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 Radiosurgery for Glioblastoma Multiforme (NCT00456612), a na phase 1, phase 2 study. The primary outcome is The Percent Progression -Free Survival at 6 Months Will be Tabulated.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00456612 |
| Phase | Phase 1, Phase 2 |
| Condition | Glioblastoma Multiforme |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 4 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Beth Israel Deaconess Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned elderly patients with high-grade gliomas and poor performance status. The registry summary refers to KPS<70 as part of its rationale, but the specific eligibility criteria and the way performance status was assessed are not reported in the registry record.
Intervention
The intervention was CyberKnife radiosurgery to an enhancing high-grade glioma, delivered in 5 fractions with escalating doses. The record identifies the procedure but does not report the dose levels or details of how escalation was organized.
Comparator
There was no comparison group. The study is listed as single-group, with allocation recorded as NA and no masking. Its results therefore cannot be read as a direct comparison with conventional radiation, another schedule, or a control group.
Primary question
The primary outcome was the percent progression-free survival at 6 months, which the registry says would be tabulated. The posted results do not include a value for that endpoint, so the record does not show the observed proportion or its precision.
The study’s stated aim was to assess the tolerability of CyberKnife radiosurgery for high-grade gliomas in elderly people with poor performance status. The registry summary explains the rationale by noting concerns about tolerating conventional radiation over 6 weeks and interest in shorter schedules. Those statements describe the motivation for the study, not results from this trial.
The record also lists secondary interests: local control, progression-free survival, overall survival, quality of life, toxicity, and steroid dependence. The secondary-outcome description says response, median time to tumor progression, overall survival, and overall survival at 1 Year would be tabulated. The registry does not provide results for those measures. The clinical question can therefore be described, but cannot be answered from the posted outcome data.
3. Trial Design
This was a Phase I/II, single-group study of CyberKnife radiosurgery for glioblastoma multiforme, also described in the official title as a study of fractionated stereotactic radiosurgery for high-grade gliomas in elderly patients with poor performance status. The registry lists an enrollment of 4 and a terminated status. It records the study start as 2007-02 and primary completion as 2010-12.
The intervention is listed as a procedure named CyberKnife. The arm description specifies radiosurgery to an enhancing high-grade glioma in 5 fractions with escalating doses. The record does not report the dose levels, the escalation rules, or how decisions about dose progression were made. Further operational details of treatment delivery are not reported in the registry record.
The design is explicitly single-group. Allocation is recorded as NA, and masking is listed as none. There is no like-for-like control arm in the record, so the study does not establish a randomized or concurrent comparison with another treatment. Its outcomes, if reported, would describe the participants treated in this group; they would not by themselves isolate the effect of the procedure from other influences or establish how outcomes would differ under an alternative.
The registry identifies both Phase I and Phase II, but does not report separate phase-specific cohorts, objectives, decision rules, or analysis plans. A protocol, eligibility details, recruitment flow, dose-escalation structure, and the rationale for the enrollment target are not reported in the registry record. The record also does not explain why the study was terminated. These omissions limit how completely the conduct of the study can be reconstructed from the registry entry.
The posted record contains no listed analyses. Although it names several outcomes, it does not include numerical outcome results. Accordingly, the design and stated questions can be summarized, but the registry information does not support an assessment of the observed efficacy or tolerability outcomes.
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 | Cyberknife |
|---|---|
| STARTED | 4 |
| COMPLETED | 1 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Cyberknife |
|---|---|
| Withdrawal by Subject | 3 |
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 | Single Arm |
|---|---|---|
| Participants analysed | 4 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 |
| Age, Categorical: >=65 years | Participants | 4 |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 2 |
| Region of Enrollment: United States | participants | 4 |
6. Primary Endpoint
The registry lists the primary outcome as The Percent Progression -Free Survival at 6 Months Will be Tabulated, measured over 6 months.
| 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 endpoint is titled “The Percent Progression -Free Survival at 6 Months Will be Tabulated.” It is intended to summarize the proportion of the study group that was progression-free at the stated assessment time. The registry does not give an observed percentage, a numerator or denominator for this endpoint, or an uncertainty interval.
In general, a fixed-time progression-free survival measure expresses how many participants are estimated to remain free of the endpoint event by a specified time. It can provide a clinically interpretable snapshot of disease status, rather than only describing the timing of events across the whole follow-up period. However, the study-specific definition of progression, the handling of death, the assessment schedule, and the rules for censoring are not reported in the registry record. Those details are needed to know precisely what event-free status means.
The endpoint is described as something that “will be tabulated,” rather than accompanied by a posted result. The record therefore states what the primary outcome was intended to summarize, but does not show what proportion was observed, how complete follow-up was, or how precisely the result could be estimated. The title alone cannot be used to infer an outcome.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical fact is that the registry lists 4 enrolled participants in a single-group study, but does not post the primary endpoint result. The primary outcome is named as percent progression-free survival at 6 months; no estimate, confidence interval, or analysis result appears in the record. The same absence applies to the listed secondary outcomes. As a result, there is no posted numerical outcome to interpret for progression, survival, response, quality of life, toxicity, or steroid dependence.
Even if the record included an outcome estimate, a group of this size would call for particular care in interpreting precision. In general, estimates based on few observations can be strongly affected by the outcome of each individual participant. A single-group design also cannot provide a direct treatment contrast. It can describe what happened among participants in the group, but it cannot by itself distinguish effects of treatment from differences in prognosis, other care, or the selection of participants.
The registry summary states that the intervention was intended to assess tolerability and gives a rationale involving shorter radiation schedules. Those statements are not findings. The record does not show whether treatment was completed, whether participants experienced progression, or whether the intervention met any tolerability criterion. It also does not report the basis for termination. The termination status should not be treated as evidence about the direction of the results, because the reason is not reported.
The safety section lists 4 participants at risk for serious adverse events and 0 affected, and 4 at risk for other adverse events and 0 affected. These are counts in the registry record, not a full description of the safety experience. The event terms are not listed, and the record does not give follow-up duration or clarify how adverse events were collected. These zero counts do not establish that no events occurred outside the recorded categories, time window, or reporting process.
Overall, the record permits a description of the study’s design, stated endpoint, enrollment, and posted adverse-event counts. It does not permit a quantitative conclusion about the primary outcome or a comparison with other care. The distinction is important: a study question and an intervention description do not substitute for posted outcome estimates.
9. Statistical Methods Explained
The registry classifies the study as single-group, with no allocation and no masking. This is a descriptive design in the sense that the listed participants received the study intervention without a concurrent control group in the record. The registry does not report a detailed statistical analysis plan. The concepts below are general explanations of how these design and outcome features are commonly understood; they should not be read as confirmation that a particular method was used in this study.
What does a single-group design show?
In general, a single-group study can describe outcomes among people who received an intervention. Without a control group, it does not directly estimate a contrast between that intervention and another option. A comparison made with historical results would require careful attention to differences in eligibility, care, follow-up, and outcome definitions. No historical comparison or adjustment strategy is reported in the registry record.
In randomized studies, random assignment is used to make treatment groups comparable in expectation. That mechanism is not part of the design: allocation is NA and the model is single-group. Consequently, the record cannot support a randomized treatment-effect estimate. This does not make the descriptive information meaningless; it does define the limits of the claims that could be supported even if outcomes were posted.
What does a fixed-time progression-free survival percentage mean?
In general, a fixed-time survival percentage describes the estimated share of participants who have not experienced a defined event by a specified time. For progression-free survival, the event definition matters: a protocol may specify what counts as progression and whether death is included. A time-to-event analysis can account for participants whose event status is not observed through the full follow-up by treating their observation as censored, subject to assumptions about censoring and follow-up. The registry names percent progression-free survival at 6 months but does not report its event definition, estimation method, censoring rules, or result.
A simple proportion and a time-to-event estimate are not interchangeable when follow-up differs among participants. A proportion calculated only among those assessed at the stated time can be misleading if some participants are not assessed or have incomplete follow-up. A survival estimate can use partial follow-up, but depends on methods and assumptions. The record does not say which approach was planned or used, nor whether any participants had incomplete follow-up.
How should uncertainty be assessed?
In general, an estimate should be read alongside a measure of uncertainty, commonly a confidence interval. A confidence interval expresses a range of values compatible with the data under the method’s assumptions; it does not guarantee that the true value lies in that particular interval. With limited information, uncertainty can be substantial, and a point estimate alone can give an incomplete impression. No confidence interval or other precision measure for the primary endpoint is reported in the registry record.
For a time-to-event endpoint, uncertainty can depend on both the number and timing of events, as well as follow-up and censoring. For a fixed-time endpoint, the number of participants with usable status at that time is relevant. The registry lists enrollment but does not report the number assessed at 6 months, the number of events, or the follow-up completeness. Those quantities cannot be inferred from enrollment alone.
What can be learned from the safety counts?
In general, an adverse-event count needs a clear denominator, event definition, observation window, and collection method. The registry lists four participants at risk in each of the serious and other adverse-event categories and zero affected in each category. The record does not give event terms, severity grading beyond the serious/other distinction, timing, or exposure duration. A zero count in a reported category is not proof that an event is impossible or that all safety outcomes were fully captured.
How should planning illustrations be read?
The accompanying sample-size material is described as a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. For time-to-event examples, it describes total events; other examples are expressed as participants per arm for 80% power. These are illustrations, not the study’s own design justification or observed power. The registry does not report its own sample-size justification, and the posted record does not include outcome analyses that would allow the study’s results to be evaluated. Planning calculations do not show that a study had a particular probability of detecting an effect after it was conducted.
More broadly, the registry’s count of zero listed analyses means there are no posted analysis results to examine. The statistical model, treatment of missing observations, population used for analysis, and any sensitivity analyses are not reported in the registry record. They should not be inferred from the phase labels or the endpoint title.
10. Multiplicity, Missing Data and Analysis Populations
The record lists a primary endpoint and several secondary outcome interests, including local control, progression-free survival, overall survival, quality of life, toxicity, steroid dependence, and response. The secondary-outcome description also names median time to tumor progression and overall survival at 1 Year. It does not report a plan for handling multiple outcomes or repeated statistical testing. The number of prespecified comparisons, any hierarchy among outcomes, and any adjustment for multiplicity are not reported in the registry record.
In general, examining several outcomes can increase the chance that at least one result appears noteworthy by chance. A prespecified primary endpoint and a transparent approach to secondary outcomes help readers distinguish the main question from exploratory analyses. Here, the primary outcome is identified, but the detailed analysis plan and multiplicity strategy are not posted. There are no listed analyses or outcome estimates to assess.
The record also does not report how missing outcome data were handled, how many participants were assessed at the 6-month time point, or whether follow-up ended early for any participant. The reason for the study’s terminated status is not reported in the registry record. It is therefore not possible to determine whether missingness occurred or, if it did, whether it was related to outcomes.
Analysis populations are also not described. The record does not say whether analyses were intended to include all enrolled participants, only participants who received treatment, or a different set. These are distinct choices that can affect interpretation. The enrollment count alone does not identify the analysis denominator for any endpoint.
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 |
|---|---|---|---|
| Single Arm Study | 0 | 4 | 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 |
|---|---|
| Single Arm Study | 0 of 4 |
The adverse-event record lists a single-arm study group with 4 participants at risk for serious adverse events and 0 affected. It also lists 4 participants at risk for other adverse events and 0 affected. These are the posted counts; no event terms are listed in the serious-event summary.
These figures should be read as registry counts rather than as a complete safety profile. The record does not report the observation period, event-collection procedures, definitions used for the categories, or whether the counts cover the entire time participants were followed. It also does not list the number of deaths: that information is not reported in the registry record. The absence of listed event terms means the record does not describe specific event types.
In general, a zero recorded count means that no affected participants are entered for that category in the reported data. It does not establish that no adverse experiences occurred, that every event was captured, or that the intervention has no safety risks. With a single group and no comparison arm, these counts also do not show how event frequency compares with another treatment or with no intervention. The registry does not provide enough detail to make broader safety comparisons.
12. What the Result Does, and Does Not, Mean
This record documents a Phase I/II, single-group study of fractionated CyberKnife radiosurgery in a population described as elderly patients with high-grade gliomas and poor performance status. It identifies the intervention as delivery in 5 fractions with escalating doses, and lists an enrollment of 4. It also records the study as terminated and names percent progression-free survival at 6 months as the primary endpoint.
What the record does not show is the outcome of that primary question. No primary endpoint estimate, confidence interval, or analysis is posted. The secondary outcomes are named but likewise have no results in the registry record. Therefore, the page cannot establish how participants fared in terms of progression, survival, response, quality of life, toxicity, or steroid dependence. The study’s stated rationale is not evidence of an observed benefit or tolerability result.
The single-group design further limits what could be concluded from the study, even if descriptive results were available. Without a concurrent comparator, outcomes cannot be directly attributed to the intervention through a treatment-group contrast. The record does not describe an external comparison or adjustment method. The enrollment count and design alone do not establish an effect or its size.
The adverse-event counts show 0 affected among 4 listed at risk for serious events and 0 affected among 4 listed at risk for other events. Those registry entries are limited by missing details about event definitions, follow-up, and collection. They should not be generalized into a claim that the procedure is free of risk.
In short, the posted information supports a description of the study and its intended questions, but not a conclusion about the observed efficacy or safety results. The reason for termination, the study’s own sample-size justification, and key analysis details are not reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically notable because its design and posted record illustrate the difference between a clearly stated research question and an answer supported by outcome data. The registry names a primary endpoint—percent progression-free survival at 6 months—and identifies several secondary outcomes, yet it does not post their results. Readers can identify what the investigators intended to assess, but cannot evaluate the corresponding estimates or their uncertainty.
The single-group design is also important. A small descriptive study can document the experience of participants who received a procedure, but a treatment comparison requires a reference group or another defensible comparison strategy. The record lists no control arm, no allocation, and no masking. As a result, the study structure cannot directly estimate how outcomes differ from another approach.
The enrollment count of 4 also makes transparency about denominators and follow-up especially important. For a fixed-time endpoint, readers need to know who had an assessable status at the stated time and how incomplete observation was treated. For safety, readers need the event definitions and observation window. Those details are not reported in the registry record.
Finally, the terminated status highlights the value of reporting the reason for study closure and the results available at closure. The registry does not state why the study was terminated. Without that context or outcome analyses, readers should not infer that the status reflects a particular result or safety finding. The statistical lesson is to separate design information, descriptive counts, and analyzed outcome evidence.
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 limitations specific to this record begin with the absence of posted efficacy outcomes. The primary endpoint is described as a measure to be tabulated, but no value for progression-free survival at 6 months is given. The listed secondary outcomes also lack results. As a result, the registry record cannot be used to assess the observed outcome trajectory or the precision of any estimate.
The study has a single-group design and no listed comparator. Any outcome description would lack a concurrent reference group, limiting causal interpretation. The enrollment is 4, and the record does not give the number included in endpoint analyses or assessed at the 6-month time point. The reason for the terminated status is not reported in the registry record.
Key population and treatment details are also absent. Although the title and summary describe elderly patients with poor performance status, the specific eligibility criteria are not reported. The record does not give the dose levels, dose-escalation rules, or other details needed to reconstruct treatment delivery. It does not report the progression definition, assessment schedule, censoring approach, or method used to estimate the primary endpoint.
Analysis methods, missing-data handling, multiplicity plans, analysis populations, and the study’s own sample-size justification are not reported in the registry record. The safety counts lack event terms, timing, and collection details, and the death count is not reported. These omissions limit both interpretation of the posted counts and reproducibility of any analysis. They also mean that absence of results must not be mistaken for evidence of a null or favorable outcome.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Radiosurgery for Glioblastoma Multiforme — NCT00456612.
- Registry record last updated 2017-03-06; status last verified 2017-01.
- Results first posted 2015-10-05.
- 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 describes a Phase I/II, single-group study of fractionated CyberKnife radiosurgery for glioblastoma multiforme and other high-grade gliomas in elderly patients with poor performance status. The intervention was described as radiosurgery to an enhancing high-grade glioma in 5 fractions with escalating doses. Enrollment was 4; the study status is terminated.
The stated primary endpoint was percent progression-free survival at 6 months. The record also lists secondary outcomes related to response, progression, survival, quality of life, toxicity, and steroid dependence. No outcome analyses or endpoint estimates are posted, and the reason for termination is not reported in the registry record.
The safety listing records 0 affected among 4 at risk for serious adverse events and 0 affected among 4 at risk for other adverse events. Event details and the death count are not reported. The record supports description of the design and stated outcomes, but not conclusions about treatment effects or comparative safety.