Feasibility Study Using the Xoft System for the Treatment of Endometrial Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feasibility Study Using the Xoft System for the Treatment of Endometrial Cancer (NCT01045187), a non-randomized na study. The primary outcome is Assess Number of Patients Who Were Able to Complete Treatment Delivery Using the Axxent Electronic Brachytherapy System.

2. Clinical Question

The clinical question is about feasibility: whether treatment delivery could be completed using the specified system in this study setting. It is not framed as a comparison of the system with another treatment. Without a concurrent control group, results cannot establish how completion or safety would compare with another approach, or separate an observed outcome from other influences on care.

The record also describes assessment of acute safety and toxicity occurrence as secondary aims. These aims concern events during and after vaginal cuff brachytherapy treatment as incorporated into the physician’s current standard of practice. The registry record does not provide detailed eligibility criteria, participant characteristics, treatment schedules, or a fuller definition of the clinical setting. Those omissions limit how specifically the clinical question can be interpreted or applied beyond the participants enrolled.

3. Trial Design

This completed study is registered as a multicenter, non-randomized, single-group feasibility study for endometrial cancer. Enrollment was 15. The record lists the phase as NA, masking as none, and allocation as non-randomized. The study began in 2008-10, reached primary completion in 2010-01, and has completed status. Xoft, Inc. is listed as sponsor.

The intervention is described as electronic brachytherapy using the Xoft Axxent Electronic Brachytherapy System, with a vaginal applicator for intracavitary vaginal cuff treatment. The study summary says treatment was to follow the physician’s current standard of care. The arm description says patients were treated with electronic brachytherapy for an FDA cleared indication. These descriptions establish the general intervention studied, but do not specify treatment schedules, dose, delivery procedures, or the criteria used to determine whether treatment was complete. Those details are not reported in the registry record.

A single-group design can describe outcomes among participants who received the intervention. It does not create a randomized contrast with another treatment or control condition. The absence of masking is also part of the registered design; the record does not explain whether outcome assessment involved any separate safeguards against subjective influence.

The primary endpoint is the number of participants able to complete treatment delivery through completion of radiation therapy. Secondary aims concern acute safety and toxicity occurrence. The registry record lists three outcome measures, but the outcome descriptions and results available in the record do not provide a complete account of their definitions or findings. It lists no analysis records. The protocol, statistical analysis plan, sample-size justification, and detailed analysis populations are not reported in the registry record. Any planning illustration should therefore be kept distinct from the trial’s actual design rationale.

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: Patients who were candidates for vaginal brachytherapy post TAH-BSO with or without EBRT were enrolled. Patient participation was voluntary for this data collection study.

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 Assess Number of Patients Who Were Able to Complete Treatment Delivery Using the Axxent Electronic Brachytherapy System, measured over through completion of radiation therapy.

The primary endpoint asks how many participants were able to complete treatment delivery using the Axxent Electronic Brachytherapy System. Its stated timeframe is through completion of radiation therapy. This is a count of participants, rather than a measure of the amount of treatment received or a direct comparison of clinical outcomes.

In a feasibility study, treatment completion can indicate whether the intended delivery process was achievable for participants in the study setting. It is a practical endpoint: it focuses on completing the procedure or course as defined by the study. The record does not give a more detailed operational definition of completion, such as which interruptions, modifications, or deviations would count as completion. That definition is important because different rules can produce different counts.

The endpoint is useful for describing implementation, but it does not by itself measure tumor control, survival, symptom change, or comparative benefit. Nor does a completion count establish that treatment was completed for reasons attributable to the device; the registry record does not describe reasons for non-completion or any events affecting delivery.

Although the endpoint is named as primary, its numerical result is not reported in the registry record. Consequently, the posted information does not show how many participants completed treatment, what proportion that count represented, or how precisely the completion rate was estimated. No interval estimate or analysis result for this endpoint is reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General explanation: statistical methods connect an endpoint’s definition to an estimate and its uncertainty. For a count endpoint, the observed count answers how many participants experienced the defined outcome. If the intent is to describe a rate or proportion, the denominator and the rules for including participants must also be clear. A confidence interval expresses uncertainty around an estimate under stated assumptions; it does not guarantee that the true value lies within the interval. No confidence interval for treatment completion is reported in the registry record.

What the single-group design can estimate

A single-group study can describe outcomes in the participants who received the intervention. The primary endpoint is a count of participants able to complete treatment delivery. If reported with a clear denominator, that count could describe feasibility in this enrolled group. A single-group count is not a randomized treatment effect. It does not estimate what would have happened to the same participants under an alternative treatment, because that counterfactual group is absent.

General explanation: randomization helps create groups that are comparable, on average, with respect to measured and unmeasured factors. Without randomization and a control group, differences from external experiences or historical expectations can reflect differences in participants, care, outcome definitions, follow-up, or other conditions. This study’s registered non-randomized, single-group design should therefore be interpreted descriptively rather than as a comparative experiment.

Why the endpoint definition matters

The stated endpoint is the number of participants able to complete treatment delivery through completion of radiation therapy. A reproducible analysis requires a rule for what counts as completion and how deviations, interruptions, or missing information are handled. The registry record does not provide those operational details. It also does not report reasons for any treatment non-completion. Thus, even if a count were available, the record would not allow a detailed assessment of how it was produced.

General explanation: binary outcomes classify each participant according to whether an event occurred, while a count across participants totals those classifications. A proportion can summarize the count relative to a defined group, but its meaning depends on who belongs in the denominator. The registry entries posted for this trial identify a binary outcome type and a participant count endpoint; they do not provide a primary result or analysis denominator beyond the enrollment information.

Uncertainty and precision

General explanation: estimates from a small study can be imprecise because each participant’s outcome has a comparatively strong influence on the overall description. Confidence intervals can make this uncertainty visible, provided the estimate and method are available. A point estimate alone would not show the range of values reasonably compatible with the data. Here, the primary endpoint result and its uncertainty are not reported in the registry record, so precision cannot be assessed.

Hypothesis tests and p-values address a specified statistical question under a model. They do not measure the size or clinical importance of an effect, and they do not correct weaknesses in design or incomplete reporting. The registry record lists no analysis records and does not report a p-value or a hypothesis test for the primary endpoint. No inferential conclusion should be inferred from the endpoint title or the study’s completion status.

Planning assumptions versus the study design

The sample-size material is described as a planning illustration based on an observed effect, not as the trial’s own design. Its stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those assumptions do not describe the registered single-group design. Any such illustration is hypothetical and should not be treated as the study’s planned enrollment rationale, an observed power calculation, or evidence that the design was adequate. The registry record does not report a sample-size justification for this trial.

General explanation: a sample-size calculation depends on the endpoint, target effect, variability or event frequency, error rate, and design. Changing an assumption changes the planning result. A planning estimate is not a measure of the probability that a completed study has detected a real effect. Nor does a calculation based on an observed result establish that the result is reliable; using an observed effect for planning can make the illustration dependent on the particular estimate.

Safety summaries and statistical scope

The safety information is presented as affected-participant counts in serious and other adverse-event categories. General explanation: event counts and participant counts are not interchangeable, since a participant may experience more than one event. The registry figures describe participants affected, not the total number of event episodes. The record does not supply detailed event listings for the other category or follow-up information that would support a time-based event rate.

General explanation: over-dispersion matters when observed counts vary more than a statistical model expects. In such settings, a model that assumes less variability may produce uncertainty estimates that are too narrow. The registry record does not report a count model or model diagnostics for this study, and the primary endpoint is not reported as a repeated event count. There is no basis to claim that over-dispersion was assessed or relevant to the sponsor’s analysis.

Overall, the registry entry is sufficient to identify the broad feasibility question, design, and limited safety counts. It is not sufficient to reproduce or audit a statistical analysis. The analysis plan, estimator, confidence-interval method, missing-data rules, and treatment of multiple outcomes are not reported 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("Endometrial Cancer")
n      <- c(15)
events <- c(15)
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  Endometrial Cancer  15  15  100.0  78.2  100.0  79.6  100.0  79.4  99.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists a primary endpoint and secondary aims concerning acute safety and toxicity occurrence. It also lists three outcome measures. Examining several outcomes can raise a multiplicity question: if many statistical tests are performed, the chance of at least one apparently notable result can increase. General explanation: methods such as a prespecified hierarchy or an adjustment to testing thresholds can address some multiplicity concerns, but their appropriateness depends on the study questions and analysis plan. The registry record does not report whether any multiplicity strategy was specified or used.

No analysis records are listed, and the record does not report statistical tests for the outcomes. It is therefore not possible to determine which outcomes were analyzed, whether analyses were prespecified, or how any results were selected for reporting. The trial’s protocol and statistical analysis plan are not reported in the registry record.

Missing-data handling is also not described. The record does not state whether all enrolled participants had evaluable primary endpoint data, how a participant with incomplete treatment information would be classified, or whether any exclusions were made. Enrollment of 15 does not establish that every participant was included in each outcome analysis. Analysis populations, including any definition of who was eligible for each analysis, are not reported in the registry record.

General explanation: missing outcome information can affect both the denominator and the interpretation of an estimate. If missingness is related to treatment delivery or participant condition, simply analyzing only observed records can give a misleading description. Without counts of missing observations and a stated handling rule, that possibility cannot be evaluated for this study.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 1.3% reporting threshold.

Most frequent non-serious adverse event terms

The registry safety entry lists 15 participants at risk for serious adverse events and zero participants affected. For other adverse events, it lists 15 participants at risk and six affected. These are participant counts, not counts of every event episode. A participant could potentially experience more than one event, but the record does not give the number of event episodes in the other category.

The serious-event terms list is empty. The deaths field has no reported value, which means deaths are not reported in the registry record; it should not be read as a stated count of zero. The record does not provide detailed event descriptions, timing, duration, attribution to treatment, or a breakdown by severity within the other category.

General explanation: an observed count of zero does not establish that the underlying risk is zero. A small group can provide limited information about uncommon events, and follow-up duration affects what can be observed. No detailed follow-up or uncertainty estimate for the safety counts is reported in the registry record. These figures should be read as the posted counts in the listed categories, not as a complete characterization of safety.

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

The registry record establishes that this was a completed feasibility study of electronic brachytherapy for endometrial cancer, with enrollment of 15 participants. Its primary question concerned the ability to complete treatment delivery with the Axxent system through completion of radiation therapy. That question is clinically and operationally distinct from whether the treatment improves a health outcome or compares favorably with another treatment.

The numerical primary endpoint result is not reported in the registry record. Therefore, the available information cannot show how often treatment was completed, or how precisely completion was estimated. The record’s completion status refers to the study status; it does not substitute for the missing primary endpoint result.

The safety entry reports zero participants affected by serious adverse events and six affected by other adverse events, each among 15 participants at risk. These counts are limited to the registry categories and do not include detailed event descriptions. The death count is not reported. The safety information therefore describes what is posted but does not establish the full safety experience or quantify uncertainty around event frequency.

The non-randomized, single-group design does not provide a like-for-like control comparison. Results from such a design cannot isolate the intervention’s effect from other influences or establish a comparative treatment effect. Masking is listed as none, and the record does not describe additional protections for subjective outcome assessment.

General explanation: feasibility findings are usually most informative when the outcome definitions, completion criteria, participant flow, missing-data handling, and uncertainty are clear. Those details are not fully reported in the registry record. The study can be characterized by its stated aim, intervention, design, and posted safety counts, but the absent primary result and analysis details restrict the conclusions that can be drawn.

14. Why This Trial Matters Statistically

This trial is statistically notable because its stated primary question is a practical feasibility question rather than a comparison of treatments. Counting participants who complete treatment delivery can help characterize whether an intervention can be delivered in a particular study setting. The interpretation depends on a clear completion rule, a defined analysis group, and transparent reporting of the resulting count. The registry record identifies the endpoint and timeframe, but does not report the numerical result or a detailed completion definition.

The single-group, non-randomized design makes the boundary between description and comparison especially important. A study can document what happened among participants who received an intervention. It cannot, without a suitable comparator, estimate how outcomes would differ under another treatment. Recognizing that boundary prevents a feasibility description from being misread as comparative evidence.

The posted safety counts also illustrate why denominators and event categories matter. The record gives participants at risk and participants affected in serious and other categories, but not a detailed event list or time-based analysis. A count can be accurately described while still leaving uncertainty about event types, timing, and completeness of follow-up.

Finally, the record distinguishes neither an actual trial sample-size rationale nor a reported analysis plan. Planning illustrations with two-arm assumptions are not a description of this single-group study’s design. The missing primary endpoint result and analysis details limit reproducibility and precision assessment. These are important statistical distinctions in reading feasibility studies: the design determines which questions can be answered, and reporting determines how much confidence readers can place in the available description.

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 trial-specific limitation in the registry record is the absence of the primary endpoint result. Although the endpoint is defined as the number of participants able to complete treatment delivery, the count is not reported. Without it, the central feasibility outcome cannot be evaluated. No confidence interval or other uncertainty estimate is reported either.

The record provides limited detail about how treatment completion was defined, what counted as a deviation, or why treatment might not be completed. It does not describe participant characteristics, eligibility criteria, treatment schedule, dose, or delivery procedures. These omissions restrict interpretation of the population and the intervention as actually implemented.

The single-group, non-randomized design has no like-for-like control comparison. Masking is listed as none. The record does not report methods for limiting bias in outcome assessment, or whether treatment delivery decisions and completion judgments followed prespecified criteria. A causal or comparative treatment effect cannot be estimated from the registered design.

The posted safety summary lacks detailed event terms for the other adverse-event category, and the serious-event terms list is empty. The deaths field is not reported. Timing, duration, attribution, follow-up completeness, and event-level counts are also not reported in the registry record. Thus, the counts should not be treated as a complete safety profile.

Finally, the registry record does not report a protocol, statistical analysis plan, sample-size justification, analysis populations, missing-data rules, or multiplicity approach. It lists three outcome measures and no analysis records. These limitations prevent independent assessment of whether analyses were prespecified, how complete the outcome data were, and how precisely findings were estimated.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Feasibility Study Using the Xoft System for the Treatment of Endometrial Cancer — NCT01045187.
• Registry record last updated 2012-08-01; status last verified 2012-07.
• Results first posted 2011-02-21.
• 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

NCT01045187 is a completed, multicenter, non-randomized, single-group feasibility study of the Xoft Axxent Electronic Brachytherapy System for endometrial cancer. The record lists enrollment of 15 participants, no masking, and phase NA. The study began in 2008-10 and reached primary completion in 2010-01. Xoft, Inc. is listed as sponsor.

The primary endpoint asks for the number of participants able to complete treatment delivery through completion of radiation therapy. Its numerical result is not reported in the registry record. The safety entry lists zero participants affected by serious adverse events and six affected by other adverse events among 15 at risk in each category. Deaths are not reported.

The design supports a description of the enrolled group, not a randomized comparison. The registry record lists three outcome measures and no analysis records. Further outcome definitions, analysis methods, and the trial’s sample-size justification are not reported in the registry record.