Post-operative Radiation With Cetuximab for Locally Advanced Cutaneous Squamous Cell Carcinoma of the Head and Neck: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Post-operative Radiation With Cetuximab for Locally Advanced Cutaneous Squamous Cell Carcinoma of the Head and Neck (NCT01979211), a na phase 2 study. The primary outcome is Percentage of Participants With Local Regional Control.

2. Clinical Question

3. Trial Design

This was a phase II, single-group clinical trial of cetuximab with radiation for locally advanced cutaneous squamous cell carcinoma of the head and neck. The registry lists enrollment of 24 participants and identifies the study as completed. Its start is recorded as 2013-10, and primary completion is recorded as 2022-01-19. The sponsor was the University of Cincinnati.

There was no randomized allocation and no masking. Because every participant was in the cetuximab-and-radiation group, the design can describe outcomes observed or estimated after that treatment approach, but it cannot isolate the effect of cetuximab from the effect of radiation or other aspects of care. There is no like-for-like control comparison in the record.

The arm description gives a cetuximab loading dose before radiation, then weekly cetuximab during radiation. Radiation is described as 60-66 Gy in daily fractions of 2 Gy. The registry’s primary endpoint was 2-year locoregional control. Disease-free survival and overall survival are listed as secondary outcomes, but their results are not reported in the registry record.

The entry describes the study purpose as examining how readily cetuximab could be added to radiation, how the combined treatment performed over time, and how it was tolerated. A more detailed protocol, eligibility criteria, sample-size justification, and statistical analysis plan are not reported in the registry record. The described design and endpoint should therefore be distinguished from any claims about a prespecified statistical plan that the record does not document.

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: 24 data points were included in the Kaplan-Meier method and yielded an predicted percentage of individuals with LRC at a 2 year mark. Analysis yielded a predicted 91% of subjects had LRC. Extrapolating this percentage to the overall number of participants analyzed, 21.84 subjects had LRC.

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 Percentage of Participants With Local Regional Control, measured over 2 years.

Locoregional control measures whether cancer recurs in the original tumor bed or the neck. The registry defines control as no evidence of recurrence in those locations, assessed through clinical examination and imaging. The primary endpoint is the estimated percentage of participants with locoregional control at 2 years.

This endpoint is used to describe control of disease in the treated local and regional areas over time. It is not the same as disease-free survival or overall survival, both of which are listed separately as secondary outcomes. A participant may have local or regional control while having an event relevant to another outcome, so the endpoints should not be treated as interchangeable.

The registry says locoregional control was estimated with the Kaplan–Meier method. This method uses the timing of follow-up and accommodates censored observations, such as participants whose event status is not observed for the entire follow-up period. The registry describes the endpoint as a 2-year estimate, not simply a count of participants known to be recurrence-free at a single shared assessment time.

The result is therefore a time-to-event estimate of the probability of remaining free of locoregional recurrence through the stated time point, subject to the available follow-up and censoring. The endpoint’s assessment schedule, handling of specific types of missing follow-up, and detailed event-adjudication procedures are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary result is reported as a Kaplan–Meier estimate of locoregional control at 2 years. This is a time-to-event approach: it uses when participants are followed and whether an event is observed, rather than requiring every participant to have the same duration of observation. The registry says that 24 data points were included in the analysis and reports a predicted 91% with locoregional control at the 2-year mark.

What Kaplan–Meier estimation does

General statistical explanation: In a time-to-event analysis, an event might be recurrence, while participants who have not experienced the event by the end of their observed follow-up contribute information up to that point. If a participant’s follow-up ends without an observed recurrence, that observation is censored. Censoring does not mean the participant had a recurrence; it means the event status is unknown after the last observed time. Kaplan–Meier estimation uses the observed event times and the participants still under observation at those times to estimate the event-free proportion over follow-up.

The registry’s description calls the outcome locoregional control and explains that censored observations are incorporated. The estimated percentage is thus not necessarily the raw fraction of all participants known to be recurrence-free at 2 years. Its interpretation depends on follow-up and censoring. How censoring was handled in specific circumstances, how often participants were assessed, and how recurrence was confirmed are not reported in the registry record.

Reading the confidence interval

General statistical explanation: A confidence interval expresses the uncertainty around an estimate using a statistical procedure. A narrower interval indicates greater precision under the assumptions of that procedure; a wider interval indicates less precision. The primary outcome identifies a 95% confidence interval, but the interval limits are not reported in the registry record. The 91% point estimate can be stated, but its reported uncertainty cannot be quantified from the record.

The registry also converts the estimated percentage to 21.84 subjects. Because people are whole individuals, this is not a literal participant count. It is an extrapolated equivalent based on the estimated percentage, and it should not be confused with a count of observed participants who had documented control at 2 years.

Why the single-group design matters

General statistical explanation: A single-group study estimates outcomes in participants receiving the study regimen. Without a concurrent comparison group, it does not directly estimate what would have happened to similar participants under a different regimen. In this trial, cetuximab and radiation were administered together, so their separate contributions cannot be identified from the reported design. The analysis can describe locoregional control in the treated group, but not a comparative treatment effect.

The registry lists no masking and allocation as not applicable, consistent with the recorded single-group design. It does not report an adjustment strategy for participant characteristics or other sources of variation. Whether any such analyses were planned or performed is not reported in the registry record.

Over-dispersion and model choice

General statistical explanation: Over-dispersion occurs when the observed variability in data is greater than a statistical model expects. If a model assumes less variability than is present, uncertainty may be understated and inferences can be too confident. The reported primary method is Kaplan–Meier estimation, and the registry does not report an over-dispersion assessment or a model-based adjustment. This concept is relevant generally, but there is no basis in the record to claim that over-dispersion was found or affected this analysis.

Planning illustrations are not trial results

The accompanying sample-size calculations are described as planning illustrations computed from the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They are not the original sample-size justification for this single-group trial. The planning rows refer to hypothetical two-arm allocation and a stated fraction of the observed effect; they do not describe participants actually allocated in this study.

General statistical explanation: A sample-size calculation asks how many participants or events a hypothetical study would need under specified assumptions. It is a planning exercise, not a measurement of how likely the completed trial was to detect an effect. Such figures are not observed power. The registry record does not report the trial’s own sample-size justification or the assumptions that may have been used when it was designed.

For time-to-event illustrations, the stated convention is to give a total number of events; other calculations give participants per arm. These planning outputs do not alter the interpretation of the observed single-group Kaplan–Meier estimate and do not create a control comparison that was absent from the trial.

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("Cetuximab and Radiation")
n      <- c(24)
events <- c(22)
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  Cetuximab and Radiation  24  22  91.7  73.0  99.0  74.2  97.7  74.0  97.5

11. Multiplicity, Missing Data and Analysis Populations

The registry lists locoregional control as the primary outcome and disease-free survival and overall survival as secondary outcomes. It does not report results for those secondary outcomes. The record also does not describe a multiplicity adjustment, a hierarchy for testing outcomes, or a plan for interpreting multiple statistical tests. Whether such procedures were prespecified is not reported in the registry record.

General statistical explanation: When a study examines multiple outcomes or performs multiple tests, the chance of at least one apparently notable result can increase. A prespecified testing strategy or adjustment can help govern interpretation. No such strategy can be inferred from the outcome list alone. The posted primary estimate should not be treated as evidence about unreported secondary outcomes.

The primary outcome uses Kaplan–Meier estimation, which can account for censored follow-up. That does not mean every missing observation or incomplete assessment is resolved automatically. The registry does not report the amount or pattern of missing follow-up, reasons for censoring, or any sensitivity analyses. It also does not report how participants with incomplete endpoint assessments were handled beyond the general method description.

The record does not specify an analysis population such as intention-to-treat, per-protocol, or a separate evaluable population. It reports 24 data points included in the Kaplan–Meier method, but does not provide further detail about exclusions or the relationship between those data points and all enrolled participants. Such details 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: dizziness (4.2%), lip pain (4.2%), hypomagnesemia (4.2%).

The adverse-event entry lists 24 participants at risk for serious adverse events and 3 affected. It also lists 24 at risk for other adverse events and 24 affected. These are separate categories in the registry record. The figures describe reported participants in the treatment group; they do not, by themselves, establish whether an event was caused by cetuximab, radiation, another factor, or a combination.

The record lists dizziness, lip pain, and hypomagnesemia among the leading serious adverse-event terms, each with a reported 4.2%. These percentages are the registry’s figures; the entry does not provide further event-level detail in the reported information. They should not be added together or interpreted as mutually exclusive categories.

Nine deaths are recorded for the group. The information reported does not specify their timing, causes, or relationship to treatment. A death count alone does not show that the treatment caused those deaths, nor does it establish the circumstances in which they occurred.

The adverse-event timeframe, grading criteria, collection procedures, and detailed attribution rules are not reported in the registry record. The counts therefore provide a limited safety description and should not be interpreted as a complete account of the nature, timing, or causality of adverse events.

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

The primary result describes an estimated 91% locoregional control at 2 years in a Kaplan–Meier analysis that included 24 data points. It gives a registry-reported estimate for control in the tumor bed and/or neck, as defined by clinical examination and imaging. The result is a time-to-event estimate, not necessarily a count of participants with a directly observed assessment at the same time point.

The registry’s conversion of this estimate to 21.84 subjects is an extrapolation and not a literal number of people. The primary outcome identifies a 95% confidence interval, but its limits are not reported. Consequently, the precision of the estimate cannot be judged from the posted result alone.

The study was single-group, with no concurrent control. It therefore does not show how the result compares with radiation alone or another treatment, and it cannot separate the contribution of cetuximab from that of radiation. It also does not establish that the regimen caused the observed outcome. The finding is descriptive of the analyzed group within the recorded study.

The result does not supply the listed disease-free survival or overall survival outcomes; those results are not reported in the registry record. Nor does the primary endpoint describe treatment tolerability or safety. The adverse-event entry gives participant counts and selected serious-event terms, but does not provide the details needed to determine causality, timing, or the full clinical context.

Important interpretive details are absent, including eligibility criteria, participant characteristics, a detailed statistical plan, the sample-size justification, confidence interval limits, and details of missing follow-up. Those omissions limit assessment of the estimate’s precision, generalizability, and analytic context. The result should be read as a reported single-group estimate, not as a controlled comparison or a complete account of all study outcomes.

14. Why This Trial Matters Statistically

This trial is statistically notable for the distinction between an estimated outcome and a direct participant count. The primary result is a Kaplan–Meier estimate at 2 years, based on 24 data points, rather than a simple report of how many participants were observed to remain recurrence-free at a common visit. That distinction matters whenever participants have different follow-up or some observations are censored.

The record also illustrates why a point estimate is not enough to assess precision. Although the primary outcome identifies a 95% confidence interval, its limits are not reported. Readers can identify the point estimate of 91%, but cannot judge the interval’s width from the posted result. The extrapolated figure of 21.84 subjects is not an observed whole-person count and should not be mistaken for one.

The single-group design further defines what can be learned. It can describe outcomes in participants treated with cetuximab and radiation, but cannot estimate a comparative effect or distinguish the contributions of the two treatments. This is a design limitation, not a statistical adjustment that can be repaired using the reported outcome alone.

Finally, the listed secondary outcomes and adverse-event figures show why outcome labels, denominators, and reporting detail matter. Disease-free survival and overall survival results are not reported, while safety details about timing and attribution are also absent. Planning sample-size illustrations are separate from the completed trial’s observed analysis and should not be confused with its original design or with observed power.

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 study has no concurrent comparator, so the primary estimate cannot establish a difference between the combined regimen and another approach. Because cetuximab and radiation were used together, their individual contributions cannot be separated. The record does not report randomization, and the study is identified as a single-group design.

The reported primary outcome has a 95% confidence interval designation, but no interval bounds are reported. This prevents readers from assessing the reported estimate’s precision. The 21.84-subject figure is an extrapolation from the estimated percentage, not a count of actual participants.

Eligibility criteria, participant characteristics, and detailed follow-up information are not reported in the registry record. The record does not give assessment schedules, censoring details, missing-data patterns, or sensitivity analyses. These omissions limit evaluation of the population represented and the assumptions underlying the time-to-event estimate.

The statistical analysis plan and sample-size justification are not reported. The listed secondary outcomes have no reported results, and multiplicity procedures are not described. Adverse-event reporting also lacks detail about timeframe, grading, attribution, and the circumstances of the recorded deaths. The registry’s safety counts therefore do not provide a full account of event context or causality.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Post-operative Radiation With Cetuximab for Locally Advanced Cutaneous Squamous Cell Carcinoma of the Head and Neck — NCT01979211.
• Registry record last updated 2024-02-29; status last verified 2024-02.
• Results first posted 2022-05-10.
• 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

This completed phase II trial evaluated cetuximab with radiation in a single group of 24 participants with locally advanced cutaneous squamous cell carcinoma of the head and neck. The primary outcome was locoregional control at 2 years, estimated by the Kaplan–Meier method. The registry reports a predicted 91% with control and an extrapolated 21.84 subjects, but does not report the bounds of the stated 95% confidence interval.

There was no comparator arm. Disease-free survival and overall survival are listed as secondary outcomes, but results are not reported in the registry record. Safety reporting lists 3 participants with serious adverse events, 24 with other adverse events, and 9 deaths; event context and attribution are not provided in detail. The sample-size justification, detailed analysis plan, and several follow-up and missing-data details are also not reported.