Optimized Intensity Modulated Irradiation for Head and Neck Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Optimized Intensity Modulated Irradiation for Head and Neck Cancer (NCT00580983), a na na study. The primary outcome is Percentage of Participants With Grade 0-1 Observer-rated Dysphagia.

2. Clinical Question

3. Trial Design

This was a completed, single-group study of optimized intensity modulated irradiation for head and neck cancer. The registry lists the study as completed, with University of Michigan Rogel Cancer Center as sponsor. The study began in 2003-08 and had primary completion in 2010-06. Phase is recorded as NA.

The intervention strategy combined IMRT with chemotherapy. The registry lists paclitaxel, carboplatin, cisplatin, and 5-Fluorouracil as interventions. Its arm description identifies a Chemo-IMRT group and gives examples of chemotherapy options, but the description is incomplete. It does not establish that all participants received the same chemotherapy regimen.

There was no random allocation or masking: allocation is recorded as NA, masking as none, and the model as single group. Consequently, this design does not provide a concurrent standard-radiation control group. Any comparison with standard treatment would not be a randomized, like-for-like comparison within this study.

The registry reports 90 enrolled patients. It states that 80 were treated and that 7 did not complete the 12-month post-radiation swallowing studies; 73 were analyzed for the primary endpoint. The primary outcome was the percentage of participants with observer-rated dysphagia graded 0–1 at 12 months. A secondary outcome concerned mean esophageal radiotherapy dose in patients with and without strictures. Numerical results for either outcome 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.

Before assignment: 90 participants were enrolled however only 80 started treatment. Only 73 participants completed treatment. 7 did not complete the 12 month post radiation therapy (RT)swallowing studies.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 90 patients were enrolled. Only 80 patients were treated and 7 patients did not complete the 12 month post-Radiation Therapy (RT) swallowing studies. Therefore only 73 patients were analyzed.

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: 90 patients were enrolled. Only 80 patients were treated and 7 patients did not complete the 12 month post-Radiation Therapy (RT) swallowing studies. Therefore only 73 participants were included in the baseline analysis.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Grade 0-1 Observer-rated Dysphagia, measured over 12 months.

The primary endpoint is the percentage of participants with observer-rated dysphagia graded 0–1 at 12 months. It is intended to describe swallowing function at a specified follow-up time, using an observer-rated measure rather than relying only on participants’ reports. The registry description says that dysphagia and aspiration were assessed objectively, but the stated endpoint is the percentage with grade 0–1 dysphagia.

In general, a percentage endpoint expresses how common a defined outcome was in the analyzed group. Its interpretation depends on the grading criteria, the time point, and which participants were included. The registry record does not describe the grading scale in further detail, nor does it state the number of analyzed participants who met the grade 0–1 definition.

The registry identifies 73 patients as analyzed for this endpoint. However, it does not report the endpoint percentage or numerator. The endpoint’s direction and definition can therefore be described, but its observed frequency and precision cannot be assessed from the registry record. The 12-month measure also does not by itself describe swallowing at other times or changes over the course of treatment.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods help distinguish an outcome’s definition from the evidence available to estimate it. In this study, the registry describes a binary endpoint: whether a participant had observer-rated dysphagia graded 0–1 at 12 months. It reports an analyzed population of 73 for that endpoint, but not the number meeting the definition. Without that count or the resulting percentage, the primary endpoint’s observed frequency cannot be reconstructed.

What does a percentage endpoint represent?

In general, a percentage for a binary outcome is the share of an analyzed group that meets a specified definition. Here, the definition is observer-rated dysphagia graded 0–1 at the stated 12-month time point. The percentage would be meaningful only alongside its denominator and outcome definition. The registry gives the denominator as 73 analyzed participants, but the numerator and percentage are not reported in the registry record.

Binary outcomes can be presented with confidence intervals. In general, a confidence interval communicates the uncertainty around an estimated percentage, with wider intervals indicating less precision. It does not show that an individual participant’s outcome is uncertain, nor does it resolve potential bias from missing follow-up or study design. No confidence interval for the primary endpoint is reported in the registry record, so its statistical precision cannot be judged.

What does a single-group design allow?

In general, a single-group study can describe outcomes observed in the participants who received the study approach. It lacks a concurrent group to distinguish the intervention’s contribution from other explanations, such as participants’ baseline characteristics, changes in supportive care, or differences in outcome ascertainment. Random allocation is useful in comparative studies because it helps balance measured and unmeasured factors across groups on average. This study is not listed as randomized and has no like-for-like control group in the registry record.

The registry mentions standard radiation therapy as context for the research question, but this is not a study comparator. A comparison with historical or external outcomes would require careful attention to differences in eligibility, treatment delivery, follow-up, and dysphagia assessment. The registry record does not report a formal external comparison.

How should missing endpoint assessments be considered?

In general, missing outcome assessments reduce the information available and can introduce bias if missingness is related to the outcome. The record says that 7 patients did not complete the 12-month post-radiation swallowing studies, while 73 were analyzed for the primary endpoint. It does not report why those studies were not completed beyond that statement, the participants’ swallowing status, or a method used to account for missing outcomes. It is therefore not possible to determine whether the analyzed participants differed systematically from those without endpoint assessments.

The enrollment, treatment, and endpoint-analysis counts represent different stages of participation, not interchangeable denominators. The primary endpoint applies to the analyzed group identified in the registry. It should not be treated as a result for every enrolled patient without additional assumptions about the unassessed participants.

What do planning calculations mean?

In general, sample-size calculations estimate how many participants a future study might need under stated assumptions about the effect to detect, statistical significance, allocation, and analysis method. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is expressed as a fraction of an observed effect. These are planning assumptions, not a report of this study’s design, and not observed power.

Such illustrations should not be interpreted as evidence that the study was adequately powered or that the assumed effect was achieved. The registry record does not report the primary endpoint result needed to assess the observed effect, nor does it report a sample-size justification or statistical plan. The single-group trial design also differs from the two-arm equal-allocation setup described for planning.

Why can over-dispersion matter?

In general, over-dispersion means that outcomes vary more than a statistical model expects. If it is ignored, estimated uncertainty can be too small and intervals or tests may appear more precise than warranted. This is a general consideration for selecting and checking models; the registry record does not report a model for the primary endpoint or any assessment of over-dispersion.

Finally, the record lists two outcome measures and no analysis entries. This does not establish which analyses were conducted outside the registry, but it means the registry record does not document a statistical analysis plan, adjusted estimates, or inferential results for the outcomes described.

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("Chemo-IMRT")
n      <- c(73)
events <- c(69)
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  Chemo-IMRT  73  69  94.5  86.6  98.5  86.7  97.8  86.7  97.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: the primary percentage with grade 0–1 observer-rated dysphagia at 12 months, and a secondary outcome concerning mean esophageal radiotherapy dose in patients with and without strictures. It does not report an approach to multiplicity, such as prioritizing tests beyond the primary designation or adjusting for multiple comparisons. Without such information, the interpretation of any collection of statistical tests would depend on an analysis plan that is not reported in the registry record. No numerical results for either outcome are reported.

Missingness is directly relevant to the primary endpoint. The registry states that 90 patients were enrolled, 80 were treated, and 7 did not complete the 12-month post-radiation swallowing studies; 73 patients were analyzed. It does not report the endpoint status of participants without those studies, a reason for each missing assessment, or a missing-data method. In general, an analysis limited to participants with measured outcomes can be biased if the probability of measurement is related to the outcome. The record does not provide enough information to assess that possibility.

The analysis population is described for the primary endpoint, but an intention-to-treat analysis, per-protocol analysis, or other analysis population is not specified. There are no analysis entries in the registry record. A statistical analysis plan, model specifications, and handling of missing data are not reported in the registry record. These omissions mean that readers cannot verify how the endpoint was calculated or whether additional analyses were used.

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

Serious events with the highest arm-level rate: nausea (9.6%), pneumonia (9.6%), vomiting (9.6%), mucositis (5.5%), dehydration (4.1%).

The registry lists a Chemo-IMRT group with 73 participants at risk for serious adverse events and 26 affected. It also lists 73 at risk and 0 affected for other adverse events. These are separate registry figures; the record does not give further detail in this summary about event attribution or the observation period. The death figure is not reported in the registry record.

The listed serious-event terms include nausea, pneumonia, and vomiting at 9.6% each; mucositis at 5.5%; and dehydration and dysphagia at 4.1% each. These percentages should be read as the registry’s reported figures, not recalculated or treated as a comparison between treatment groups. The registry record does not provide a concurrent control group.

In general, an affected-participant count is not the same as an event count: a participant may experience more than one event. The record does not clarify how event terms relate to the overall number affected, or provide enough detail to establish whether the listed terms are mutually exclusive. These data describe reported safety events in the listed group; they do not by themselves establish that treatment caused an event or quantify comparative risk.

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

The registry record establishes that a single-group study of IMRT with chemotherapy for head and neck cancer was completed, and it defines a primary swallowing endpoint at 12 months. It also reports how many patients were enrolled, treated, and included in the primary endpoint analysis. These registry entries describe the study’s scope and the population contributing to the endpoint.

The record does not report the primary endpoint percentage or the count of participants with grade 0–1 dysphagia. Therefore, the endpoint result itself cannot be interpreted from the registry record. There is no basis in the reported endpoint information to describe the frequency of the outcome, its confidence interval, or the degree of uncertainty around it. The secondary outcome’s numerical result is also not reported.

Even if a single-group outcome estimate were available, it would describe the observed group rather than establish what would have happened under standard radiation therapy. There is no concurrent control group or randomized comparison. The study description’s comparison with standard methods provides the motivation for the research question, not a control condition in this trial.

The 12-month assessment addresses swallowing at that time point. It does not, by itself, describe outcomes at other times, long-term change, or all aspects of treatment experience. The registry record also does not provide enough detail to judge how missing swallowing assessments might affect the analyzed result.

The serious adverse event figures provide a description of reported events in the Chemo-IMRT group. They do not establish comparative safety, and the registry does not report the death figure. Overall, the record documents a clinically focused study question and selected participation and safety information, but does not contain the numerical primary outcome result needed to assess the principal endpoint.

14. Why This Trial Matters Statistically

This study raises a statistical question that is important in treatment research: whether a technique intended to spare normal tissue can be evaluated using a patient-centered outcome at a defined follow-up time. Observer-rated dysphagia at 12 months gives the primary question a concrete endpoint, while the secondary outcome concerning esophageal dose and strictures reflects a different aspect of treatment and possible toxicity.

The record also illustrates why a clearly stated endpoint is not enough for interpretation. To assess a percentage outcome, readers need the observed numerator and denominator, and ideally an uncertainty interval. The registry identifies 73 analyzed patients but does not report the number with grade 0–1 dysphagia or the percentage. The endpoint is therefore defined, but its observed frequency cannot be assessed from the registry record.

Design matters as well. A single-group study can contribute descriptive evidence about participants who received a treatment approach, but it cannot supply the direct randomized comparison needed to separate treatment effects from other explanations. The study description invokes standard radiation therapy as context, while the registry lists no concurrent comparator.

Finally, the participation figures draw attention to the analysis population and missing follow-up. The registry reports enrollment, treatment, and primary endpoint analysis counts, and states that some patients did not complete the 12-month swallowing studies. Without outcome information for those participants or a documented missing-data approach, the influence of missing assessments remains uncertain. These are general statistical considerations made particularly relevant by the study’s stated endpoint and design.

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 registry record does not report a numerical result for the primary endpoint: neither the count with grade 0–1 observer-rated dysphagia nor the corresponding percentage is given. It also does not report a confidence interval or other uncertainty measure. The secondary outcome, mean esophageal radiotherapy dose in patients with and without strictures, is listed without numerical results.

The single-group design has no concurrent control group, and allocation is recorded as NA. The registry lists masking as none. These features limit comparative interpretation and leave the outcome open to influences that a concurrent randomized comparison could help address. The description of standard radiation therapy does not establish that it was a study arm.

There is incomplete follow-up for the primary swallowing assessment: the registry says 7 patients did not complete the 12-month post-radiation studies. Their outcomes and reasons for not completing those studies are not reported in the registry record. Although 73 patients are identified as analyzed for the primary endpoint, the record does not explain a missing-data method or report additional analysis populations.

The chemotherapy arm description is incomplete, so the registry record does not establish the full treatment regimen for each participant. It also does not report the dysphagia grading criteria in detail, a statistical analysis plan, a sample-size justification, or an approach to multiplicity. The secondary outcome result and the death figure in the safety information are not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Optimized Intensity Modulated Irradiation for Head and Neck Cancer — NCT00580983.
• Registry record last updated 2016-09-07; status last verified 2016-07.
• Results first posted 2014-11-14.
• 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

NCT00580983 is a completed, single-group study of IMRT with chemotherapy for head and neck cancer, sponsored by University of Michigan Rogel Cancer Center. The registry lists 90 patients enrolled, 80 treated, and 73 analyzed for the primary swallowing endpoint. The primary endpoint is the percentage with observer-rated dysphagia graded 0–1 at 12 months.

The registry record does not report the primary endpoint percentage or its participant count. It also does not report numerical results for the secondary outcome concerning esophageal dose and strictures. The study has no concurrent control group, and details about the statistical plan and handling of missing endpoint assessments are not reported in the registry record. Serious adverse event information is listed for the Chemo-IMRT group.