Involved Field Elective Volume De-Intensification Radiation Therapy for Head and Neck Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Involved Field Elective Volume De-Intensification Radiation Therapy for Head and Neck Cancer (NCT03067610), a na phase 2 study. The primary outcome is Number of Patients With Solitary Elective Volume Recurrence.

2. Clinical Question

3. Trial Design

The registry describes NCT03067610 as a prospective phase II study of involved-field elective-volume de-intensification for oropharyngeal and laryngeal squamous cell carcinoma treated with intensity modulated radiation therapy. It lists the study as completed, with an enrollment of 72. The recorded start date is 2017-01-20, and the primary completion date is 2020-12-21. These record details describe the study's registration and timeline; they do not provide the primary endpoint result.

The design is single-group, and allocation is recorded as not applicable. Masking is recorded as none. The registered arm is called Radiation Therapy and is described as intensity modulated radiation therapy with or without chemotherapy. The listed chemotherapy options are cisplatin, cetuximab, or carboplatin-paclitaxel. The record does not give counts for participants receiving radiation alone or each chemotherapy option, nor does it describe treatment selection in enough detail to compare those treatment variations.

A single-group phase II study can describe outcomes observed under a treatment strategy, but this design does not establish a randomized treatment contrast. In particular, there is no like-for-like control comparison in the registry record. Differences between participants or other influences on outcomes cannot be separated from treatment effects by comparing randomized groups because no such groups are registered.

The registered primary endpoint is a count of participants with solitary elective volume recurrence, with a timeframe of 2 years. Its description specifies a crude risk calculation among patients followed for at least 2 years and says that deaths before 2 years without an SEVR remain in the denominator. The registry record does not state the number meeting the follow-up requirement, the number with recurrence, or the resulting risk. It also does not report the analysis population used for this endpoint.

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 Number of Patients With Solitary Elective Volume Recurrence, measured over 2 years.

The primary endpoint is the number of patients with solitary elective volume recurrence, or SEVR, within the 2-year timeframe. The registry describes the planned summary as a crude risk among patients followed for at least 2 years. It also specifies that patients who die before 2 years without an SEVR are included in the denominator. This definition matters because it determines which outcomes and participants contribute to the reported risk; it does not treat death without SEVR as a recurrence.

As a general statistical concept, a crude risk is the proportion of an eligible group that experiences the defined event over the stated follow-up period. It is a direct description of event occurrence in that group, not a comparison with an untreated or alternative-treatment group. The endpoint is used to describe the occurrence of a particular recurrence pattern after the registered treatment approach. Its interpretation depends on the event definition, the follow-up rule, and the denominator specified in the analysis.

The registry states the endpoint definition and timeframe but does not report its observed count, denominator, or risk. It also does not report a confidence interval or other measure of precision for the endpoint. Consequently, the registry record alone does not establish how often SEVR occurred in the analyzed population or how precisely that frequency was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a binary primary outcome: participants with a defined event, solitary elective volume recurrence. It describes a crude risk and a follow-up timeframe of 2 years, but does not report a primary outcome analysis. The methods below explain the statistical ideas relevant to interpreting such an endpoint and distinguish general statistical context from methods actually documented for this study.

What does a crude risk describe?

As general statistical context, a risk is the proportion of an analysis group that experiences a specified event during a defined period. For this endpoint, the event is SEVR and the timeframe is 2 years. The registry specifies that the crude risk is calculated among patients followed for at least 2 years and that people who die before 2 years without SEVR are included in the denominator. Applying that rule requires knowing the analyzed participants, their follow-up status, and whether the event occurred. The registry record does not report those endpoint data or the resulting risk.

A crude risk is descriptive. It does not adjust for differences in participant characteristics or treatment received. It also does not estimate a treatment contrast in a single-group design. The term “crude” therefore signals that the reported summary is not an adjusted model-based estimate. Whether additional analyses were planned or conducted is not reported in the registry record; the record lists no analyses.

How should the follow-up rule be understood?

As general statistical context, outcomes with a fixed follow-up timeframe need a rule for people whose observation ends before that timeframe. The registry's endpoint description explicitly includes deaths before 2 years without SEVR in the denominator, while defining the crude risk among patients followed for at least 2 years. The record does not explain how other forms of incomplete follow-up, such as loss to follow-up, were handled. It does not state whether time-to-event methods were used for the primary endpoint. Therefore, it would be inappropriate to assume a censoring method, imputation method, or other handling strategy not recorded.

The distinction between a crude risk and a time-to-event estimate is important in general. A crude risk uses a defined numerator and denominator, whereas time-to-event methods incorporate the timing of events and can accommodate differing observation times under assumptions about censoring. The endpoint description names a crude risk; it does not document a time-to-event method for that endpoint.

What does the single-group design permit?

The design is registered as single-group, with allocation not applicable and masking none. As general statistical context, a single-group study can estimate or describe outcomes in the observed group, subject to data quality and follow-up. It cannot use random assignment to balance measured and unmeasured influences between treatment groups. Nor does it provide a concurrent randomized control group for estimating a relative treatment effect. The registry record does not report a comparative control group or a randomized comparison.

The treatment description allows intensity modulated radiation therapy with or without chemotherapy. The listed chemotherapy choices are cisplatin, cetuximab, or carboplatin-paclitaxel. The registry does not give treatment-specific outcome analyses, participant counts by treatment variation, or a statistical adjustment for differences among treatment choices. Consequently, the registered description cannot support a comparison of radiation alone with radiation plus a particular chemotherapy regimen.

What can an interval estimate contribute?

As general statistical context, an interval estimate communicates uncertainty around an estimated quantity. For a risk, a confidence interval depends on the observed events, the denominator, and the chosen calculation method. It helps readers distinguish the point estimate from the range of values that remain compatible with the data under that method. It does not remove bias, correct incomplete follow-up, or establish causation. Neither an observed primary risk nor a confidence interval for it is reported in the registry record.

The record also does not report a hypothesis test for the primary endpoint, a null value, or a prespecified decision threshold. Without those details and an observed analysis, no inferential conclusion about the primary endpoint can be drawn from the registry record. A missing reported result should not be treated as either a favorable or unfavorable finding.

How should sample-size planning be read?

The record describes a planning illustration based on an observed effect, not the trial's own design. It states assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. For time-to-event illustrations, the stated output is the total number of events using the Schoenfeld method; for other illustrations, it is participants per arm. These are planning assumptions, not evidence that this single-group study randomized participants between two arms.

The registry record does not report the sample-size values for these illustrations, and it does not report a design justification for the trial's enrollment of 72. Planning illustrations are not observed power and do not show the probability that the completed study detected an effect. The record does not report a trial-specific sample-size calculation or the assumptions behind one.

What remains undocumented?

The record does not report the statistical analysis plan, endpoint analysis population, missing-data procedures, confidence-interval method, hypothesis-testing procedure, or any interim analysis. Those omissions limit reproducibility and interpretation. They should not be filled with assumptions based on common practice. General statistical concepts can clarify what the endpoint and design mean, but they cannot substitute for the unreported study-specific analysis details.

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("Radiation Therapy")
n      <- c(72)
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  Radiation Therapy  72  0  0.0  0.0  5.0  -0.0  5.1  0.0  4.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists eight secondary outcome measures alongside the primary endpoint. They cover quality-of-life patient-reported outcomes, protocol-related toxicities, gastrostomy dependence, patient utilities, overall survival, progression-free survival, and locoregional or distant tumor failure. The existence of multiple outcomes raises a general multiplicity issue: when many outcomes or tests are examined, the chance of at least one apparently notable result can increase if each is interpreted without regard to the others. Whether that issue is addressed depends on the planned analysis strategy.

The registry record does not report a multiplicity adjustment, a hierarchy among secondary outcomes, or a statistical analysis plan. It also records no analyses. Therefore, it is not possible to determine whether secondary outcomes were tested, whether any testing was adjusted, or how results should be interpreted across outcomes. The outcome list should not be treated as evidence that each outcome was analyzed or that any particular result was found.

Missing-data methods and analysis populations are also not reported in the registry record. The primary endpoint description gives a specific rule for patients who die before 2 years without SEVR, but does not describe handling of other incomplete follow-up or missing outcome information. The record does not state whether the analysis included all enrolled participants, only participants meeting a follow-up criterion, or another defined population. It does not describe imputation, exclusion rules, or sensitivity analyses.

As general statistical context, incomplete follow-up can affect both the denominator and the interpretation of an outcome estimate. Different assumptions or analysis populations can produce different results, so these details are needed for a reproducible assessment. The registry's endpoint definition is informative, but it does not resolve the unreported data-handling and analysis-population questions.

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: dysphagia (19.4%), dehydration (11.1%), anorexia (9.7%), dyspnea (5.6%), nausea (5.6%).

The registry reports safety figures for the Radiation Therapy group, with 72 at risk. Serious adverse events affected 35 participants, and other adverse events affected 65 participants. The record also lists 1 death. These are descriptive counts in the registry record; they do not by themselves establish that treatment caused an event or death. The record does not provide a causal attribution for these figures.

The listed serious adverse-event terms and percentages are dysphagia, 19.4%; Dehydration, 11.1%; Anorexia, 9.7%; Dyspnea, 5.6%; nausea, 5.6%; and Lung infection, 4.2%. These percentages are the registry's reported figures. Event-specific denominators and details about overlap among terms are not reported in the registry record, so the terms should not be added together or interpreted as mutually exclusive categories.

As general context, adverse-event summaries depend on definitions, severity grading, observation periods, attribution procedures, and whether repeat events are counted by participant or event. The registry lists the number of participants with definite, possible, and probable protocol-related toxicities of grade 3-5 as a secondary outcome, but does not report its analysis. The available safety figures should therefore be read as reported counts and percentages, not as a complete account of treatment-related risk or a causal comparison.

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

The registry record establishes the study's registered question and design: a prospective, single-group phase II study of involved-field elective-volume de-intensification radiation therapy for oropharyngeal and laryngeal squamous cell carcinoma. It identifies a primary endpoint of solitary elective volume recurrence by 2 years and specifies a crude-risk denominator rule that includes deaths before 2 years without SEVR. It also lists the registered treatment approach and secondary outcomes.

What the record does not establish is the observed primary endpoint result. It does not report the count of participants with SEVR, the number included in the endpoint analysis, the crude risk, or its precision. No primary endpoint analysis is listed. The completed status and enrollment of 72 do not substitute for an outcome estimate or tell readers how many participants met the endpoint's follow-up criterion.

Even if a single-group outcome estimate were available, it would describe the observed group under the registered treatment approach rather than provide a randomized comparison with another treatment. The design does not separate treatment effects from other influences through random assignment. The treatment description also permits chemotherapy choices, but the record does not report counts or outcome analyses by treatment variation.

The adverse-event figures describe events reported in the Radiation Therapy group, but do not establish causation. The registry does not provide enough information to determine how the reported events relate to radiation, chemotherapy, the underlying disease, or other factors. Nor does the list of secondary outcomes establish that analyses were completed or that particular effects were observed.

As general statistical context, a result is most interpretable when its event definition, denominator, follow-up, analysis population, uncertainty, and analysis methods are all clear. Several of those study-specific details and all primary endpoint results are not reported in the registry record. Accordingly, the record supports a description of the registered study and its planned outcome, but not a conclusion about the frequency of SEVR or the effect of the treatment strategy.

14. Why This Trial Matters Statistically

This study is statistically notable for asking a focused recurrence question in a single-group phase II setting. Its primary endpoint is not a broad composite: it names solitary elective volume recurrence and sets a 2-year timeframe. The registry also describes a specific denominator rule for deaths before that timeframe without SEVR. Those choices matter because outcome definitions and denominator rules determine what a risk estimate represents.

The record also illustrates the distinction between a clearly registered endpoint and a reported result. The study is marked completed and lists enrollment of 72, yet the primary endpoint count, risk, analysis denominator, and uncertainty are not reported in the registry record. Without those elements, readers cannot evaluate the observed frequency or its precision. The endpoint description alone does not reveal whether the result was small, large, or statistically uncertain.

The single-group design is another important statistical feature. It can provide a description of outcomes in the enrolled cohort, but it does not create a randomized comparison with another treatment. That limits conclusions about comparative effects, especially when the treatment description allows radiation with or without different chemotherapy options and the record does not report outcomes by treatment variation.

Finally, the record lists multiple secondary outcomes and adverse-event summaries, while reporting no analyses. This underscores why registration, outcome reporting, and analysis documentation are distinct. A registered plan clarifies what was intended; an analysis reports what the data show; a transparent methods description lets readers assess how the analysis was done. In this record, the endpoint definition is available, but the primary analysis and several details needed for interpretation are not reported.

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 central limitation for interpreting this trial from the registry record is that the primary endpoint result is not reported. Although the endpoint is defined as a crude risk of solitary elective volume recurrence by 2 years, the record gives neither the event count nor the analyzed denominator, risk estimate, or confidence interval. The endpoint description says the denominator includes people who die before 2 years without SEVR, but it does not explain the handling of other incomplete follow-up.

The record marks the study completed and reports enrollment of 72, but does not describe the primary endpoint analysis population or state how many participants were followed for at least 2 years. Enrollment should not be assumed to equal the endpoint denominator. The statistical analysis plan, missing-data procedures, and sensitivity analyses are not reported in the registry record.

The study is single-group and has no registered like-for-like control comparison. Thus, even an outcome estimate would describe the observed group rather than establish a causal comparison with another treatment strategy. The treatment description permits chemotherapy or radiation alone, but treatment-specific counts and outcome analyses are not reported. The registry does not provide enough detail to evaluate differences in outcomes across those treatment choices.

The record lists eight secondary outcome measures but no analyses. It does not describe multiplicity control, analysis populations for secondary outcomes, or the methods used to estimate uncertainty. The safety figures include aggregate affected-participant counts and selected serious-event percentages, but event-specific denominators, attribution, and additional clinical context are not reported. These omissions constrain interpretation of efficacy and safety without implying any particular direction of result.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Involved Field Elective Volume De-Intensification Radiation Therapy for Head and Neck Cancer — NCT03067610.
• Registry record last updated 2022-03-17; status last verified 2022-02.
• Results first posted 2022-03-17.
• 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

NCT03067610 is registered as a completed prospective phase II, single-group study of involved-field elective-volume de-intensification for oropharyngeal and laryngeal squamous cell carcinoma treated with intensity modulated radiation therapy. Enrollment is 72. The record lists radiation therapy with or without chemotherapy, naming cisplatin, cetuximab, or carboplatin-paclitaxel as options. Allocation is not applicable and masking is none.

The primary endpoint is the number of patients with solitary elective volume recurrence by 2 years, described as a crude risk with a specified denominator rule for deaths before 2 years without SEVR. The primary endpoint result and analysis are not reported in the registry record. Eight secondary outcome measures are listed, and the record lists no analyses.

The registry reports serious adverse events affecting 35 of 72 at risk, other adverse events affecting 65 of 72 at risk, and 1 death. These figures are descriptive and do not establish causation. The record does not report the study's statistical analysis plan, primary endpoint precision, missing-data procedures, or analysis populations.