Radiotherapy for Solid Tumor Spine Metastases: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Radiotherapy for Solid Tumor Spine Metastases (NCT01752036), a na phase 2 study. The primary outcome is Number of Participants With Radiographic Recurrence at 12 Months.

2. Clinical Question

The clinical question concerns local control in the tumor bed after surgery and radiation, rather than a comparison between concurrently randomized treatments. The intended endpoint is radiographic recurrence at the tumor bed, assessed at the stated 12-month timeframe. The registry record frames the study as an evaluation against an expected rate after conventional radiation therapy, so interpretation depends on that external reference as well as on how recurrence was defined and assessed. Those details, along with the expected recurrence rate, are not reported in the registry record.

The trial also identifies outcomes involving re-treatment, symptomatic recurrence, radiation myelopathy, wound dehiscence, return to chemotherapy, and symptomatic local recurrence in participants with radio-sensitive tumors. The registry record identifies eight outcome measures overall. It does not report results for the primary endpoint or provide outcome counts for these secondary measures in the posted results. As a result, the record establishes the question being studied but does not permit an assessment of the observed recurrence outcome.

3. Trial Design

This is a phase II, completed, single-group study sponsored by Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins. The registry record gives an enrollment of 35 and identifies the intervention as post-operative stereotactic radiosurgery for solid tumor spine metastases. Its official title describes a study of post-operative stereotactic radiosurgery after resection of spine metastases.

Allocation is listed as not applicable, the model is single-group, and masking is listed as none. There is no randomized comparison group in this record. Accordingly, the stated comparison with the expected recurrence rate following conventional radiation therapy is not a concurrent, like-for-like control comparison. The record does not report how that expected rate was selected, whether it came from a particular population, or how differences between the study participants and the external reference were considered.

The study began on 2013-05-20, reached primary completion on 2018-04-02, and is marked completed. These dates describe the registry record; they do not establish the follow-up duration for each participant. The primary endpoint timeframe is listed as 1 year, but the record does not report the timing of individual assessments or the completeness of follow-up.

The listed primary measure is the number of participants with radiographic recurrence at 12 months. Secondary outcomes named in the registry include receipt of re-treatment, symptomatic recurrence, radiation myelopathy, wound dehiscence, time to return to chemotherapy, and symptomatic local recurrence among participants with radio-sensitive tumors. The registry record does not report detailed measurement procedures, analysis populations, or the statistical plan for these outcomes. It records zero analyses. Consequently, the design and objective are identifiable, while the analysis approach and the primary outcome result are not available 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: 33 of the 35 enrolled participants received treatment.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: 35 participants were enrolled and baseline data was collected on all 35. However, only 33 participants actually started treatment.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Radiographic Recurrence at 12 Months, measured over 1 year.

The primary endpoint is the number of participants with radiographic recurrence at 12 months, with a timeframe also stated as 1 year. The description specifies radiographic local recurrence in the tumor bed after resection of spine metastases and post-operative stereotactic radiosurgery. This endpoint is intended to quantify recurrence at the treated site, addressing the study’s stated objective of estimating the recurrence rate after the post-operative radiation approach.

In general, a fixed-time endpoint focuses attention on whether a defined outcome has been observed by a stated assessment time. A radiographic endpoint uses imaging findings rather than symptoms alone, which makes its operational definition and assessment procedures important. The registry record does not report the imaging criteria for recurrence, the schedule or review process for imaging, or how missing assessments were handled. It also does not report the observed participant count or rate at the primary time point.

The endpoint is expressed as a count of participants, not as a time-to-event measure in the registry description. The stated objective refers to estimating a rate and comparing it with an expected rate after conventional radiation therapy. Because no recurrence result or expected reference rate is reported, the intended estimand can be described, but the numerical estimate and its precision cannot be evaluated from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record provides a limited basis for evaluating statistical methods. It identifies a single-group phase II design, a participant-count primary endpoint at 12 months, eight outcome measures, and zero analyses. A detailed statistical analysis plan, endpoint analysis, and numerical primary result are not reported in the registry record. The explanations below distinguish general statistical principles from methods actually documented for this study.

What does a single-group design estimate?

In general, a single-group study can describe outcomes observed among participants who received the study intervention. For a binary event such as whether a participant has radiographic recurrence by a defined time, an analysis might report the event count and the proportion of an identified analysis population. An uncertainty interval can communicate how much imprecision accompanies that estimate. These are general descriptions, not claims about the analysis used in this study. The registry record reports neither a recurrence count nor a recurrence proportion, and it does not identify the population used for an endpoint analysis.

The study’s stated reference is an expected recurrence rate following conventional radiation therapy. Because the design is single-group, that reference is not an internal randomized control. In general, comparing an observed rate with an external expectation requires attention to whether the reference population, eligibility criteria, endpoint definition, assessment timing, and follow-up are sufficiently comparable. The registry record does not report the reference rate or the information needed to evaluate comparability. It also does not report a statistical test or model for this comparison.

What does the endpoint timeframe imply?

The primary measure concerns radiographic recurrence at 12 months, with the timeframe also stated as 1 year. In general, an endpoint at a fixed time requires a rule for assigning outcome status at that time. Participants without an assessment may have unknown status rather than a confirmed absence of recurrence. An analysis plan can specify how such cases are treated and whether the estimate uses all enrolled participants or a defined evaluable group. These procedures are not reported in the registry record. The record also does not report imaging criteria, the assessment window, or whether imaging was centrally reviewed.

The listed measure is a count of participants, not a time-to-event outcome. In general, a count at a fixed time differs from an analysis of time until recurrence: the latter uses event timing and may account for differing follow-up, while the former classifies status at the specified assessment time. The registry’s stated endpoint should therefore be read as a fixed-time participant count unless further analysis details are available. No time-to-event analysis is recorded.

How should precision and statistical significance be understood?

In general, a confidence interval gives a range of estimates compatible with the observed data and the chosen statistical method. Its width reflects uncertainty and depends on factors such as the amount of information and the analysis model. A significance test addresses a specified null hypothesis under its assumptions; a p-value does not measure the size or clinical importance of an effect. These general concepts cannot be applied numerically to the primary endpoint because the registry record reports no recurrence estimate, confidence interval, or p-value.

The record includes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it describes detecting a stated fraction of the observed effect. The record explicitly distinguishes that illustration from the trial’s own design. It is not evidence that this single-group study used two arms, nor does it establish the trial’s sample-size justification. Planning sample sizes are prospective illustrations under assumptions, not observed power and not a substitute for the study’s actual results. The trial’s own sample-size justification is not reported in the registry record.

What do over-dispersion and model choice mean in general?

For count data, a model may assume a particular relationship between the average event count and its variability. Over-dispersion means the observed variation is greater than the model assumes. If a model ignores substantial over-dispersion, its uncertainty estimates can be too small, making results appear more precise than warranted. This is a general concept; the primary endpoint is described as a count of participants with an event, and no model or dispersion estimate is reported. It would not be appropriate to infer that over-dispersion was assessed or that a count regression model was used.

For a binary participant outcome, common analytic choices include estimating an event proportion and its uncertainty. The choice of interval or model can matter, particularly when event counts are sparse. The registry record does not identify the estimator, confidence interval method, model, or any adjustment. No specific method can therefore be attributed to this study.

What is available for evaluating the analysis?

The registry record lists eight outcome measures and zero analyses. It does not report the primary recurrence result, secondary outcome results, statistical analysis plan, prespecified hypotheses beyond the primary objective, or analysis populations. These gaps prevent assessment of whether the reported analyses, if any, followed a prespecified plan or how uncertainty was quantified. General statistical principles can explain what such methods would address, but they cannot fill in methods absent from the record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Treatment")
n      <- c(31)
events <- c(3)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Treatment  31  3  9.7  2.0  25.8  3.3  24.9  3.5  25.0

11. Multiplicity, Missing Data and Analysis Populations

The registry record identifies eight outcome measures, including the primary measure of radiographic recurrence at 12 months and secondary measures involving re-treatment, symptomatic recurrence, radiation myelopathy, wound dehiscence, return to chemotherapy, and symptomatic recurrence in participants with radio-sensitive tumors. It records zero analyses. No results across these outcomes, or plan for controlling multiplicity, are reported in the registry record.

In general, multiplicity arises when several outcomes or hypotheses are examined. If each is tested separately without an adjustment or a prespecified hierarchy, the chance of at least one apparently notable result can increase. A study may address this through a defined primary endpoint, a testing sequence, or an adjustment method, but the approach depends on the scientific question and analysis plan. The registry identifies a primary endpoint, yet it does not report whether or how secondary outcome analyses were planned, or whether any multiplicity procedure was specified.

Missing data are also relevant to a fixed-time endpoint. In general, a participant without an assessment at the stated time cannot automatically be classified as having no recurrence. Interpretation depends on the amount and reasons for missingness, the analysis population, and the handling method. The registry record does not report missing primary endpoint assessments, follow-up completeness, reasons for missing data, or a missing-data strategy.

The record does not describe intention-to-treat, per-protocol, or evaluable-population definitions. It is therefore not possible to determine which participants would enter the primary analysis, or whether all enrolled participants were included. These omissions limit assessment of both the recurrence estimate and the comparability of outcome reporting across measures.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry safety record lists a Treatment group with 33 participants at risk for serious adverse events and 0 affected by serious adverse events. For other adverse events, it lists 33 at risk and 31 affected. The record also lists 2 deaths. These are counts as recorded; no percentages or adjusted comparisons are reported.

In general, an adverse-event count describes what was recorded in the specified group and does not by itself establish that an event was caused by the intervention. The registry record does not report event timing, causes of death, severity details beyond the serious-event category, relatedness assessments, or the period over which participants were monitored. It also does not explain why the safety denominator is 33 when enrollment is recorded as 35, or how missing safety information was handled.

The count of participants affected by other adverse events should not be conflated with the number of distinct event types or the total number of event episodes; those details are not reported in the registry record. The serious-event count of 0 is limited to the listed safety record and does not establish that no events occurred outside the recorded group or observation period. The available counts support a narrow description of what the registry reports, not a causal safety comparison.

13. What the Result Does, and Does Not, Mean

The registry record establishes that a completed phase II, single-group study evaluated post-operative stereotactic radiosurgery after resection of solid tumor spine metastases. It identifies radiographic recurrence at 12 months as the primary endpoint and describes comparison with an expected rate after conventional radiation therapy. It does not provide the observed primary recurrence count or rate, the external expected rate, or an uncertainty interval.

Consequently, the record does not support a conclusion about whether the observed recurrence rate was higher or lower than the expected rate, or how precisely any such difference might be estimated. It also does not support a causal comparison between stereotactic radiosurgery and conventional radiation therapy, because the registry describes no randomized control group. The external reference is not characterized sufficiently to assess comparability.

The safety information is similarly descriptive: 0 of 33 participants at risk are recorded as affected by serious adverse events, 31 of 33 are recorded as affected by other adverse events, and 2 deaths are listed. The record does not report attribution, timing, causes, or details needed to interpret these counts as treatment-related or to compare safety across interventions.

In general, a study’s objective and design are not equivalent to its findings. A planned endpoint explains what investigators intended to measure; it does not establish the observed value. Likewise, a completed status does not mean that outcome analyses are available in the registry. The registry record records eight outcome measures but zero analyses. A fuller interpretation would require the primary result, its precision, endpoint definitions, analysis population, missing-data information, and details of the external comparison. Without these, the appropriate conclusion is limited to what the record documents about study design and selected safety counts.

14. Why This Trial Matters Statistically

This study is statistically notable for asking a focused fixed-time recurrence question in a single-group phase II design. The primary endpoint—radiographic recurrence at 12 months—targets a clinically specific outcome in the tumor bed after resection and post-operative stereotactic radiosurgery. Defining a clear endpoint and timeframe is an important part of making a study question interpretable.

The design also illustrates the distinction between an external benchmark and a concurrent control group. The registry states that recurrence would be evaluated against the expected rate following conventional radiation therapy, but no randomized comparison is described. In general, an external reference can help frame an estimate, yet its usefulness depends on how closely the reference data match the study population, endpoint definition, and observation process. Those details are not reported in the registry record, so the benchmark’s statistical role cannot be evaluated.

Another important issue is the difference between reporting an objective and reporting an analysis. The record names the endpoint and identifies eight outcome measures, but records zero analyses and does not include the primary recurrence result. This makes the record useful for understanding the study question and design, while leaving the central outcome unanswered in the posted results.

The listed enrollment of 35 also places the importance of uncertainty in view, although the registry does not provide an outcome estimate or interval from which to assess precision. In general, a point estimate alone can conceal substantial uncertainty; a count and an appropriate interval are needed to communicate what the data can support. This study therefore highlights why outcome availability, endpoint definitions, and analysis details matter alongside trial status and design.

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 most direct limitation for interpreting this study is that the registry record does not report the primary recurrence result. It also does not report an uncertainty interval, the expected conventional-radiation recurrence rate, or a statistical comparison with that expectation. The primary clinical question therefore cannot be answered from the outcome information recorded.

The single-group design offers no randomized concurrent comparator. The registry does not describe the source or characteristics of the external expected rate, so comparability cannot be assessed. It also does not report eligibility details, participant characteristics, or treatment and imaging procedures beyond the intervention description. Those omissions constrain interpretation of both the study population and the endpoint measurement.

For the primary endpoint, the record does not specify radiographic recurrence criteria, imaging review procedures, the assessment window around 12 months, follow-up completeness, or handling of missing assessments. It does not identify the primary analysis population or provide a statistical analysis plan. These are important details for interpreting a fixed-time participant count.

The recorded enrollment is 35, while the safety record lists 33 participants at risk for serious and other adverse events. The registry does not explain this difference. It lists 2 deaths but does not give their causes or timing, or state whether they were related to treatment. The record also names secondary outcomes without providing their results. Together, the missing outcome, analysis, follow-up, and safety context limit the conclusions that can be drawn from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Radiotherapy for Solid Tumor Spine Metastases — NCT01752036.
• Registry record last updated 2020-06-25; status last verified 2020-06.
• Results first posted 2020-06-25.
• 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.

19. Record Summary

The registry record describes NCT01752036, a completed phase II, single-group study of post-operative stereotactic radiosurgery for solid tumor spine metastases. Enrollment is recorded as 35. The primary endpoint is the number of participants with radiographic recurrence at 12 months, with a stated timeframe of 1 year. The study objective refers to comparison with the expected recurrence rate following conventional radiation therapy, but no randomized comparator is described.

The record identifies eight outcome measures and records zero analyses. It does not report the primary recurrence result, the expected reference rate, or the statistical analysis plan. Safety entries list 0 serious adverse events among 33 participants at risk, 31 affected by other adverse events among 33 at risk, and 2 deaths. Attribution and further safety context are not reported in the registry record.