Xeloda (Capecitabine) and External Beam Radiation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Xeloda (Capecitabine) and External Beam Radiation (NCT00916578), a na phase 2 study. The primary outcome is Response Rate of Patients Who Receive Pre-operative or Palliative Concurrent Radiation w/ Capecitabine to the Breast & at Risk or Involved Regional Lymph Nodes Basins..

2. Clinical Question

As a result, the record identifies the clinical question and the treatment being evaluated, but it does not give the primary outcome result needed to assess the observed response. The question is about response following a combined treatment course, not about which component contributed to any response. Without a comparator, differences from another treatment strategy cannot be estimated from this study alone.

3. Trial Design

This was a Phase II, single-group, open-label study sponsored by M.D. Anderson Cancer Center. The registry lists enrollment of 33 and a completed status. The recorded study start date is 2009-06-05, and the primary completion date is 2017-06-06. The primary outcome description says participants were monitored from 2009 to 2012; the relationship between that monitoring period and the broader registry dates is not explained.

All participants were assigned to the combination of radiation therapy and capecitabine; there was no randomized allocation or masking. With no control arm, the design can describe outcomes among participants treated under the study protocol, but it cannot estimate a randomized treatment contrast. The lack of masking also means the registry does not describe a blinded assessment process. Whether outcome assessors were otherwise kept unaware of treatment is not reported in the registry record.

The registry describes the primary outcome population as all patients who received protocol-specified treatment. It does not state how many of the 33 enrolled participants received that treatment, how many contributed to the primary outcome, or whether any participants were excluded from the analysis. The safety record gives a separate at-risk count of 26; the reason that count differs from enrollment is not reported in the registry record.

The treatment description specifies concurrent administration, including the capecitabine dose and its timing in relation to radiation. The complete protocol, radiation schedule, treatment adherence, and any treatment modifications are not reported in the registry record. The record lists one outcome measure and no analysis entries. This means it contains no detailed analysis output for the primary endpoint; it does not establish whether analyses were or were not conducted outside the registry entry.

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: All patients who received protocol - specified 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.

Population: Patients who enrolled into the study and signed consent.

6. Primary Endpoint

The registry lists the primary outcome as Response Rate of Patients Who Receive Pre-operative or Palliative Concurrent Radiation w/ Capecitabine to the Breast & at Risk or Involved Regional Lymph Nodes Basins., measured over Participants were monitored from 2009 to 2012..

The primary endpoint is described as the response rate among patients receiving pre-operative or palliative concurrent radiation with capecitabine to the breast and at-risk or involved regional lymph-node basins. The outcome description says response was assessed by RECIST after 45 Gy of radiation. The registry records the outcome as a number of participants, rather than posting a response estimate or a percentage. Neither the number classified as responding nor the response rate is reported in the registry record.

In general, a response endpoint is used to describe whether disease shows a defined change after treatment. RECIST is a standardized approach for classifying tumor response from assessments of disease. Standardization can make outcome definitions more consistent across participants, although the registry does not state which RECIST version was used, the specific response categories included in the endpoint, or how assessments were conducted.

Response is an intermediate, disease-focused outcome. It does not by itself describe how long a response lasted, whether disease later progressed, or survival. Those outcomes are not reported as measures in this registry entry. The stated timing anchors assessment to a radiation dose, but the exact assessment procedures and any rules for missing or unevaluable assessments are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

In general, a single-group study describes outcomes within the group receiving the study treatment. For a binary endpoint such as whether a participant is classified as having a response, the basic descriptive result is a count and a proportion among the participants assessed. A confidence interval can describe the uncertainty around an estimated proportion. It does not remove design limitations or create a comparison group.

For this study, the registry identifies the outcome as a participant count and describes the outcome population as all patients who received protocol-specified treatment. However, the response count, the number assessed, the response proportion, and an interval estimate are not reported in the registry record. Without those results, there is no posted primary estimate to interpret. Enrollment alone cannot stand in for the number analyzed or the number who responded.

Why does the absence of a comparator matter?

In general, a treatment contrast compares outcomes between groups that differ in the treatment strategy being evaluated. Random allocation can help make the groups comparable in expectation, while a suitable control group supplies a reference for interpreting the treated group’s outcome. This study is recorded as single-group, with no allocation to a separate comparator. It can therefore describe outcomes in the treated cohort but cannot directly estimate a difference attributable to treatment relative to a control strategy.

This is not simply a matter of choosing a different statistical test. A statistical model cannot recover a randomized contrast that the design did not collect. Nor does a within-group response result, even if one were posted, establish how the same participants would have fared under another strategy. The registry record does not report an adjusted or external comparison.

What does a confidence interval add?

In general, a confidence interval expresses the statistical uncertainty around an estimate under the assumptions of the method used. A narrower interval indicates greater precision for that estimate, while a wider interval indicates less precision. The interval does not account automatically for every source of bias, such as selection into the analyzed group, missing outcome assessments, or differences between the study population and other patients.

No confidence interval for the primary response outcome is reported in the registry record. Its width therefore cannot be assessed, and the precision of the primary result cannot be characterized from this entry. The sample-size illustrations associated with the posted material are planning calculations, not observed power and not a substitute for a confidence interval around the trial’s result.

How should planning assumptions be distinguished from the trial design?

In general, sample-size planning describes how many participants might be needed under specified assumptions about an effect and a statistical procedure. A planning result depends on those assumptions; it is not an outcome observed in a trial. The registry record does not report the study’s own sample-size justification or planned target. Enrollment of 33 should therefore be read as the recorded enrollment, not as evidence about the rationale used to choose the study size.

The planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Those are illustration assumptions, not a description of this single-group trial’s allocation. They do not establish that this trial planned equal allocation, had two arms, or used those assumptions in its protocol. The actual calculated planning results are not included in the registry entries, so no planning sample-size result can be stated.

What does the binary outcome imply?

In general, a binary outcome places each assessed participant into a defined category, such as response or no response. Its interpretation depends on a clear outcome definition and on knowing who was assessed. A count without its analysis denominator is incomplete for estimating a proportion; a proportion without an uncertainty interval does not show how precise the estimate is. RECIST provides a framework for response assessment, but the specific version, category rules, and handling of unevaluable cases are not reported in the registry record.

The registry describes the primary measure as a participant number and says assessment occurred after 45 Gy of radiation. It does not report how response categories were combined to create the endpoint, whether review was independent, or how a participant with no assessable follow-up was treated. These details matter because analytic choices can affect the denominator and the resulting estimate.

Why can over-dispersion matter in other outcome types?

In general, over-dispersion occurs when observed variation is greater than a statistical model expects. It can matter for count outcomes or clustered data because a model that assumes less variability than is present may produce uncertainty estimates that are too narrow. This trial’s listed primary endpoint is a binary participant response count, not a reported repeated count outcome. The registry record gives no over-dispersion assessment or model-based analysis, so this concept does not provide a basis for a further inference about the posted results.

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("Single Arm Institution, Open Label, Phase II")
n      <- c(33)
events <- c(26)
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  Single Arm Institution, Open Label, Phase II  33  26  78.8  61.1  91.0  62.2  89.3  62.1  89.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, the primary response measure, and no analysis entries. The record does not report a multiplicity adjustment, a hierarchy of endpoints, or a plan for handling multiple statistical tests. With no posted primary analysis and no detailed analysis plan, it is not possible to determine whether multiple comparisons were considered or how any such comparisons were handled. The absence of analysis entries should not be interpreted as proof that no analyses were conducted; it means the registry entry does not contain those analyses.

The registry identifies the primary outcome population as all patients who received protocol-specified treatment. It does not report the number in that population, the number assessed for response, or the number included in an analysis. It also does not describe an intention-to-treat population or another analysis population. How participants who did not receive the specified treatment, lacked an assessment, or had an unevaluable assessment were handled is not reported in the registry record.

Missing-data methods are not reported in the registry record. There is no stated imputation method, sensitivity analysis, or account of missing outcome assessments. In general, missing outcomes can affect both the estimated response proportion and its interpretation, particularly when the reasons for missingness are related to participants’ outcomes. The extent and potential impact of missing response data cannot be assessed from this entry.

The safety group has 26 participants at risk, whereas enrollment is 33. The record does not explain the difference or link the safety group to the primary endpoint analysis population. These counts should not be treated as interchangeable denominators.

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 registry lists a single safety group, described as a single-arm, open-label Phase II study. Among 26 participants at risk, 0 were recorded as affected by serious adverse events, 18 were recorded as affected by other adverse events, and 0 deaths were recorded. These are counts in the registry entry, not comparative estimates against another treatment group.

The safety denominator of 26 differs from the enrollment of 33. Why only 26 participants are listed as at risk is not reported in the registry record. The entry does not report the safety observation period, event definitions, severity grading rules, event timing, or whether participants could contribute more than one event. It also lists no serious adverse-event terms. The absence of listed terms does not provide further detail about event ascertainment or classification.

In general, adverse-event counts describe what was recorded under a study’s reporting rules. A count of 0 serious adverse events does not establish that a treatment has no serious risks, especially without information about the observation period, completeness of reporting, and the participants included. The safety figures should be read as descriptive registry counts only, with no inference about comparative safety.

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

The record documents a completed Phase II investigation of concurrent capecitabine and radiation in women with advanced inflammatory or non-inflammatory breast cancer. It gives the broad treatment schedule, identifies response by RECIST after 45 Gy as the primary outcome, and reports safety counts for a group of 26 participants at risk. Those details describe what the study set out to examine and some of the recorded safety information.

The record does not report the primary response count or rate. It therefore does not show the observed response frequency, and it provides no interval estimate with which to judge the precision of such a result. No claim about the magnitude of response can be drawn from the entry. The lack of a primary result should not be replaced by interpretation of enrollment, study status, or safety counts.

The single-group design also limits what an outcome could establish. Without a comparator, the study cannot directly quantify how outcomes differed from another treatment strategy. In general, observing an outcome after treatment does not alone establish that treatment caused it. The registry does not report a randomized comparison or an adjusted comparison that would address that limitation.

The safety counts show 0 serious adverse events among 26 at risk, 18 other adverse events among 26 at risk, and 0 deaths. They do not describe event timing or severity beyond the distinction recorded, and they cannot be compared with a control group. The difference between enrollment and the safety at-risk count is unexplained.

Accordingly, the record supports a description of the study question, design, endpoint timing, and posted safety counts. It does not support a conclusion about the primary response result, its precision, treatment effects relative to alternatives, or the full safety profile. Those details are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why the design and the completeness of outcome reporting both matter in statistical interpretation. The registry clearly identifies a single-group treatment strategy and a response outcome, but it does not post the response count or rate. A well-defined endpoint is important, yet readers also need the observed estimate and information about how many participants contributed to it to understand the result.

The distinction between enrollment and analysis population is also important. The record reports enrollment of 33, describes the primary population as patients who received protocol-specified treatment, and gives a safety at-risk count of 26. It does not explain how these groups relate. Without the number assessed for the primary outcome and an account of exclusions or missing assessments, the denominator for the response endpoint cannot be confirmed.

The design matters independently of reporting. A single-group study can describe outcomes in the treated cohort, but does not provide a concurrent control for estimating a treatment contrast. Statistical methods can quantify uncertainty around an estimate when the relevant data are available; they cannot supply the missing comparator or determine a causal effect from a within-group result alone.

Finally, the safety counts demonstrate why denominators and event definitions are essential context. Counts without a clear observation period, event details, or comparison group have a limited descriptive interpretation. Together, these features make this record useful for identifying the study’s aims and structure, while leaving its primary efficacy result and several key analytic details unresolved.

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 limitation for interpreting the primary endpoint is that the registry record does not report the response count or response rate. It also does not provide a confidence interval, a test result, or a detailed analysis. The endpoint is described as response by RECIST after 45 Gy, but the RECIST version, response categories included, assessment process, and handling of unevaluable cases are not reported.

The single-group design has no direct comparator. Any within-group outcome could not establish a comparative effect against another treatment strategy. The open-label designation indicates that masking was absent, but the registry does not explain how response assessments were conducted or whether any safeguards against assessment bias were used.

The record reports enrollment of 33 and a safety at-risk count of 26, but does not explain the difference. It states that the primary outcome population includes patients who received protocol-specified treatment, without reporting the number who did so or the number analyzed. Missing-outcome handling, exclusions, treatment adherence, and the reasons for any differences between these counts are not reported.

Additional protocol details are limited. The treatment description gives the capecitabine dose and timing in relation to radiation, but the complete treatment schedule and radiation details are not reported in the registry record. The study’s sample-size justification, analysis plan, multiplicity procedures, and missing-data methods are also not reported. The safety entry lacks event definitions, observation period, and detailed terms. These omissions restrict assessment of both the primary result and the completeness and context of safety reporting.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Xeloda (Capecitabine) and External Beam Radiation — NCT00916578.
• Registry record last updated 2018-07-26; status last verified 2018-06.
• Results first posted 2018-06-28.
• 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

NCT00916578 is a completed, open-label, single-group Phase II study sponsored by M.D. Anderson Cancer Center. It enrolled 33 women with advanced inflammatory or non-inflammatory breast cancer and evaluated capecitabine given concurrently with radiation. The registry lists capecitabine at 825 mg/m2 twice a day, with one daily dose approximately 2 hours before radiation.

The primary endpoint was the participant response assessed by RECIST after 45 Gy of radiation. The registry does not report the response count, response rate, or precision estimate. Safety counts are 0 serious adverse events among 26 at risk, 18 other adverse events among 26 at risk, and 0 deaths. The reason the safety count differs from enrollment is not reported in the registry record. With no comparator and no posted primary outcome result, the record supports a description of the study design and recorded safety counts, but not a comparative treatment-effect estimate.