This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Using the Active Breathing Control Device to Reduce Radiation Side Effects to Critical Structures in Breast Cancer (NCT00328783), a na na study. The primary outcome is Dosimetric Evaluation Magnitude of Reduction in Irradiated Normal Tissues.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00328783 |
| Phase | NA |
| Condition | Breast Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 112 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sidney Kimmel Comprehensive Cancer Center at Thomas Jefferson University |
| Results posted | Yes |
2. Clinical Question
Population
Patients with breast cancer receiving radiation therapy were the population of interest. The registry describes a pilot study and records an enrollment of 112. Demographic characteristics and other eligibility details are not reported in the registry record.
Intervention
Patients breathe through the Active Breathing Coordinator (ABC) device during radiation treatment. The study’s stated purpose was to evaluate whether coordinating the breathing cycle could reduce radiation dose to normal structures around the breast.
Comparator
The primary question describes comparing generated dose distributions from ABC plans with standard, free-breathing plans. This is a comparison of planning conditions, not a randomized comparison between separately assigned treatment groups. Further details about how plans were paired or compared are not reported in the registry record.
Primary question
At the time of radiation, what is the magnitude of reduction in irradiated normal tissues, particularly the heart and lung, when using ABC compared with standard free-breathing? The record also describes evaluating dose-volume measures for the liver and contralateral breast, as well as target volume. It states that patients would be treated with ABC if there was at least 5 % relative reduction in the volume of a normal tissue irradiated to prescription dose. The registry record does not report the resulting dose-volume estimates or whether that treatment criterion was met.
3. Trial Design
This was a completed pilot study with a single-group model. The registry lists an enrollment of 112, masking as none, and allocation as NA. The study phase is listed as NA. Its start is recorded as 2002-10 and its primary completion as 2011-07. The sponsor was Sidney Kimmel Comprehensive Cancer Center at Thomas Jefferson University.
The intervention included the Active Breathing Coordinator device and radiation therapy. The arm description says patients breathe through the ABC device. Although the primary endpoint description compares ABC and free-breathing dose distributions, the registry does not describe a separately assigned control group. The planned dosimetric comparison therefore should not be read as evidence of randomized allocation or a like-for-like comparison between independent groups.
The primary outcome is a continuous dosimetric evaluation of the magnitude of reduction in irradiated normal tissues, with the mean and a 95% confidence interval specified as the summary. The timeframe is at the time of radiation. The record also lists toxicity evaluation and changes in organ-at-risk dosimetric parameters among secondary outcomes. It names five outcome measures overall, but does not give the full analysis details for each measure.
The registry records zero analyses. This means no analysis results are posted in the record; it does not establish whether analyses were performed outside the registry. Details of the statistical analysis plan, participant flow, and the handling of the planning comparison are not reported in the registry record.
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
| Stage | Active Breathing Coordinator |
|---|---|
| STARTED | 112 |
| COMPLETED | 86 |
| NOT COMPLETED | 26 |
Reasons for not completing this period:
| Reason | Active Breathing Coordinator |
|---|---|
| Could not tolerate ABC | 21 |
| No heart in RT field | 4 |
| Withdrawal by Subject | 1 |
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.
| Characteristic | Unit | Active Breathing Coordinator |
|---|---|---|
| Participants analysed | 112 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 97 |
| Age, Categorical: >=65 years | Participants | 15 |
| Age, Continuous | years | 54.19 (SD 10.82) |
| Sex: Female, Male: Female | Participants | 112 |
| Sex: Female, Male: Male | Participants | 0 |
| Region of Enrollment: United States | participants | 112 |
6. Primary Endpoint
The registry lists the primary outcome as Dosimetric Evaluation Magnitude of Reduction in Irradiated Normal Tissues, measured over At time of radiation.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Gy |
| Endpoint classification | Continuous Endpoint |
The primary endpoint concerns how much irradiated normal tissue is reduced when radiation plans using the Active Breathing Coordinator are compared with standard free-breathing plans. It is described as a dosimetric evaluation, summarized by a mean with a 95% confidence interval, and assessed at the time of radiation. The primary description emphasizes the heart and lung, while also listing dose-volume evaluations for the liver and contralateral breast and evaluation of target volume.
Dose-volume measures describe how much of a structure receives radiation at specified dose levels. The registry names heart volumes receiving 55 and 40 Gy, liver volumes receiving 50 and 36 Gy, lung volume receiving 20 Gy, and contralateral breast volumes receiving 20 Gy, 30 Gy and 50 Gy. These are planned evaluation thresholds, not reported findings. The record does not specify the units used for the volume measures.
General: Dosimetric endpoints can characterize the distribution of planned radiation across tissues, allowing a treatment-planning comparison even when the outcome is not a clinical event. They do not by themselves establish whether a difference in dose leads to a difference in symptoms or other patient outcomes. The registry record does not report the endpoint estimates, confidence intervals, or results of the planned comparison.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a question about dose distributions, not a reported estimate of the size of a reduction. It specifies a mean and a 95% confidence interval for the primary dosimetric evaluation, but gives no observed means, confidence limits, or analysis results. Consequently, the posted information does not quantify how ABC and free-breathing plans differed for any organ or dose threshold.
The record’s enrollment of 112 describes the study enrollment, not the number of observations contributing to any particular endpoint. The analysis population, evaluable sample size for dosimetry, and participant-level availability of plan data are not reported in the registry record. It is therefore not possible to infer the precision of the endpoint estimate from the enrollment alone.
General: A confidence interval expresses uncertainty around an estimated quantity under the assumptions of the analysis. Its width depends on the variability of the observations and the amount of information available. Without the estimate and interval limits, neither the direction nor the precision of a result can be assessed. A confidence interval also does not resolve possible bias in how observations were selected, measured, or compared.
The study model is listed as single group, with allocation NA and no masking. The primary description nevertheless proposes comparison of ABC and free-breathing plans. This distinction matters: the registry does not describe a randomized control arm, and it does not specify whether each patient had both plans or how the plan-level observations were handled statistically. The comparison should therefore be interpreted only as a planned dosimetric contrast as described in the record, not as a randomized treatment effect.
The record lists five outcome measures and several organ-specific dose thresholds. It posts zero analyses and no primary result. No conclusions about statistical significance, uncertainty, or consistency across structures can be drawn from the registry entry. The secondary outcome list includes toxicity evaluation, but toxicity results and details of follow-up are not reported in the registry record. Thus, the available record supports describing the study question and design features, but not a claim about the magnitude or clinical consequences of any dose difference.
The criterion that patients would be treated with ABC if there was at least 5 % relative reduction in the volume of a normal tissue irradiated to prescription dose is part of the endpoint description. It is not accompanied by a reported result showing whether the criterion was achieved. No evidence about adherence to that criterion or the resulting treatment decisions is reported in the registry record.
9. Statistical Methods Explained
The primary endpoint is a continuous measure summarized as a mean, with a 95% confidence interval. The study description frames the key comparison as dose distributions generated under ABC and standard free-breathing plans. The registry record does not specify the estimator for the difference, the statistical test, or how dependence between plans would be addressed.
What does a mean describe?
General: A mean describes the average value across the observations included in an analysis. For a dosimetric endpoint, the meaning of that average depends on what one observation represents: it could be a participant-level quantity, a plan-level quantity, or another defined measurement. The registry record does not say how the observations were constructed for the primary comparison, so the precise interpretation of the mean cannot be recovered from the entry alone.
Because ABC and free-breathing plans are the stated comparison, the analysis needs to define whether the contrast is based on matched observations or independent groups. General: When two measurements come from the same participant, they are usually related; an analysis can account for that pairing. Treating related measurements as independent can misrepresent uncertainty. The registry record does not state whether both planning conditions were evaluated for each participant, whether observations were paired, or what model was used.
How should the confidence interval be read?
General: A 95% confidence interval gives a range of values compatible with the estimate under the statistical procedure and its assumptions. It communicates uncertainty about the estimated mean or contrast; it is not a guarantee that the true value lies in the interval. The interval’s interpretation also depends on which quantity was estimated. The record identifies a mean and a 95% confidence interval but does not clarify whether the interval applies to each condition separately, to a difference, or to another endpoint summary.
The endpoint description lists dose-volume thresholds for multiple structures. Heart volumes at 55 and 40 Gy, liver volumes at 50 and 36 Gy, lung volume at 20 Gy, and contralateral breast volumes at 20 Gy, 30 Gy and 50 Gy are named. These measures create several opportunities for comparison, alongside target-volume evaluation and the listed secondary outcomes. The record does not identify a single prespecified contrast among these measures as the sole basis for an overall conclusion.
Why can variability matter?
General: Dosimetric values can vary across participants and across structures. A mean alone does not show how observations are distributed. The confidence interval reflects uncertainty in the estimated quantity under the chosen method, while measures of spread describe variability among observations. The registry specifies a confidence interval but does not report a separate measure of dispersion, the underlying distribution, or any method for handling unusual values.
General: Over-dispersion means that observations vary more than a statistical model expects. When present, it can make standard errors too small and intervals too narrow if the model does not account for it. The registry does not state that over-dispersion was assessed, and no distributional model is reported. This is relevant as a general consideration for analysis, not a claim about these data.
What can be said about planning calculations?
The record describes a sample-size planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also says the effect to detect is a stated fraction of the observed effect. The record’s main design is single group, and no observed endpoint estimate or computed planning values are included in the registry record for this analysis. These assumptions therefore describe a planning illustration, not the trial’s reported design or an observed-power result. Sample-size illustrations are planning quantities; they do not establish the probability that a completed study detected an effect.
For the endpoint itself, the registry does not report the statistical plan, the confidence-interval method, an adjustment for the multiple listed dose thresholds, or any sensitivity analyses. It also does not report whether the primary endpoint was calculated from absolute values, relative reductions, or both, beyond the stated 5 % relative-reduction criterion for treatment. The analysis methods and their assumptions cannot be evaluated without those details and the results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists five outcome measures, including the primary dosimetric evaluation and secondary outcomes concerning toxicity, changes in organ-at-risk dosimetric parameters, and toxicity of adjuvant radiotherapy with the ABC device. The primary description further names multiple organs and dose thresholds: heart at 55 and 40 Gy, liver at 50 and 36 Gy, lung at 20 Gy, and contralateral breast at 20 Gy, 30 Gy and 50 Gy. Target volume is also mentioned.
General: When multiple outcomes or contrasts are examined, the chance of finding at least one apparently notable result can increase. Statistical approaches may control that risk or distinguish a primary comparison from exploratory analyses. The registry record does not report a multiplicity strategy, a hierarchy among the organ-specific endpoints, or which comparisons were intended to support confirmatory conclusions. No analyses are posted to assess how multiplicity was handled.
Missing-data methods and analysis populations are not reported in the registry record. The entry does not specify how many participants had usable plans, how incomplete dosimetric measurements were handled, or whether all enrolled participants were included in each analysis. It also does not describe exclusions, withdrawals, or the handling of missing toxicity assessments. Enrollment alone cannot establish the sample size for any endpoint analysis.
The record’s adverse-event group lists 0 participants at risk and 0 affected for serious and other events. Those entries do not provide an interpretable incidence estimate for the enrolled study population, and the registry does not explain the zero denominators. Details of adverse-event ascertainment and analysis are not reported in the registry record.
11. What the Result Does, and Does Not, Mean
The registry record establishes that the study was designed to investigate ABC use during breast radiation therapy and to evaluate dose distributions against standard free-breathing plans. It identifies normal-tissue dosimetry as the primary question and lists organs and dose thresholds of interest. It does not provide the numerical results needed to say whether a reduction was observed, how large it was, or how precisely it was estimated.
General: A dosimetric difference is a difference in planned or measured radiation distribution. By itself, it does not establish a difference in toxicity, symptoms, or other clinical outcomes. Such interpretations require clinical outcome data and an analysis that connects the dose measure to those outcomes. The registry lists toxicity-related outcomes, but does not report their results or the details needed to interpret them.
The single-group design and NA allocation do not describe a randomized treatment comparison. The primary endpoint’s comparison of ABC and free-breathing plans may provide a planning contrast, but the record does not explain the unit of analysis or whether the same patients contributed measurements under both planning conditions. These omissions limit interpretation of the comparison and its uncertainty.
The 5 % relative-reduction criterion is a stated condition for treating patients with the ABC device when the volume of normal tissue irradiated to prescription dose is reduced by at least that amount. It is a protocol description, not evidence that the threshold was reached or that a particular outcome followed. No treatment-decision results are reported.
Accordingly, the posted record supports describing the research question and its intended dosimetric measures, but not a conclusion about the magnitude, statistical significance, reliability, or clinical meaning of a result. Results, analysis methods, and relevant denominators are not reported in the registry record.
12. Why This Trial Matters Statistically
This study raises a statistical question that is distinct from a conventional comparison of outcomes between randomized groups. Its primary description proposes comparing ABC and free-breathing dose distributions, while the registered model is single group and allocation is NA. Clear definition of the measurement unit and the relationship between plans is essential for interpreting the mean and its confidence interval.
The endpoint also spans several normal structures and dose thresholds. A coherent analysis needs to clarify which measures are primary, how multiple comparisons are addressed, and how any reduction is defined. The registry identifies a 5 % relative-reduction condition for treatment, but does not report how that condition was operationalized in analysis or whether it was met.
General: Statistical precision depends not only on enrollment but also on the number of usable observations, the variability of the outcome, and the analysis design. The registry’s enrollment of 112 cannot substitute for endpoint-specific denominators or a reported confidence interval. The absence of posted analyses leaves both effect estimation and precision unassessable.
The registry’s description is useful for distinguishing planned dosimetry from clinical outcomes. It includes toxicity among secondary outcomes, but provides no toxicity results. This distinction matters because radiation-dose distributions and patient experiences are different types of evidence, and one cannot be used as a numerical stand-in for the other.
Statistically, the most important feature of the record is the gap between a detailed endpoint description and the absence of results and analysis methods. Without estimates, uncertainty intervals, analysis populations, and a clear comparison method, readers cannot evaluate the strength or consistency of the planned dosimetric evidence.
13. 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 principal limitation of the registry entry for statistical interpretation is that it contains no posted analyses or primary endpoint estimates. It gives no means, confidence-interval limits, organ-specific results, or participant-level denominators. The enrollment of 112 cannot show how many participants contributed to the dosimetric endpoint.
The comparison is described as ABC versus standard free-breathing plans, but the study model is single group and allocation is NA. The record does not state whether each participant had plans under both conditions, how the plan comparison was constructed, or whether observations were treated as paired. This prevents assessment of the comparison’s statistical assumptions and uncertainty.
The endpoint description names multiple organs, dose thresholds, and target volume. The registry does not explain how these measures were prioritized, whether multiplicity was addressed, or how the treatment criterion based on at least 5 % relative reduction was applied. Full definitions and units for the volume measures are not reported.
Other relevant details are not reported in the registry record: eligibility criteria, participant characteristics, endpoint-specific analysis populations, missing-data procedures, analysis models, and sensitivity analyses. Although toxicity is listed among secondary outcomes, follow-up details and toxicity results are not available. The adverse-event group’s zero at-risk and affected counts do not supply a usable denominator for estimating event incidence.
These limitations concern what can be learned from the registry record; they do not establish that the study team did not collect or analyze additional data outside the registry.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Using the Active Breathing Control Device to Reduce Radiation Side Effects to Critical Structures in Breast Cancer — NCT00328783.
- Registry record last updated 2025-04-30; status last verified 2025-04.
- Results first posted 2014-04-30.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
17. Record Summary
NCT00328783 is a completed pilot study of the Active Breathing Coordinator during breast radiation therapy. It lists enrollment of 112, a single-group model, allocation NA, and no masking. The sponsor is Sidney Kimmel Comprehensive Cancer Center at Thomas Jefferson University.
The primary endpoint is a mean dosimetric evaluation with a 95% confidence interval, assessed at the time of radiation. The stated comparison is between ABC and standard free-breathing dose distributions, focusing on normal tissues and also naming target volume. Secondary outcomes include toxicity and organ-at-risk dosimetric measures.
The registry lists five outcome measures and zero analyses. It does not report primary endpoint results, confidence limits, analysis methods, or endpoint-specific participant counts. The posted record therefore describes the study question and planned measures, but does not allow estimation of the size or precision of a dosimetric difference.