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 Neoadjuvant GW572016 to Treat Breast Cancer (NCT00206427), a na phase 2 study. The primary outcome is Clinical Response.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00206427 |
| Phase | Phase 2 |
| Condition | Breast Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 49 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Baylor Breast Care Center |
| Results posted | Yes |
2. Clinical Question
Population
Patients with HER2-overexpressing breast cancer, as described in the trial’s official title. The registry record lists breast cancer as the condition and records enrollment of 49.
Intervention
The intervention is listed as GW572016 and lapatinib. The arm description calls it “Intervention/Lapatinib (GW572016),” with an arm title of “GW572016 1500mg.”
Comparator
No separate comparator group is recorded. The registry describes a single-group trial, with allocation listed as not applicable and no masking.
Primary question
The stated primary outcome is clinical response at the end of week 6, assessed using bidimensional measurements of the primary cancer. The record does not report how many participants had each response category.
The clinical question is whether treatment with lapatinib (GW572016) is associated with clinical response in this trial population. That is a question about observed response during a specified treatment period, not a randomized comparison against another treatment or a control condition. Without a comparator group, changes in tumor measurements cannot be separated from other influences through a between-group contrast.
The endpoint distinguishes complete response, partial response, progressive disease, and stable disease using prespecified tumor-measurement definitions. The primary outcome’s timeframe is the end of week 6. The registry describes the assessment at baseline and at that endpoint, but the response counts and any statistical estimate of the treatment effect are not reported in the registry record. Consequently, the registry information does not establish the size or precision of a clinical response estimate.
3. Trial Design
The registry identifies this as a phase II, single-group trial titled “Neoadjuvant GW572016 to Treat Breast Cancer.” Its official title describes a biologic correlative study in HER2-overexpressing breast cancer. The named intervention is GW572016, also listed as lapatinib. The arm description refers to “Intervention/Lapatinib (GW572016),” and the arm title is “GW572016 1500mg.”
Enrollment is recorded as 49. Allocation is listed as not applicable, masking is listed as none, and the model is single group. These features mean that the registry does not describe a randomized, masked comparison with a separate control arm. The trial is marked completed. Its recorded start is 2004-08, and its primary completion is 2011-06.
The primary outcome is clinical response, measured in participants at the end of week 6. The endpoint description says tumor measurements were taken at baseline and at the end of week 6. For this outcome, the stated population includes patients who finished 6-week therapy; two patients who dropped off therapy early were excluded. The registry does not report further detail about the timing or reasons for those early departures.
Two secondary outcomes concern inhibition of HER1 and HER2 signaling: one determined by EGFR, HER2, and pHER2, and another determined by ki67 and CC3. The registry lists three outcome measures, but does not report analysis entries. It also does not report the statistical plan, a sample-size justification for the trial, or interim-analysis procedures. Any planning calculations based on an observed effect should therefore be understood as illustrations, not as evidence of the trial’s original design rationale or as observed power.
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
| Stage | GW572016 1500mg |
|---|---|
| STARTED | 49 |
| COMPLETED | 47 |
| NOT COMPLETED | 2 |
Reasons for not completing this period:
| Reason | GW572016 1500mg |
|---|---|
| Adverse Event | 2 |
Analysis population for the primary outcome, as defined in the registry: All patients finished 6-week therapy were included. Two patients dropped off therapy early were excluded.
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 | GW572016 1500mg |
|---|---|---|
| Participants analysed | 49 | |
| Age, Continuous | years | 53 (27 to 83) |
| Sex: Female, Male: Female | Participants | 49 |
| Sex: Female, Male: Male | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Clinical Response, measured over at the end of week 6..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is “Clinical Response,” recorded as a number of participants and assessed at the end of week 6. The registry describes bidimensional measurements of the primary cancer at baseline and at the endpoint. It classifies complete disappearance of the primary tumor as clinical complete response (cCR). A decrease of at least 50% in the sum of the products of the largest perpendicular diameters qualifies as clinical partial response (cPR). An increase of more than 25% qualifies as clinical progressive disease (cPD). A response that meets none of these definitions is classified as stable disease (cSD).
These categories translate measured changes into clinically interpretable response groups. They also make clear that response is not a single undifferentiated category: tumor disappearance, a sufficiently large reduction, sufficient growth, and changes outside those definitions are treated differently. The endpoint is therefore a categorical outcome based on the recorded tumor measurements.
For an endpoint expressed as participant counts, the number in each category and the relevant analysis population are important to interpretation. The registry states that patients who finished 6-week therapy were included and that two patients who dropped off therapy early were excluded. It does not report the category counts, a response proportion, or an uncertainty interval. As a result, the endpoint definition can be described, but the observed clinical response distribution cannot be evaluated from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a completed, phase II, single-group study with enrollment of 49 and a primary clinical response assessment at the end of week 6. It defines four response categories using tumor measurements. However, it does not report the number of participants in any primary response category, an overall response estimate, or an uncertainty interval. The endpoint’s observed result and its statistical precision are therefore not available in the registry record.
This distinction matters because an endpoint definition is not itself an outcome result. The definitions specify how measurements would be classified; they do not show how participants were classified. Without the category counts and analysis denominator, readers cannot determine the observed distribution across complete response, partial response, progressive disease, and stable disease. Nor can they assess how stable an estimate might be under sampling variation.
The trial has no separate comparator group in the registry description. A single-group result, even if the category counts were available, would describe outcomes among those assessed under the trial’s conditions. It would not provide a randomized estimate of the difference between lapatinib and another treatment or a control. In general, a comparator can help distinguish an intervention-associated difference from changes that may also occur over time or under other care. That kind of contrast is not recorded for this trial.
The analysis population also requires attention. The primary outcome description includes patients who finished 6-week therapy and excludes two patients who dropped off therapy early. The registry does not provide the response results for the included population, nor does it describe outcome handling for early departures beyond their exclusion. This limits assessment of how the reported endpoint would relate to all enrolled participants.
The safety record lists 3 serious adverse events among 49 at risk and 32 other adverse events among 49 at risk for the GW572016 1500mg group. It also lists several serious-event terms at 2.0% each. These entries describe recorded safety information, but do not fill the gap in the primary response results. They should be read as separate outcome information rather than as evidence about clinical response.
Overall, the registry supports description of the trial’s design, response definitions, analysis-population statement, and reported adverse-event figures. It does not support a quantitative conclusion about the size or precision of the primary clinical response result. No treatment-versus-control effect, p-value, or confidence interval for that endpoint is reported in the registry record.
9. Statistical Methods Explained
The registry describes a participant-count endpoint, so the primary result would ordinarily be presented as counts assigned to the response categories. Counts are useful because they show how many assessed participants fell into each category. To interpret such counts, readers also need to know the population included in the analysis and the number assessed. The record states that patients who finished 6-week therapy were included and that two patients who dropped off therapy early were excluded. It does not report the primary category counts or a response estimate.
What does a confidence interval communicate?
General statistical explanation: A confidence interval expresses the uncertainty around an estimate under a statistical model and its assumptions. It gives readers a range of values compatible with the observed data and method; it is not a guarantee that the true value lies in that range. For a participant-level binary outcome, uncertainty depends in part on how many participants contribute information and how the outcome is distributed. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be evaluated.
What can a single-group result establish?
General statistical explanation: A single-group analysis can describe outcomes observed in that group. It does not, by itself, estimate a randomized contrast with a comparator. Without a concurrent comparison group, observed changes may reflect the intervention, the natural course of the condition, measurement variation, or other influences. This is a design limitation on causal interpretation, not a flaw in the arithmetic of a group’s outcome count. The registry records a single-group model and no separate comparator.
How should the response categories be read?
The primary outcome uses defined tumor-measurement categories. Complete disappearance is cCR; a decrease of at least 50% in the specified measurement product is cPR; an increase of more than 25% is cPD; and a response that meets none of these criteria is cSD. The thresholds establish classification rules. They do not disclose the observed counts, and the record does not report an analysis comparing categories or an inferential procedure for the primary endpoint.
What do the planning calculations represent?
General statistical explanation: A sample-size calculation asks how much information a future study might need under stated assumptions. The planning description for the illustrations specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it also describes detecting a stated fraction of an observed effect. For time-to-event calculations, it specifies a total number of events, while other calculations are expressed as participants per arm. These are planning conventions, not findings from this single-group trial. In particular, an illustration using two-arm allocation does not describe the actual trial’s single-group design. Sample-size illustrations are not observed power, and they do not establish that the trial was designed using those assumptions.
Why does over-dispersion matter in general?
General statistical explanation: Over-dispersion occurs when outcome variability exceeds what a chosen model assumes. If ignored, standard errors can be too small and intervals too narrow, making results appear more precise than they are. This concern is relevant to some count-data models, but the registry’s primary endpoint is described as a participant count for a binary or categorical response, and the record does not report a model or an over-dispersion assessment. It would not be appropriate to claim that such a method was used or was necessary for this analysis.
The registry reports no analysis entries for the outcome measures. Thus, the statistical method used to estimate or test clinical response, any adjustment for covariates, and any approach to missing outcomes are not reported in the registry record. General statistical concepts can clarify what such analyses would mean, but they cannot substitute for the absent analysis details or outcome values.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary clinical response outcome and two secondary outcomes related to inhibition of HER1 and HER2 signaling. One secondary outcome is determined by EGFR, HER2, and pHER2; the other is determined by ki67 and CC3. The registry record does not report analysis entries for the outcomes, or a statistical approach for handling multiple outcomes. Any multiplicity strategy, such as adjusting significance thresholds or identifying a single confirmatory test, is not reported in the registry record.
The distinction matters because interpreting several outcomes can raise the chance of an apparently notable result occurring by chance when many tests are considered. General statistical explanation: Multiplicity methods define how inference is controlled across multiple comparisons or endpoints. Whether such control is needed, and how it should be implemented, depends on the prespecified analysis plan. No such plan is reported for this trial, so it is not possible to determine how outcome-level inference was intended to be interpreted.
For the primary endpoint, the registry says the analysis included patients who finished 6-week therapy and excluded two patients who dropped off therapy early. It does not report reasons for early departure, whether any endpoint measurements were missing for other reasons, or how missing measurements were handled. Imputation, sensitivity analyses, and other missing-data procedures are not reported in the registry record. The outcome counts needed to assess the resulting analysis population are also not reported.
These omissions limit evaluation of selection and missing-data effects. Excluding participants who did not finish treatment can make an analysis population differ from the enrolled population, while the direction and extent of any resulting influence depend on information that is not reported. The registry does not describe an intention-to-treat analysis or another broader analysis population, so none should be assumed.
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 |
|---|---|---|---|
| GW572016 1500mg | 3 | 49 | 6.1% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| GW572016 1500mg | 32 of 49 |
Most frequent serious adverse event terms
| Event term | Organ system | GW572016 1500mg |
|---|---|---|
| rash | Skin and subcutaneous tissue disorders | 1 of 49 |
| Neutrophils/ANC | Blood and lymphatic system disorders | 1 of 49 |
| Leukocytes | Blood and lymphatic system disorders | 1 of 49 |
| Hypocalcemia | Blood and lymphatic system disorders | 1 of 49 |
| Constipation | Gastrointestinal disorders | 1 of 49 |
| Febrile neutropenia | Blood and lymphatic system disorders | 1 of 49 |
| Infection-oral thrush | Infections and infestations | 1 of 49 |
| Mucositis-oral | Gastrointestinal disorders | 1 of 49 |
| Left Ventricular Systolic Dysfunction | Cardiac disorders | 1 of 49 |
Most frequent non-serious adverse event terms
| Event term | Organ system | GW572016 1500mg |
|---|---|---|
| Diarrhea | Gastrointestinal disorders | 23 of 49 |
| Rash | Skin and subcutaneous tissue disorders | 18 of 49 |
| Elevated AST | Hepatobiliary disorders | 4 of 49 |
| Nausea | Gastrointestinal disorders | 4 of 49 |
| Bruising | Skin and subcutaneous tissue disorders | 3 of 49 |
| Pruritis | Skin and subcutaneous tissue disorders | 3 of 49 |
Serious events with the highest arm-level rate: rash (2.0%), neutrophils/anc (2.0%), leukocytes (2.0%), hypocalcemia (2.0%), constipation (2.0%).
For the GW572016 1500mg group, the registry records 49 at risk for serious adverse events and 3 with serious adverse events. It records 49 at risk for other adverse events and 32 with other adverse events. These are separate entries in the safety record; they should not be added together or treated as mutually exclusive categories.
The listed serious adverse-event terms are rash, Neutrophils/ANC, Leukocytes, Hypocalcemia, Constipation, and Febrile neutropenia. Each is reported at 2.0%. These term-level figures describe the registry’s listed serious events, not the overall frequency of all events. The record does not provide further detail in these entries about event timing, severity grading, or individual participant overlap across terms.
Safety figures describe what was recorded in this treatment group. Because the trial is single group and no separate comparator is recorded, these numbers do not estimate a difference in safety relative to another treatment or control. They also do not convey the primary clinical response result, which is not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a phase II, single-group trial assessed clinical response after 6-week therapy, using defined tumor-measurement categories. It also records a safety group and lists serious and other adverse-event counts. These details allow readers to understand the outcome definitions, the broad design, and what safety figures are recorded.
What the record does not establish is the observed distribution of clinical response. Although the endpoint definition is detailed, no counts for cCR, cPR, cPD, or cSD are reported. There is also no reported response estimate or confidence interval from which to judge precision. Accordingly, the endpoint information alone cannot show the magnitude of the observed response or how uncertain an estimate would be.
The single-group design also limits interpretation. There is no separate comparator, so the record does not provide a randomized estimate of how outcomes differ from another treatment or control condition. In general, a descriptive outcome in one group and a comparative treatment effect answer different questions. The former summarizes what was observed in the group; the latter requires a comparison and appropriate design and analysis.
The analysis population is defined as patients who finished 6-week therapy, with two early departures excluded. The registry does not report the reasons for those departures or the handling of missing measurements. The effect of these choices cannot be determined from the record.
These limitations do not make the recorded design or safety information meaningless; they define what can responsibly be inferred from it. The record supports a description of the trial and its outcome definitions, but not a conclusion about the size, precision, or comparative effect of the primary clinical response outcome. It should not be read as proof for or against treatment efficacy.
13. Why This Trial Matters Statistically
This trial illustrates why an endpoint definition and an endpoint result are different kinds of information. The registry gives explicit rules for classifying clinical response using bidimensional tumor measurements, including thresholds for partial response and progressive disease. Those rules make the intended measurement interpretable. But without the numbers classified into each category, readers cannot assess the outcome distribution or its statistical precision.
It also illustrates the importance of aligning study design with the question being asked. A single-group study can describe outcomes under the trial’s conditions. It does not provide a randomized contrast with a separate comparator. That distinction remains important even when the outcome is measured objectively, because measurement precision does not eliminate the need for a comparison when the question concerns relative effects.
The analysis population matters as well. The registry specifies that patients who finished 6-week therapy were included and that two early departures were excluded. Readers need to know who was analyzed and how missing outcomes were handled to understand what a result represents. The registry does not report the response counts or missing-data methods, leaving those interpretive questions open.
Finally, the sample-size illustrations are described with assumptions for two-arm planning, while the recorded trial model is single group. This contrast demonstrates why planning calculations must be distinguished from the design that was actually conducted. A planning illustration is not evidence about the original protocol, observed power, or a treatment effect. Taken together, these features show how statistical interpretation depends on outcome reporting, population definition, analysis methods, and design—not only on the endpoint label.
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.
A central limitation is that the registry record does not report the primary clinical response counts or an effect estimate. Although it defines the endpoint categories and the time of assessment, it does not show how participants were distributed among those categories. No confidence interval or p-value for the primary endpoint is reported, so the size and precision of any response result cannot be assessed.
The single-group design provides no separate comparator. It therefore cannot support a randomized comparison of clinical response or safety against another treatment or control. The registry also records no masking. These design features constrain the conclusions that could be drawn even if the outcome counts were available.
The primary analysis population excludes two patients who dropped off therapy early and includes patients who finished 6-week therapy. The record does not report why the early departures occurred, whether further endpoint measurements were missing, or how such missingness was handled. It does not describe an intention-to-treat analysis or sensitivity analyses. This leaves uncertainty about how the analyzed population relates to enrollment.
The registry lists secondary biologic outcomes, but does not report analyses or a multiplicity strategy. Statistical methods for the primary outcome, covariate adjustment, interim analyses, and sample-size justification are not reported in the registry record. The planning assumptions described for illustrations should not be mistaken for the trial’s own analysis plan.
Safety entries include counts and selected serious-event terms, but the record does not provide further detail about event timing, severity grading, or overlap among terms. The available record is therefore informative about design and selected definitions, but incomplete for evaluating the primary result and several aspects of analysis and safety interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Neoadjuvant GW572016 to Treat Breast Cancer — NCT00206427.
- Registry record last updated 2021-09-29; status last verified 2021-09.
- Results first posted 2012-03-07.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes NCT00206427, “Neoadjuvant GW572016 to Treat Breast Cancer,” as a completed phase II, single-group study in breast cancer. Its official title refers to a biologic correlative study in HER2-overexpressing breast cancer. The intervention is listed as GW572016 and lapatinib, and enrollment is recorded as 49. Allocation is not applicable, and masking is none.
The primary outcome is clinical response at the end of week 6, based on bidimensional measurements and defined categories. The stated analysis population includes patients who finished 6-week therapy; two patients who dropped off therapy early were excluded. The registry lists two secondary signaling outcomes. It records serious and other adverse-event counts for the GW572016 1500mg group.
Primary response counts, a statistical analysis of that endpoint, and details of missing-data handling are not reported in the registry record. The record supports a description of the design and definitions, but not a quantitative interpretation of the primary clinical response result.