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 Letrozole in Breast Cancer Who Have Received 5 Years of Aromatase Inhibitor Therapy (NCT00754845), a randomized phase 3 study. The primary outcome is Disease-free Survival (DFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00754845 |
| Phase | Phase 3 |
| Condition | Breast Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 1918 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Canadian Cancer Trials Group |
| Results posted | Yes |
2. Clinical Question
Population
Women with primary breast cancer who had completed 5 years of adjuvant aromatase inhibitor therapy, either as initial therapy or after tamoxifen; the official title also includes women who had been in the MA.17 study. The primary analysis included all randomized women according to their assigned treatment arm.
Intervention
Oral letrozole once daily for up to 5 years, unless unacceptable toxicity, disease recurrence, or a second malignancy occurred.
Comparator
Oral placebo once daily for up to 5 years, with the same stated conditions for stopping treatment.
Primary question
What was the probability of disease-free survival at 5 years in each randomized arm, and how did the time-to-event comparison between letrozole and placebo look during study follow-up?
The trial addressed a question about extending hormone therapy after an initial course of aromatase inhibitor treatment. Its registry rationale notes that estrogen can contribute to breast cancer cell growth and describes letrozole as hormone therapy that lowers the amount of estrogen the body makes. The clinical question was whether outcomes differed between continued letrozole and placebo in this treatment setting; the rationale itself does not establish the result.
The primary endpoint was disease-free survival (DFS). It counted recurrence of the primary disease, including recurrence in the breast, chest wall, or nodal sites, metastatic disease, and contralateral breast cancer. The registry also reports secondary outcomes concerning contralateral breast cancer, overall survival, and change in role function on the physical scale of the SF-36 health survey. Results for the different outcomes need to be interpreted according to their distinct definitions and follow-up periods rather than treated as interchangeable measures of one effect.
3. Trial Design
This was a randomized, phase III, parallel-group trial with triple masking. The registry lists 1,918 participants and identifies the Canadian Cancer Trials Group as sponsor. It records the study as completed. The recorded start date is 2004-11-23, and the primary completion date is 2015-12-21. The masking label is triple, but which groups or roles were masked is not reported in the registry record.
Participants were assigned to letrozole or placebo. The registry lists 959 participants in each primary-outcome arm. The treatment descriptions specify oral treatment once daily for up to 5 years, ending earlier in the event of unacceptable toxicity, disease recurrence, or development of a second malignancy. The registry does not report additional details about allocation concealment, stratification, or the sequence-generation procedure.
The population described in the official title comprised women previously diagnosed with primary breast cancer who had completed 5 years of adjuvant aromatase inhibitor therapy, either as initial therapy or after tamoxifen. The title also explicitly includes those in the MA.17 study. Further eligibility criteria and the numbers enrolled from any particular prior-treatment subgroup are not reported in the registry record.
The primary endpoint was assessed as the probability of DFS at 5 years. The recorded timeframe describes assessment until the end of study with a median follow-up of 75 months. The reported primary analysis used a log-rank method to compare the arms and expressed the comparison as a hazard ratio. The registry states that all randomized women were included in the primary analysis based on the arm to which they were randomized. Detailed information about endpoint adjudication, analysis populations for secondary outcomes, or planned interim analyses is not reported in the registry record.
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 | Letrozole | Placebo |
|---|---|---|
| STARTED | 959 | 959 |
| COMPLETED | 959 | 959 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: All women randomized were included in the analysis based on treatment arm they were randomized.
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 | Letrozole | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 959 | 959 | 1918 | |
| Age, Continuous | years | 65.6 (43 to 92.2) | 64.8 (43.4 to 89.9) | 65.1 (43 to 92.2) |
| Sex: Female, Male: Female | Participants | 959 | 959 | 1918 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 11 | 13 | 24 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 940 | 939 | 1879 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 8 | 7 | 15 |
| Region of Enrollment: Canada | Participants | 276 | 285 | 561 |
| Region of Enrollment: United States | Participants | 683 | 674 | 1357 |
| ECOG Performance Status: Grade 0 | Participants | 852 | 856 | 1708 |
| ECOG Performance Status: Grade 1 | Participants | 100 | 95 | 195 |
| ECOG Performance Status: Grade 2 | Participants | 7 | 8 | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Disease-free Survival (DFS), measured over Unitil the end of study with a median follow up of 75 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | probability of DFS at 5 years |
| Endpoint classification | not reduced to a single comparison |
Disease-free survival measures the time from randomization until the first qualifying event. In this trial, the qualifying events were recurrence of the primary disease in the breast, chest wall, or nodal sites; development of metastatic disease; or contralateral breast cancer. The registry reports the estimated probability of remaining free of these events at 5 years.
The event definition also specifies how observations without a recorded event were handled. A participant who died without a recorded recurrence or contralateral breast cancer was censored at the date of death. A participant who had not experienced a qualifying event or died was censored at the last date known to be alive. Censoring means that the participant contributes information up to the stated date, without being counted as having experienced the endpoint event. The registry does not provide further details about how censoring was assessed or whether any sensitivity analyses addressed it.
General: A time-to-event endpoint uses both whether an event occurred and when it occurred. It can make use of follow-up that varies among participants, provided that censoring is handled and interpreted appropriately. The estimated probability at a specified time gives an absolute description of event-free status, while a hazard ratio summarizes a relative comparison of event rates over follow-up under the model and analysis used. Neither quantity alone describes every feature of the event-time distributions.
DFS is used in this trial because the question concerns recurrence and new contralateral breast cancer after prior treatment. It is not the same outcome as overall survival: deaths without a qualifying disease event were censored for DFS under the registry definition. The endpoint therefore addresses disease events rather than counting every death as a DFS event.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted 5-year DFS probability was 0.95 for letrozole, with a 95% confidence interval from 0.93 to 0.96. For placebo, it was 0.91, with a 95% confidence interval from 0.89 to 0.93. These estimates describe each arm separately. Their confidence intervals express uncertainty around the arm-specific estimates; they are not, by themselves, a formal test of the between-arm comparison.
The registry reports a log-rank comparison with a hazard ratio of 0.66 and a 95% confidence interval from 0.48 to 0.91, with p = 0.01. The point estimate is below 1, indicating a lower estimated hazard of a DFS event in the letrozole arm under this comparison. The confidence interval does not include 1, and the reported p-value is consistent with evidence of a between-arm difference under the analysis used. These statistics describe the posted trial results; they do not establish how the result applies to every patient or setting.
Precision should be considered alongside the point estimate. The confidence interval for the hazard ratio includes values corresponding to different magnitudes of relative effect, so the estimate is not exact. The confidence intervals around the arm-specific 5-year probabilities also show that those probabilities are estimates rather than known quantities. The registry reports a median follow-up of 75 months, while the endpoint is expressed at 5 years; the number of participants contributing information at each time point is not reported in the registry record.
The probability estimates and hazard ratio answer related but distinct questions. The probabilities describe estimated DFS at a fixed time in each arm. The hazard ratio is a relative time-to-event comparison over the analysis period. It should not be translated directly into an absolute change in the probability of DFS or treated as a guarantee that the relative contrast was identical at every point in follow-up. The registry does not report a proportional-hazards assessment or other details that would clarify how the hazard ratio should be interpreted if hazards varied over time.
Overall, the primary result is a reported difference in DFS between randomized arms, with the point estimate favoring letrozole on the relative hazard scale and higher posted 5-year DFS probability in that arm. The record does not include a complete protocol or statistical analysis plan, and it does not report details such as subgroup results, interim monitoring, or sensitivity analyses. Those omissions limit what can be concluded about robustness beyond the posted primary analysis.
9. Statistical Methods Explained
Several statistical quantities describe different aspects of the trial results. Reading them together helps distinguish estimated outcomes in each arm from the formal comparison between arms.
What does a confidence interval express?
General: A confidence interval describes the uncertainty associated with an estimate under the statistical method used. A narrower interval indicates greater precision on the scale being reported, while a wider interval indicates less precision. A 95% confidence interval is not a statement that a particular realized interval has a 95% probability of containing the true value. Rather, the confidence level refers to the long-run behavior of the procedure under its assumptions.
For DFS, the registry gives 95% confidence intervals for both arm-specific probabilities and the hazard ratio. The interval for an arm-specific probability describes uncertainty in that arm’s estimated probability. The interval for the hazard ratio describes uncertainty in the relative comparison. Whether an interval includes a particular reference value can inform interpretation, but it should not replace attention to the estimate, the interval’s width, and the endpoint definition.
How do the probability and hazard ratio differ?
General: A probability at a fixed time is an absolute measure. A hazard ratio is relative and compares event hazards over follow-up according to the specified time-to-event analysis. The log-rank test is commonly used to compare time-to-event experience between groups, and the registry identifies a log-rank method for the primary comparison. The hazard ratio should not be read as a difference in probabilities or as a direct description of how many participants experienced an event. The registry does not report the event counts for the primary endpoint.
The endpoint’s censoring rules matter because some participants may not have a recorded qualifying event during their observed follow-up. The registry states that deaths without recurrence or contralateral breast cancer were censored at death, and participants without an event or death were censored at their last known date alive. General: Time-to-event methods rely on assumptions about the censoring process. The registry does not report diagnostic checks or sensitivity analyses for those assumptions.
What do the secondary comparisons contribute?
The contralateral breast cancer outcome is reported as a rate per 1,000 person years, with arm-specific 95% confidence intervals. A recalculated rate ratio is also available, based on posted summary statistics, together with an unadjusted p-value. General: A rate accounts for the amount of observed person-time, while a rate ratio compares rates between groups. A Poisson-based calculation can be a useful approximation for event rates, but its validity depends on assumptions about event generation and the available summary data. It does not replace the sponsor’s analysis or make a comparison adjusted for other variables.
The registry reports an 8-year role-function outcome as least-squares mean change with standard errors, and a mixed-model analysis with a reported p-value. A separate unadjusted recalculation is based on summary statistics and uses an approximate pooled standard deviation. General: A standard error describes uncertainty in an estimated mean, whereas a standard deviation describes variation among individual measurements. They are not interchangeable. Reconstructing variation from summary values is an approximation and may not reproduce a model that accounts for repeated observations, covariates, or a particular missing-data structure. Such model details are not reported in the registry record.
What are the planning illustrations?
The planning illustrations use the observed effect as a reference and show scenarios for detecting 100%, 75%, or 50% of that effect. The stated assumptions are a two-sided significance level of 0.05, equal allocation, and a normal approximation. For time-to-event outcomes, the illustration reports total events; for other outcomes, it reports participants per arm. These are planning calculations based on the observed effect, not the trial’s own design justification, and they are not observed power. The registry does not report the trial’s original sample-size assumptions or justification.
General: Planning calculations are conditional on the effect size, variability, allocation, analysis, and significance threshold assumed. Smaller effects generally require more information to detect with a given design, while the actual requirements depend on the endpoint and its data structure. A planning illustration cannot show whether a completed study had a particular probability of detecting its true effect, nor can it establish the effect that would be found in another study.
The recalculated comparisons are explicitly unadjusted and derive from posted summary statistics. They should therefore be read as supplementary calculations, not as substitutes for the reported trial analyses. For the primary endpoint, the registry reports a sponsor analysis but no recalculated comparison. For secondary outcomes, the sponsor’s named analysis methods and p-values remain distinct from the simpler recalculations, which do not reproduce all potentially relevant features of the original models.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Log Rank | Hazard Ratio (HR) 0.66 | 0.48 to 0.91 | 0.010 |
The registry’s primary result is the sponsor-reported log-rank comparison: hazard ratio 0.66, 95% confidence interval 0.48 to 0.91, and p = 0.01. No separate recalculated primary comparison is reported in the registry record. The arm-specific 5-year probabilities and their confidence intervals are also posted, but they are not themselves a recalculation of the sponsor’s time-to-event analysis.
For the secondary outcomes, the registry identifies a log-rank method for contralateral breast cancer and a mixed-model analysis for role function. It reports p = 0.007 for the former and p < 0.01 for the latter. The supplementary recalculations use posted summary statistics and are unadjusted. For contralateral breast cancer, the recalculated rate ratio is 0.429, with a 95% confidence interval from 0.215 to 0.854 and p = 0.016. For role function, the recalculated mean difference is -1.46, with a confidence interval from -4.467 to 1.547 and p = 0.341. These do not replicate the sponsor’s analysis methods.
The recalculations are useful as transparent checks based on summary information, but they may not capture the sponsor’s model specifications or analysis data. The registry does not report enough detail to determine why the secondary p-values differ. The reported analysis and the recalculation should therefore be understood as distinct statistical results, not silently substituted for one another.
11. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary endpoint and lists secondary outcomes, but a multiplicity plan is not reported in the registry record. It is therefore unclear whether the trial controlled the family-wise error rate across secondary outcomes, prioritized a defined subset, or treated them as exploratory. A nominal p-value for a secondary outcome should not automatically be interpreted as confirmatory evidence when the number and hierarchy of planned tests are unknown.
The primary analysis population is described: all randomized women were included according to the treatment arm to which they were randomized. This description supports interpreting the primary result as based on randomized assignment rather than treatment received. The registry does not report corresponding population details for each secondary analysis, the number of participants with available measurements, or whether analysis populations differed across outcomes.
For DFS, the registry specifies censoring for deaths without a qualifying disease event and for participants with no event who were last known alive. This explains the endpoint’s event and censoring definitions, but does not describe missing-data procedures for other outcomes. The role-function result is a change from baseline with an 8-year timeframe; the amount and pattern of missing questionnaire data, the number assessed at each time, and any imputation or sensitivity analyses are not reported in the registry record. The registry likewise does not describe missing-data handling for the secondary rate outcome.
General: Missing outcome data can affect precision and can also introduce bias if the chance of having an observed measurement is related to outcome status. Censoring in a time-to-event analysis is not identical to ordinary missingness, and its interpretation depends on assumptions about participants’ event experience after their last observed time. The registry’s stated censoring rules clarify what was done at the endpoint-definition level, but they do not establish whether those assumptions were examined.
Details of interim analyses, stopping rules, protocol amendments, and the full statistical analysis plan are not reported in the registry record. Their absence means that the public record does not establish whether analyses or decision rules were specified before outcomes were examined. This is a limit on what can be assessed from the registry entry, not evidence that such procedures were or were not used.
12. 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 |
|---|---|---|---|
| Arm I | 15 | 959 | 1.6% |
| Arm II | 19 | 954 | 2.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Arm I | 100 of 959 |
| Arm II | 100 of 954 |
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 |
|---|---|
| Arm I | 863 of 959 |
| Arm II | 841 of 954 |
Most frequent serious adverse event terms
| Event term | Organ system | Arm I | Arm II |
|---|---|---|---|
| Second malignacy | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 3 of 959 | 3 of 954 |
| Cardiac-ischemia/infarction | Cardiac disorders | 2 of 959 | 4 of 954 |
| Renal failure | Renal and urinary disorders | 3 of 959 | 2 of 954 |
| Infection without neutropenia | Infections and infestations | 2 of 959 | 3 of 954 |
| Sudden death | General disorders | 4 of 959 | 1 of 954 |
| CNS cerebrovascular ischemia | Nervous system disorders | 0 of 959 | 3 of 954 |
| Hypoxia | Respiratory, thoracic and mediastinal disorders | 1 of 959 | 1 of 954 |
| Pulmonary - Other | Respiratory, thoracic and mediastinal disorders | 0 of 959 | 2 of 954 |
| Ventricular arrhythmia (PVCs/bigeminy/trigeminy/ ventricular tachycardia) | Cardiac disorders | 1 of 959 | 1 of 954 |
| Cardiac left ventricular function | Cardiac disorders | 1 of 959 | 1 of 954 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Arm I | Arm II |
|---|---|---|---|
| Arthralgia | General disorders | 513 of 959 | 475 of 954 |
| Hot flashes/ flushes | Endocrine disorders | 360 of 959 | 354 of 954 |
| Fatigue | General disorders | 346 of 959 | 355 of 954 |
| Arthritis | Musculoskeletal and connective tissue disorders | 317 of 959 | 288 of 954 |
| Insomnia | Nervous system disorders | 269 of 959 | 243 of 954 |
| Myalgia | General disorders | 268 of 959 | 240 of 954 |
| Hypercholesterolemia | Metabolism and nutrition disorders | 203 of 959 | 184 of 954 |
| Sweating | General disorders | 176 of 959 | 175 of 954 |
| Dyspnea | Respiratory, thoracic and mediastinal disorders | 148 of 959 | 165 of 954 |
| Bone pain | General disorders | 174 of 959 | 133 of 954 |
Serious events with the highest arm-level rate: cardiac-ischemia/infarction (0.4%), sudden death (0.4%), infection without neutropenia (0.3%), cns cerebrovascular ischemia (0.3%), second malignacy (0.3%).
The safety figures are reported under the labels Arm I and Arm II, with 959 and 954 participants at risk, respectively, for the serious-event counts. Serious adverse events affected 15 participants in Arm I and 19 in Arm II. Other adverse events affected 863 participants in Arm I and 841 in Arm II. The record also lists 100 deaths in each arm. The safety labels do not identify the interventions in this summary, so these counts should not be assigned to letrozole or placebo based on the arm names alone.
The registry lists cardiac-ischemia/infarction and sudden death at 0.4% each among the most frequent serious terms, followed by infection without neutropenia and CNS cerebrovascular ischemia at 0.3% each, second malignacy at 0.3%, and renal failure at 0.3%. The record does not give arm-specific percentages for these terms in the posted summary.
These figures are descriptive counts, not adjusted comparisons of safety risk. The registry does not report exposure-adjusted rates, event timing, seriousness criteria, attribution to treatment, or whether events were collected for the same duration in each arm. The counts alone cannot establish that treatment caused an event or support a complete comparison of safety between interventions.
13. What the Result Does, and Does Not, Mean
The primary result is evidence from a randomized comparison of letrozole and placebo in women who had completed 5 years of adjuvant aromatase inhibitor therapy. The posted arm-specific estimates show the probability of DFS at 5 years, and the reported log-rank analysis summarizes the time-to-event comparison. The estimated hazard ratio is below 1, with a confidence interval that does not include 1, and the registry reports p = 0.01. These are statistical descriptions of the recorded trial analysis.
They do not mean that every participant had the same experience, that a future population would have identical outcomes, or that the estimated effect is known without uncertainty. A confidence interval allows for a range of values under the method used, and the median follow-up of 75 months does not mean that every participant was observed for that length of time. The registry does not report the number at risk at individual times or detailed event counts for DFS.
The result also does not establish the effects of treatment outside the population and treatment history described in the record. The trial concerns women with primary breast cancer who had completed 5 years of adjuvant aromatase inhibitor treatment, including the pathways specified in the official title. Eligibility details beyond that description and results for particular subgroups are not reported in the registry record.
DFS is not overall survival. Under the trial’s endpoint definition, deaths without recurrence or contralateral breast cancer were censored rather than counted as DFS events. The presence of a separate overall-survival outcome in the registry does not provide its result; that result is not reported in the registry record. The primary finding therefore should not be extended to claims about overall survival.
Finally, statistical significance does not by itself describe clinical importance. The registry does not report a threshold for a clinically meaningful difference in DFS, and the statistical result cannot answer that question on its own. The primary analysis provides a relative time-to-event estimate and arm-specific probabilities, each with uncertainty; interpretation should keep those quantities, the endpoint definition, and the trial population in view.
14. Why This Trial Matters Statistically
This trial illustrates why it is useful to distinguish an endpoint’s absolute estimates from its relative comparison. The reported 5-year DFS probabilities describe each randomized arm, while the hazard ratio summarizes the log-rank time-to-event comparison. These measures complement one another, but they are not interchangeable. Reading both helps prevent a relative estimate from being mistaken for an absolute probability difference.
It also demonstrates the importance of endpoint definitions. DFS in this record includes recurrence, metastatic disease, and contralateral breast cancer, while deaths without those events are censored. That definition determines what the primary result means. A separate outcome such as overall survival addresses a different question, and the registry does not report its result.
The trial also shows why sponsor analyses and summary-statistic recalculations should be kept distinct. The sponsor’s named methods and reported p-values arise from the registered analyses. The recalculated secondary comparisons are unadjusted illustrations based on posted summary information and do not reproduce every feature of the original methods. Similar-looking quantities can differ because they answer questions under different assumptions or models; the registry does not report enough detail to identify the reasons for the secondary differences.
Finally, the record highlights the role of uncertainty and reporting completeness. Confidence intervals qualify point estimates, while missing information about multiplicity, missing-data handling, interim monitoring, and the original sample-size justification limits methodological appraisal. Planning illustrations based on observed effects can help readers understand design sensitivity, but they are not evidence of the power of the completed trial. Statistical interpretation depends not only on the estimated result, but also on what was measured, how it was analyzed, and what is not documented.
15. 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 registry record does not report the full protocol or statistical analysis plan. Details of random-sequence generation, allocation concealment, stratification, the roles included in triple masking, interim analyses, and stopping rules are not reported. This limits assessment of design and analysis safeguards beyond the labels and methods stated in the record.
The primary outcome is described with explicit censoring rules, but the record does not provide primary DFS event counts, numbers at risk over time, or sensitivity analyses for censoring assumptions. The median follow-up is 75 months, while the primary result is expressed at 5 years; individual follow-up distribution and precision at the endpoint time are not reported. The registry also does not report a proportional-hazards assessment or related analyses for the hazard ratio.
Secondary outcomes have different timeframes, including 10 years for contralateral breast cancer and 8 years for role function. The registry does not report the outcome-specific numbers observed at those times, missing questionnaire-data patterns, or detailed handling of missing measurements. It also lists overall survival as a secondary outcome without reporting its result. Multiplicity adjustment and the hierarchy among secondary outcomes are not reported.
The safety record gives counts and selected serious-event terms, but does not report exposure-adjusted rates, treatment attribution, event timing, or arm-specific percentages for the listed terms. The safety groups are labeled Arm I and Arm II in the summary, without mapping those labels to the named interventions there.
Planning illustrations use the observed effects and stated assumptions; the original sample-size justification is not reported. As with any calculation based on posted summary statistics, recalculated comparisons may not reproduce model details or analysis data used by the sponsor. These limitations concern what can be evaluated from the registry record and should not be taken as evidence that unreported procedures were absent.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Letrozole in Breast Cancer Who Have Received 5 Years of Aromatase Inhibitor Therapy — NCT00754845.
- Registry record last updated 2023-08-25; status last verified 2020-04.
- Results first posted 2018-11-19.
- 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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19. Record Summary
NCT00754845 is a completed randomized phase III parallel-group study sponsored by the Canadian Cancer Trials Group. It compared letrozole with placebo in women who had completed 5 years of adjuvant aromatase inhibitor therapy. The registry describes triple masking and lists 1,918 participants.
The primary endpoint was the estimated probability of DFS at 5 years. The registry reports arm-specific estimates and a log-rank comparison with a hazard ratio of 0.66, a 95% confidence interval from 0.48 to 0.91, and p = 0.01. The secondary outcomes include contralateral breast cancer, overall survival, and SF-36 physical role function; results for overall survival are not reported in the registry record.
The posted record gives some outcome definitions, follow-up timeframes, and analysis methods, but does not report multiplicity procedures, detailed missing-data handling, interim analyses, or the original sample-size justification. Secondary recalculations are unadjusted and should be distinguished from the sponsor’s named analyses.