Study of Gefitinib Retreatment in Non-Small Cell Lung Cancer (NSCLC): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Gefitinib Retreatment in Non-Small Cell Lung Cancer (NSCLC) (NCT00824746), a na phase 2 study. The primary outcome is Disease Control(DC) Rate of Gefitinib Retreatment Per RECIST Criteria (V1.1) and Assessed by CT.

2. Clinical Question

The clinical question is therefore descriptive: it concerns tumor response among a selected group with a history of response to gefitinib, rather than a contrast between retreatment and another treatment or no retreatment. Because eligibility included prior response and subsequent progression after further treatment, the findings would pertain to that defined clinical history, not to all patients with NSCLC or all patients previously treated with gefitinib.

3. Trial Design

The registry describes a prospective, open-label, single-arm phase II study of gefitinib retreatment. It lists 23 enrolled participants and a single treatment group. Allocation is recorded as not applicable, and masking as none. These features mean the registry does not describe random assignment or blinded outcome assessment. No concurrent comparator is listed, so the design cannot directly estimate a treatment difference against another group.

The target population was patients with advanced or metastatic NSCLC, described as stage IIIb or IV, who had previously responded to gefitinib. The study summary further specifies disease progression after at least one regimen following prior gefitinib failure. This selection is important when interpreting any response: the endpoint concerns retreatment in people with the stated treatment history, rather than initial gefitinib use or an unselected NSCLC population.

The primary endpoint was disease-control rate, defined in the outcome description as the percentage with a best response of complete response, partial response, or stable disease according to RECIST version 1.1. The registry lists an 8-week timeframe. Its description says CT assessment was performed after the first 4 weeks. These are both stated in the record; the timing difference is not reconciled there. Progression-free survival and overall survival are listed as secondary outcomes, but their result values are not reported in the registry record.

The study status is completed. The registry lists a start of 2009-01 and primary completion of 2011-06. It does not report a control arm, a detailed allocation procedure, or a masking procedure beyond stating that masking was none. The sponsor is Chonnam National University Hospital. The registry record does not report a sample-size justification or enough statistical-plan detail to establish how the investigators intended to handle uncertainty, missing assessments, or secondary outcomes.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: we analysed the data of 23 patients who were enrolled to this study(intention-to-treat (ITT) population).

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 Disease Control(DC) Rate of Gefitinib Retreatment Per RECIST Criteria (V1.1) and Assessed by CT, measured over 8 weeks.

The primary endpoint is disease-control rate under RECIST version 1.1. It counts participants whose best tumor response is complete response, partial response, or stable disease, and expresses this as a percentage. Tumor response was evaluated by computed tomography. The registry lists an 8-week timeframe and states in the endpoint description that assessment was performed after the first 4 weeks; it does not explain the difference between those timing statements.

Disease control combines tumor shrinkage responses with stable disease. In general, this measure can describe whether disease was classified as responding or stable at the assessment, rather than measuring the size of a treatment effect against a comparator. It is used as a response summary, but it does not by itself describe how long disease control lasted or establish that treatment caused the observed response.

The registry identifies the intention-to-treat population as the 23 enrolled patients. However, the disease-control result itself—including the number classified as complete response, partial response, stable disease, or another response category—is not reported in the registry record. The stated 95% confidence interval is a dispersion measure named for the endpoint, but its bounds are not reported in the registry record. Without the rate and its interval, the primary endpoint’s observed magnitude and precision cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group study and names a percentage as the primary endpoint. The statistical interpretation of such an endpoint differs from that of a randomized comparison: it is a summary of outcomes in the enrolled group, not an estimate of a difference between treatment groups.

What does a disease-control percentage represent?

In general, a proportion is formed by identifying the participants who meet a defined outcome and relating that count to the population being analyzed. Here, disease control is defined as a best response of complete response, partial response, or stable disease under RECIST version 1.1. The primary-outcome description identifies the intention-to-treat population as the 23 enrolled patients. However, the registry does not report the response-category counts or the disease-control percentage. The endpoint definition therefore explains what would be counted, but it does not reveal the observed result.

A proportion can be accompanied by a confidence interval to communicate uncertainty. In general, a confidence interval gives a range of values compatible with the data under the statistical method used; it is not a guarantee that the true value lies within that particular interval. The registry names a 95% confidence interval for the primary measure, but the interval bounds and the method used to calculate it are not reported in the registry record. As a result, the precision cannot be evaluated.

Why does the design matter?

This is a single-arm study, with no randomized or concurrent comparator listed. A single-group estimate can describe the observed outcome in the enrolled population, but it cannot on its own identify how outcomes would have differed under another treatment or without retreatment. In general, comparison with historical experience is also vulnerable to differences in eligibility, assessment, follow-up, and patient characteristics. The registry does not report a planned historical comparison or a comparator outcome.

The study is open label, and masking is listed as none. In general, knowledge of treatment assignment can influence aspects of care, reporting, or assessment, although the extent depends on the outcome and assessment process. The endpoint description names CT assessment and RECIST version 1.1, but the registry does not report whether image review was independent or blinded. It also does not provide detail on assessment procedures beyond the timing statements in the endpoint description.

How should the response criteria be understood?

RECIST is a framework for classifying tumor response. The registry’s disease-control definition groups complete response, partial response, and stable disease. This combined measure treats those categories as meeting the endpoint, although they represent different response classifications. In general, the combined rate does not communicate the distribution among those categories, response duration, or time until progression. Those details require additional outcome reporting. The registry does not provide the component counts or a duration-based disease-control measure.

The record gives two timing statements: an 8-week primary-outcome timeframe and assessment after the first 4 weeks in the description. Timing affects the interpretation of a response measure because tumor status can change over follow-up. The registry does not reconcile the statements or report subsequent assessment schedules, so the precise assessment schedule cannot be established from the record.

What can be inferred about time-to-event analysis?

Progression-free survival and overall survival appear as secondary outcomes. In general, time-to-event methods account for both the timing of events and participants whose event status is not observed through the end of follow-up. A survival estimate depends on definitions of the event, censoring rules, and follow-up information. Those details, the results, and the analysis methods are not reported in the registry record. No time-to-event estimate or interpretation of its precision can therefore be made from the listed endpoint names alone.

The registry does not report the statistical methods used for the primary or secondary outcomes. In particular, it does not identify the confidence-interval procedure, any hypothesis test, adjustment for baseline characteristics, or handling of missing outcome assessments. These are not details that can be inferred from the endpoint label or study phase.

What do planning calculations mean?

Any planning illustration based on an observed effect is not an observed trial result and is not the trial’s original sample-size justification. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Those assumptions describe a hypothetical planning exercise, not this single-arm design. The registry does not report a sponsor sample-size justification, and a planning illustration should not be interpreted as observed power or evidence that the study was adequately powered.

In general, a planning sample size depends on assumptions about the outcome, effect to detect, variability, significance level, power, and allocation. If an assumed effect is based on an observed result, the illustration inherits uncertainty in that result. The registry does not report the primary result needed to assess such an illustration from the endpoint data. No planning value can replace the missing disease-control estimate or its confidence interval.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies disease-control rate as the primary endpoint and lists progression-free survival and overall survival as secondary outcomes. It does not report a detailed statistical analysis plan, testing hierarchy, or procedure for controlling multiplicity. When several outcomes are examined, chance findings can become more likely if each is tested without an adjustment or prespecified hierarchy. Whether that issue applies to formal tests in this study cannot be established because the analysis methods and results are not reported in the registry record.

The registry’s primary-outcome description states that the analysis used the 23 enrolled patients as the intention-to-treat population. It does not report how many had evaluable CT assessments, whether any response data were missing, or how missing assessments were handled. The intention-to-treat label does not by itself specify how missing outcome values were treated. The record also does not report exclusions, withdrawals, or sensitivity analyses for the primary endpoint.

For the secondary outcomes, the registry does not report analysis populations, follow-up completeness, event definitions, censoring rules, or methods for handling missing time-to-event information. These details are important for interpreting progression-free and overall survival estimates, but no such estimates or methods are reported in the registry record.

The registry lists no analyses in its analysis count. That entry does not supply a statistical analysis plan or establish how outcomes were analyzed. A sample-size justification, interim-analysis plan, and prespecified missing-data approach are not reported in the registry record. Their absence from the record should not be treated as evidence that a particular procedure was or was not conducted.

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: disease progression (13.0%).

The safety record lists one single arm, with 23 at risk for the serious-adverse-event category and 3 affected. It also lists 23 at risk and 10 affected for other adverse events. These are registry figures for the retreatment group; there is no comparator arm against which to contrast them. The record’s top serious-event term is disease progression, listed at 13.0%.

The adverse-event entries do not provide a detailed event listing, timing, duration, severity grading beyond the serious-versus-other categories, or attribution to gefitinib. The registry does not report a death count. These missing details prevent a fuller assessment of the safety profile from the listed figures alone. In general, adverse-event counts depend on how events are defined, collected, and reported, and a single-arm count does not establish how event frequency compares with another treatment.

The disease-progression term should be read as a reported serious-event term, not as an independent estimate of treatment-related harm. The registry does not provide further context for that classification. The safety figures describe what is recorded for this group and should not be interpreted as a causal comparison or as a complete account of all possible adverse events.

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

The registry record documents a phase II investigation of gefitinib retreatment in patients with advanced or metastatic NSCLC who had previously responded to gefitinib and later experienced progression after further treatment. It defines disease-control rate as the primary endpoint and specifies that complete response, partial response, and stable disease count toward disease control under RECIST version 1.1.

The record does not report the observed disease-control rate, its 95% confidence interval, or the response-category counts. It also does not report results for the listed secondary outcomes of progression-free survival and overall survival. Therefore, it does not support a numerical conclusion about the amount of disease control observed, how precisely that outcome was estimated, or how long disease control or survival lasted.

The single-arm design can describe outcomes in the treated group, but it cannot establish a treatment effect relative to a comparator. In general, an outcome observed after treatment is not by itself evidence that treatment caused the outcome. The design also does not answer how retreatment compares with another strategy. Because the enrolled group had a specific prior response and treatment history, any findings would not automatically apply to patients with different histories.

The safety record lists serious and other adverse-event counts and identifies disease progression as the top serious-event term. Those data do not provide a comparative safety estimate, and the death count is not reported in the registry record. The available entries should be understood as limited registry reporting rather than a complete description of harms.

Statistically, the key distinction is between a clearly specified endpoint and a reported endpoint result. The former is present; the latter is not. Without the outcome values and their uncertainty, the registry record allows assessment of the study question and design, but not a conclusion about the primary result or its precision.

13. Why This Trial Matters Statistically

This study is statistically notable for asking a focused retreatment question in a population selected by prior response to gefitinib and subsequent disease progression. That eligibility history defines the population of interest and illustrates why the applicability of a result depends on who was enrolled, not only on the treatment name or disease label.

Its single-arm design makes the distinction between describing an outcome and estimating a comparative effect especially important. A disease-control proportion, if reported, would summarize the enrolled group’s response classification. It would not estimate a randomized treatment contrast. Readers need to distinguish that descriptive role from evidence about what would have happened under another treatment or no retreatment.

The registry also illustrates that endpoint definitions and endpoint results are separate forms of information. It gives a RECIST-based definition and names a confidence interval, yet the actual rate and interval are not reported in the registry record. Without those values, readers cannot judge the magnitude or precision of the primary endpoint. The mismatch between the listed 8-week timeframe and the description of assessment after the first 4 weeks is another reason to examine outcome timing carefully.

Finally, the record lists secondary survival outcomes and safety counts but does not give the corresponding survival results or detailed safety context. This highlights the importance of complete outcome reporting: endpoint names and design descriptions do not substitute for estimates, uncertainty, follow-up details, and analysis methods. The study’s statistical contribution cannot be fully evaluated from the registry outcome information available.

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 most direct limitation for interpretation is that the primary disease-control result is not reported in the registry record. The record supplies an endpoint definition and names a 95% confidence interval, but gives neither the observed rate nor interval bounds. The response-category counts are also not reported. The primary endpoint’s magnitude and precision therefore cannot be evaluated.

The study is single arm, with no randomized or concurrent comparator. It can describe outcomes in the treated group, but it cannot estimate a between-group treatment difference. The open-label design and absence of masking are also relevant; the registry does not report whether CT assessment involved independent or blinded review.

The registry describes an 8-week timeframe while also stating that CT assessment was performed after the first 4 weeks. It does not reconcile those timing descriptions or provide a fuller assessment schedule. This leaves uncertainty about the exact timing represented by the primary endpoint.

Progression-free survival and overall survival are listed as secondary outcomes, but their results and analysis details are not reported in the registry record. The record does not report follow-up completeness, censoring rules, missing-data handling, or analysis populations for those outcomes. For the primary endpoint, it identifies the intention-to-treat population but does not report the number with evaluable assessments or how missing assessments were handled.

The safety entries are limited to counts for serious and other adverse events, a top serious-event term, and the stated at-risk figures. Detailed event context, attribution, and a death count are not reported in the registry record. The record also does not report a sample-size justification or detailed statistical analysis plan. These omissions limit assessment of precision, outcome handling, and the completeness of the reported results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Gefitinib Retreatment in Non-Small Cell Lung Cancer (NSCLC) — NCT00824746.
• Registry record last updated 2013-02-26; status last verified 2013-01.
• Results first posted 2013-02-26.
• 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

The registry describes NCT00824746, a completed, prospective, open-label, single-arm phase II study of gefitinib retreatment in advanced or metastatic NSCLC. The target population had previously responded to gefitinib and then experienced progression after at least one subsequent regimen following gefitinib failure. The registry lists 23 enrolled participants.

Disease-control rate under RECIST version 1.1 is the primary endpoint. It includes complete response, partial response, and stable disease; the registry lists an 8-week timeframe and describes CT assessment after the first 4 weeks. Progression-free survival and overall survival are listed as secondary outcomes.

The primary outcome value and confidence interval, secondary outcome results, detailed analysis methods, and sample-size justification are not reported in the registry record. Safety entries list 3 serious adverse events and 10 other adverse events, with disease progression as the top serious-event term at 13.0%. The record does not report a death count.