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 Tamoxifen Citrate, Letrozole, Anastrozole, or Exemestane With or Without Chemotherapy in Treating Patients With Invasive RxPONDER Breast Cancer (NCT01272037), a randomized phase 3 study. The primary outcome is Invasive Disease-Free Survival (IDFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01272037 |
| Phase | Phase 3 |
| Condition | Breast Ductal Carcinoma In Situ, Invasive Breast Carcinoma, Multicentric Breast Carcinoma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 5018 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
The trial concerns patients with hormone receptor-positive and HER2-negative breast cancer, 1-3 positive nodes, and a recurrence score of 25 or less. The title describes invasive breast cancer. The conditions listed in the registry record also include breast ductal carcinoma in situ, invasive breast carcinoma, multicentric breast carcinoma, multifocal breast carcinoma, and synchronous bilateral breast carcinoma. The primary outcome description notes that changes in eligibility status for three participants were identified after the primary analysis. The record does not provide a complete account of how those changes affected each analysis population.
Intervention
One randomized group receives a protocol-approved chemotherapy regimen, followed by adjuvant endocrine therapy. The endocrine options are tamoxifen citrate, an aromatase inhibitor (anastrozole, letrozole, or exemestane), or both. The treatment description specifies endocrine therapy for 5-10 years in the absence of disease progression or unacceptable toxicity. Chemotherapy choice is based on the patient and/or physician preference, according to the registry record.
Comparator
The other group receives protocol-approved endocrine therapy without chemotherapy. The listed options are tamoxifen citrate, an aromatase inhibitor (anastrozole, letrozole, or exemestane), or both, with treatment described for 5-10 years in the absence of disease progression or unacceptable toxicity. The groups therefore differ in whether chemotherapy is included alongside the endocrine treatment strategy.
Primary question
The primary endpoint is invasive disease-free survival (IDFS), measured as a percentage of participants at 5 years after randomization. The comparison asks how the IDFS experience differs between randomized treatment strategies. The definition counts invasive recurrence, a second invasive primary cancer, or death from any cause as an event. Numerical IDFS results by treatment group, and a numerical comparison between groups, are not reported in the registry record.
That question is narrower than asking whether any one endocrine drug is superior to another: the listed endocrine options are available within both strategies, while the central randomized contrast is chemotherapy plus endocrine therapy versus endocrine therapy alone. The record does not report a separate randomized comparison among tamoxifen citrate, anastrozole, letrozole, and exemestane.
The clinical context in the registry describes estrogen-related treatment approaches and chemotherapy, but the trial description alone does not establish the size or direction of an outcome difference. Interpretation requires the outcome estimates, their uncertainty, and details of the analysis. Those numerical primary outcome results are not reported in the registry record.
3. Trial Design
RxPONDER is a phase III, randomized, parallel-group trial with no masking reported. Its official title specifies adjuvant endocrine therapy with or without chemotherapy in patients with 1-3 positive nodes, hormone receptor-positive and HER2-negative breast cancer, and a recurrence score of 25 or less. The registry lists enrollment of 5018. The sponsor is the National Cancer Institute (NCI).
The two arms represent treatment strategies rather than single-drug assignments. Participants in the chemotherapy and endocrine therapy arm receive a protocol-approved chemotherapy regimen based on patient and/or physician preference, then protocol-approved adjuvant endocrine therapy. The endocrine therapy arm receives protocol-approved endocrine therapy without chemotherapy. The listed endocrine choices include tamoxifen citrate, an aromatase inhibitor—anastrozole, letrozole, or exemestane—or both. The record describes endocrine treatment for 5-10 years, subject to disease progression or unacceptable toxicity.
Randomization is a design feature intended to allocate participants to groups without choosing treatment based on observed characteristics. In general, this can support a fair comparison of assigned strategies, though the strength of an inference also depends on follow-up, outcome ascertainment, adherence, and analysis. The registry record does not report the randomization sequence method, allocation concealment procedures, or details of any stratification factors. Masking is listed as none, so the trial is described as unmasked; further details about masking of outcome assessors are not reported in the registry record.
The listed start date is 2011-02-28, the primary completion date is 2023-02-01, and the status is active, not recruiting. The record says the NCI and data and safety monitoring committee recommended early reporting after the primary analysis, following results of the third prespecified interim analysis. It does not report the interim-analysis boundaries, decision rules, or the statistical details behind the recommendation. The registry record's brief summary describes the question as whether adding combination chemotherapy to endocrine treatment changes outcomes; it does not give the primary outcome estimates.
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: 9383 participants were screened and 5083 were randomized to the trial: 2547 to the Chemo and Endocrine Therapy arm and 2536 to the Endocrine Therapy Alone arm. In the Chemo and Endocrine Therapy Arm, 36 were ineligible. In the Endocrine Therapy Alone arm, 29 were ineligible. Ultimately, 5018 participants were eligible in the participant flow: 2511 in the Chemo and Endocrine Therapy arm and 2507 in the Endocrine Therapy Alone arm.
Overall Study
| Stage | Chemo and Endocrine Therapy | Endocrine Therapy Alone |
|---|---|---|
| STARTED | 2511 | 2507 |
| COMPLETED | 1504 | 1547 |
| NOT COMPLETED | 1007 | 960 |
Reasons for not completing this period:
| Reason | Chemo and Endocrine Therapy | Endocrine Therapy Alone |
|---|---|---|
| Death | 25 | 28 |
| Adverse Event | 12 | 7 |
| Withdrawal by Subject | 175 | 93 |
| Disease progression | 70 | 111 |
| Other reason | 42 | 41 |
| Delinquent data | 24 | 19 |
| Reason under review | 33 | 29 |
| On treatment | 626 | 632 |
Analysis population for the primary outcome, as defined in the registry: For the participants flow and baseline characteristics summary, 5018 eligible participants were included. However, among them, there were 34 participants (10 in the chemo and endocrine arm, and 24 in the endocrine alone arm) that withdrew consent immediately after randomization; thus these participants were excluded from the survival analyses.
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: Randomized participants who were eligible for the study.
| Characteristic | Unit | Chemo and Endocrine Therapy | Endocrine Therapy Alone | Total |
|---|---|---|---|---|
| Participants analysed | 2511 | 2507 | 5018 | |
| Age, Continuous | years | 57.9 (28.0 to 87.6) | 57.2 (18.3 to 86.0) | 57.5 (18.3 to 87.6) |
| Age, Customized: < 40 years | Participants | 67 | 80 | 147 |
| Age, Customized: 40-49 years | Participants | 530 | 547 | 1077 |
| Age, Customized: 50-59 years | Participants | 837 | 838 | 1675 |
| Age, Customized: 60-69 years | Participants | 777 | 761 | 1538 |
| Age, Customized: >= 70 years | Participants | 300 | 281 | 581 |
| Sex: Female, Male: Female | Participants | 2511 | 2507 | 5018 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 297 | 325 | 622 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 1731 | 1695 | 3426 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 483 | 487 | 970 |
| Race/Ethnicity, Customized: White | Participants | 1667 | 1628 | 3295 |
| Race/Ethnicity, Customized: Black | Participants | 130 | 121 | 251 |
| Race/Ethnicity, Customized: Asian | Participants | 154 | 170 | 324 |
| Race/Ethnicity, Customized: Other/Unknown | Participants | 560 | 588 | 1148 |
| Menopausal Status: Premenopausal | Participants | 834 | 831 | 1665 |
| Menopausal Status: Postmenopausal | Participants | 1677 | 1676 | 3353 |
| Recurrence Score: 0-13 | Participants | 1076 | 1071 | 2147 |
| Recurrence Score: 14-25 | Participants | 1435 | 1436 | 2871 |
| Axillary Surgery: Axillary lymph-node dissection, with or without sentinel-node mapping | Participants | 1569 | 1571 | 3140 |
| Axillary Surgery: Sentinel-node biopsy without axillary lymph-node dissection | Participants | 942 | 936 | 1878 |
| Positive Nodes: 1 node | Participants | 1628 | 1647 | 3275 |
| Positive Nodes: 2 nodes | Participants | 643 | 623 | 1266 |
| Positive Nodes: 3 nodes | Participants | 231 | 229 | 460 |
| Positive Nodes: Not reported | Participants | 9 | 8 | 17 |
6. Primary Endpoint
The registry lists the primary outcome as Invasive Disease-Free Survival (IDFS), measured over 5 years after randomization.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
Invasive disease-free survival (IDFS) is the primary endpoint. The registry defines the event as the first of invasive recurrence at a local, regional, or distant site; a second invasive primary cancer, whether breast or not; or death from any cause. The endpoint clock starts at randomization, identified in the record as 2nd Registration. Participants last known to be alive without recurrence or a second primary cancer are censored at their last contact date. This is identified as the STEEP definition of IDFS.
IDFS brings several clinically important events into one time-to-event outcome. Counting death from any cause means that death is included regardless of whether it was attributed to cancer or treatment. Including a second invasive primary cancer also makes the endpoint broader than recurrence of the original cancer alone. Such a composite can summarize multiple ways in which a participant may experience an event, but it does not reveal which event type accounts for any observed difference unless those components are also examined.
The registry specifies Kaplan-Meier estimates for the 5-year IDFS rate. In general, a time-to-event endpoint can use information from participants whose follow-up ends before an event, provided they are censored appropriately. The resulting estimate reflects the event-free probability over time under the method's assumptions; it is not simply a count of participants with events divided by the randomized group size.
The percentage estimates and associated uncertainty for the primary endpoint are not reported in the registry record. Therefore, the endpoint definition can be described, but the magnitude and precision of the treatment-group comparison cannot be assessed from the record's primary outcome entry.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the trial question and endpoint definition but does not report the primary IDFS estimates. It identifies 5-year IDFS as the primary outcome and states that Kaplan-Meier estimates were calculated, yet it gives no group-specific percentages, confidence intervals, event counts, or numerical treatment contrast. Without those estimates, the direction, size, and precision of the primary comparison cannot be characterized.
For a time-to-event endpoint, the point estimate describes the estimated event-free experience over follow-up. A confidence interval, when reported, communicates uncertainty around an estimate under the analysis method. A narrow interval generally indicates greater statistical precision than a wide interval, but precision alone does not establish clinical importance. Neither the primary outcome confidence intervals nor a numerical test result are reported in the registry record.
The record states that separate analyses for all outcomes by menopausal status were conducted after results of the third prespecified interim analysis. This matters for interpretation because an overall result and subgroup results answer different questions. A subgroup estimate may be less precise than an overall estimate, and a difference between subgroup estimates is not by itself proof that treatment effects differ. The record does not provide menopausal-status-specific IDFS estimates or a test of treatment-effect variation.
The sponsor and data and safety monitoring committee recommended early reporting of the data. The record does not report the interim-analysis boundaries, whether any stopping threshold was crossed, or the decision rules used. Those details are important when interpreting results from a trial with interim looks, because repeated examination of accumulating data can affect how statistical evidence is assessed. No assumptions about those procedures can be made from the information recorded.
Some analysis-population details differ across registry portions. The primary outcome description says eligibility changes for three participants were identified after the primary analysis, making the eligible and evaluable population different between the reporting of this outcome and the Participant Flow and Adverse Events sections. It also says that 34 participants withdrew consent immediately after randomization, with 10 in the chemotherapy and endocrine therapy arm and 24 in the endocrine therapy arm. Those statements identify population accounting issues, but do not provide enough detail to reconstruct a complete participant-level analysis or determine the effect of the changes on the endpoint estimate.
In short, the registry record supports a description of the design, population, treatment strategies, and primary endpoint. It does not support a numerical conclusion about the primary outcome. Statistical interpretation of the treatment comparison would require the group estimates and uncertainty, the analysis population definition, and sufficient information about follow-up and censoring.
9. Statistical Methods Explained
The methods explicitly identified for the primary endpoint are Kaplan-Meier estimation of the 5-year IDFS rate. The registry defines IDFS from randomization to the first invasive recurrence, second invasive primary cancer, or death from any cause. A participant last known alive and free of recurrence or a second primary cancer is censored at the last contact date. Other details of the primary statistical analysis are not reported in the registry record.
What does Kaplan-Meier estimation do?
In general, Kaplan-Meier estimation is a way to describe time until an event when participants may have different lengths of follow-up. Participants who have an event contribute information up to that time. Participants whose event status is not observed through their last contact contribute information up to that contact and are then censored. Censoring is not counted as an event. The method combines the observed event-time information to estimate the probability of remaining event-free over time.
This approach relies on assumptions about censoring. In general, censoring should not systematically hide a participant's future event risk in a way that distorts the estimated event-free experience, after accounting for the analysis design. If follow-up ends for reasons related to prognosis, the estimate may be biased. The registry describes censoring at last contact but does not report follow-up completeness, reasons for loss to follow-up, or diagnostics of the censoring assumption.
What does the 5-year rate represent?
The registry reports the endpoint as a percentage of participants and specifies the 5-year time point after randomization. A Kaplan-Meier rate at that time is an estimate derived from follow-up over time, rather than a simple fraction using all randomized participants as the denominator. Its precision depends on the event and follow-up information available. The registry record does not report the number of events contributing to the primary analysis, the number at risk at the 5-year time point, or uncertainty intervals.
Why is the endpoint composite?
IDFS combines invasive recurrence, second invasive primary cancer, and death from any cause. In general, a composite can capture more than one important type of event and provide an overall time-to-event outcome. The trade-off is that a combined estimate may not show whether its components have similar frequency or importance. Component-specific primary outcome results are not reported in the registry record.
The death component is all-cause death, according to the definition. Therefore, the endpoint does not depend on assigning a cause of death. Conversely, the composite estimate alone cannot distinguish deaths from cancer-related recurrence events. The registry lists overall survival and distant disease-free survival among secondary outcomes, along with local disease-free interval, participant-reported anxiety, participant-reported health status, and adverse events. Their numerical results are not reported in the registry record.
What can randomization contribute?
In general, randomization is intended to make treatment assignment independent of participants' baseline characteristics, supporting comparison of assigned strategies. A randomized design does not guarantee that every measured characteristic is identical between groups, nor does it resolve problems arising after assignment, such as incomplete follow-up or changes in eligibility. The registry identifies the trial as randomized and parallel, but does not report the randomization sequence generation, allocation concealment, stratification, or a detailed analysis plan.
The record lists no masking. In general, knowledge of assigned treatment can influence care, participant reports, and decisions about whether an outcome has occurred. The primary outcome includes defined clinical events and death, but adjudication procedures and assessor masking are not reported in the registry record. The effect of the unmasked design therefore cannot be quantified from the record alone.
How should uncertainty and testing be understood?
In general, a confidence interval gives a range of estimates compatible with the observed data and analysis assumptions. It helps distinguish a precise estimate from one with substantial uncertainty. A p-value, if reported, summarizes how unusual the data would be under a specified null hypothesis and statistical model; it does not measure the probability that the null hypothesis is true or the clinical importance of an effect. The primary confidence intervals and p-values are not reported in the registry record, so neither precision nor statistical evidence can be assessed numerically.
The registry notes separate analyses by menopausal status for all outcomes following the third prespecified interim analysis. The statistical methods used for those subgroup analyses, including whether estimates were adjusted or formally compared, are not reported in the registry record. The record also does not report a multiplicity strategy for testing multiple outcomes, time points, or subgroups.
Interim analyses examine accumulating trial information before final reporting. In general, statistical plans may account for repeated looks at the data to control the chance of false-positive findings. Here, the registry mentions a third prespecified interim analysis and early reporting recommended by the NCI and data and safety monitoring committee, but does not report the decision boundaries or adjustment method. It would be inappropriate to infer those details.
10. Multiplicity, Missing Data and Analysis Populations
The registry describes separate analyses for all outcomes by menopausal status after results of the third prespecified interim analysis. This creates distinct overall and subgroup questions. The record does not report the specific subgroup definitions, the statistical test for differences between menopausal groups, or whether the subgroup analyses were adjusted for other characteristics. It also does not report whether the subgroup analyses were designated in the analysis plan beyond saying the analyses were prespecified.
Several outcomes are listed, including IDFS, overall survival, distant disease-free survival, local disease-free interval, adverse events, anxiety, and health status. The registry does not report a multiplicity procedure for interpreting tests across these outcomes, subgroup analyses, or any repeated interim looks. In general, multiplicity refers to the increased chance of at least one apparently strong result when many statistical hypotheses are examined. Whether and how that issue was addressed is not reported in the registry record. The third prespecified interim analysis is mentioned, but its boundaries and statistical adjustment are not given.
Missing outcome data and censoring also matter. The IDFS definition says participants last known alive without recurrence or a second primary cancer are censored at last contact. The record does not report the amount or pattern of missing follow-up, the number censored, or sensitivity analyses. Those details are needed to judge how dependent estimates may be on assumptions about follow-up.
The population description identifies 34 participants who withdrew consent immediately after randomization, including 10 in the chemotherapy and endocrine therapy arm and 24 in the endocrine therapy arm. It also states that eligibility changes for three participants were identified after the primary analysis, leaving different eligible and evaluable populations across the primary outcome, Participant Flow, and Adverse Events reporting. The record does not provide a full account of the analysis population rule or the impact of these participants on the primary estimate. The numerical IDFS results and further analysis-population details are not reported in the registry record.
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 |
|---|---|---|---|
| Chemo and Endocrine Therapy | 14 | 2062 | 0.7% |
| Endocrine Therapy Alone | 9 | 2342 | 0.4% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Chemo and Endocrine Therapy | 161 of 2487 |
| Endocrine Therapy Alone | 175 of 2497 |
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 |
|---|---|
| Chemo and Endocrine Therapy | 151 of 2062 |
| Endocrine Therapy Alone | 2 of 2342 |
Most frequent serious adverse event terms
| Event term | Organ system | Chemo and Endocrine Therapy | Endocrine Therapy Alone |
|---|---|---|---|
| Cardiac arrest | Cardiac disorders | 2 of 2062 | 2 of 2342 |
| Sepsis | Infections and infestations | 3 of 2062 | 0 of 2342 |
| Stroke | Nervous system disorders | 0 of 2062 | 3 of 2342 |
| Death NOS | General disorders | 1 of 2062 | 1 of 2342 |
| Thromboembolic event | Vascular disorders | 2 of 2062 | 0 of 2342 |
| Anemia | Blood and lymphatic system disorders | 1 of 2062 | 0 of 2342 |
| Gastrointestinal disorders-Other | Gastrointestinal disorders | 1 of 2062 | 0 of 2342 |
| Typhlitis | Gastrointestinal disorders | 1 of 2062 | 0 of 2342 |
| Upper gastrointestinal hemorrhage | Gastrointestinal disorders | 1 of 2062 | 0 of 2342 |
| Multi-organ failure | General disorders | 0 of 2062 | 1 of 2342 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Chemo and Endocrine Therapy | Endocrine Therapy Alone |
|---|---|---|---|
| Neutrophil count decreased | Investigations | 151 of 2062 | 2 of 2342 |
Serious events with the highest arm-level rate: sepsis (0.1%), stroke (0.1%), cardiac arrest (0.1%), thromboembolic event (0.1%), anemia (0.0%).
The adverse-event summary gives group-level counts for participants at risk, serious events affecting participants, other events affecting participants, and deaths. For the chemotherapy and endocrine therapy group, the record lists 2062 at risk, 14 affected by serious adverse events, 151 affected by other adverse events, and 161 deaths. For the endocrine therapy alone group, it lists 2342 at risk, 9 affected by serious adverse events, 2 affected by other adverse events, and 175 deaths. These are reported counts; no rates or adjusted comparisons are given.
The listed serious adverse-event terms include sepsis, stroke, cardiac arrest, and thromboembolic event, each reported as 0.1%. Anemia and gastrointestinal disorders-Other are each reported as 0.0%. These percentages are quoted as recorded and should not be read as a complete account of every safety outcome. The registry lists the primary safety-related outcome as the number of participants with grade 3 through 5 adverse events related to study drugs, but those results are not reported in the registry record.
The death counts are not identified as treatment-related deaths and should not be interpreted as such. The record does not give event timing, exposure duration, severity breakdown for all events, attribution procedures, or uncertainty around group comparisons. The differing counts at risk also mean that raw counts alone do not describe comparative risk. No percentages or ratios should be inferred from these counts without a defined analysis and appropriate data.
12. What the Result Does, and Does Not, Mean
The registry record describes a randomized phase III trial designed to compare two adjuvant treatment strategies in a defined breast cancer population. The primary endpoint is IDFS at 5 years after randomization, with a stated definition that includes invasive recurrence, a second invasive primary cancer, or death from any cause. These details explain what the trial set out to measure and what counts as an event.
They do not establish the direction or size of the treatment-group difference. The primary outcome estimates, confidence intervals, event counts, and numerical statistical comparison are not reported in the registry record. Thus, the relative IDFS experience of the randomized groups and the precision of any estimated difference cannot be evaluated from this record.
The trial's design is relevant to the question: participants were randomized to chemotherapy plus endocrine therapy or endocrine therapy alone, and the registry identifies a parallel, unmasked design. Randomization can support a comparison of assigned strategies in general, but interpretation also depends on the analysis population, follow-up, adherence, endpoint ascertainment, and missing-data handling. The record notes immediate consent withdrawals and post-analysis eligibility changes, but does not provide enough detail to establish their influence on the primary result.
The registry also lists secondary outcomes and adverse-event summaries. Those records should be distinguished from the primary IDFS outcome. The adverse-event counts are not adjusted comparisons, and deaths in the safety summary are not identified as treatment-related. The menopausal-status analyses are noted, but their numerical results and formal interaction assessment are not reported.
Accordingly, the available information supports a description of the trial question and its measurement framework, not a conclusion that one strategy produced a larger or smaller benefit. It also does not show whether an observed difference, if estimated in the trial, would be statistically precise or clinically important. Such judgments require the actual estimates, uncertainty, and analysis details, which are not reported in the registry record.
13. Why This Trial Matters Statistically
RxPONDER illustrates a common statistical challenge in clinical research: a treatment strategy can include several acceptable therapies, while the randomized contrast focuses on a particular addition to care. Here, endocrine options are listed in both groups, and the central comparison is chemotherapy plus endocrine therapy versus endocrine therapy alone. Keeping that contrast clear is essential when interpreting any eventual estimate.
The primary endpoint also demonstrates how endpoint definition shapes interpretation. IDFS includes invasive recurrence, a second invasive primary cancer, and death from any cause. Such a composite can represent more than one clinically important event, but a combined estimate does not identify which component contributes to the result. Separate outcomes such as overall survival and distant disease-free survival are listed, yet their numerical results are not reported in the registry record.
The record draws attention to subgroup and interim-analysis questions. It notes a third prespecified interim analysis, a recommendation for early reporting, and separate analyses by menopausal status. These features make the statistical plan, multiplicity approach, and uncertainty around subgroup estimates important. The relevant boundaries, adjustment procedures, and subgroup estimates are not reported in the registry record.
Finally, the record identifies differences in population accounting between the primary outcome and other reporting, including immediate consent withdrawals and eligibility changes identified after the primary analysis. Such details matter because the population included in an analysis affects what its estimate represents. This case therefore underscores that a well-defined randomized question is only one part of statistical interpretation: transparent outcome estimates, analysis populations, follow-up, and uncertainty are also necessary.
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 limitation for interpreting the trial's main question is that the registry record does not report numerical IDFS results. It gives the endpoint definition and says Kaplan-Meier estimates were calculated for the 5-year rate, but does not report group-specific estimates, confidence intervals, event counts, or a treatment contrast. This prevents assessment of effect direction, magnitude, and precision.
Analysis-population reporting requires care. The registry says 34 participants withdrew consent immediately after randomization, with 10 in the chemotherapy and endocrine therapy arm and 24 in the endocrine therapy arm. It also says eligibility changes for three participants were identified after the primary analysis, making the eligible and evaluable population different between the primary outcome and the Participant Flow and Adverse Events reporting. The full population definition and consequences for the estimates are not reported in the registry record.
The endpoint includes different event types and all-cause death. Without component-specific results, a composite estimate would not by itself show how much each component contributed. The record specifies censoring at last known contact for participants alive without recurrence or second primary cancer, but follow-up completeness, censoring counts, and sensitivity analyses are not reported.
The record identifies an interim analysis and early reporting recommendation, as well as menopausal-status analyses. It does not report interim decision boundaries, multiplicity procedures, detailed subgroup methods, or formal evidence that treatment effects differ by menopausal status. Masking is listed as none; outcome adjudication procedures are not reported. These omissions limit evaluation of potential analytic and ascertainment concerns, without establishing that any particular bias occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Tamoxifen Citrate, Letrozole, Anastrozole, or Exemestane With or Without Chemotherapy in Treating Patients With Invasive RxPONDER Breast Cancer — NCT01272037.
- Registry record last updated 2026-10-26; status last verified 2026-07.
- Results first posted 2023-06-27.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
RxPONDER is a randomized, parallel, unmasked phase III trial sponsored by the National Cancer Institute (NCI), with enrollment listed as 5018. It compares protocol-approved chemotherapy followed by endocrine therapy with endocrine therapy alone in patients described as having hormone receptor-positive, HER2-negative breast cancer, 1-3 positive nodes, and a recurrence score of 25 or less. The registry lists a start date of 2011-02-28, primary completion date of 2023-02-01, and status of active, not recruiting.
The primary endpoint is 5-year invasive disease-free survival, defined to include invasive recurrence, a second invasive primary cancer, or death from any cause. The record states that Kaplan-Meier estimates were calculated but does not report the numerical primary outcome results. It notes menopausal-status analyses, a third prespecified interim analysis, immediate consent withdrawals, and eligibility changes identified after the primary analysis. These details are relevant to interpretation, but further analysis methods and the primary estimates are not reported in the registry record.