Radiation Therapy After Surgery in Treating Women With Phyllodes Tumor of the Breast: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Radiation Therapy After Surgery in Treating Women With Phyllodes Tumor of the Breast (NCT00003404), a na na study. The primary outcome is Local Recurrence Rate.

2. Clinical Question

The study title and official title frame the question around radiotherapy after surgical resection of borderline and malignant phyllodes tumors. The brief summary describes a phase II study of radiation therapy after surgery. The registry’s phase field, however, is listed as NA. The record therefore supports describing the study as prospective and single-group, but does not establish a randomized treatment comparison.

The clinical question is descriptive as well as evaluative: the primary endpoint is the occurrence of local recurrence over a stated follow-up period after initial excision in the radiotherapy group. Without a concurrent control group, the study cannot directly estimate how that outcome differs from what would have occurred under another treatment strategy. The registry lists survival rate as a secondary outcome, but does not give its result. Eligibility details, participant characteristics, and further information about the tumor or surgery are not reported in the registry record, so the scope of the population cannot be described more narrowly.

3. Trial Design

NCT00003404 is listed as a completed, prospective study sponsored by Dartmouth-Hitchcock Medical Center. The registry gives an enrollment of 46. Its official title describes adjuvant radiotherapy after resection of borderline and malignant phyllodes tumors. The brief summary characterizes the study as phase II, while the phase field itself is NA; the record does not resolve that difference.

The design is single-group, with adjuvant radiotherapy as the only listed intervention. The allocation field is NA and masking is listed as none. The registry record does not describe a randomized allocation or a concurrent control arm. Consequently, the study can describe outcomes in the treated group, but it does not provide a like-for-like estimate comparing radiotherapy with an alternative. Comparisons with outcomes from other populations or studies would require information not contained in this record and would be vulnerable to differences in participants, care, follow-up, and outcome assessment.

The intervention description states that adjuvant radiation was started within 12 weeks of local excision or breast re-excision. The record lists a study start of 1998-01 and a primary completion date of 2008-11-17. These dates describe the registry timeline; they do not by themselves establish how long each participant was followed or whether all participants had complete outcome assessment at the endpoint time.

The primary outcome is local recurrence rate, measured as a count of participants, with a timeframe of 36 months after initial excision. Survival rate is listed as a secondary outcome. The record identifies 2 outcome measures and 1 analysis, but does not describe the statistical analysis plan, analysis populations, endpoint adjudication, or handling of follow-up. Those details 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

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 Local Recurrence Rate, measured over 36 months after initial excision.

The primary endpoint is local recurrence of phyllodes tumors, expressed as a count of participants, at 36 months after initial excision. It addresses whether a participant experienced a return of tumor at the local site during the defined period. A participant count is a binary-outcome summary: each participant is classified according to whether the event was recorded or not. The registry uses the label local recurrence rate, but the recorded measure is a count rather than a reported percentage or rate estimate.

As a general statistical point, a fixed-time recurrence endpoint can make a clinical question more concrete by tying the event to a specified point after surgery. It is useful only when the event definition, observation period, and completeness of follow-up are understood. The registry record does not provide a detailed recurrence definition, say how recurrence was assessed, or report the number of participants with recurrence. It also does not report a confidence interval or an estimated recurrence rate. Therefore, the endpoint’s intended meaning is clear at a high level, but its observed value and precision cannot be evaluated from the registry record.

The stated timeframe begins after initial excision, while the intervention description allows local excision or breast re-excision before radiotherapy. The record does not explain how timing was handled for participants who had re-excision, or whether all participants contributed the same amount of follow-up. Those details matter when interpreting a fixed-time outcome, particularly if some participants have incomplete observation. The registry record does not report those details.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a binary primary outcome: participants are counted according to whether local recurrence occurred. It labels the endpoint a rate, but the measurement unit is participants and the parameter is a count of participants. No recurrence count or rate estimate is reported. The analysis method used for this outcome is not reported in the registry record, so it would be inappropriate to attribute a particular model, test, adjustment strategy, or estimator to the investigators.

What does a participant count say?

As a general statistical explanation, a count of participants with an event is a direct summary of how many observed participants experienced that event. A rate or proportion additionally relates the event count to a population at risk, while an estimate of risk at a specified time also depends on how follow-up and censoring are handled. The registry specifies a 36-month timeframe after initial excision, but does not report the recurrence count, denominator used for the endpoint, or method for accounting for incomplete follow-up. A numerical rate cannot be reconstructed from the endpoint description alone.

When participant follow-up differs, simple event counts can be difficult to interpret as a fixed-time risk. General methods for time-to-event outcomes can accommodate differing follow-up, but the registry does not say that such a method was used for local recurrence. The primary outcome is presented as a binary count, and the listed secondary outcome is survival rate. The specific definitions and analyses for those outcomes are not reported in the registry record.

How should uncertainty be read?

As a general statistical concept, a confidence interval presents a range of values compatible with the observed data and the method’s assumptions. It communicates precision, not certainty that the true value lies within the range. A narrow interval generally indicates more precision than a wide interval, though its interpretation also depends on the design and method. The registry record does not report a confidence interval for local recurrence, and does not give an event estimate from which one could interpret precision.

A p-value is a measure of how compatible the observed data are with a specified null model, given the test assumptions. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of an outcome. The registry record does not report a p-value or identify a hypothesis test for the primary endpoint. Because this is a single-group study without a control arm, there is no registry-reported randomized treatment contrast to interpret.

What can planning calculations mean?

General sample-size calculations describe the amount of information a hypothetical study design might need to detect a chosen effect under stated assumptions. They are planning illustrations, not evidence that a study had a particular probability of detecting an effect after the results are observed. The planning assumptions associated with this record specify 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. For time-to-event calculations, the stated quantity is total events; for other calculations, it is participants per arm.

Those assumptions describe hypothetical planning, not this study’s observed single-group design. The registry does not describe a two-arm allocation for NCT00003404, and does not report the observed local recurrence effect needed to understand those planning illustrations. They must not be interpreted as the trial’s actual design or as observed power. The sample-size justification for the trial is not reported in the registry record.

What remains unspecified?

The registry lists 1 analysis, but does not name the statistical procedure, provide model assumptions, or say whether any covariates were used. It does not report how recurrence was verified, how participants with missing visits were handled, or whether results were analyzed according to an intention-to-treat principle or another population definition. It also does not describe interim analyses or any adjustment for multiple outcome testing. These omissions prevent a full audit of the analytic decisions.

General statistical methods can address issues such as uneven follow-up, missing measurements, or multiple endpoints, but each method relies on assumptions and requires relevant study information. For example, time-to-event methods require information about event times and censoring; methods for missing data depend on the pattern and reasons for missingness. Neither set of details is reported for the primary endpoint. The registry record therefore supports a limited methods description: the study is prospective and single-group, the endpoint is a participant count at a stated time, and the analysis method and several essential implementation details are not reported.

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("Adjuvant Radiotherapy")
n      <- c(46)
events <- c(0)
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  Adjuvant Radiotherapy  46  0  0.0  0.0  7.7  0.0  7.7  0.1  7.5

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies 2 outcome measures and lists local recurrence as the primary endpoint and survival rate as a secondary outcome. Considering more than one endpoint can raise multiplicity concerns because multiple statistical tests may increase the chance of at least one apparently unusual result under a set of null hypotheses. As a general statistical principle, researchers may define a hierarchy of outcomes or use an adjustment strategy, but the registry record does not report whether either approach was planned or used. It also does not report p-values or estimates for the listed outcomes, so no multiplicity-adjusted interpretation is available.

The record lists 1 analysis but does not explain its scope. It is not possible to tell whether that analysis covered the primary endpoint, the secondary outcome, or another measure, or how the analysis population was defined. The registry record does not report whether all enrolled participants were included in the primary analysis, whether participants were excluded, or whether analyses were conducted for any specified subgroup.

Missing data and incomplete follow-up are also not described. The record does not say how many participants had outcome information at 36 months, whether follow-up ended early for any participants, or how missing recurrence status was handled. General methods for missing data require assumptions about why information is missing; without the pattern and reasons for missingness, those assumptions cannot be assessed. Completed study status does not, on its own, establish complete follow-up or complete reporting. The extent and treatment of missing outcome data are not reported in the registry record.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry safety information lists 46 participants at risk for serious adverse events and 0 affected, and 46 at risk for other adverse events and 0 affected. It also lists 2 deaths. These are separate safety counts; the record does not say whether the deaths were counted as serious adverse events, whether they were related to radiotherapy, or when they occurred. No top serious adverse event terms are listed.

As a general statistical point, a zero count in a study group does not establish that an event cannot occur, nor does it prove the absence of risk. The precision of a safety estimate depends on the number of participants observed, duration and completeness of follow-up, event definitions, and how events were collected. Those details are not reported in the registry record. These counts should therefore be read as the events recorded in this study, not as a comprehensive estimate of safety across other populations or settings.

The 2 deaths do not provide a cause-specific or treatment-related conclusion. The registry does not report causes, timing, attribution, or a comparison group for mortality. No medical or causal interpretation of these counts can be drawn from the reported information alone.

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

The record describes a prospective, single-group study of adjuvant radiotherapy after surgery for borderline and malignant phyllodes tumors. It establishes an enrollment of 46 and identifies local recurrence 36 months after initial excision as the primary endpoint. The intervention description places radiotherapy within 12 weeks of local excision or breast re-excision. These features define the study question and setting, but the primary recurrence result is not reported in the registry record.

Accordingly, the record does not show how many participants experienced local recurrence, the estimated recurrence rate, or the uncertainty around that estimate. It also does not give a numerical result for the listed secondary outcome, survival rate. Without those results, readers cannot assess the observed outcome magnitude or precision from the registry information. The reported 0 serious adverse events, 0 other adverse events, and 2 deaths are safety counts, not substitutes for recurrence or survival estimates.

The study has no concurrent control group. As a general interpretation principle, an outcome observed in a treated group describes that group; it does not by itself establish what would have happened under a different treatment. A comparative effect requires a valid comparison and suitable analysis. The registry record explicitly notes that the arms do not constitute a like-for-like control comparison, so a causal contrast cannot be drawn from it.

Nor does the completed status establish that all findings have been reported. The analysis method, missing-data handling, analysis populations, recurrence assessment procedures, and sample-size justification are not reported in the registry record. The appropriate conclusion is therefore bounded: this record identifies the study’s design, intervention timing, primary endpoint, follow-up timeframe, enrollment, and limited safety counts, but it does not provide the numerical efficacy outcomes needed to describe the observed recurrence or survival results.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of how design and reporting shape what can be concluded. Its prospective, single-group structure identifies a treated cohort and a clinically defined endpoint, local recurrence at 36 months after initial excision. The registry also gives the intervention timing and enrollment. Those details make the intended question more interpretable than a vague outcome description, while leaving the reported result unavailable.

The absence of a control group is central to interpretation. A treated-group outcome can describe what was recorded among participants who received the intervention, but it cannot isolate the effect of treatment from other influences. In a single-group design, factors such as participant selection, tumor features, surgery, follow-up, and outcome assessment may affect observed outcomes. The registry record does not provide enough information to evaluate those factors or make a comparative causal claim.

The record also illustrates why outcome reporting needs more than an endpoint label. A count or rate, a clear denominator, follow-up completeness, and a measure of uncertainty are needed to understand the observed result and its precision. Here, the primary endpoint and timeframe are identified, but no recurrence count, estimate, or confidence interval is reported. The listed secondary survival outcome likewise has no numerical result in the registry record.

Finally, the safety counts need context. The registry lists no serious or other adverse events among the participants recorded at risk, along with 2 deaths, but does not describe event attribution, timing, or follow-up completeness. The counts are useful as a record of what was entered, not as a complete characterization of risk. This combination of a clear high-level design and important gaps in outcomes and methods underscores why statistical interpretation depends on transparent reporting of both results and analytic details.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most important limitation specific to this record is the absence of the primary endpoint result. Although local recurrence is named and its timeframe is stated as 36 months after initial excision, the registry does not report the number of recurrences, an estimated rate, or an uncertainty interval. The listed survival rate outcome also lacks a numerical result. The record therefore cannot support an assessment of the observed primary or secondary outcome magnitude.

The single-group design limits causal interpretation. There is no concurrent control group described, and the registry notes that the arms are not a like-for-like control comparison. Any outcome among participants receiving radiotherapy would not alone show how outcomes would differ under another approach. Participant characteristics and detailed eligibility criteria are not reported, which also limits assessment of how broadly the study population can be understood.

Several details needed to evaluate outcome quality are absent. The recurrence definition and assessment process are not described. The registry does not state how many participants had complete observation through the endpoint timeframe, how incomplete follow-up was handled, or what analysis population was used. The statistical method, sample-size justification, multiplicity approach, and any interim analyses are not reported in the registry record.

The safety information gives counts but not event definitions, timing, attribution, or follow-up duration. The 2 deaths cannot be interpreted as treatment-related from the record. Finally, the registry describes the study as phase II in its brief summary while listing phase as NA; it does not explain the discrepancy. Together, these limitations constrain interpretation to the documented design and counts rather than any conclusion about treatment effects or the completeness of outcome ascertainment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Radiation Therapy After Surgery in Treating Women With Phyllodes Tumor of the Breast — NCT00003404.
• Registry record last updated 2019-01-22; status last verified 2018-12.
• Results first posted 2019-01-22.
• 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

NCT00003404 is a completed prospective, single-group study sponsored by Dartmouth-Hitchcock Medical Center, with enrollment of 46. The official title concerns adjuvant radiotherapy after resection of borderline and malignant phyllodes tumors. The registry describes radiation as starting within 12 weeks of local excision or breast re-excision. The primary endpoint is local recurrence, measured as a count of participants 36 months after initial excision; survival rate is listed as a secondary outcome.

The registry does not report numerical results for local recurrence or survival, nor the primary analysis method, missing-data handling, or analysis populations. Safety information lists 0 serious adverse events among 46 at risk, 0 other adverse events among 46 at risk, and 2 deaths; attribution and timing are not reported. The study has no concurrent control group, so it does not provide a like-for-like treatment comparison.