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 Melatonin Postoperative Sleep Study in Breast Cancer Patients (NCT00506064), a randomized phase 1 study. The primary outcome is Objective Sleep Response of Patients.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00506064 |
| Phase | Phase 1 |
| Condition | Breast Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 4 |
| Arms in the primary outcome | n/a |
| Lead sponsor | M.D. Anderson Cancer Center |
| Results posted | Yes |
2. Clinical Question
Population
Older breast cancer patients undergoing unilateral segmental mastectomy, with or without intraoperative lymph node mapping, sentinel node biopsy and axillary node dissection. The registry record gives total enrollment as 4, and states that an adequate number of cases with data could not be accrued for analysis.
Intervention
Daily oral melatonin capsules at 0.15 mg/kg. The study objective was to assess postoperative nocturnal melatonin supplementation during the period after anesthesia and surgery.
Comparator
Daily oral starch capsules as placebo. The trial is described as randomized, double-masked and parallel, although the registry record does not report further details about sequence generation, concealment or masking procedures.
Primary question
Whether postoperative melatonin was associated with changes in objective sleep-related measurements and the early regulation of the sleep-wake cycle during the first postoperative week. The stated clinical objectives also included subjective sleep quality and cardiopulmonary events. The registry record reports no primary outcome analysis, so it does not provide an estimated treatment contrast or its precision.
The primary outcome description identifies wrist actigraphy, which measures movement during sleep, and an SpO2 monitor, which measures the percentage of oxy-hemoglobin in the blood. The planned longitudinal observation covered day 0, the day of operation, and days 1-6 post-operative. A secondary objective was to collect data and validate the Postoperative Srejic Sleep SAT Survey Questionnaire. SAT scores represent relative subjective satisfaction with sleep on a scale out of 100, with 100 described as the highest degree of satisfaction. The registry record does not report a completed validation analysis or questionnaire results.
3. Trial Design
The registry record describes a phase 1, randomized, double-masked, parallel trial sponsored by M.D. Anderson Cancer Center. It lists breast cancer as the condition and enrollment of 4. The study status is terminated. The recorded start is 2004-02, and primary completion is recorded as 2008-09. These dates and status describe the registry entry; they do not establish why the study ended or how long individual participants were followed.
Two drug arms are described. Participants assigned to the melatonin arm received 0.15 mg/kg capsules by mouth daily; participants assigned to the placebo arm received starch capsules by mouth daily. A questionnaire is also listed as a behavioral intervention. The registry record does not describe the daily dosing time, the precise treatment duration, adherence monitoring, or procedures used to implement randomization and masking. Those details are not reported in the registry record.
The target population was older breast cancer patients receiving unilateral segmental mastectomy, with or without the listed lymph node procedures. The stated primary objective focused on postoperative sleep-wake regulation during the first postoperative week after anesthesia and surgery. The primary outcome timeframe describes major measurements on day 0 and days 1-6 post-operative. The registry record does not give a more detailed schedule for each measurement or explain how readings from different days would be combined in an analysis.
The registry entry says that an adequate number of cases with data could not be accrued and that analysis could not be provided. It therefore offers a design description and objectives, but not an analyzed randomized comparison. The reason for termination, intended enrollment target, sample-size justification, and any changes to the original design are 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.
Before assignment: Protocol terminated early as unable to accrue cases. There were four patients accrued of which three were not assigned, therefore data available for only one case.
Overall Study
| Stage | Melatonin | Placebo |
|---|---|---|
| STARTED | 1 | 0 |
| COMPLETED | 1 | 0 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Since unable to accrue an adequate number of cases with data, unable to provide analysis.
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 | Melatonin | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 1 | 0 | 1 | |
| Age Categorical: <=18 years | years | 0 | — | 0 |
| Age Categorical: Between 18 and 65 years | years | 1 | — | 1 |
| Age Categorical: >=65 years | years | 0 | — | 0 |
| Gender: Female | participants | 1 | — | 1 |
| Gender: Male | participants | 0 | — | 0 |
| Region of Enrollment: United States | participants | 1 | — | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Objective Sleep Response of Patients, measured over Longitudinal study with major responses measured on days 0 (day of operation) and days 1-6 post-operative.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled Objective Sleep Response of Patients. It is described as a longitudinal assessment using wrist actigraphy to measure sleep movement and an SpO2 monitor to measure the percentage of oxy-hemoglobin in the blood. Major responses were to be measured on day 0, the day of operation, and days 1-6 post-operative. These measures address different aspects of postoperative observation: actigraphy records movement associated with sleep, while oxygen monitoring records a physiological measure over the observation period.
As a general statistical point, repeated measurements can describe how a response changes over time, rather than reducing the question to a single reading. A treatment comparison in such a setting might concern a difference in the level or pattern of measurements between randomized groups. The registry record does not specify the planned summary measure, model, contrast, handling of repeated observations, or decision rule. It also does not report analyzed endpoint values. The registry states that there were too few cases with data to provide an analysis, so there is no reported estimate of the melatonin-placebo difference or its uncertainty.
The stated broader clinical objective included subjective improvement in sleep quality and reduction of cardiopulmonary events, while the secondary objective concerned collecting data and validating the Postoperative Srejic Sleep SAT Survey Questionnaire. These objectives provide context for why sleep and oxygen-related monitoring were selected. They do not constitute reported endpoint results. The SAT survey's described scale runs to 100, with 100 indicating the highest degree of subjective sleep satisfaction, but no scores or validation findings are reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The main statistical feature of this registry record is the absence of a primary outcome analysis. Although the study is described as randomized and provides a defined objective sleep measurement approach, the record states that an adequate number of cases with data could not be accrued. It therefore reports no treatment-effect estimate for objective sleep response. There is no reported contrast between melatonin and placebo, no uncertainty interval, and no outcome-specific significance test. The posted information cannot establish the size, direction or precision of a treatment difference.
Enrollment was 4, but enrollment alone does not indicate how many participants contributed usable outcome data, how participants were distributed between the two arms, or whether the measurements were complete. The registry record explicitly says that analysis was not possible because there were too few cases with data. It does not provide participant-level flow, reasons for missing measurements, or summaries by arm. Consequently, neither the planned longitudinal question nor the subjective and cardiopulmonary objectives can be evaluated from reported outcome estimates.
The record identifies the intended measurement schedule as day 0 and days 1-6 post-operative, but it does not state how repeated observations were to be analyzed. General statistical context: repeated measurements from the same participant are related, so treating every reading as if it came from a different participant can overstate the amount of independent information. Methods for longitudinal data account for within-participant dependence, but the analysis method intended for this trial is not reported in the registry record. With no reported analysis, there is no basis to infer which approach was used.
The safety entries are also sparse. The melatonin group lists 1 participant at risk for serious adverse events and 0 affected; it also lists 1 at risk for other adverse events and 0 affected. The placebo group lists 0 at risk and 0 affected for both serious and other adverse events. The record does not report death counts, and no top serious adverse event terms are listed. These entries are counts in a very small and incomplete record, not a basis for comparing safety between groups.
The registry status is terminated, but the reason for termination is not reported in the registry record. The record also does not report a sample-size justification, interim analyses, a statistical analysis plan, or completed secondary analyses. The stated planning assumptions for sample-size illustrations do not replace results or demonstrate that the study had a particular probability of detecting an effect. Any such illustration is a planning calculation, not observed evidence from this trial.
9. Statistical Methods Explained
Randomization is a general method for assigning participants to study groups by chance. Its purpose is to reduce systematic differences between groups at assignment, so that an outcome comparison can be interpreted as a randomized comparison. The registry record labels this trial randomized, but does not describe sequence generation, allocation concealment, randomization blocks, or stratification. Those implementation details are not reported in the registry record. With enrollment of 4 and no primary analysis, the record does not show whether the groups were balanced on participant characteristics.
Double masking is a design label indicating that masking was intended for two parties, but the registry record does not identify which parties or explain how masking was maintained. The use of starch capsules as placebo suggests a comparator intervention, but the record does not describe whether the capsules were matched in appearance or how treatment assignment was protected. It is not possible to infer masking success from the design label alone. The record also does not report whether masking was assessed.
The outcome is longitudinal because measurements were planned over multiple postoperative days. General statistical explanation: observations made on the same person often share characteristics and are statistically dependent. A longitudinal analysis should account for this dependence; otherwise, uncertainty can be understated if repeated readings are treated as independent observations. Common general approaches include models that represent within-person correlation or summaries that first reduce repeated observations to a participant-level measure. The registry record does not identify a chosen method, define a summary across days, or say whether actigraphy and SpO2 were to be analyzed separately or jointly.
Actigraphy and SpO2 are distinct measures, and a clear analysis plan would ordinarily specify how each is represented. For example, it would be important to define what constitutes a sleep-related response from movement data, and how readings over time are summarized for oxygen monitoring. This is general methodological context, not a description of the trial's actual analysis plan. The registry record gives the instruments and broad timeframe, but no endpoint algorithm, scale, threshold, or planned treatment contrast. It does not report outcome data from which any such measure could be reconstructed.
A confidence interval is a general statistical way to express uncertainty around an estimated treatment contrast. Its width reflects both the variability of the data and the amount of information available; a wide interval indicates imprecise estimation. A significance test addresses compatibility between data and a specified null hypothesis under the assumptions of the test, but a p-value alone does not give the size or clinical importance of an effect. In this trial, no primary effect estimate, confidence interval or p-value is reported. Thus, neither the direction nor the precision of a primary comparison can be assessed.
The registry record includes assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation between arms, a normal approximation, and a target effect expressed as a fraction of the observed effect. These are described as planning assumptions, not as the trial's own design justification. No sample-size justification is reported in the registry record. A planning illustration, when available, estimates the number of participants per arm under specified assumptions; it is not an observed result and is not observed power. No specific sample-size illustration values are stated in the registry record.
General statistical context: power is the probability that a planned test will reject a null hypothesis under a particular assumed effect and set of conditions. A calculation based on an observed effect can be especially unstable when the observed estimate comes from sparse data. It should not be interpreted as evidence that a completed study was capable of detecting a clinically important difference. The record's lack of analyzable outcome data means that it does not establish an observed effect on which to base an interpretation of the treatment contrast.
Over-dispersion is a general issue for count outcomes when observed variability exceeds what a simple probability model assumes. If cardiopulmonary events had been analyzed as counts, an appropriate method might need to account for such variability, depending on the data and outcome definition. The registry record does not report event counts for the primary clinical objective, a count model, or any finding of over-dispersion. This concept therefore explains a possible methodological consideration, not a trial result or documented analysis decision.
Missing data are particularly consequential in a study where the registry explicitly notes insufficient cases with data. General statistical explanation: missing measurements can reduce precision, and may also bias an estimate if missingness is related to outcomes or treatment. Evaluating that possibility requires information about who was missing data, when, and why. The registry record does not give those details, nor does it describe an imputation method, a complete-case approach, or sensitivity analyses. No assumption about the missingness mechanism can be justified from the record.
The study's stated secondary objective was to collect data and validate the Postoperative Srejic Sleep SAT Survey Questionnaire. General measurement validation can involve assessing whether a questionnaire produces scores that are interpretable and suitable for its intended purpose. The record describes SAT as relative subjective sleep satisfaction on a scale out of 100, with 100 the highest degree of satisfaction, but does not report validation criteria or results. It is not possible to conclude from the stated objective alone that validation was completed.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary objective involving early sleep-wake regulation, subjective sleep quality and cardiopulmonary events, and identifies objective responses measured by actigraphy and an SpO2 monitor. It also describes a secondary objective to collect data and validate the Postoperative Srejic Sleep SAT Survey Questionnaire. Several measurement types and postoperative time points can create multiple possible comparisons. General statistical context: when many hypotheses are tested, the chance of at least one apparently unusual result can increase unless the analysis plan accounts for multiplicity or clearly identifies a primary comparison. The registry record does not report a multiplicity strategy, a hierarchy of tests, or a distinction among confirmatory and exploratory comparisons.
The record identifies day 0 and days 1-6 post-operative as major measurement times, but does not specify whether each day was a separate endpoint, whether an overall summary was intended, or how multiple outcomes were to be handled together. These planned details are not reported in the registry record. No analysis results are available to assess whether multiplicity affected interpretation.
The record states that an adequate number of cases with data could not be accrued and that analysis could not be provided. It does not report how many measurements were missing, whether missingness differed by arm or time, why data were unavailable, or which participants were included in any analysis population. It also does not report an intention-to-treat population, a per-protocol population, or rules for inclusion. Therefore, the available record cannot establish how missing data or analysis populations were handled.
General statistical context: complete-case analysis can exclude participants with any missing outcome, while imputation or likelihood-based approaches use explicit assumptions about missingness. Each approach has limitations, and sensitivity analyses can explore how conclusions might change under alternative assumptions. None of these methods is identified as having been used in this study. The reason for termination and any interim analyses 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 |
|---|---|---|---|
| Melatonin | 0 | 1 | 0.0% |
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 |
|---|---|
| Melatonin | 0 of 1 |
| Placebo | 0 of 0 |
The adverse-event entries should be read as sparse registry counts, not as comparative rates or a complete safety evaluation. In the melatonin group, the record lists 1 participant at risk for serious adverse events and 0 affected. It lists 1 at risk for other adverse events and 0 affected. In the placebo group, it lists 0 at risk and 0 affected for serious adverse events, and 0 at risk and 0 affected for other adverse events. The registry record lists no top serious adverse event terms.
The listed at-risk counts are not equal across arms, and the placebo arm has no participants listed at risk in these entries. The record also reports total enrollment of 4 and states that adequate cases with data were not accrued. These details prevent meaningful group-level safety comparisons. Zero affected in a small or empty recorded group does not establish absence of risk, and these entries should not be interpreted as evidence that one arm is safer.
Death counts are null in the registry entries, not reported as zero. The record does not provide further information about adverse-event collection, event timing, severity grading, relatedness, or follow-up. The safety information is therefore limited to the counts recorded and does not support conclusions beyond those descriptive entries.
12. What the Result Does, and Does Not, Mean
The registry record documents a randomized, double-masked study intended to examine postoperative melatonin and sleep-related outcomes in older breast cancer patients undergoing unilateral segmental mastectomy. It identifies daily melatonin at 0.15 mg/kg and daily starch capsules as the placebo comparator, and describes objective monitoring with wrist actigraphy and an SpO2 monitor. It also states a secondary questionnaire-validation objective. These registry entries describe the study's aims and design, not evidence that the intervention changed sleep or clinical outcomes.
The key result is that the primary outcome was not analyzed because an adequate number of cases with data could not be accrued. No treatment contrast or uncertainty estimate is reported. As a result, the registry record does not show whether objective sleep responses differed between arms, how large any difference might have been, or how precisely a difference could be estimated. It also does not report findings for subjective sleep quality, cardiopulmonary events, or questionnaire validation.
This lack of an analysis is not evidence that the treatments were equivalent, nor does it establish that either treatment improved or worsened an outcome. Equivalence or absence of a meaningful difference would require an appropriate analysis with a prespecified margin and sufficiently precise estimates; such information is not reported in the registry record. Likewise, the absence of a reported adverse event in a small and incomplete record cannot establish safety.
The enrollment figure, the termination status and the absence of analyzable results place strong limits on interpretation. The record does not explain why recruitment or data accrual was inadequate, why the study was terminated, or whether any unreported analyses were conducted. The appropriate reading is therefore descriptive: the trial posed a clinically focused sleep question and specified measurement tools, but the posted record does not provide outcome evidence to answer that question.
13. Why This Trial Matters Statistically
This trial illustrates the distinction between a research question and an answer supported by data. The registry describes a randomized comparison, a postoperative setting, two treatment assignments and a planned sequence of objective measurements. Yet it also states that too few cases with data were available for analysis. Without an estimated treatment contrast, readers cannot assess effect direction, magnitude or precision, regardless of how clearly the clinical objective is stated.
It also illustrates why design labels do not replace analytic detail. Randomized, double-masked and parallel describe broad features, but the registry record does not report allocation procedures, the planned longitudinal model, the primary contrast, or how multiple measures and time points would be handled. These details matter for interpreting repeated observations and distinguishing a primary test from exploratory analyses. Their absence in the record means readers should not infer a statistical plan.
For clinical researchers, the record emphasizes the importance of usable outcome data as well as enrollment. Total enrollment is reported as 4, but the primary analysis could not be provided because an adequate number of cases with data could not be accrued. Enrollment by itself does not establish complete follow-up or an analyzable dataset. Reporting participant flow and the availability of outcome measurements would help readers understand where information was lost.
Finally, the sparse safety counts demonstrate why zero recorded events should be interpreted in context. The placebo group has zero participants listed at risk in the adverse-event entries, while the melatonin group has one. Such entries cannot support a balanced comparison. Overall, the statistical importance of this trial lies in how its record exposes the limits of inference when a study ends without enough outcome data to estimate its planned effects.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most important limitation is explicit in the registry record: an adequate number of cases with data could not be accrued, and no primary outcome analysis is available. Enrollment is recorded as 4, but the number with usable measurements by arm and time point is not reported in the registry record. There are no outcome summaries, treatment-effect estimates, confidence intervals or significance tests with which to assess the primary objective.
The study is marked terminated, but the reason for termination is not reported in the registry record. Nor are recruitment targets, a sample-size justification, or the circumstances behind inadequate data accrual described. The recorded start and primary completion dates do not explain why data were insufficient. The registry entry also does not report whether there were protocol changes, early stopping criteria, or interim analyses.
The primary outcome description identifies actigraphy and SpO2 monitoring, but does not define the precise derived measures or the statistical handling of repeated observations. No analysis plan is reported for the several stated outcomes and time points. The secondary questionnaire-validation objective has no reported results or validation criteria. These omissions restrict interpretation even apart from the small amount of analyzable information.
Participant flow, arm-specific outcome availability, missing-data reasons, adherence, and analysis-population definitions are not reported. Safety entries are limited and imbalanced, with no participants at risk recorded for placebo adverse-event counts and null death fields. These details prevent robust efficacy or safety comparisons. Overall, the record supports description of the trial's intent and its failure to yield an analyzed primary outcome, but not conclusions about treatment effects.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Melatonin Postoperative Sleep Study in Breast Cancer Patients — NCT00506064.
- Registry record last updated 2012-12-05; status last verified 2012-12.
- Results first posted 2011-01-25.
- 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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18. Record Summary
The registry record describes NCT00506064, a phase 1 randomized, double-masked, parallel study of postoperative melatonin versus starch placebo in older breast cancer patients undergoing unilateral segmental mastectomy. The recorded sponsor is M.D. Anderson Cancer Center. Enrollment is 4, the status is terminated, the recorded start is 2004-02, and primary completion is 2008-09.
Melatonin was specified as 0.15 mg/kg capsules by mouth daily; placebo was starch capsules by mouth daily. The primary objective concerned longitudinal objective sleep response, measured by wrist actigraphy and an SpO2 monitor on day 0 and days 1-6 post-operative. The record also describes subjective sleep and cardiopulmonary aims and a secondary questionnaire-validation objective.
The registry states that an adequate number of cases with data could not be accrued, so analysis could not be provided. No primary outcome estimate, statistical analysis plan, sample-size justification, or reason for termination is reported in the registry record. The adverse-event entries are sparse and do not permit meaningful comparison between arms.