own, estimate a contrast against another treatment or establish what would have occurred in a control group.

The treatment combines ADT, SBRT and radium Ra 223 dichloride. A single-group outcome cannot isolate the contribution of one component from the others. Nor can it establish from the record alone whether any observed outcome is attributable to the regimen rather than other influences. These are general limitations of interpreting uncontrolled treatment outcomes, not statements that a particular bias occurred in this study.

What does the composite endpoint imply?

The treatment-failure definition includes PSA thresholds, radiographic or clinical progression, and resumption of ADT by physician's choice. A composite endpoint can capture several ways a treatment course may be considered to have failed, but its overall time-to-event estimate depends on which component occurs first. If component events differ in importance or frequency, the composite result may be driven more by some components than others. The record does not report component-specific counts or times, so the contribution of each component cannot be assessed.

The PSA rule uses whichever is smaller of an increase above the pre-ADT level or a PSA value above 10. The record does not provide additional operational details, such as how measurements were confirmed or how missing measurements affected classification. Those details matter for reproducibility and interpretation, but are not reported in the registry record.

What can be inferred from the analysis information?

The record lists 13 outcome measures and 0 analyses. It names the primary endpoint and several secondary outcomes, but does not provide numerical endpoint results, analysis populations or a statistical plan. The absence of a listed analysis does not establish that no analysis was conducted; it means that analysis details are not reported in this registry entry.

Multiplicity is a general concern when many outcomes or comparisons are tested: the chance of a chance-positive finding can increase if tests are interpreted without accounting for the number of analyses. The record does not report whether multiplicity adjustments or a hierarchy among outcomes were specified. It is therefore not possible to characterize the approach used. Similarly, the analysis model, handling of missing data, and any planned interim analyses are not reported in the registry record.

Statistical methods can summarize uncertainty, but they cannot compensate for missing outcome reporting or create a control comparison where none is described. The available record supports describing the planned endpoint and design, not judging the magnitude of the primary outcome or the strength of a treatment effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 13 outcome measures, including time-to-event, response, duration and safety outcomes. It lists 0 analyses. A count of outcomes does not reveal how many statistical tests were conducted, which outcomes were analyzed, or which results were prespecified. The record does not report a hierarchy among outcomes or any adjustment for multiplicity. In general, when many outcomes are tested, interpreting isolated findings without considering the testing strategy can overstate the evidence; whether that issue arose in this trial cannot be determined from the record.

The analysis populations are not reported in the registry record. Although enrollment is listed as 25, the number included in each outcome analysis, the number followed for the primary endpoint, and the number excluded from any analysis are not reported. The record also does not describe missing-data methods, censoring rules, or the handling of incomplete endpoint measurements. These omissions limit assessment of how representative the analyzed participants were of those enrolled and how robust estimates might be to incomplete follow-up.

The statistical analysis plan, including any interim analyses and stopping rules, is not reported in the registry record. The primary endpoint has a specified timeframe of up to 5 years, but actual follow-up duration and the completeness of follow-up are not reported. These are reporting limitations; they do not show that a particular method was or was not used.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event entries are separated by de novo mCSPC and oligoprogressive mCSPC patients receiving the listed treatment. For the de novo group, the record lists 6 at risk for serious adverse events, 0 affected by serious adverse events, 6 at risk for other adverse events, 6 affected by other adverse events, and 1 death. For the oligoprogressive group, it lists 18 at risk for serious adverse events, 0 affected by serious adverse events, 18 at risk for other adverse events, 18 affected by other adverse events, and 5 deaths.

These are group-level registry counts, not rates or comparisons between randomized arms. The record’s serious-adverse-event term list is empty, so it does not identify specific serious events in this entry. The other-adverse-event counts do not describe event type, severity, timing, duration or attribution. The death counts are reported in the safety entries; the record does not state in the registry record whether the deaths were treatment-related.

These figures should be read as reported counts, not as proof that an event was caused by or unrelated to treatment. The registry record does not report the safety analysis period, detailed definitions or individual-level context. No treatment-safety conclusion can be drawn from the counts alone.

12. What the Result Does, and Does Not, Mean

The registry record describes a phase 2, single-group study of ADT, SBRT and radium Ra 223 dichloride in oligometastatic castration-sensitive prostate cancer. It specifies time to treatment failure as the primary endpoint, defines the event criteria, and gives a timeframe of up to 5 years. These details clarify what the study is intended to assess.

The record does not report a median time to treatment failure, its 95% confidence interval, or another primary-outcome result. It therefore does not show how long participants remained free of the defined event or how precise such an estimate might be. It also does not report numerical results for the secondary outcomes in the information.

Even if an outcome estimate were available, the single-group design would describe the participants treated under the regimen rather than provide a randomized comparison with another treatment. The record cannot establish whether an outcome was caused by the regimen or distinguish the effects of ADT, SBRT and radium Ra 223 dichloride from one another. This design limitation does not negate descriptive value; it defines the type of question the study can answer.

The safety entries report counts for serious and other adverse events and deaths in the two named patient groups. They do not provide event terms, attribution or sufficient context for a treatment-safety conclusion. The registry entry also does not report the analysis populations, missing-data approach or statistical plan. Taken together, the record supports understanding the trial’s design and endpoint definitions, but it does not support a conclusion about efficacy, comparative benefit or overall safety.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a treatment question and a study design set limits on interpretation. Its primary endpoint is a time-to-event measure with a defined starting point and a composite failure rule. That definition makes clear that failure may be based on PSA, radiographic or clinical progression, or resumption of ADT by a physician. Readers need to know which events count before they can interpret any estimate.

The single-group design also matters. Outcomes can be described in the treated group, but there is no randomized comparator in the registry record to support a treatment contrast. Combining ADT, SBRT and radium Ra 223 dichloride further means a group outcome cannot separate the contribution of each component. These distinctions help prevent a descriptive result from being read as proof of comparative effect.

Reporting matters as much as endpoint choice. The record names a median and 95% confidence interval as the primary summary, but does not report either value. It lists secondary outcomes and adverse-event counts, yet the analysis populations, missing-data methods and statistical plan are not reported. Without estimates and their uncertainty, readers cannot assess the magnitude or precision of the primary outcome.

These are general statistical lessons illustrated by the record: define the event, distinguish precision from causal evidence, and interpret results in light of the design and completeness of reporting. They do not imply that an unreported result is favorable or unfavorable.

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 trial is listed as a single-group study with allocation marked NA and no masking. The registry record describes no separate control arm, so it cannot support a randomized comparison. The combined regimen also prevents a single-group outcome from identifying the effect of any one component independently.

The primary endpoint is composite. Its event criteria include PSA thresholds, clinical or radiographic progression, and resumption of ADT at the physician's choice. These components may represent different kinds of events, but component-specific results are not reported in the registry record. The record also does not provide further operational detail on PSA confirmation, event adjudication or the handling of missing measurements.

The primary result itself is not reported: no median time to treatment failure or 95% confidence interval is available in the record. Actual follow-up completeness and the number included in the endpoint analysis are also not reported. Enrollment is listed as 25, but that does not establish the analyzed population for any outcome.

The treatment description is incomplete: the radium schedule ends mid-description, and full protocol details are not reported in the registry record. The record does not report a statistical analysis plan, missing-data methods, multiplicity approach, interim analyses or sample-size justification. The adverse-event entries provide counts but no serious-event terms, event attribution or detailed safety context. These limitations restrict interpretation of both outcome estimates and safety, without indicating what unreported results would show.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Radium Ra 223 Dichloride, Hormone Therapy and Stereotactic Body Radiation Therapy in Treating Patients With Metastatic Prostate Cancer — NCT03361735.
• Registry record last updated 2026-04-09; status last verified 2026-03.
• Results first posted 2026-04-09.
• 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.

18. Record Summary

The registry identifies NCT03361735 as a phase 2 study of ADT, SBRT and radium Ra 223 dichloride in patients with oligometastatic castration-sensitive prostate cancer. It is listed as single-group, with allocation marked NA and no masking. Enrollment is listed as 25, and the status is active, not recruiting.

The primary endpoint is median time to treatment failure, with a 95% confidence interval, assessed up to 5 years. The registry defines treatment failure using PSA criteria, progression or resumption of ADT by physician's choice. It lists secondary outcomes, but does not report the primary estimate or its interval in the information available for this account.

The record includes adverse-event counts for de novo and oligoprogressive mCSPC groups. It does not report a statistical analysis plan, analysis populations or missing-data methods. The available information describes the design and intended outcomes but does not establish a comparative treatment effect.