Endoesophageal Brachytherapy for Patients With Esophageal Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Endoesophageal Brachytherapy for Patients With Esophageal Cancer (NCT03335813), a na na study. The primary outcome is Dose of Radiation Delivered to 90% of Tumor Volume (D90).

2. Clinical Question

In general, a device-focused treatment study can describe whether a delivery approach was used and report measures of dose distribution and safety. Those descriptions are not equivalent to evidence from a controlled comparison. Without a comparator, observed outcomes cannot separate the effects of the treatment approach from other influences, and the study cannot estimate how outcomes would have differed under another treatment strategy.

The registry lists secondary measures concerning radiation treatment volume, radiation dose to organs at risk, tumor response, and esophageal complications. These outcomes could add context about dose delivery and events observed during follow-up. Their results, definitions, assessment methods, and completeness are not reported in the registry record. The clinical question is therefore framed by the study's stated objectives, while the record does not provide the primary endpoint result needed to describe the observed tumor-dose distribution.

3. Trial Design

NCT03335813 is a completed study titled “Endoesophageal Brachytherapy for Patients With Esophageal Cancer.” Its official title describes a balloon repositioning, multichannel radiation applicator intended to optimize treatment delivery. The sponsor is Case Comprehensive Cancer Center. The listed condition is esophageal cancer, and the intervention is endoesophageal brachytherapy, classified as a device intervention.

The registry identifies the model as single group, with allocation listed as NA and masking as NONE. The arm description refers to brachytherapy with a multichannel balloon applicator. The record explicitly indicates that the study was not a randomized comparison and that its arms are not a like-for-like control comparison. Accordingly, the design is best read as a single-group treatment and outcome description, not as a trial estimating a randomized treatment difference.

Enrollment is listed as 7. The study start date is 2018-03-06, the primary completion date is 2020-11-14, and the status is COMPLETED. The phase is listed as NA. The registry record does not report how enrollment was determined, whether all enrolled participants received treatment, or how many contributed data to each outcome.

The primary outcome concerns the median dose delivered to 90% of the tumor volume, expressed as a percentage of prescription dose, with a timeframe of up to 6 months of follow-up. The listed population is participants who received treatment. Secondary outcomes address radiation treatment volume, doses to the bronchus, heart, and aorta, tumor response based on Resist criteria, and esophageal ulceration, fistula, and stricture. The registry lists 12 outcome measures, but the registry record does not report their numerical results or the analysis methods used for them.

The completed status indicates the registry's recorded study status; it does not by itself establish that all planned assessments were completed or reported. The registry record does not report a protocol, detailed treatment procedures, eligibility criteria, or a statistical analysis plan.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Number of participants who received treatment

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 Dose of Radiation Delivered to 90% of Tumor Volume (D90), measured over Up to 6 months of follow-up.

The primary endpoint is titled “Dose of Radiation Delivered to 90% of Tumor Volume (D90).” It is described as the percentage of prescription dose received by 90% of the planning target volume (PTV). The registry specifies a median as the summary measure, the full range as the dispersion measure, and a timeframe of up to 6 months of follow-up. The population is described as participants who received treatment.

In general, a dose-volume endpoint summarizes how prescribed radiation is distributed across a defined target volume. D90 expresses the dose level that reaches the specified proportion of that volume, rather than describing only a point dose. Reporting a median and full range can convey both a typical value and the spread of observed values, while making clear that individual values may differ.

The registry record does not report the median D90, its full range, or the number of treated participants included in its calculation. It therefore does not permit a numerical interpretation of the endpoint. The endpoint definition describes what was intended to be measured; it is not itself a result, and it does not establish tumor response, safety, or comparative benefit.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a median describe?

The primary endpoint specifies a median and a full range. In general, a median identifies the central point of an ordered set of observations: half the measured values lie at or below it and half lie at or above it, subject to ties. A full range describes the smallest and largest observed values. Together, these summaries give information about the center and span of observed measurements without requiring an assumption that the values follow a particular symmetric distribution.

These summaries do not show the shape of the distribution or how densely values occur across the range. They also do not, by themselves, quantify uncertainty in the estimated median. An interval estimate for a population quantity would answer a different question from the range of individual observations. The registry record specifies the descriptive summaries but does not report their values or an uncertainty interval for the endpoint.

What does D90 represent?

The endpoint describes the percentage of prescription dose received by 90% of the planning target volume. In general, dose-volume measures condense a spatial dose distribution into a summary linked to the fraction of a target volume covered at a given dose. Such a measure is useful for describing delivery across a target, but it does not fully represent the three-dimensional dose distribution or establish a clinical outcome.

The registry record describes D90 as a radiation-delivery measure. It does not report the observed D90 value, the full range, or additional details about dose calculation and verification. Without those results and methods, the endpoint's intended meaning can be explained, but the actual delivery recorded in the study cannot be characterized numerically.

Why does the design matter?

The record identifies a single-group model and says the study is not a randomized comparison. In general, a single-group study can describe what was observed in the participants assessed, but it does not directly estimate what would have happened to comparable participants under an alternative intervention. A control group and a clear comparison method are needed to estimate a between-group contrast; randomization is one way to support comparability, but no randomized allocation is reported for this study.

Without a comparator, observed outcomes may reflect the intervention, patient characteristics, clinical decisions, follow-up, or other influences. This is a general limitation of uncontrolled comparisons, not a claim about which influences affected this study. The registry record does not report a comparative analysis that could address these issues.

How should the adverse-event counts be read?

In general, an “at risk” count identifies the group denominator used for an event category, while an “affected” count records participants with a reported event in that category. Serious adverse events and other adverse events are separate reporting categories. These entries do not alone describe event timing, severity beyond the category, recurrence, or causal attribution. They also do not establish that unlisted events did not occur.

The registry lists 7 at risk and 5 affected for serious adverse events, with deaths listed as 5. It lists 7 at risk and 0 affected for other adverse events. The serious term “Death, NOS” is reported as 14.3%. These are the recorded figures; the registry record does not provide the clinical narratives, attribution, or further explanation needed to reconcile or contextualize them. They should not be combined or interpreted as a causal estimate.

What can sample-size planning illustrations show?

In general, sample-size planning estimates describe the number of participants that might be required to detect a specified effect under stated assumptions. They are not observed results and are not a measure of the probability that a completed study has found a real effect. The study-specific assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects expressed as stated fractions of the observed effect. Time-to-event illustrations use a total event count; other illustrations use participants per arm.

Those assumptions describe a planning illustration, not the registered single-group design. They do not establish that the study planned a two-arm comparison, and they do not constitute observed power. Sample-size illustrations based on an observed effect are also dependent on the effect estimate used; the registry record does not report a primary endpoint result from which to assess such a planning calculation. No planning illustration can substitute for a reported endpoint estimate and an account of its uncertainty.

What does statistical uncertainty mean?

In general, a confidence interval is a range generated by a statistical procedure intended to reflect uncertainty about an estimated quantity. Its width depends on factors such as the amount of information and variability in the observations. A narrow interval usually indicates greater precision under the method's assumptions; a wide interval indicates less precision. A confidence interval is not the same as a range of individual observations.

The registry record does not report a confidence interval for the primary endpoint or a statistical test for a treatment comparison. With no reported endpoint estimate, there is no basis to assess its numerical precision. In a single-group study, uncertainty around a descriptive measure could characterize the estimate for the measured group or a target population under assumptions, but it would not create a controlled treatment contrast.

Why might over-dispersion matter?

In general, over-dispersion occurs when observed variation in count data exceeds what a chosen statistical model expects. If ignored, the model can understate uncertainty and make inferential results appear more precise than warranted. Methods that allow extra variation can be appropriate for some count outcomes, depending on the data structure and assumptions.

The registry record does not report the outcome data, statistical models, or an analysis plan, so it is not possible to determine whether over-dispersion was relevant or addressed. This general concept should not be read as a description of an analysis performed in this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures, including the primary dose endpoint and secondary measures concerning radiation volume, organ-at-risk doses, tumor response, and esophageal complications. The registry record lists 0 analyses. It does not report a statistical analysis plan, a hierarchy among secondary outcomes, a multiplicity adjustment, or a prespecified approach to interpreting multiple outcomes.

In general, when several outcomes or tests are examined, the chance of at least one apparently unusual result can increase if each is interpreted without accounting for the number of analyses. Multiplicity procedures can adjust inference or identify a primary outcome in advance. The registry record does not state whether such procedures were planned or used. Because outcome results and analysis details are not reported, the effect of multiple testing on interpretation cannot be assessed.

Missing-data methods and analysis populations are also not reported in the registry record. The primary endpoint population is described as participants who received treatment, but the record does not state how many participants contributed endpoint data, whether any measurements were missing, or how missing observations were handled. It does not describe an intention-to-treat population, a per-protocol population, or another analysis set. Enrollment 7 alone does not establish the denominator for each outcome.

For a single-group study, transparent reporting of the number assessed for each endpoint and the handling of missing observations is important for understanding how representative the results may be of the enrolled group. Without those details, the completeness and potential selection effects of outcome reporting cannot be evaluated. The registry record also does not report interim analyses or stopping rules.

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 serious adverse event terms

Serious events with the highest arm-level rate: death, nos (14.3%).

The registry lists 7 participants at risk for serious adverse events and 5 affected in the brachytherapy with multichannel balloon applicator group. Deaths are listed as 5. The serious adverse-event term “Death, NOS” is reported as 14.3%. For other adverse events, the record lists 7 at risk and 0 affected.

These are safety-reporting counts, not estimates of causal risk. The registry record does not report whether events were judged related to the intervention, when they occurred, or the clinical circumstances. The “Death, NOS” entry should be retained as reported; the record does not provide further context or an explanation linking that term to the group-level death count. No additional calculation or reconciliation is warranted from the entries alone.

In general, a zero count in a recorded category means no events were entered for that category in the reported data. It does not prove that no events occurred outside the recorded category or reporting period. The registry record does not provide enough detail to assess ascertainment, follow-up completeness, or event adjudication. These figures should therefore be interpreted as the reported safety record, not as evidence for or against a causal relationship.

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

The study's stated focus is the use of a balloon repositioning, multichannel applicator for endoesophageal brachytherapy in esophageal cancer. Its primary endpoint is a dose-volume measure: the percentage of prescription dose received by 90% of the planning target volume, summarized by its median and full range. That definition identifies the intended measurement, but the registry record does not report the observed median or range. The actual primary endpoint result therefore cannot be described from the registry record.

The record does report safety counts: 5 affected by serious adverse events among 7 at risk, deaths listed as 5, and 0 affected by other adverse events among 7 at risk. It also lists the serious term “Death, NOS” as 14.3%. These entries are important to describe accurately, but they do not establish that the intervention caused an event. Attribution and clinical context are not reported in the registry record.

The study is single group and not randomized. Its design can provide descriptive observations for the participants assessed, but cannot estimate a treatment effect relative to a control group. It does not show how outcomes would compare with another approach, and it does not separate intervention effects from other possible influences. The record does not report a comparative analysis.

More broadly, the stated secondary outcomes could have characterized dose to organs at risk, tumor response, and esophageal complications. Their results are not reported in the registry record. The listed outcome topics should not be mistaken for findings. Likewise, completed status and enrollment 7 do not establish that every planned outcome was measured or that every enrolled participant contributed data.

In general, clinical interpretation depends on the actual estimates, their uncertainty, the population analyzed, and the design's ability to support the intended comparison. Here, the endpoint definition and design are identifiable, but the primary result, analysis population, missing-data handling, and detailed statistical methods are not reported in the registry record. The evidence described should therefore be limited to the information recorded: study structure, stated outcomes, and safety entries. It does not establish a treatment benefit, lack of benefit, or causal safety conclusion.

13. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a technically focused measurement and a clinical treatment comparison. The primary endpoint is D90, a dose-volume summary of how much prescription dose reaches a specified portion of the planning target volume. Such an endpoint can describe treatment delivery, but it is not itself a comparative clinical outcome. Its value depends on a reported estimate and relevant measurement details, which are not reported in the registry record.

The single-group design also makes the scope of inference important. A descriptive study can contribute information about the intervention as recorded, but it cannot estimate a randomized difference between treatment strategies. Recognizing that distinction prevents an observed outcome, if reported, from being interpreted as a causal treatment effect without an appropriate comparator.

The record also illustrates why outcome definitions and outcome results must be distinguished. It lists multiple measures addressing dose delivery, organs at risk, tumor response, and esophageal complications, but does not report their numerical findings. A list of intended measures is useful for understanding the study's scope; it cannot show what was observed or how precisely it was estimated.

Finally, safety counts require careful reading alongside denominators, event definitions, and attribution. The reported serious-event and death entries provide a record of what was entered, while leaving clinical context and causal assessment unreported. These limitations are particularly relevant when interpreting small-group descriptions: counts and descriptive summaries alone may provide limited precision, and no uncertainty estimates are reported.

The statistical importance of this record lies in keeping claims aligned with design and reporting. It defines a device-focused treatment study and a dose-distribution endpoint, while illustrating that endpoint results, analytic details, and comparative evidence are needed for stronger conclusions.

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 registry record identifies a single-group study with allocation listed as NA and masking as NONE. It is not a randomized comparison, so there is no like-for-like control group for estimating a treatment contrast. This design limits causal interpretation independently of whether descriptive outcomes were measured.

Enrollment is listed as 7, but the registry record does not report the number treated or the number analyzed for the primary or secondary outcomes. The primary endpoint population is described as participants who received treatment, without a reported denominator or result. This leaves uncertainty about outcome completeness and the relationship between enrollment and analysis populations.

The primary endpoint result, its full range, and an uncertainty estimate are not reported in the registry record. Secondary outcome results are also not reported, despite the listing of 12 outcome measures. The record lists 0 analyses and does not report methods for estimating uncertainty, handling multiple outcomes, or addressing missing data.

The listed safety counts lack reported attribution, timing, and clinical context. The record does not explain the relationship between the “Death, NOS” term and the group-level death count. The other-adverse-event entry of 0 affected is limited to the recorded category and does not describe event ascertainment or reporting completeness.

Further trial details that could inform interpretation—including eligibility criteria, participant characteristics, treatment schedule, endpoint assessment procedures, and a statistical analysis plan—are not reported in the registry record. The completed status does not resolve these reporting gaps. These limitations restrict interpretation to the design and entries that are explicitly recorded; they do not establish that unreported procedures or outcomes did or did not occur.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Endoesophageal Brachytherapy for Patients With Esophageal Cancer — NCT03335813.
• Registry record last updated 2022-06-09; status last verified 2022-05.
• Results first posted 2022-06-09.
• 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

NCT03335813 is a completed, single-group study of endoesophageal brachytherapy for esophageal cancer, sponsored by Case Comprehensive Cancer Center. The intervention is described as a 6 channel balloon repositioning, multichannel applicator for localized radiation therapy. Enrollment is listed as 7; the phase and allocation are listed as NA, and masking as NONE. The study start date is 2018-03-06 and the primary completion date is 2020-11-14.

The primary outcome is the median percentage of prescription dose received by 90% of the planning target volume, with the full range specified and follow-up up to 6 months. Its numerical result is not reported in the registry record. The registry lists 12 outcome measures and 0 analyses. Safety entries list 5 affected by serious adverse events among 7 at risk, deaths as 5, and 0 affected by other adverse events among 7 at risk; “Death, NOS” is listed as 14.3%. Attribution and detailed analysis methods are not reported.