This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Feasibility of IMRT Modulation to Account for Scattered Radiation From Dental Fillings in Head and Neck Cancer (NCT01576939), a na na study. The primary outcome is Time Until the Maximum Oral Mucositis Measured From the Start of Radiation Treatment..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01576939 |
| Phase | NA |
| Condition | Head and Neck Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 30 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Stanford University |
| Results posted | Yes |
2. Clinical Question
Population
People with head and neck cancer. The registry reports an enrollment of 30 and says the entire cohort was analyzed.
Intervention
Intensity modulated radiation therapy (IMRT) modulation intended to account for scattered radiation from dental fillings. The study objective was to use mucosal dose measurements adjacent to fillings when optimizing the treatment plan.
Comparator
No separate comparator group is described. This was a single-group study with no masking; it is not a randomized comparison.
Primary question
The stated objective concerns feasibility: whether treatment planning could reduce mucosal dose adjacent to fillings to < 35 Gy without compromising tumor coverage or increasing dose to the remaining oral cavity or nearby parotid glands. The registered primary endpoint is time from the start of radiation treatment until oral mucositis is first visually observed by a clinician.
These are related but different questions. The objective describes a treatment-planning goal involving dose and tumor coverage, while the primary endpoint concerns the timing of mucositis. The registry record does not report the dose measurements or results for the planning goal. Nor does it report the primary endpoint estimate, so the clinical timing result cannot be quantified from this record.
The listed secondary outcomes concern the relationship between measured lateral tongue mucosal dose and narcotic use, and whether soreness or pain scores relate to quality of life while adjusting for measured dose. The record does not provide estimates for those relationships. With one group and no stated control condition, the study can describe observations in the enrolled cohort, but it cannot establish a comparative effect against an alternative treatment based on the design information in the registry.
3. Trial Design
This completed study is registered as a single-group feasibility study of IMRT modulation for head and neck cancer. The registry lists an enrollment of 30, a start in 2011-08, primary completion in 2014-01, and overall status of COMPLETED. The phase and allocation are recorded as NA, and masking is listed as NONE. No separate control arm is described.
The intervention is listed as Intensity Modulated Radiation Therapy. The objective is to optimize an IMRT plan using dosimeter measurements of mucosal radiation dose next to dental fillings, with the aim of lowering that dose to < 35 Gy without compromising tumor coverage or increasing dose to the remaining oral cavity or nearby parotid glands. The registry’s arm description is incomplete, so the full treatment sequence and implementation details are not reported in the registry record. It does state that treatment planning involved CT simulation, with or without PET, using slices of ≤ 3mm.
The primary analysis population is described as the entire cohort. The primary outcome is a time-to-event measure analyzed by Kaplan-Meier, with the median and a 95% confidence interval specified as the summary. Its timeframe is listed as 3 years. The endpoint description says that mucositis was assessed during weekly checkups during radiation treatment and that later assessments continued after treatment until mucositis was below grade 2. The registry also describes repeated clinical assessments and pain-medication evaluation at mucositis time points.
Although the registry marks the study completed, completion status does not itself indicate that all planned outcomes are reported. The median time, confidence interval, dose-planning results, and estimates for the listed secondary outcomes are not reported in the registry record. The design is therefore best understood from the information available as a single-cohort feasibility study with a registered mucositis endpoint, rather than as a controlled test of comparative treatment effects.
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: No pre-assignment details as the patients were recruited and placed directly in the study.
Overall Study
| Stage | Intensity Modulated Radiotherapy Treatment |
|---|---|
| STARTED | 30 |
| COMPLETED | 30 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The entire cohort was 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.
| Characteristic | Unit | Intensity Modulated RT Treatment |
|---|---|---|
| Participants analysed | 30 | |
| Age, Continuous | years | 61.5 (42 to 82) |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 25 |
| Region of Enrollment: United States | participants | 30 |
| Primary Tumor location: Pharynx | Participants | 23 |
| Primary Tumor location: Oral Cavity | Participants | 7 |
| Tongue dose | Gy | 30.5 (11.2 to 70) |
6. Primary Endpoint
The registry lists the primary outcome as Time Until the Maximum Oral Mucositis Measured From the Start of Radiation Treatment., measured over 3 years.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | Days |
| Endpoint classification | Time-to-Event Analysis |
The registered primary outcome is titled “Time Until the Maximum Oral Mucositis Measured From the Start of Radiation Treatment.” Its description, however, defines the event as the first time oral mucositis was visually observed by a clinician, measured from the start of radiation treatment. That wording describes time to first observed onset, not necessarily time until maximum severity. The registry does not resolve this difference in terminology, so the operational definition in the description is the clearest account of what was measured.
Time-to-event outcomes include both whether an event is observed and when it occurs. Kaplan-Meier analysis is commonly used to estimate the distribution of event times while accommodating participants whose event time is not observed during follow-up, provided that appropriate assumptions about follow-up and censoring hold. A median time summarizes when the estimated event distribution reaches its midpoint. A confidence interval conveys uncertainty around that estimate; it is not a range expected to contain individual event times.
For this study, the registry specifies the median and a 95% confidence interval, with a timeframe of 3 years. It states that clinicians assessed mucositis at weekly checkups during radiation treatment, with further assessments after treatment. It does not report the median or confidence interval, the number of events contributing to the analysis, or how incomplete follow-up was handled. As a result, the endpoint’s estimate and its precision cannot be assessed from the registry record.
The endpoint can describe the timing of observed mucositis in the cohort, but it does not directly report whether the dose-planning objective was achieved. The record does not provide results for the target dose reduction, tumor coverage, or dose to nearby tissues.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record gives the study objective, design, and endpoint definition, but not a numerical estimate for the primary outcome. It specifies a median time to oral mucositis with a 95% confidence interval and Kaplan-Meier analysis, yet neither the median nor its interval is reported in the record. Consequently, no conclusion about the observed timing or the precision of that estimate can be drawn from the registered information.
The objective focuses on feasibility of adjusting IMRT planning to account for scattered radiation from dental fillings. It sets a target of reducing mucosal dose adjacent to fillings to < 35 Gy, while avoiding compromises in tumor coverage or increases in dose to the remaining oral cavity or nearby parotid glands. The record does not report whether those planning conditions were met, nor does it provide dose measurements or related estimates. The primary endpoint, as operationally described, is time to first clinician-observed mucositis; it is not a direct measure of whether the dose-planning target was reached.
The study has a single group and no stated comparator. Its observations therefore cannot be interpreted as a randomized or controlled estimate of the difference between IMRT approaches. A result from one cohort could describe events in that cohort, but the design information does not establish what would have happened under a different planning strategy.
For safety, the registry lists 11 participants with serious adverse events among 30 at risk, and identifies Mucositis Oral as a serious adverse-event term at 36.7%. It lists 0 participants affected in the other adverse-event category. These entries are descriptive registry figures; they do not by themselves establish that treatment caused an event. The record does not provide detail about event timing, duration, or individual-level overlap with the mucositis endpoint.
Five outcome measures and five analyses are listed, and three secondary outcomes are named. Results for those secondary questions are not reported in the registry record. The available information therefore supports a description of the study’s intended question and design, along with the listed safety counts, but not a quantitative appraisal of its primary endpoint or planning objective.
9. Statistical Methods Explained
What does a Kaplan-Meier analysis estimate?
Kaplan-Meier analysis is a general method for describing time from a defined starting point to an event. In this study, the starting point is the start of radiation treatment, and the endpoint description defines the event as clinician-observed oral mucositis for the first time. The method estimates the probability that the event has not yet occurred over follow-up. It can incorporate participants whose event is not observed before their follow-up ends, rather than treating their unobserved event time as if it were known.
This method relies on follow-up information being handled appropriately. In general, censoring means that an event time is not observed beyond a participant’s last known follow-up. Kaplan-Meier estimates are most useful when the reasons for censoring and the analysis procedures are adequately described. The registry record does not report the censoring rules, the number of censored observations, or the amount of follow-up contributing to the estimate. Those details therefore cannot be assessed.
How should the median and confidence interval be read?
The median time is a summary of the estimated event-time distribution: it marks the point at which the estimated proportion remaining event-free reaches its midpoint. It is not the average event time, and it does not describe the timing for every participant. The registry specifies a 95% confidence interval for the median. In general, a confidence interval represents statistical uncertainty about an estimated quantity under the analysis assumptions; it is not a prediction interval for individual outcomes.
No median or confidence interval is reported in the registry record. Their absence means there is no posted estimate to interpret and no interval from which to judge precision. The timeframe is listed as 3 years, but that label does not supply an estimate or establish how complete follow-up was.
What does the endpoint wording imply?
The outcome title refers to time until “the maximum” oral mucositis, whereas the description defines the event as the first visual observation of oral mucositis. These phrases can refer to different points in the course of symptoms. The registry does not explain the discrepancy. The description’s operational definition indicates that the event was first observed mucositis; it does not say that the endpoint was time to peak severity. The record also states that clinicians graded mucositis using CTCAE Version 4.0 and assessed the measured site repeatedly during and after radiation treatment.
Repeated clinical checks mean the true onset could occur between assessments. In general, when an event is identified only at scheduled visits, its recorded time reflects the detection visit rather than necessarily the exact biological onset. The registry does not report any adjustment for this interval between visits. This is a consideration when interpreting a time-to-first-observation endpoint, not evidence that a particular analysis was or was not performed.
What can a single-group design establish?
A single-group study can describe outcomes observed among participants receiving the intervention, and it can address whether the procedures or measurements were feasible if those results are reported. It does not, without a comparator, provide a direct estimate of how outcomes differ from another treatment or planning approach. The registry marks allocation as NA and identifies a single-group model. No like-for-like control comparison is described.
The study objective includes several planning considerations: dose adjacent to dental fillings, tumor coverage, and dose to the rest of the oral cavity and nearby parotid glands. Those are not interchangeable outcomes. A finding about mucositis timing alone would not establish that every dose-planning condition was met. The dose measurements and results for those conditions are not reported in the registry record.
How should planning illustrations be interpreted?
The registry’s sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For time-to-event outcomes, the stated planning quantity is the total number of events; for other outcomes, it is participants per arm. These are hypothetical planning assumptions, not the design description for this single-group study. The registry does not report an observed effect estimate alongside these registry entries, and no numerical planning results are available in the record.
In general, sample-size calculations explore what study size might be required to detect a chosen effect under specified assumptions. They are not a retrospective measure of the probability that this completed study detected an effect. Any planning illustration based on a fraction of an observed effect is sensitive to the selected fraction and to the calculation assumptions. Equal allocation between two arms does not describe the registered single-group design. These illustrations should therefore not be read as the study’s actual design or as observed power.
The record also does not report a detailed statistical analysis plan, assumptions for any hazard-ratio model, interim-analysis procedures, or a sample-size justification for the single-group feasibility objective. No claims about those procedures can be made from the registry information.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists five outcome measures and five analyses, and names three secondary outcomes. Those secondary questions concern measured lateral tongue mucosal dose in relation to narcotic use, and the relationship of soreness or pain scores to quality of life while adjusting for measured dose. The primary outcome concerns time to observed mucositis. The record does not report estimates or results for the secondary outcomes.
When a study examines multiple outcomes or relationships, the chance of at least one apparently notable result can increase if each is tested separately. General approaches to this issue include prespecifying a primary outcome, adjusting statistical thresholds, or treating secondary analyses as exploratory. The registry information does not describe a multiplicity adjustment or a hierarchy for interpreting the listed analyses. It is therefore not possible to determine how the analyses were intended to be interpreted collectively.
The primary population is described as the entire cohort. That identifies the intended population for the primary analysis, but does not explain how missing outcome measurements, incomplete follow-up, or participants with no observed event were handled. The record does not report missing-data methods, censoring details, or the amount of missing information for the primary or secondary outcomes.
As a result, the stated analysis population can be reported, but the completeness of its outcome data and the handling of missing observations cannot be evaluated. The absence of these details is especially relevant for a time-to-event endpoint, for which follow-up and censoring affect interpretation. The registry record also does not report whether all planned analyses were completed or whether any analysis decisions changed after study initiation.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Intensity Modulated Radiotherapy Treatment | 11 | 30 | 36.7% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Intensity Modulated Radiotherapy Treatment | 0 of 30 |
Most frequent serious adverse event terms
| Event term | Organ system | Intensity Modulated Radiotherapy Treatment |
|---|---|---|
| Mucositis Oral | Gastrointestinal disorders | 11 of 30 |
Serious events with the highest arm-level rate: mucositis oral (36.7%).
The registry lists one treatment group, with 30 participants at risk for serious adverse events and 11 affected. It reports Mucositis Oral as a serious adverse-event term at 36.7%. In the other adverse-event category, it lists 30 at risk and 0 affected. These figures are registry summaries, not a comparison between treatment groups.
A serious adverse event is a safety classification; it should not be confused with the primary endpoint’s timing estimate. The registry describes clinical mucositis assessments and also lists oral mucositis as a serious adverse-event term, but it does not provide enough detail to determine how these records correspond participant by participant. The serious-event count and the term percentage should therefore be read as reported categories, not as a complete account of event timing, severity changes, duration, or recurrence.
These counts do not establish causation. A single-group safety summary cannot separate events associated with the underlying illness or other factors from events attributable to the intervention. The record does not provide a comparator, event-level narratives, or further details on attribution. The zero in the other adverse-event category should be understood as the registry’s reported count for that category, not as proof that no symptoms or clinical observations occurred.
12. What the Result Does, and Does Not, Mean
The study addresses a specific radiotherapy-planning problem: scattered radiation from dental fillings may affect mucosal dose, and the stated objective is to incorporate dosimeter measurements into IMRT optimization. The registry describes a target of reducing mucosal dose adjacent to fillings to < 35 Gy without compromising tumor coverage or increasing dose to the remaining oral cavity or nearby parotid glands. These are the aims of the study, not reported findings in the registry record.
The primary endpoint is a time-to-mucositis measure. As described operationally, it records the time from the start of radiation treatment until a clinician first visually observes oral mucositis. The registry specifies Kaplan-Meier analysis, a median, and a 95% confidence interval, but does not report the estimate or interval. The endpoint title’s reference to maximum mucositis differs from the description’s definition of first observation, and the record does not clarify that difference.
The available safety information lists 11 participants with serious adverse events among 30 at risk, with Mucositis Oral reported at 36.7%; the other adverse-event category lists 0 affected. These descriptive entries do not show whether the intervention caused the events or how they related to the primary endpoint.
The record does not report results for the dose-planning objective or the named secondary outcomes. It also does not describe a control group. Thus, the registry information establishes what the study set out to investigate and how it characterized its primary endpoint, but it does not establish whether the planning goal was achieved, quantify the timing of mucositis, or estimate comparative effects against another treatment approach. Completion status alone cannot fill those gaps.
13. Why This Trial Matters Statistically
This study is statistically notable because it connects a treatment-planning objective with a clinical time-to-event endpoint, while those measures answer different questions. Dose measurements adjacent to dental fillings relate to whether the planning strategy achieves its stated dosimetric aim. Time to observed mucositis describes when a clinical event was first detected. Reporting both kinds of results would be important for understanding feasibility and clinical observations together; the registry record does not report the dose-planning results or the primary time estimate.
The single-group design also shapes what can be inferred. It can describe outcomes in the treated cohort, but it does not provide a randomized comparison with another planning strategy. This distinction matters when readers encounter an intervention objective framed around reducing dose: an objective is not evidence that a reduction occurred, and a single cohort does not itself establish the counterfactual outcome under another approach.
The endpoint description illustrates why operational definitions matter. The title refers to maximum oral mucositis, while the description defines first visual observation. Those are not necessarily equivalent event times. Clarifying which event is analyzed affects the interpretation of the median, the handling of repeated assessments, and what clinical course the estimate represents.
Finally, the registry’s planning assumptions include equal allocation between two arms, while the study is registered as a single-group design. Such planning illustrations can be useful as hypothetical calculations, but should not be mistaken for the enrolled design or evidence of observed power. Clear separation of study objectives, endpoint definitions, analysis assumptions, and reported results is particularly important when the registry contains incomplete outcome reporting.
14. 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 primary result is not reported in the registry record: there is no median time to mucositis or 95% confidence interval to assess. The record also does not provide dose measurements or findings for the stated goal of reducing mucosal dose adjacent to fillings while maintaining tumor coverage and limiting dose to nearby tissues. The named secondary outcomes have no reported estimates.
The endpoint title and its description are not fully aligned. The title refers to time until maximum oral mucositis, while the description specifies time until mucositis is first visually observed. Without clarification, readers cannot tell whether the intended event was onset or a later point of greatest severity. The registry identifies clinical assessments and their frequency, but does not describe the censoring rules, missing-data handling, or how the timing of events between visits was treated analytically.
The study is single-group, with no stated comparator. This limits interpretation to descriptive observations in the cohort and does not support a direct estimate of the difference between alternative planning approaches. The phase and allocation are listed as NA, and the arm description is incomplete, leaving some implementation details unreported in the registry record.
Although the registry lists five outcome measures and five analyses, it does not describe a multiplicity strategy or explain how missing data were handled. The safety entries lack event-level detail and cannot establish attribution. The record also does not report a statistical analysis plan, sample-size justification for the registered design, or interim-analysis procedures. These limitations concern what can be assessed from the registry record; they do not establish whether additional information exists elsewhere.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Feasibility of IMRT Modulation to Account for Scattered Radiation From Dental Fillings in Head and Neck Cancer — NCT01576939.
- Registry record last updated 2017-06-14; status last verified 2017-05.
- Results first posted 2017-06-14.
- 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.
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18. Record Summary
NCT01576939 is a completed, single-group study of IMRT modulation intended to account for scattered radiation from dental fillings in head and neck cancer. The registry lists an enrollment of 30, no masking, and an entire-cohort primary analysis. Its stated planning objective is to reduce mucosal dose adjacent to fillings to < 35 Gy without compromising tumor coverage or increasing dose to the remaining oral cavity or nearby parotid glands.
The primary endpoint is described as time from the start of radiation treatment to first clinician-observed oral mucositis, analyzed by Kaplan-Meier and summarized by a median with a 95% confidence interval. The endpoint title instead refers to maximum mucositis. The primary estimate, dose-planning results, and secondary-outcome estimates are not reported in the registry record.
The safety summary lists 11 participants with serious adverse events among 30 at risk, with Mucositis Oral at 36.7%; the other adverse-event category lists 0 affected. The single-group design does not provide a controlled treatment comparison.