A Study of Definitive Therapy to Treat Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Definitive Therapy to Treat Prostate Cancer (NCT02716974), a na phase 2 study. The primary outcome is Efficacy as Assessed by 2-year PSA Progression-free Survival Rate.

2. Clinical Question

The clinical question combines a treatment-safety aim with an efficacy outcome. The brief summary says the study was designed to assess the safety of the multimodality treatment. The named primary outcome, however, is the 2-year PSA progression-free survival rate, expressed as a participant count. Secondary outcomes include safety assessed through neutropenia and surgical or radiation toxicities, and time to PSA recurrence.

These aims involve different kinds of evidence. Safety outcomes describe events observed during treatment and follow-up. A PSA-based outcome describes disease status according to a specified laboratory threshold and testosterone condition at a specified time. Neither description alone establishes how the regimen compares with another treatment. Because the design has no comparator group, the study is descriptive of outcomes among those assessed under this regimen rather than a controlled estimate of its relative effect.

3. Trial Design

The registry record identifies this as a phase II, single-group study with no masking. Allocation is listed as not applicable. The record reports enrollment of 26 and status as completed. The listed start is 2016-06, and primary completion is recorded as 2022-04. These dates describe the registry timeline; they do not establish how long each participant was followed or whether all enrolled participants contributed to every outcome.

The planned treatment sequence began with systemic chemo-hormonal therapy, followed by definitive local tumor control with prostatectomy with or without adjuvant radiation, then consolidative stereotactic radiation to oligometastatic lesions. The description specifies up to 6 months of neoadjuvant androgen deprivation and up to 6 cycles of docetaxel, with androgen deprivation planned for a total of 1 year. Leuprolide acetate and bicalutamide are listed as drugs, alongside docetaxel, prostatectomy, and radiation. The registry record does not report how many participants received each component, completed the planned sequence, or received adjuvant radiation.

A single-group design can document the outcomes and toxicities observed among participants treated in a defined study, but it does not itself separate treatment effects from other explanations for those outcomes. Without a concurrent comparison group, differences from another treatment or from usual care cannot be estimated directly from this design. This is especially relevant when interpreting the primary outcome: a PSA status at a specified time is a reported endpoint, not by itself a comparative treatment effect.

The registry record does not report a statistical analysis plan, an interim-analysis plan, or a sample-size justification. It also does not report the analysis population or the number assessed at the primary time point. The record lists no analyses for the outcome data. Those omissions limit assessment of how participants were handled in the efficacy analysis and how uncertainty around the observed result was intended to be quantified.

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 Efficacy as Assessed by 2-year PSA Progression-free Survival Rate, measured over 2 years.

The primary endpoint is titled “Efficacy as Assessed by 2-year PSA Progression-free Survival Rate.” It is recorded as a count of participants and defined as the number who have PSA below 0.2 ng/ml and non-castrate testosterone levels 2 years after enrollment. The time point and thresholds make the endpoint operational: they specify when status is assessed and what laboratory conditions qualify.

PSA is used in this endpoint as a marker of recurrence or progression, while the testosterone condition identifies participants whose PSA status is assessed after testosterone is no longer castrate. The endpoint therefore is not simply a count of everyone enrolled who has low PSA at any time. Its definition is conditional on the testosterone status at the specified follow-up time. The registry record does not report how participants who did not have non-castrate testosterone at that time were handled in the analysis.

A fixed-time endpoint can be clinically interpretable because it asks about status at a stated follow-up point. Statistical interpretation still depends on who was assessed, how missing measurements were handled, and whether the reported count is accompanied by a denominator and uncertainty interval. The outcome result and those supporting details are not reported in the registry record. Consequently, the endpoint definition is available, but the observed rate and its precision cannot be described from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a binary outcome expressed as a count of participants with an event or qualifying status. For the primary endpoint, the qualifying status is PSA below 0.2 ng/ml together with non-castrate testosterone at 2 years after enrollment. Although the outcome title calls this a rate, the measurement is recorded as a participant count. To interpret a rate, readers need both the count meeting the definition and the relevant denominator. Neither the primary count nor its denominator is reported in the registry record.

What does a confidence interval add?

As a general statistical principle, a confidence interval expresses the uncertainty around an estimate under the assumptions of the analysis. A point estimate alone does not show how compatible the data are with a range of underlying values. For a participant proportion, uncertainty depends in part on how many participants contribute usable outcome information and how the outcome is distributed. The registry record does not report a confidence interval for the primary endpoint, so its precision cannot be assessed.

An interval does not correct problems in the data or design. It cannot address selection into the study, missing follow-up, outcome misclassification, or the absence of a comparison group. It quantifies sampling uncertainty as defined by a statistical procedure; it does not establish causation or eliminate bias. Because the primary outcome result itself is not reported, no trial-specific interval interpretation is possible.

Why does the single-group structure matter?

In a randomized comparison, allocation can support a controlled comparison between groups, subject to the quality of conduct and analysis. This study is recorded as single-group, with allocation not applicable and no masking. It therefore has no concurrent control group in the registry record. An outcome observed in this group cannot be interpreted as a treatment difference relative to an alternative arm. A comparison with external expectations would require an appropriate and explicitly described reference; none is reported in the registry record.

The open-label nature of the study means masking is listed as none. This does not automatically invalidate measured outcomes, but it can matter for outcomes that involve judgment or reporting. PSA is a laboratory measure, whereas some toxicity outcomes may depend on clinical ascertainment and classification. The registry record does not report outcome-adjudication procedures, so the extent to which assessments were standardized cannot be evaluated.

What does over-dispersion mean in general?

For count outcomes, a statistical model may assume a particular relationship between the average count and its variability. Over-dispersion means the observed variability is greater than the model assumes. If not accounted for, standard errors may be too small and intervals or tests may appear more precise than warranted. This is a general consideration, not a finding about this study. The primary endpoint is recorded as a count of participants meeting a binary definition, and the registry record does not report a model or dispersion estimate.

For a binary outcome, interpretation commonly focuses on the number meeting the definition relative to the number assessed. For time-to-event outcomes, the timing of events and censoring can matter, and methods account for follow-up time rather than only a final count. The secondary outcome of time to PSA recurrence is named, but its analysis method and results are not reported in the registry record. No time-to-event estimate or event count should be inferred from its title.

How should planning illustrations be interpreted?

As a general statistical principle, a sample-size calculation is conditional on assumptions about the outcome, target effect, significance level, allocation, and analysis method. The registry’s planning description refers to a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and detecting a stated fraction of an observed effect. It distinguishes planning illustrations for time-to-event outcomes, which use total events, from other outcomes, which use participants per arm.

Those assumptions describe a planning illustration, not the design of this single-group trial. The illustration’s assumed equal allocation between two arms does not make this study randomized or create a control arm. A planning sample size is not an observed outcome and is never observed power. The registry record does not report the study’s own sample-size justification, its planned target effect, or a statistical decision rule. The numerical planning outputs are not reported in the registry record, so they cannot be described or checked against trial-specific results.

More broadly, statistical interpretation requires a clear link between the question, endpoint, population, and analysis. The record defines the primary endpoint but does not report the analysis population, missing-data method, or inferential analysis. These details are needed to understand whether an estimate represents everyone enrolled, those with available measurements, or a narrower subset meeting the testosterone condition. Without them and without the result, the endpoint’s statistical evidence remains unquantified in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Chemohormonal and Definitive Therapy")
n      <- c(26)
events <- c(17)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Chemohormonal and Definitive Therapy  26  17  65.4  44.3  82.8  46.2  80.6  46.0  80.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures: the primary PSA progression-free survival endpoint and secondary outcomes concerning treatment safety and time to PSA recurrence. It lists no analyses. The record does not report how the outcomes were prioritized in the statistical analysis, whether there were multiple comparisons within an outcome, or whether any adjustment for multiplicity was planned. The number of outcome measures alone does not establish how many statistical tests were performed.

As a general statistical principle, examining multiple outcomes or multiple comparisons can increase the chance that at least one result appears notable by chance. Methods for addressing multiplicity depend on the inferential aims and analysis plan. Without a reported plan or analysis results, it is not possible to determine whether multiplicity was addressed or how it might affect interpretation. No claim about a statistically significant finding is supported by the registry record.

The registry record does not report a missing-data method for the primary endpoint. That matters because the definition requires a measurement at 2 years and non-castrate testosterone at that time. The record does not explain how participants without a PSA measurement, without the required testosterone status, or without follow-up at the specified time were treated analytically. It also does not state the number included in the endpoint assessment.

The analysis population is not reported in the registry record. It is therefore unclear whether the planned analysis was based on all enrolled participants, participants who received treatment, participants who completed treatment, or participants with evaluable follow-up. These are distinct analysis choices in general; the record does not identify which applies. The enrollment figure should not be substituted for an outcome denominator. No imputation, sensitivity analysis, or handling of withdrawals is described in the registry record.

12. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: back pain (3.8%), abdominal pain (3.8%), partial bowel obstruction (3.8%), neutropenic fever (3.8%).

The serious adverse-event summary lists 26 participants at risk and 2 affected. The other-event summary lists 26 at risk and 26 affected. The record lists deaths as 0. These are counts in the registry’s safety summary, not a complete description of every event or of the circumstances in which events occurred.

The serious adverse-event terms shown include back pain, abdominal pain, partial bowel obstruction, and neutropenic fever, each with 3.8%. The percentages are reproduced as recorded; the registry record does not provide a term-specific count in this summary. It also does not state whether the listed terms were considered related to treatment, how severity was graded, or whether terms could overlap within participants. A list of terms should not be interpreted as an exhaustive profile of all possible toxicities.

The safety outcomes named elsewhere in the record concern neutropenia and surgical or radiation toxicities. Outcome-specific results for those measures are not reported in the registry record. The broad “other” summary and the serious-event terms do not replace those planned safety outcomes, and the registry record does not provide enough detail to compare risks across treatment components or over time.

As a general statistical principle, safety counts are most interpretable when their definitions, observation periods, denominators, severity, and attribution are clear. The registry summaries give at-risk and affected counts, but do not report these additional details. They describe what is recorded, not a causal estimate of treatment-related risk.

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

The registry record establishes that a phase II, single-group study evaluated a planned sequence of chemo-hormonal therapy, definitive local treatment, and consolidative stereotactic radiation in men with newly diagnosed oligometastatic prostate cancer. It defines a primary PSA-based outcome at 2 years and lists safety and recurrence outcomes. It also reports safety-summary counts and serious-event terms.

The record does not report the primary endpoint result. It therefore does not show how many participants met the PSA and testosterone definition, the rate among those assessed, or the uncertainty around that estimate. The secondary outcome results are also not reported in the registry record. The study’s completed status does not, by itself, fill in those missing results.

The study’s design also limits what could be concluded even if outcome estimates were available. With a single group and no randomized comparator, observed outcomes would not provide a direct estimate of how the regimen compares with another treatment. A before-and-after description or comparison with an external benchmark would require additional information and assumptions; neither is reported in the registry record.

The safety summary indicates recorded affected-participant counts and lists serious-event terms, but does not give enough detail to attribute events to treatment or characterize their timing and severity fully. Zero deaths in the summary is a recorded count, not proof that every safety concern was absent. The registry record does not report all outcome definitions and analysis details needed to make broader safety claims.

Accordingly, the defensible reading is limited: the registry describes the treatment strategy, the population, and the endpoints, while leaving the primary efficacy result and further outcome analyses unreported. Neither efficacy nor comparative benefit can be inferred from the endpoint title, enrollment, or study completion status alone.

14. Why This Trial Matters Statistically

This trial raises several statistical issues that are common in studies of complex treatment strategies. The intervention has multiple sequential components, including systemic treatment, local prostate treatment, and radiation to metastatic lesions. An outcome after this sequence reflects the experience of the treatment strategy as a whole; without further analyses, it cannot isolate the contribution of any individual component.

The primary endpoint also illustrates why outcome definitions and analysis populations must be read together. The qualifying PSA status is assessed at a fixed time and is conditional on non-castrate testosterone. A count of participants meeting that definition is interpretable only when the relevant denominator and handling of participants without qualifying measurements are known. Those details are not reported in the registry record.

The single-group structure is central to the statistical meaning of any observed result. It can describe what happened among participants treated under the study approach, but it does not provide a randomized estimate against a concurrent alternative. This design distinction is not a technical footnote: it determines whether a result is descriptive or comparative.

The record also separates a safety aim from the named primary efficacy endpoint. Safety summaries and efficacy outcomes answer different questions and need their own definitions and analysis details. The available safety counts do not substitute for the unreported primary endpoint, and the endpoint definition does not quantify safety.

Finally, this record demonstrates the difference between trial registration information and a complete statistical report. The registry gives design and endpoint details, but does not report outcome analyses, uncertainty estimates, missing-data procedures, or an analysis population. Those omissions prevent a full assessment of precision and robustness. Clear reporting of denominators, follow-up, and analysis choices would be necessary to evaluate the results statistically.

15. 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 main limitation for statistical interpretation is that the primary outcome result is not reported in the registry record. The outcome definition is available, but the count meeting it, the denominator assessed, and a measure of uncertainty are not. The listed enrollment cannot be assumed to be the primary endpoint denominator.

The outcome is conditional on non-castrate testosterone at 2 years after enrollment. The registry record does not explain how participants who did not meet that condition were handled, whether they had outcome measurements, or whether their status affected inclusion in the analysis. It does not report the missing-data approach or analysis population.

The study is single-group, with no randomized comparator. Any observed outcomes would consequently be descriptive for the participants studied rather than a controlled estimate of comparative effect. The record also does not report how many participants received or completed each treatment component, so treatment exposure and outcome cannot be related from the registry summary.

The registry record does not report detailed eligibility criteria, participant characteristics, outcome-adjudication methods, or a statistical analysis plan. It does not describe interim analyses, multiplicity procedures, or the study’s sample-size justification. These gaps prevent assessment of the intended inferential framework and of how well the analysis matched the study question.

Safety reporting is also limited in detail. Counts and serious-event terms are listed, but event timing, severity grading, treatment attribution, and term-specific counts are not reported in the registry summary. These limitations are specific to the information recorded and should not be filled by assumptions about the protocol or conduct.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of Definitive Therapy to Treat Prostate Cancer — NCT02716974.
• Registry record last updated 2022-08-04; status last verified 2022-07.
• Results first posted 2022-08-04.
• 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.

19. Record Summary

This phase II study is registered as a completed, unmasked, single-group trial of multimodality treatment for newly diagnosed men with oligometastatic prostate cancer. Enrollment is listed as 26. The treatment strategy includes chemo-hormonal therapy, prostatectomy with or without adjuvant radiation, and consolidative stereotactic radiation to oligometastatic lesions.

The primary endpoint is the count of participants with PSA below 0.2 ng/ml and non-castrate testosterone at 2 years after enrollment. The registry record does not report the primary outcome result, its denominator, or an uncertainty estimate. Secondary outcomes concern safety and time to PSA recurrence; their results are not reported in the registry record.

The safety summary lists serious events affecting 2 participants, other events affecting 26 participants, and 0 deaths. Serious-event terms are listed with percentages. The record does not report detailed event attribution or the statistical analysis plan, missing-data method, or analysis population. The design does not include a randomized comparison group.