TARGeted Intraoperative radioTherapy With INTRABEAM as a Boost for Breast Cancer - A Quality Control Registry: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for TARGeted Intraoperative radioTherapy With INTRABEAM as a Boost for Breast Cancer - A Quality Control Registry (NCT01440010), a registered phase not stated study. The primary outcome is Number of Patients With Local Recurrence.

2. Clinical Question

3. Trial Design

TARGIT BQR is a quality control registry for intraoperative radiotherapy (IORT) used as an anticipated boost in patients with breast cancer. The registry title specifies the INTRABEAM system, and the listed intervention is IORT with 20 Gy. Its arm description specifies 50 kV x-rays and states that the boost was delivered during breast-conserving surgery, followed by whole-breast irradiation with EBRT of 46-50 Gy.

The registry lists Universitätsmedizin Mannheim as the sponsor. Enrollment is recorded as 1133. The study started on 2011-09-01, its primary completion date is 2020-12-31, and its status is COMPLETED. These administrative entries describe the registry record; they do not establish that every enrolled participant had complete follow-up or contributed to the primary outcome analysis.

The primary outcome is the number of patients with local recurrence over 5 years. Follow-up is described as occurring every six months for the first two years and then once a year, with mammography and clinical examination at each follow-up. The outcome description says Kaplan-Meier estimates were used to calculate the local recurrence rate. A secondary outcome concerns the percentage of patients with chronic higher grade fibrosis after the IORT boost.

This is not a randomized comparison, and the allocation method is not stated. The record describes a treatment group but does not establish a concurrent, comparable control group. It therefore supports a description of the registry’s treatment and outcome framework, not a causal comparison between treatment strategies. Participant eligibility details, baseline characteristics, and further protocol information 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

Analysis population for the primary outcome, as defined in the registry: Planned IORT Boost plus whole breast irradiation

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.

Population: 902 with complete paper work and minimum follow-up data set

6. Primary Endpoint

The registry lists the primary outcome as Number of Patients With Local Recurrence, measured over 5 years.

The primary endpoint is the number of patients with local recurrence, measured over 5 years. Local recurrence is a clinically relevant outcome for a registry evaluating a radiotherapy boost because it records whether cancer returns locally during follow-up. The registry describes follow-up that includes mammography and clinical examination, with assessments every six months for the first two years and then once a year. These scheduled assessments provide the stated context for detecting and recording recurrence.

The outcome description also says Kaplan-Meier estimates were done to calculate the local recurrence rate. This is a time-to-event approach: in general, it uses information about when events occur and accounts for participants whose event status is not observed for the full follow-up period. The registry’s endpoint title refers to a number of patients, while its description names a Kaplan-Meier estimate of a rate. Those are related but not identical summaries: a count gives the number recorded as having an event, while a time-to-event estimate incorporates follow-up timing.

The registry record does not report the local recurrence count, a Kaplan-Meier estimate, its uncertainty, or the number of participants included in that endpoint analysis. The posted information therefore identifies what the endpoint was intended to measure and how it was described analytically, but it does not show the observed primary outcome result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome description combines a participant count with a time-to-event method. It names the outcome as the number of patients with local recurrence and gives a 5 years timeframe. It then states that Kaplan-Meier estimates were done to calculate the local recurrence rate. This distinction matters when reading any eventual result: a raw event count and a Kaplan-Meier estimate answer related but different questions.

What does a Kaplan-Meier estimate represent?

In general, Kaplan-Meier methods estimate the probability of remaining free of an event over time, or equivalently can be used to express the estimated occurrence of an event over time. They use the timing of events rather than treating every participant’s follow-up as if it ended at the same time. A participant whose event has not been observed by the end of their available follow-up can contribute information up to that point and then be censored. Censoring is a statistical way to represent incomplete event observation; it does not mean that the event occurred.

For such an estimate to be interpretable, readers need information about the event definition, follow-up, censoring, and the number at risk over time. The registry describes follow-up every six months for the first two years and then once a year, including mammography and clinical examination. It does not report the operational definition of local recurrence, the censoring rules, the risk sets over time, or the extent of loss to follow-up. Those details are not reported in the registry record.

Why does the distinction between counts and rates matter?

A count says how many participants were recorded with the event in the analyzed population. A time-to-event estimate uses the follow-up timing and can account for incomplete observation under its assumptions. It therefore cannot be reconstructed simply from an enrollment figure. The registry lists enrollment of 1133, but the endpoint analysis population and the number with complete follow-up are not reported in the registry record. The primary endpoint count and the Kaplan-Meier estimate are also not reported, so neither summary can be interpreted from the posted results.

In general, confidence intervals communicate uncertainty around an estimate. A narrow interval indicates greater precision under the assumptions of the method; a wide interval indicates less precision. No confidence interval for local recurrence is reported in the registry record. A p-value would address a specified statistical comparison or hypothesis, but no primary outcome p-value or comparison analysis is reported either. No claim about statistical significance or precision can therefore be made.

What can be inferred from the analysis record?

The record lists 0 analyses. The primary outcome description names Kaplan-Meier estimation, but the presence of a method description is not the same as a posted estimate or a fully reported statistical analysis. The record does not state the model specification, software, treatment of competing events, or planned hypothesis tests. These methods are not reported in the registry record. It would be inappropriate to infer that any particular additional analysis was performed.

The registry also lists a secondary outcome: the percentage of patients with chronic higher grade fibrosis after IORT boost. A percentage requires a clearly defined numerator and denominator, and interpretation depends on the outcome definition and the population evaluated. The record does not report the observed percentage, the denominator, or an analysis for this outcome. No further assumptions about its analysis can be made from the entry.

How should planning illustrations be read?

General sample-size calculations can illustrate how the number of participants needed for a future study changes under stated assumptions about an effect and a statistical method. The registry’s planning description says the illustration uses a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. It also distinguishes time-to-event planning, which gives a total number of events, from other planning, which gives participants per arm.

Those calculations are planning illustrations based on an observed effect, not the study’s original design and not observed power. The registry record does not report a sample-size justification or the trial’s own planning assumptions. Since the study is not described as a randomized comparison and no observed primary effect is reported, a planning illustration should not be read as evidence that the registry was designed to detect a particular treatment difference.

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("IORT Boost")
n      <- c(902)
events <- c(10)
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  IORT Boost  902  10  1.1  0.5  2.0  0.6  2.0  0.6  2.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: local recurrence as the primary outcome and chronic higher grade fibrosis as a secondary outcome. It lists 0 analyses and does not report outcome estimates for either measure. The statistical plan, including any prespecified testing hierarchy or adjustment for examining multiple outcomes, is not reported in the registry record. It is therefore not possible to determine whether multiplicity was addressed or to interpret any unreported hypothesis tests.

Missing-data handling is also not reported in the registry record. The follow-up description specifies mammography and clinical examination every six months for the first two years and then once a year. It does not state how missed visits, incomplete examinations, withdrawals, or loss to follow-up were handled. These details matter because incomplete observation may affect the number of events available and, for a Kaplan-Meier estimate, the timing and censoring information used.

The analysis population is not reported in the registry record. Enrollment is recorded as 1133, while the adverse-event entry gives an at-risk count of 902 for its group. That adverse-event count does not establish the denominator used for the local recurrence or fibrosis outcomes. The record does not say whether the primary analysis included all enrolled participants, only those with follow-up, or another defined population. It also does not give endpoint-specific denominators. Enrollment, the adverse-event at-risk count, and the analysis population should not be assumed to be interchangeable.

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 4% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event entry lists an at-risk count of 902 for serious events and an affected count of 0. For other adverse events, it lists an at-risk count of 902 and an affected count of 83. It also records 16 deaths. These are registry counts, not comparative estimates, and the record does not provide a control group that would support a treatment comparison.

The serious-event field records 0 participants affected. This should be read as the value entered in that field, not as proof that every possible serious event was absent or that the treatment caused no harm. The record lists no top serious terms. It does not give event definitions, observation windows, event-level details, or an explanation of how the death count relates to the serious- and other-event counts. The counts should not be added or assumed to represent separate people.

The 83 affected by other adverse events and the 16 deaths are not accompanied by further detail that would establish timing, cause, severity, or relationship to treatment. The posted information does not report exposure time or provide a comparative safety analysis. These figures therefore describe the recorded fields but cannot establish rates, causes, or comparative safety.

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

The registry record describes a quality control registry for an IORT boost with 20 Gy during breast-conserving surgery, followed by whole-breast irradiation. It specifies a primary outcome of local recurrence over 5 years and describes a follow-up schedule that includes mammography and clinical examination. It also states that Kaplan-Meier estimates were used for the local recurrence rate. These details clarify what the registry set out to document.

They do not show the outcome result. No local recurrence count, rate estimate, confidence interval, or analysis result is reported in the registry record. The record’s enrollment figure cannot be used in place of an endpoint denominator, and the lack of a reported result is not evidence that there were no recurrences. The secondary fibrosis outcome is listed but also has no reported result.

The registry does not describe a randomized comparison or a like-for-like control group. Allocation is not stated. Consequently, the record cannot establish a causal difference between the boost strategy and another approach. Nor can the adverse-event counts alone establish comparative safety: detail about event definitions, timing, causes, and comparison groups is not reported in the registry record.

In general, statistical conclusions depend both on the observed estimates and on how precisely they were measured. Here, neither the primary estimate nor its uncertainty is available. The appropriate conclusion is limited to the registry’s stated intervention, follow-up, and outcome framework, together with the fact that outcome analyses are not reported. Claims about the size, direction, or certainty of treatment effects are not supported by the posted information.

14. Why This Trial Matters Statistically

This registry is statistically important as an example of the difference between a clearly described outcome plan and a reported outcome result. It identifies local recurrence as the primary outcome, sets a 5 years timeframe, describes a follow-up schedule, and names Kaplan-Meier estimation. Those details indicate the intended focus and the broad analytic approach. They do not, on their own, reveal how many recurrences were observed or how precisely a rate was estimated.

The record also illustrates why enrollment should not be mistaken for an analysis denominator. Enrollment is recorded as 1133, but endpoint-specific analysis populations, follow-up completeness, and risk sets are not reported in the registry record. For a time-to-event outcome, these details are central to interpretation because participants can contribute different amounts of observed follow-up. A count of enrolled participants alone cannot resolve that uncertainty.

Study design also sets limits on statistical interpretation. The registry is not a randomized comparison, allocation is not stated, and no like-for-like control group is described. The information therefore cannot support a treatment-effect contrast. The record’s planning description is explicitly an illustration rather than the study’s own design, an important distinction when planning calculations are read alongside trial or registry results.

Finally, the absence of posted analyses matters. The registry lists a primary and a secondary outcome but no analyses and no outcome estimates. Clear reporting of analysis populations, event definitions, missing-data handling, and uncertainty would be needed to assess the findings. In this case, the record defines the questions but does not provide the results needed to answer them.

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 is that the registry record does not report results for the primary local recurrence outcome. Although the endpoint timeframe is 5 years and the description names Kaplan-Meier estimation, the recurrence count, estimated rate, and uncertainty are not reported in the registry record. The secondary outcome of chronic higher grade fibrosis is also listed without a result.

The registry is not a randomized comparison, the allocation method is not stated, and the available description does not identify a like-for-like control group. A comparative treatment effect cannot be estimated from the information recorded. Participant characteristics, eligibility criteria, and details of treatment delivery or adherence are not reported in the registry record, limiting assessment of the population represented and the consistency of exposure.

Follow-up procedures are described, but completeness of follow-up, losses, censoring rules, and endpoint definitions are not reported. The primary analysis population and outcome-specific denominators are also not reported. Thus the enrollment figure cannot be taken as the number evaluated for local recurrence, and the adverse-event at-risk count cannot be assumed to be the endpoint denominator.

The record lists 0 analyses. It does not provide a statistical analysis plan, a sample-size justification for the registry, a multiplicity approach, or a missing-data method. The adverse-event entry gives counts but lacks event details, timing, and an explanation of the deaths’ relationship to the other fields. These limits restrict conclusions about efficacy, precision, and safety to the recorded descriptions; they do not establish that an unreported event or analysis did not occur.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: TARGeted Intraoperative radioTherapy With INTRABEAM as a Boost for Breast Cancer - A Quality Control Registry — NCT01440010.
• Registry record last updated 2025-12-12; status last verified 2025-12.
• Results first posted 2025-12-12.
• 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

NCT01440010 is a completed quality control registry sponsored by Universitätsmedizin Mannheim. It concerns IORT with 20 Gy as an anticipated boost during breast-conserving surgery, followed by whole-breast irradiation; the arm description specifies 50 kV x-rays and EBRT with 46-50 Gy. Enrollment is recorded as 1133, with a start date of 2011-09-01 and a primary completion date of 2020-12-31.

The primary outcome is the number of patients with local recurrence over 5 years. The record describes scheduled follow-up and Kaplan-Meier estimation but reports no primary outcome result. Chronic higher grade fibrosis is listed as a secondary outcome, also without a reported result. The registry is not a randomized comparison, allocation is not stated, and 0 analyses are listed. The available record therefore describes the intervention and intended outcome assessment, but does not provide results to estimate recurrence, compare treatment strategies, or assess outcome precision.