Ph II Long Term/Low Dose Xeloda in Head and Neck Squamous Cell Carcinoma After Surgery, Radiation & or Chemo: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ph II Long Term/Low Dose Xeloda in Head and Neck Squamous Cell Carcinoma After Surgery, Radiation & or Chemo (NCT00258310), a na phase 2 study. The primary outcome is Compliance With Treatment ..

2. Clinical Question

3. Trial Design

This was a phase II study with a single group and no randomized allocation. The registry records masking as none and enrollment as 35. The study is listed as completed, with a start date of 2003-12 and a primary completion date of 2011-02. These dates describe the registry record; they do not provide participant-level follow-up times.

The study intervention was capecitabine after surgery, chemotherapy and/or radiotherapy. The arm description specifies capecitabine 1000mg/day for one year. Because there is no concurrent control group, the design can describe treatment experience in the enrolled group but cannot estimate a randomized between-group treatment contrast. Prior treatments could also differ among participants; the distribution of those treatment histories is not reported in the registry record.

The stated primary outcome is compliance with treatment, defined as taking at least 80% of the prescribed dose for one year and assessed within 365 days. The registry also identifies recurrence-free survival, overall survival and incidence of second primary tumors as secondary outcomes. It records four outcome measures and one analysis, but detailed outcome estimates and the analysis methods are not reported in the registry record.

The stated aim concerns the feasibility of long-term, low-dose capecitabine after prior treatment. The registry record does not report the protocol’s sample-size justification, interim analysis plan or a detailed statistical analysis plan. Planning illustrations based on an observed effect are not the trial’s own design rationale and do not turn this single-group study into a controlled comparison.

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 Compliance With Treatment ., measured over within 365 days.

The primary endpoint is compliance with treatment within 365 days. Compliance is defined as taking at least 80% of the prescribed capecitabine dose for one year. The endpoint is expressed as a percentage of participants, so it is intended to describe how many met that predefined dose-taking criterion rather than to measure tumor response or survival directly.

Compliance is relevant to a feasibility question: a regimen intended to continue for a year depends on participants being able to take the prescribed treatment over that period. The endpoint does not, by itself, establish why a participant did or did not meet the criterion. The registry record does not report how dose-taking was measured, how interruptions or dose changes were handled, or which analysis population was used.

The registry specifies a 95% confidence interval as the measure of dispersion, but the compliance estimate and its interval are not reported in the registry record. In general, a confidence interval expresses statistical uncertainty around an estimate; it does not describe every participant’s experience or resolve possible bias from missing observations. Without the estimate and interval, the degree of precision for this endpoint cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a participant-level compliance criterion summarized as a percentage. Each participant would be classified according to whether the prescribed-dose threshold was met over the one-year period, as defined in the registry. A percentage is a way to describe the frequency of participants meeting that criterion in the analyzed group. The registry record does not report the numerator, denominator used for the primary analysis, or resulting percentage, so the estimate cannot be reconstructed.

What does a confidence interval convey?

The registry identifies a 95% confidence interval for the primary outcome. In general, a confidence interval communicates the statistical uncertainty associated with an estimated quantity under the assumptions of the method used. A narrower interval indicates greater precision than a wider interval, while the estimate itself describes the observed result. A confidence interval is not a guarantee that the true value lies within a particular interval, and it does not account automatically for selection bias, measurement problems or missing data.

The interval endpoints, calculation method and underlying result are not reported in the registry record. Consequently, precision cannot be judged, and the interval cannot be checked against the observed data. No p-value or hypothesis test result for the primary endpoint is reported in the registry record. For a descriptive feasibility endpoint, the percentage and its uncertainty are central to interpretation; a test result alone would not describe the size of the observed compliance proportion.

How does the single-group design shape the analysis?

With one treatment group, the primary endpoint can be summarized within that group, but the study does not estimate a randomized difference between capecitabine and a control treatment. General statistical methods for comparing two independent groups do not create a valid trial comparator when none was enrolled. Any external comparison would require additional data and assumptions that are not reported in the registry record.

The absence of masking means the registry records the study as open-label. That design feature may matter for how behavior, treatment taking or outcome assessment is measured, depending on the endpoint and procedures. The record does not describe compliance monitoring, adjudication, or safeguards against assessment bias, so their use cannot be assumed.

What do the planning assumptions mean?

Planning illustrations use a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. They express the effect to detect as a stated fraction of the observed effect. For time-to-event calculations, the planning quantity is the total number of events; for other calculations, it is participants per arm. These are general planning assumptions, not the design of this single-group trial. They should not be read as observed power or as evidence that the enrolled study had a particular probability of detecting an effect.

The registry record does not report the trial’s own sample-size justification. Nor does it report a primary outcome estimate from which a reader could judge the observed effect or relate it to a planning target. The planning assumptions do not fill that gap, and their hypothetical two-arm allocation is not evidence that the study had two arms.

What is needed to assess the other outcomes?

Recurrence-free survival and overall survival are time-to-event outcomes, for which interpretation generally depends on the time origin, event definition, follow-up, censoring and analysis method. The registry record lists these outcomes but does not report their estimates or detailed methods. The incidence of second primary tumors likewise needs a defined observation period and a clear account of how cases and follow-up were handled. Those details are not reported in the registry record. Without them, neither the magnitude nor precision of the secondary outcome findings can be assessed.

Over-dispersion is a general concern when the variability in data exceeds what a simple statistical model assumes; it can make uncertainty estimates too optimistic if ignored. The registry record does not describe a model for the primary compliance endpoint or report evidence about over-dispersion. It would therefore be inappropriate to claim that over-dispersion was present, absent or addressed in the analysis.

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("Capecitabine")
n      <- c(35)
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  Capecitabine  35  26  74.3  56.7  87.5  57.9  85.8  57.8  85.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures: the primary compliance outcome and the secondary outcomes of recurrence-free survival, overall survival and incidence of second primary tumors. It also records one analysis. The statistical analysis plan, including whether hypotheses were prespecified and how multiple outcomes were handled, is not reported in the registry record. No multiplicity adjustment method is reported. When several outcomes are examined, general statistical practice recognizes that the chance of at least one apparently notable result can increase; whether or how that concern was addressed in this study cannot be determined from the registry record.

Missing-data handling for the primary outcome is not reported in the registry record. The record does not say how participants who stopped treatment, had incomplete dose-taking information or lacked follow-up were classified. It also does not identify the analysis population or state whether all enrolled participants were included in the primary analysis. Those choices can affect a compliance percentage and its confidence interval, so the reported definition alone is not enough to evaluate the analysis.

Follow-up and censoring details for the secondary survival outcomes are also not reported in the registry record. In general, time-to-event methods need to account for participants whose event status is unknown after their last observed follow-up. The record does not specify how that situation was handled, what follow-up duration was available, or how missing outcome data were treated. No assumptions about these procedures can be made from the outcome names alone.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hand foot syndrome (5.7%), respiratory failure (2.9%).

The registry lists 35 at risk for the capecitabine group, with 2 affected for serious adverse events and 3 affected for other adverse events. These are counts within the treated group, not comparisons against an untreated or alternative-treatment group. The registry also lists Hand Foot Syndrome at 5.7% and Respiratory Failure at 2.9% among the top serious adverse event terms.

The term-level percentages and the affected counts answer different descriptive questions. The registry record does not report whether a participant could contribute to more than one event category, or how the term-level percentages were calculated. The figures should therefore be read as registry-reported safety summaries, not as evidence of a causal relationship or as a comparative risk estimate.

The record does not report deaths in the adverse-event summary. It also does not provide further detail in this summary about event timing, duration, severity beyond the serious classification, or attribution to treatment. Such details are not reported in the registry record. These limitations matter when interpreting event counts from a single group: the figures describe recorded events but do not show what would have occurred under a different treatment strategy.

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

The study addresses a practical question about taking capecitabine for an extended period after prior treatment. Its primary endpoint sets a clear threshold: participants must take at least 80% of the prescribed dose for one year, within 365 days. That definition indicates what the investigators intended to count as compliance, but the registry does not report how many participants met it or the confidence interval around the percentage.

As a result, the posted registry information does not establish the observed level of compliance or its precision. It cannot show whether compliance was common or uncommon in this enrolled group, nor whether the estimate was stable or uncertain. The recorded enrollment of 35 participants is not a substitute for the missing outcome result and does not indicate how many were included in the primary analysis.

The design also limits what can be concluded beyond the treated group. There was no concurrent control group, so the study does not provide a randomized comparison of capecitabine with another strategy. The secondary outcomes are named, but their numerical results are not reported in the registry record. No treatment effect on recurrence, survival or second primary tumors can be inferred from outcome labels alone.

The serious adverse event counts and listed terms describe safety observations in the capecitabine group. They do not demonstrate that capecitabine caused the events or indicate how event frequency compares with another group. The absence of a death count in the registry summary means deaths are not reported there; it should not be interpreted as evidence that none occurred.

In general, a registry record is most informative when the outcome estimates, uncertainty, analysis population and missing-data procedures are all available. Here, the endpoint definition and study design are described, but the key primary estimate and several supporting analysis details are not reported in the registry record. The conclusions should remain limited to those design details and descriptive safety figures.

14. Why This Trial Matters Statistically

This study is statistically notable for asking a feasibility question in a single-group setting. A compliance endpoint is different from a direct comparison of clinical outcomes: it describes whether participants followed a long-term prescribed regimen according to a stated threshold. That can be relevant when evaluating whether an intervention can be sustained after surgery, radiation therapy and/or chemotherapy. The registry record, however, gives the endpoint definition without its result, leaving the central feasibility quantity unavailable.

The example also illustrates why the study design and endpoint need to be read together. With one group, a percentage can describe the enrolled participants, but it cannot isolate an effect attributable to capecitabine by comparing outcomes against a concurrent control. The secondary outcomes could have clinical relevance, but their names alone do not convey event counts, estimates, uncertainty or follow-up. Statistical interpretation requires those results as well as an understanding of how they were analyzed.

The registry lists safety counts and term-specific percentages, which are useful as descriptive information but do not serve as comparative evidence. Separating event description from causal interpretation is important in any uncontrolled study. The record also shows why a defined threshold does not replace transparent reporting of the numerator, denominator, analysis population and handling of missing observations.

Finally, hypothetical sample-size planning assumptions should not be mistaken for the original study rationale or evidence of observed power. The registry does not report the trial’s own sample-size justification. Keeping planning concepts distinct from trial results helps prevent a design illustration from being read as a finding. Overall, the record supports a careful description of the question and design, while the missing primary and secondary estimates prevent a fuller assessment of what the study observed.

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 principal limitation for interpretation is that the registry record does not report the primary compliance percentage or its 95% confidence interval. Without those values, neither the observed result nor its statistical precision can be evaluated. The record also does not report the numerator and analysis denominator, compliance measurement procedures, or the population included in the analysis.

The single-group design provides no concurrent control for separating treatment-associated observations from other influences. Participants had prior surgery, radiation therapy and/or chemotherapy, but the distribution of prior treatments is not reported in the registry record. Further details about participant characteristics, eligibility, dose modifications, treatment interruptions and adherence assessment are also not reported in the registry record.

Although recurrence-free survival, overall survival and incidence of second primary tumors are listed as secondary outcomes, their numerical results and analysis details are not reported in the registry record. Follow-up duration, event definitions, censoring procedures and missing-data methods are not described. The statistical analysis plan, multiplicity approach and protocol-level sample-size justification are likewise not reported in the registry record.

The safety summary is limited to affected counts and listed serious adverse event terms. It does not report event timing or attribution, and deaths are not reported in the summary. The counts cannot be compared with an external treatment group within this trial. These limitations constrain interpretation of both feasibility and safety, even though the study is marked completed.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Ph II Long Term/Low Dose Xeloda in Head and Neck Squamous Cell Carcinoma After Surgery, Radiation & or Chemo — NCT00258310.
• Registry record last updated 2023-03-10; status last verified 2023-03.
• Results first posted 2015-01-19.
• 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

The registry describes a completed phase II, single-group study of oral capecitabine after surgery, chemotherapy and/or radiotherapy for head and neck squamous cell carcinoma. It records 35 participants enrolled and a regimen of 1000mg/day for one year. The primary outcome is compliance, defined as taking at least 80% of the prescribed dose for one year within 365 days.

Recurrence-free survival, overall survival and incidence of second primary tumors are listed as secondary outcomes. The primary estimate, its 95% confidence interval and numerical results for the secondary outcomes are not reported in the registry record. The safety summary lists 2 affected for serious adverse events and 3 affected for other adverse events among 35 at risk, with Hand Foot Syndrome at 5.7% and Respiratory Failure at 2.9% among the top serious terms.

Because the study has no concurrent control group, the results described are not a randomized treatment comparison. The registry record does not report the detailed analysis plan, missing-data procedures or trial-specific sample-size justification.