Vaginal Cuff Brachytherapy Followed by Chemotherapy in Endometrial Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vaginal Cuff Brachytherapy Followed by Chemotherapy in Endometrial Cancer (NCT03189446), a na phase 2 study. The primary outcome is Number of Patients Completing the Protocol.

2. Clinical Question

In statistical terms, the principal question is whether participants in this treatment group completed the specified sequence. This is a feasibility question: it focuses on completion of the protocol rather than estimating a comparative treatment effect. The study also listed outcomes concerning acute toxicity, sites of failure, recurrence-free survival, contributing cause of death, and overall survival.

Because the record does not report a primary outcome result, the degree of protocol completion cannot be assessed from the posted information. Nor can the listed outcomes establish how this sequence compares with an alternative. The registry describes the intervention and outcome definitions, but the reported results available for interpretation are limited to adverse-event counts.

3. Trial Design

This was a phase II, single-group clinical study sponsored by the University of Oklahoma. The registry lists enrollment of 39 and a completed status. The recorded study start date is 2017-10-02, and the primary completion date is 2019-12-13. Masking is recorded as none, and allocation is not applicable because no randomized treatment allocation is listed.

Participants were assigned to a treatment sequence described as vaginal cuff brachytherapy followed by chemotherapy. The chemotherapy regimen is specified as carboplatin (AUC 6) on day 1 and paclitaxel 80 mg/m2 intravenously over 1 hour on days 1, 8, and 15 for 3 total cycles. The primary outcome timeframe is 4 months. Its definition requires completion of vaginal cuff brachytherapy and all 3 cycles of dose-dense paclitaxel and carboplatin chemotherapy.

A single-group design can describe outcomes among people receiving the specified sequence, but it does not estimate a randomized difference between treatment groups. No separate control arm is listed, so there is no like-for-like comparator in this record. This matters when reading any outcome: an event count in the treatment group alone does not establish what would have occurred under another approach.

The registry lists 6 outcome measures and zero analyses. The primary measure concerns protocol completion; listed secondary measures concern acute toxicity, sites of failure, recurrence-free survival, contributing cause of death, and overall survival. The record does not report a rationale for the enrollment target, a statistical analysis plan, interim analyses, or the methods used to analyze these secondary outcomes. The registry’s enrollment of 39 should therefore be understood as the recorded study enrollment, not as evidence of a particular design calculation or achieved statistical power.

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.

Before assignment: Of 39 enrolled participants, 32 met inclusion criteria and evaluable then assign to the single arm treatment.

Overall Study

Reasons for not completing this period:

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 Number of Patients Completing the Protocol, measured over 4 months.

The primary endpoint is the number of participants completing the protocol. Completion is defined as receiving vaginal cuff brachytherapy followed by 3 cycles of dose-dense paclitaxel and carboplatin chemotherapy, with a 4-month timeframe. This endpoint captures whether participants get through the planned treatment sequence, rather than measuring a comparative treatment effect.

A completion count can be useful in a feasibility study because it describes how many participants reached the specified end of the regimen. It is a count, not a time-to-event measure or a direct measure of cancer control. By itself, it does not explain why a participant did or did not complete treatment. Reasons for non-completion and the number completing are not reported in the registry record.

The distinction between an endpoint definition and its result is important. The registry gives the definition and timeframe, but does not provide the observed count of participants who completed the protocol. Consequently, the endpoint’s outcome cannot be evaluated from the posted results. The record also does not report a threshold for what would count as feasible, or a formal statistical criterion for judging the completion count. Any conclusion about feasibility would require results and interpretation beyond the endpoint description alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Clinical trial results can be described using counts, proportions, estimates of differences, or time-to-event measures, depending on the outcome and design. General statistical explanation: a count states how many participants had an event, while a proportion relates that count to a defined group at risk or analyzed. The denominator is essential because a count alone does not show how frequently an event occurred within a group. Here, the registry reports event counts and at-risk group sizes for adverse events, but does not report a primary completion count.

What does a confidence interval add?

General statistical explanation: a confidence interval expresses the uncertainty around an estimated quantity under a statistical model. A narrow interval indicates greater precision than a wide interval, while neither guarantees that the model is appropriate or that the result is free of bias. The registry record does not list confidence intervals for the primary endpoint or adverse-event counts. Their absence means the precision of those results cannot be assessed from interval estimates in the record.

Why does the single-group design matter?

General statistical explanation: randomized comparisons are designed to compare outcomes across groups whose treatment assignment is determined by random allocation. In a single-group study, there is no concurrent randomized comparison in the record. Descriptive results can characterize the observed group, but cannot by themselves separate treatment effects from other influences or establish what would have happened under a different treatment. The allocation field is not applicable, and the study model is single-group.

How should the completion endpoint be understood?

The endpoint is a count of participants completing a defined sequence within a specified timeframe. General statistical explanation: for a binary outcome such as completion or non-completion, the underlying information is whether each participant meets the endpoint definition. A total count can summarize this outcome, but interpretation also depends on knowing the relevant analysis population and how missing or incomplete outcome information was handled. The registry defines completion but does not report the observed count, analysis population, or missing-data handling.

What do the sample-size illustrations represent?

The sample-size assumptions describe planning illustrations rather than the trial’s own design. They use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect set as a stated fraction of the observed effect. General statistical explanation: such calculations describe the number of participants that would be needed under specified assumptions to detect a particular effect with a chosen power. They are sensitive to the assumed effect size and analysis method.

These illustrations are not observed power and do not show that the study was adequately sized for its actual objectives. The record does not report the study’s own sample-size justification. Further, the primary endpoint result needed to characterize an observed completion effect is not reported, and the study itself has no two-arm randomized comparison. The illustration assumptions should not be mistaken for the study design or a comparative finding.

What can be said about the adverse-event counts?

The registry lists 0 serious adverse events among 32 participants at risk, 10 other adverse events among 32 at risk, and 1 death. General statistical explanation: counts are descriptive and do not show precision or causality on their own. Small or limited groups can leave substantial uncertainty about the range of event frequencies compatible with the observations. No interval estimates or comparative safety analyses are listed. The record also does not explain the relationship between the adverse-event group and the enrollment of 39.

The record reports zero analyses, so no statistical analysis results are available for the listed outcomes. General statistical explanation: an analysis plan typically specifies how endpoints, populations, missing observations, and multiple outcomes will be handled. Those details affect how estimates should be interpreted. The analysis plan is not reported in the registry record, so it is not possible to determine whether particular modeling choices, adjustments, or sensitivity analyses were planned or conducted.

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("Vaginal Cuff Brachytherapy + Chemotherapy")
n      <- c(32)
events <- c(27)
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  Vaginal Cuff Brachytherapy + Chemotherapy  32  27  84.4  67.2  94.7  68.2  93.1  68.1  93.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 6 outcome measures, including the primary protocol-completion outcome and secondary measures concerning acute toxicity, sites of failure, recurrence-free survival, contributing cause of death, and overall survival. It lists zero analyses. No multiplicity procedure is reported in the registry record. General statistical explanation: when several outcomes are tested, the chance of at least one apparently noteworthy result can increase if each is assessed without accounting for the collection of tests. Whether and how that issue was addressed cannot be determined from the record.

Missing-data methods are not reported. The registry defines the primary endpoint and timeframe but does not state how participants with incomplete treatment, missing outcome status, or unavailable follow-up were handled in analysis. It also does not report reasons for non-completion. These omissions matter because an endpoint count depends on which participants are included and how unknown outcomes are treated.

The analysis population is not reported. Enrollment is 39, whereas the adverse-event figures use groups of 32 participants at risk. The record does not explain the group composition or the difference in denominators. No assumptions about exclusions, follow-up, or evaluability should be inferred from that difference.

Because analysis methods and outcome results are not listed, the record cannot establish whether all enrolled participants were included in each outcome analysis, whether missing data were imputed, or whether sensitivity analyses were used. The primary completion result and secondary outcome analyses remain unreported 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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists 0 participants affected by serious adverse events among 32 at risk. For other adverse events, it lists 10 affected among 32 at risk. It also records 1 death. These figures are counts, and should be read separately rather than as a complete account of safety across all enrolled participants.

The record does not identify any top serious adverse-event terms. It does not provide event-level descriptions, timing, severity details beyond the serious/other categories, relatedness assessments, or an explanation of the death. The relationship of the adverse-event group to the enrolled group of 39 is also not reported in the registry record. The recorded counts therefore do not establish the cause of an event or whether it was related to treatment.

General statistical explanation: a zero count in a group does not prove that an event cannot occur; it describes what was recorded in that group. With no interval estimates, comparative group, or detailed safety analysis, the precision and comparative meaning of the counts cannot be assessed. The figures are descriptive registry results, not a basis for claims about safety relative to another treatment.

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

The record describes a phase II, single-group study of vaginal cuff brachytherapy followed by carboplatin and dose-dense paclitaxel. It defines protocol completion as the primary outcome and gives a 4-month timeframe. It also records adverse-event counts in a group of 32 participants at risk. These details provide a limited description of the study and its posted safety counts.

The main result needed to assess the stated feasibility question is not reported: the registry does not give the number of participants who completed the protocol. Therefore, the outcome definition cannot be converted into a conclusion about how often the treatment sequence was completed. The record also does not state a feasibility threshold against which completion could be judged.

The adverse-event counts do not establish comparative safety or causation. There is no separate randomized comparator, and the record does not explain the difference between enrollment of 39 and the 32 participants at risk in the adverse-event group. It also does not report results for the listed recurrence-free survival, overall survival, sites-of-failure, or other secondary outcomes.

These limitations do not make the study design meaningless: a single-group study can describe treatment delivery and observed events. But interpretation must remain descriptive. The registry record does not support conclusions about relative benefit, relative harm, or long-term outcomes, nor does it show whether the primary protocol-completion objective was met. Such conclusions would require outcome results and analyses that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study raises a distinct statistical question from a randomized efficacy trial. Its primary measure is completion of a specified treatment sequence, so the endpoint is focused on treatment delivery and feasibility. Clear definitions matter: the registry states that completion requires vaginal cuff brachytherapy followed by 3 cycles of dose-dense paclitaxel and carboplatin chemotherapy, within a 4-month timeframe.

Its single-group design also illustrates why outcome counts need context. An event count can describe what was recorded among participants in a group, but it cannot estimate a treatment contrast without a comparator. That distinction applies to both completion and adverse events. Even a precisely measured count would not answer what would have happened under a different treatment sequence.

The record also highlights the importance of reporting denominators, analysis populations, and missing-data handling. Enrollment is 39, while the adverse-event group is 32 at risk; the record does not explain the relationship. Without the primary completion count, the endpoint definition alone cannot answer the feasibility question. Without outcome analyses, the listed secondary measures cannot be interpreted as results.

Statistically, the study is a reminder that a registry entry can give useful information about design and planned outcomes while leaving key result-level questions unresolved. For readers, distinguishing the registered objective from the reported findings prevents a protocol description from being mistaken for evidence that the objective was achieved.

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 most direct limitation of the posted record is that it does not report the primary outcome count. The study’s stated aim concerns feasibility, and its primary endpoint is protocol completion, but the number completing the defined sequence is absent. The record also does not state a threshold for interpreting feasibility.

The single-group design has no like-for-like randomized control. Consequently, the results cannot establish a comparative treatment effect. The adverse-event group contains 32 participants at risk, while study enrollment is 39; the registry record does not explain this difference or identify the analysis populations. The reason for the difference should not be inferred.

Although the record lists secondary outcomes, it does not report their results or analyses. Follow-up details for recurrence-free and overall survival are not reported. The handling of missing data, reasons for non-completion, multiplicity, and the statistical analysis plan are also not reported in the registry record. No sample-size justification for the trial is given.

Safety interpretation is limited by the absence of serious-event terms, event descriptions, relatedness assessments, and an explanation of the listed death. The posted counts are descriptive and do not provide comparative estimates or measures of precision. Together, these limitations mean that the registry record supports a basic description of the design and selected counts, but not a full assessment of treatment completion, comparative outcomes, or safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Vaginal Cuff Brachytherapy Followed by Chemotherapy in Endometrial Cancer — NCT03189446.
• Registry record last updated 2024-03-08; status last verified 2024-03.
• Results first posted 2021-01-12.
• 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 completed phase II study is listed as a single-group trial sponsored by the University of Oklahoma, with enrollment of 39. The treatment sequence was vaginal cuff brachytherapy followed by carboplatin and dose-dense paclitaxel chemotherapy. The primary endpoint was the number of participants completing the protocol within 4 months.

The registry lists 6 outcome measures and zero analyses. It does not report the primary completion count or results for the listed secondary outcomes. Adverse-event information records 0 serious events among 32 participants at risk, 10 other events among 32 at risk, and 1 death. The record does not explain the difference between enrollment and the adverse-event denominator. Interpretation is therefore limited to the design, endpoint definition, and posted descriptive counts.