Selumetinib in Treating Patients With Papillary Thyroid Cancer That Did Not Respond to Radioactive Iodine: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Selumetinib in Treating Patients With Papillary Thyroid Cancer That Did Not Respond to Radioactive Iodine (NCT00559949), a na phase 2 study. The primary outcome is Objective Response Rate (ORR).

2. Clinical Question

The study is registered as a phase II trial of selumetinib for papillary thyroid cancer that did not respond to radioactive iodine. Its official title also includes papillary thyroid carcinoma with follicular elements. The registry lists recurrent disease and stages I through IV among the conditions. These eligibility descriptions establish the clinical setting, but the registry record does not provide further detail about participant characteristics or the distribution of disease stages.

The primary endpoint focuses on tumor response rather than a comparison of treatment strategies. A complete or partial response is a radiographic outcome defined by RECIST. The question is therefore whether evaluable participants met one of those response criteria during the assessment period, which is stated as up to 2 years. This endpoint does not, by itself, describe how long a response lasted, whether disease progression was delayed, or overall survival. Progression-free survival and overall survival are separately listed as secondary outcomes.

Because this is a single-group study, the observed response rate would describe outcomes among participants receiving selumetinib; it would not estimate a treatment contrast against a concurrent control. The registry record does not report the response result, so the primary clinical question cannot be answered from the posted results described in the record. Nor does the record establish whether the investigators’ threshold for further pursuit was met.

3. Trial Design

This is a phase II, single-group study sponsored by the National Cancer Institute. The registry lists enrollment of 39 participants. Allocation is recorded as not applicable, consistent with the listed single-group model, and masking is recorded as none. No randomized or masked comparison is described.

The intervention arm is described as oral selumetinib twice daily on days 1–28. Treatment was to repeat every 28 days in the absence of unacceptable toxicity or disease progression. Laboratory biomarker analysis is also listed. The registry record does not report additional details about how treatment exposure was summarized, dose changes, adherence, or biomarker procedures.

The study began in 2007-12, reached primary completion in 2016-08, and is marked completed. The primary outcome is objective response rate, assessed using RECIST, with a timeframe of up to 2 years. The primary population is listed as all evaluable participants. The registry does not report the number evaluable, the timing or frequency of assessments, or the handling of participants without an evaluable assessment.

Secondary outcomes listed are median progression-free survival, occurrence of treatment-related adverse events, and overall survival. The record does not report their results or the details of their analysis. Although the registry lists four outcome measures, it has no analysis entries. It therefore does not provide enough information to reconstruct how the outcomes were statistically analyzed, including the exact definitions or methods used for the secondary endpoints.

The single-group design can describe response and safety outcomes observed during treatment, but it does not provide a concurrent control for separating treatment-associated outcomes from the natural course of disease, participant selection, or other influences. The registry description mentions a historical response-rate benchmark as part of the rationale for the primary endpoint. That benchmark is not a randomized comparison and does not make the study a controlled trial.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All evaluable participants

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: All participants, unless specified differently in an Outcome Measure.

6. Primary Endpoint

The registry lists the primary outcome as Objective Response Rate (ORR), measured over Up to 2 years.

The primary endpoint is objective response rate, defined in the registry as the number of participants with a complete response or partial response under RECIST. A complete response means disappearance of all target lesions. A partial response means at least a 30% decrease in the sum of the longest diameters of target lesions, using the baseline sum as the reference. The stated assessment timeframe is up to 2 years, and the population is all evaluable participants.

Response rate is a binary endpoint at the participant level: each evaluable participant either meets the response definition or does not. It provides a direct summary of how many participants had sufficient tumor shrinkage to satisfy the specified criteria. As a general statistical point, binary outcomes are often summarized by a count and a proportion, with a confidence interval used to convey uncertainty around the proportion. The registry record does not report the response count, response rate, or confidence interval, so none can be interpreted for this study from the record.

The registry description explains the investigators’ rationale by citing an approximate 5% response rate for doxorubicin as a conservative estimate for the best-studied agent in this disease. It says selumetinib would be considered worth further pursuit if the response rate were at least 20%. These are contextual benchmarks and a stated decision threshold, not observed outcomes for selumetinib and not a control-group result.

Objective response is useful for describing tumor shrinkage, but it does not measure the duration of response or directly establish an effect on progression-free survival or overall survival. Those outcomes are listed separately as secondary outcomes. Their results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies objective response rate as the primary endpoint and describes it as a count of participants. It does not provide analysis entries or report a response result. The methods concepts below explain how this kind of endpoint is generally interpreted; they should not be read as a description of unreported analyses in this trial.

What does a binary response endpoint represent?

As a general statistical point, a binary endpoint assigns each participant to one of two outcome categories. For this study’s primary endpoint, the categories are meeting or not meeting the RECIST definition of complete or partial response. A response count is the number of participants who meet the definition. A response proportion places that count in relation to the relevant analysis population. The registry names all evaluable participants as that population, but does not report its size or the response count.

A binary endpoint is straightforward to describe, but its interpretation depends on clear outcome definitions and a clear denominator. The registry specifies complete response as disappearance of all target lesions and partial response as at least a 30% decrease in the sum of longest target-lesion diameters from baseline. The record does not describe assessment schedules, independent review, or how missing or unevaluable assessments were classified. Those details can affect which participants contribute to a response estimate, so they should not be inferred.

How should uncertainty be understood?

As a general statistical point, a confidence interval gives a range of estimates compatible with the observed data under a specified method. For a response proportion, it communicates uncertainty arising from the finite number of observed participants. A point estimate alone can conceal substantial uncertainty, especially when the analysis population is limited. No confidence interval or other precision estimate for the primary endpoint is reported in the registry record.

A confidence interval is not a guarantee that the true value lies within its limits, nor does it account automatically for design limitations such as the absence of a concurrent comparator. It also cannot resolve missing information about endpoint ascertainment. In this record, the lack of a response estimate means there is no interval to interpret and no basis for judging the precision of the primary result.

What does the single-group design allow?

As a general design principle, a single-group study estimates outcomes observed in participants receiving the study intervention. Without a concurrent comparison group, it does not directly estimate the difference between treatment strategies. An observed response may be clinically informative as a description, but attribution is limited because there is no randomized control group balancing other influences on outcomes. This trial’s allocation is recorded as not applicable and its model as single group.

The registry’s mention of an approximate 5% response rate for doxorubicin and a 20% threshold provides context for the investigators’ stated rationale. It does not replace a concurrent comparator. Differences between historical and current study populations, outcome assessment, and other features can complicate comparisons; the registry record does not provide details that would resolve those issues.

What do the planning assumptions mean?

The record describes a sample-size planning illustration based on an observed effect, rather than the trial’s own design. It specifies a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Such assumptions are planning inputs, not outcomes from this single-group study. The record does not report the numerical planning results in the information available for interpretation, and the two-arm planning framework should not be mistaken for the design actually used.

As a general statistical point, a sample-size calculation depends on the effect to be detected, variability or event assumptions, error rates, and design structure. Changing the assumed effect changes the required sample size. A planning illustration is not observed power, and it does not show that a trial had a particular probability of detecting an effect after the data have been observed. Here, the stated illustration should be read as hypothetical planning context, not as an analysis of the single-group trial’s results.

Why can over-dispersion matter?

As a general statistical point, over-dispersion occurs when observed variability exceeds what a chosen statistical model expects. When present, standard errors from a model that assumes less variability can be too small, leading to intervals that are too narrow or tests that are too optimistic. A suitable analysis may need to account for the extra variability. The registry record does not report a model for the primary binary endpoint, does not report an over-dispersion assessment, and does not provide enough analysis detail to determine whether this issue arose.

How should time-to-event outcomes differ from response?

Progression-free survival and overall survival are listed as secondary outcomes. In general, time-to-event outcomes concern the time until a defined event, and their analysis may need to account for participants whose event time is not observed during follow-up. Median survival summaries and event-based methods answer different questions from a binary response count. The registry record does not report the event definitions, follow-up summaries, censoring rules, estimates, or uncertainty for these outcomes. No result can therefore be inferred from their listing alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists objective response rate as the primary outcome and lists median progression-free survival, occurrence of treatment-related adverse events, and overall survival as secondary outcomes. It also reports four outcome measures, but no analysis entries. The record does not describe a statistical plan for controlling multiplicity across outcomes, define a testing hierarchy, or explain whether secondary analyses were intended to be confirmatory or descriptive. Those details are not reported in the registry record.

As a general statistical point, evaluating multiple outcomes can increase the chance of at least one apparently notable finding when each is tested separately. A prespecified hierarchy or multiplicity adjustment can address some of that concern, while clearly descriptive reporting can help readers distinguish exploratory results from confirmatory claims. The registry record does not indicate which approach, if any, was used. No multiplicity-adjusted or unadjusted test results are reported.

The primary endpoint population is described as all evaluable participants, but the number evaluable is not reported. The record does not explain how participants with missing assessments, early discontinuation, or other incomplete outcome information were handled. It also does not report whether any imputation or sensitivity analyses were used. These missing-data procedures should not be inferred from the endpoint label.

The registry record likewise does not provide further analysis-population definitions, such as whether all enrolled participants were included in any secondary analysis. Enrollment was 39, but that figure alone does not establish the denominator for each outcome. The treatment-related adverse-event outcome is listed, but the record does not report its analysis population or event-attribution rules. Overall, the absence of analysis details limits assessment of how robust the reported—or unreported—outcomes are to missing data, participant exclusions, and multiple comparisons.

11. Safety Results

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

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death nos (5.1%), atrial fibrillation (2.6%), dehydration (2.6%), memory impairment (2.6%), syncope (2.6%).

The serious adverse-event listing reports 39 participants at risk and 7 participants affected. The separate other-adverse-event listing reports 39 participants at risk and 39 affected. These categories may overlap and should not be added or treated as mutually exclusive groups. The registry record also lists serious-event terms with percentages: Death NOS at 5.1%, and atrial fibrillation, dehydration, memory impairment, syncope, and confusion at 2.6% each.

These figures describe the safety entries in the registry, not a complete account of each participant’s clinical course. The term Death NOS is a serious-event listing, while the corresponding death-count field is not reported in the registry record. The listed percentage should not be used to infer a total death count or to establish cause. The record does not give event timing, duration, severity grades, outcome, or detailed attribution for each listed term. It also does not report a complete set of treatment-related event frequencies in the information available for interpretation.

As a general statistical point, adverse-event counts and percentages depend on the event definition, observation period, and denominator. They are descriptive and do not establish that the intervention caused an event. Because the study has no concurrent comparator, the registry safety figures cannot directly quantify an excess risk relative to another treatment or to no treatment. Interpretation should remain limited to what the registry lists.

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

The registry record establishes that a phase II, single-group study evaluated selumetinib in participants with papillary thyroid carcinoma that was iodine-131 refractory or included follicular elements. It describes an oral dosing schedule and identifies objective response rate as the primary endpoint. It also lists progression-free survival, treatment-related adverse events, and overall survival as secondary outcomes.

The record does not report the observed objective response rate, the number of complete or partial responses, or the number of evaluable participants. It therefore does not show whether the response endpoint met the investigators’ stated 20% threshold. The approximate 5% response rate cited for doxorubicin is contextual background, not a concurrent comparison, and it cannot establish a treatment effect in this study.

Nor does the record report results for progression-free survival or overall survival. A response endpoint concerns whether tumor shrinkage met RECIST criteria; it is not interchangeable with how long disease remains controlled or how long participants live. Those outcomes require their own reported estimates and analysis details. Their inclusion in the registry does not establish what the study found.

The safety listing documents participants affected by serious and other adverse events and identifies selected serious-event terms. It does not, on its own, determine whether an event was caused by treatment, and it lacks details needed to assess timing, severity, and clinical course. The single-group design also means that these descriptive figures cannot be contrasted with a concurrent control group.

As a general statistical point, trial evidence is strongest when estimates are accompanied by clear denominators, uncertainty intervals, and transparent methods. Those elements are not reported for the primary response outcome in this registry record. Accordingly, the available information describes the study question and some safety reporting, but it does not support a conclusion that selumetinib did or did not produce a clinically meaningful effect.

13. Why This Trial Matters Statistically

This trial illustrates an important distinction between a study’s clinical question and the evidence available to answer it. The registry defines a response endpoint using RECIST and states a threshold investigators considered worth further pursuit. Yet the record does not report the response count, rate, or precision. A clearly defined endpoint is necessary for interpretation, but it is not a substitute for the result itself.

The single-group design is also central to the statistical reading. It can describe outcomes observed among participants receiving selumetinib, but it cannot directly compare outcomes with a concurrent control. The historical response-rate context in the registry may help explain the study rationale, but it does not remove the limitations of historical comparison. The distinction matters whenever readers encounter a benchmark alongside a treatment result.

The record also highlights why analysis populations and missing-data rules matter. The primary population is all evaluable participants, while the enrollment figure is 39. Because the number evaluable and the handling of missing assessments are not reported, the endpoint denominator cannot be established from the registry information. These details affect both the estimate and its precision.

Finally, safety listings require careful interpretation. Counts, event terms, and percentages provide descriptive information, but do not alone establish causality or comparative risk. The absence of a concurrent control and of detailed event-level context limits what can be concluded. These issues are broadly relevant in biostatistics: design, endpoint definitions, denominators, uncertainty, and reporting completeness jointly determine how far a result can be interpreted.

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 main trial-specific limitation for interpreting efficacy is that the registry record does not report the primary response result. It gives no response count, response rate, confidence interval, or number of evaluable participants. Although the primary endpoint timeframe is up to 2 years, the record does not explain assessment timing or provide a result within that period.

The single-group design lacks a concurrent control, and masking is recorded as none. Thus, any descriptive outcomes would not provide a randomized treatment contrast. The historical response benchmark cited in the rationale is not a control arm. The record does not provide details sufficient to assess how comparable that benchmark is to the study population or outcome ascertainment.

The study enrolled 39 participants, but the endpoint population is all evaluable participants. The registry does not state how many met that definition, how missing assessments were handled, or whether all enrolled participants contributed to secondary outcomes. The absence of analysis entries also leaves the statistical methods, uncertainty calculations, and any sensitivity analyses unreported.

Safety reporting is limited in the registry information described: selected serious-event terms and counts are listed, but event timing, severity grades, outcome, and detailed treatment attribution are not. The treatment-related adverse-event outcome is named, but its result is not reported. Progression-free survival and overall survival are likewise listed without results or analysis details.

These limitations concern the available registry record; they do not establish that the underlying study lacked additional analyses or reporting elsewhere. Such information is not reported in the registry record and should not be assumed.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Selumetinib in Treating Patients With Papillary Thyroid Cancer That Did Not Respond to Radioactive Iodine — NCT00559949.
• Registry record last updated 2017-01-30; status last verified 2016-12.
• Results first posted 2017-01-30.
• 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.

18. Record Summary

NCT00559949 is a completed phase II, single-group study sponsored by the National Cancer Institute. It enrolled 39 participants and studied oral selumetinib in iodine-131-refractory papillary thyroid carcinoma and papillary thyroid carcinoma with follicular elements. Treatment was described as twice daily on days 1–28, repeating every 28 days in the absence of unacceptable toxicity or disease progression. Allocation was listed as not applicable, and masking as none.

The primary endpoint was objective response rate under RECIST, among all evaluable participants, with a timeframe of up to 2 years. Secondary outcomes were median progression-free survival, treatment-related adverse events, and overall survival. The record reports serious adverse events affecting 7 participants and other adverse events affecting 39 participants, among 39 at risk for each category. It does not report the primary response result, the number evaluable, or results for the listed secondary outcomes. Analysis details are not reported in the registry record.