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 Simvastatin and Anastrozole in Treating Postmenopausal Women With Ductal Carcinoma In Situ or Invasive Breast Cancer (NCT00354640), a na phase 2 study. The primary outcome is Change in Blood Concentrations.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00354640 |
| Phase | Phase 2 |
| Condition | Breast Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 11 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins |
| Results posted | Yes |
2. Clinical Question
Population
Postmenopausal women with breast cancer receiving anastrozole as adjuvant therapy. The registry’s broader description also refers to ductal carcinoma in situ, invasive breast cancer, or high risk of breast cancer. The primary endpoint population was participants with blood samples for trough concentrations.
Intervention
Concurrent simvastatin while receiving anastrozole, for up to 14 days.
Comparator
No separate comparator group is described. The study is registered as a single-group study, with measurements at baseline and 14 days.
Primary question
What change in blood concentrations of anastrozole was measured between baseline and 14 days during concurrent simvastatin use?
The clinical question is pharmacological: it concerns anastrozole concentrations during concurrent simvastatin use, rather than a comparison of cancer outcomes between treatment groups. The registry describes a phase II trial and identifies change in blood concentrations as the primary outcome. A secondary outcome is change in serum estradiol levels.
The registry record does not report a numerical estimate of the change, its direction, or its precision. It therefore describes what the study set out to measure but does not allow readers to determine the size or distribution of the observed change from the recorded results. Nor does the single-group design provide a concurrent control group for separating changes associated with simvastatin from other possible influences over the measurement period.
3. Trial Design
The study is registered as phase II, with a single-group model and allocation listed as not applicable. Masking is listed as none. The record gives enrollment as 11 and status as completed. The study began in 2006-06, with primary completion in 2008-10. The sponsor is Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins.
The described group consisted of women on anastrozole as adjuvant therapy for breast cancer who received concurrent simvastatin for up to 14 days. The primary outcome concerns anastrozole blood concentrations at baseline and 14 days. Participants with blood samples for trough concentrations were included in the endpoint population. These details define the basic design, but the registry record does not report further procedural details such as the timing of individual blood draws or how adherence was assessed.
Because there is one group and no masking, this is not a randomized, blinded comparison of simvastatin against a control treatment. The two measurement times provide a before-and-after frame for the concentration outcome, but the record does not describe a separate untreated group or another comparison condition. The registry’s study description includes women with ductal carcinoma in situ, invasive breast cancer, or high risk of breast cancer; the specific arm description focuses on women receiving anastrozole as adjuvant therapy for breast cancer.
The registry record does not report a sample-size justification, recruitment targets by subgroup, or a statistical analysis plan. The small enrollment means that any observed distribution would need to be interpreted in the context of the actual number of participants contributing blood samples, which is not separately stated. The study’s listed status is completed, but that status alone does not establish that every planned measurement was available or that a particular analysis was conducted.
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: Women were required to be taking anastrozole as adjuvant treatment for breast cancer.
Overall Study
| Stage | Anastrozole and Simvastatin |
|---|---|
| STARTED | 11 |
| COMPLETED | 11 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Participants with blood samples for trough concentrations were included.
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 | Anastrozole and Simvastatin |
|---|---|---|
| Participants analysed | 11 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 8 |
| Age, Categorical: >=65 years | Participants | 3 |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 0 |
| Region of Enrollment: United States | participants | 11 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Blood Concentrations, measured over Baseline and 14 days.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | ng/ml |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled “Change in Blood Concentrations.” It measures the change in blood concentrations of anastrozole between baseline and 14 days, with concentrations expressed in ng/ml. The registry identifies the endpoint statistic as the median and its dispersion as the full range. The endpoint population consists of participants with blood samples for trough concentrations.
Drug concentration measurements are used in pharmacological studies to describe exposure to a medicine. In general, comparing measurements across time can help characterize whether concentrations differ during concurrent treatment. A median describes the central position of observed values, while the full range describes the lowest and highest observed values. Neither summary alone gives a confidence interval or states how precise an estimated change is.
The registry record does not report the numerical median, full range, or a numerical change estimate. It also does not report a confidence interval, p-value, or the method used to calculate participant-level changes. The endpoint description therefore establishes what was measured and how the result was intended to be summarized, but not the magnitude or uncertainty of the observed result.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record identifies a focused pharmacokinetic question: anastrozole blood concentrations were to be measured at baseline and 14 days while participants received concurrent simvastatin. The outcome description specifies a median and full range. However, the registry record does not report numerical outcome values. There is consequently no recorded estimate from which to describe the size, direction, or variability of the concentration change.
No confidence interval or p-value is reported in the registry record. A confidence interval, in general, communicates the uncertainty around an estimate under the assumptions of the analysis. A p-value, in general, assesses how compatible data are with a specified statistical null model; it does not measure the size or clinical importance of an effect. Without these values, and without an outcome estimate, the precision and statistical evidence for a change cannot be assessed from the record.
The design also shapes what can be inferred. The registry describes a single group and no masking, with no separate comparator. Measurements at two times may describe within-study change, but they do not by themselves establish that any change was caused by simvastatin. Other influences over time cannot be separated by a concurrent control comparison that is not part of the registered design.
Enrollment is listed as 11, but the number with usable samples for the primary endpoint is not reported in the registry record. The endpoint population is defined as participants with blood samples for trough concentrations; the record does not give the count or explain whether any samples were unavailable. This matters because the amount of information in the analysis depends on who contributed data, not only on enrollment.
The secondary outcome is change in serum estradiol levels. Numerical results for that outcome are not reported in the registry record either. In general, when several outcomes are examined, interpretation can depend on whether the study planned adjustments or a hierarchy among outcomes. Such plans are not reported in the registry record. Overall, the available record supports a description of the study question, design, and intended summaries, but not a conclusion about the observed concentration change or its uncertainty.
9. Statistical Methods Explained
The registry describes a median with full range for the primary concentration outcome. It does not report the numerical result or a statistical analysis plan. The following explanations describe the statistical concepts in general and distinguish them from methods specifically documented for this study.
What does a median describe?
In general, the median is the middle value when observations are ordered. It can be useful when a distribution is skewed or when a few extreme observations would strongly affect an arithmetic mean. A median does not show every feature of a distribution, and it does not directly quantify uncertainty about the population value. The registry record names the median as the summary statistic but does not explain why it was selected.
What does the full range add?
In general, the full range gives the smallest and largest observed values. It conveys the spread between the extremes, but it can be sensitive to unusual observations and does not show how values are distributed between those extremes. A range is not a confidence interval: it describes observed data rather than uncertainty around an estimated effect. The registry record identifies full range as the dispersion measure but does not provide its values.
How should two measurement times be understood?
The endpoint is defined around baseline and 14 days. In general, measurements at two times in the same participants can be analyzed as paired data, with each participant’s later measurement related to their earlier measurement. Such an approach accounts for within-person pairing. But a measurement schedule alone does not establish the analysis method: the registry record does not say whether the analysis used participant-level differences, a model, or another approach. It also does not report how the stated change was calculated.
For paired data, in general, the distribution of individual changes can differ from the distribution of values at either time point. A summary of each time point separately is not necessarily the same as a summary of the changes. The registry’s outcome title and description refer to change, but the numerical summaries needed to assess how change was presented are not reported in the registry record.
What would uncertainty measures contribute?
In general, a confidence interval gives a range of values compatible with an estimate under the model and assumptions used. Its width reflects statistical precision: greater uncertainty produces a wider interval. A p-value addresses compatibility with a specified null hypothesis, but it does not tell readers how large an effect is or whether it matters in a clinical context. Neither a confidence interval nor a p-value is reported for the primary endpoint in the registry record. The analysis model and hypothesis test are also not reported there.
What do the planning assumptions mean?
The registry includes a planning framework based on a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. That framework is hypothetical planning, not a description of the registered single-group study, which has no two-arm allocation. It is not the study’s sample-size justification, and the registry record does not report such a justification. Planning illustrations are not observed power: they concern hypothetical future study sizes under specified assumptions, rather than the probability that this completed study detected an effect. Numerical planning results are not reported in the registry record.
These assumptions also cannot supply an outcome estimate that is absent from the registry record. The observed effect used as a planning reference, and the resulting numerical planning illustrations, are not reported in the registry record. The planning framework should therefore be read as a general scenario, not as evidence that the study was designed or powered for a particular effect.
Why can over-dispersion matter?
In general, over-dispersion means that variability in the data is greater than a statistical model assumes. When present and not accounted for, standard errors may be too small and confidence intervals too narrow. Whether over-dispersion is relevant depends on the outcome and analysis model. The registry record does not report a model or diagnostics, so it is not possible to assess this issue for the study.
More broadly, a statistical result depends on the analysis population, missing-data handling, outcome definition, and model assumptions. The record identifies the blood-sample population for the primary endpoint, but does not report the number analyzed, missing-data procedures, or the inferential method. These omissions prevent readers from reproducing or fully evaluating the statistical analysis from the registry record alone.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies two outcome measures: change in blood concentrations of anastrozole and change in serum estradiol levels. The anastrozole concentration measure is designated primary. The registry record does not report a hierarchy for interpreting the outcomes, a multiplicity adjustment, or a statistical analysis plan specifying how multiple outcomes would be handled. It also does not report numerical results for either measure.
In general, examining multiple outcomes can increase the chance of finding an apparently notable result by chance if each is tested separately. A prespecified hierarchy or adjustment can address that issue, but the appropriate approach depends on the study question and analysis plan. No such approach is reported in the registry record, so the status of multiplicity control cannot be determined.
The primary endpoint population is described as participants with blood samples for trough concentrations. The enrolled total is 11, but the number with endpoint data is not reported in the registry record. Reasons for unavailable samples, the extent of missing data, and any imputation or sensitivity analysis are also not reported. In general, missing-data methods can affect estimates when data availability is related to participant characteristics or outcomes; the record does not provide enough information to assess whether that concern applies.
Analysis populations beyond the blood-sample population are not reported in the registry record. The record does not state whether all enrolled participants were included in safety summaries or how participants with incomplete measurements were handled for efficacy analyses. These gaps limit assessment of both the amount of information used and the robustness of any analysis.
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 |
|---|---|---|---|
| Anastrozole and Simvastatin | 0 | 11 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Anastrozole and Simvastatin | 0 of 11 |
The registry lists 11 participants at risk for serious adverse events and 0 affected. It also lists 11 at risk for other adverse events and 0 affected. These are participant counts in the single group, not event rates calculated. The registry record does not list serious adverse event terms.
A count of participants affected is not necessarily the same as a count of event episodes: a participant could experience more than one event, and the registry’s listed figures do not give episode totals. The zero affected counts should therefore be read as the recorded participant counts for the reported categories, not as evidence that no symptoms or other experiences occurred.
The death count is not reported in the registry record. The record also does not describe the period over which adverse events were collected, how events were defined or assessed, or whether events were considered related to study treatment. Those details are important to interpreting safety summaries, and cannot be inferred from the counts alone. In particular, these figures do not establish a comparative safety profile because the study is single-group and has no separate comparator.
12. What the Result Does, and Does Not, Mean
The registry record describes a completed phase II, single-group study of concurrent simvastatin and anastrozole. Its primary question concerns change in anastrozole blood concentrations between baseline and 14 days. The outcome was to be summarized using a median and full range among participants with trough-concentration blood samples.
The record does not report the numerical primary outcome, a confidence interval, or a p-value. It therefore does not show how large the concentration change was, whether concentrations increased or decreased, or how precisely any estimate was measured. The secondary outcome, change in serum estradiol levels, also has no numerical result reported in the registry record. The available safety counts are limited to participant counts for serious and other adverse events; deaths are not reported.
Even if numerical before-and-after results were available, a single-group design would describe change over time without a concurrent control comparison. In general, this design cannot by itself distinguish a treatment-associated change from other influences that occur over the measurement period. No masking is listed, which is another design feature readers can consider when assessing measurement and reporting.
The findings described in the registry cannot be used to make claims about cancer outcomes: the primary endpoint is a concentration measure, not a cancer-control endpoint. Nor does the registry record establish that the combination changes clinical outcomes. Its contribution, as registered, is a pharmacological measurement question. Interpreting that question requires the missing numerical results, analysis details, and information about the participants contributing data.
13. Why This Trial Matters Statistically
This study is statistically notable for the distinction between a pharmacological measurement question and a clinical outcome question. Its primary endpoint concerns anastrozole blood concentrations, not tumor response, recurrence, or survival. The endpoint can describe drug exposure over the stated measurement period, but it does not itself answer whether a clinical outcome changes.
The design also illustrates the limits of before-and-after measurement in a single group. Repeated observations can characterize change within participants, but without a separate comparator they do not isolate the influence of concurrent simvastatin from other time-related influences. The listed absence of masking is another feature relevant to how measurements and study conduct should be interpreted.
Precision is central to reading a quantitative result. A median and full range can describe the center and spread of observed values, but without the numerical summaries or an uncertainty measure, readers cannot assess the estimated change’s magnitude or precision. The registry record does not report those results. This makes the distinction between a defined endpoint and a reported result especially important: an outcome can be clearly specified without the record enabling an evaluation of its observed value.
Finally, the record identifies a small enrolled group and an endpoint population based on available blood samples, but does not report how many participants contributed primary outcome data. That missing denominator limits assessment of the information underlying the endpoint. The case underscores why design, analysis population, missing-data reporting, and numerical effect estimates all matter when interpreting pharmacological studies.
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 registry record leaves several trial-specific limitations unresolved. It describes a single group, allocation as not applicable, and no masking. There is no separate comparator group in the registered design, so the record does not support a controlled estimate of the effect of adding simvastatin. The study’s primary outcome is a drug concentration measure, which is distinct from a clinical cancer outcome.
Although enrollment is listed as 11, the number of participants with blood samples for the primary endpoint is not reported in the registry record. The record does not say whether all enrolled participants had measurements at both time points, why any samples might be missing, or how incomplete observations were handled. It also does not provide the numerical median or full range, a measure of uncertainty, or an inferential analysis method.
The registry identifies a secondary outcome of change in serum estradiol levels but does not report its numerical result or how multiple outcomes were addressed. A statistical analysis plan, sample-size justification, and details of any interim analyses are not reported in the registry record. The hypothetical planning assumptions listed for two-arm sample-size illustrations do not describe the actual single-group design and are not a substitute for a study-specific justification.
The record also does not report the schedule and procedures for blood collection beyond the baseline and 14-day time points, or further details of adverse-event collection and attribution. These limitations constrain reproducibility and interpretation. They do not establish that an unreported procedure was or was not performed; they indicate only that the registry record does not describe it.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Simvastatin and Anastrozole in Treating Postmenopausal Women With Ductal Carcinoma In Situ or Invasive Breast Cancer — NCT00354640.
- Registry record last updated 2013-06-24; status last verified 2013-05.
- Results first posted 2013-06-24.
- 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
NCT00354640 is titled “Simvastatin and Anastrozole in Treating Postmenopausal Women With Ductal Carcinoma In Situ or Invasive Breast Cancer.” Its official title is “A Trial Assessing the Effect of Simvastatin on the Pharmacokinetics of Anastrozole.” The registry lists phase II, a single-group model, allocation as not applicable, and no masking.
Enrollment is listed as 11. The study began in 2006-06, reached primary completion in 2008-10, and is listed as completed. The intervention group received concurrent simvastatin while on adjuvant anastrozole for up to 14 days. The primary outcome was change in anastrozole blood concentrations at baseline and 14 days; the secondary outcome was change in serum estradiol levels.
Numerical outcome results and the statistical analysis plan are not reported in the registry record. The primary endpoint population is defined by availability of blood samples for trough concentrations, but its analyzed count is not reported. Serious and other adverse-event summaries each list 0 affected among 11 at risk; the death count is not reported.