PET Scanning to Evaluate Zoledronate Efficacy in Metastatic Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PET Scanning to Evaluate Zoledronate Efficacy in Metastatic Prostate Cancer (NCT01205646), a na na study. The primary outcome is PET Response Rate in Metastatic Prostate Cancer Patients Treated With Zoledronate Therapy..

2. Clinical Question

The trial’s primary aim was to assess change in PET uptake after zoledronate therapy in people with metastatic prostate cancer. The protocol-defined response used the change in mean standardized uptake value, or SUVmean, across two scans: Scan 2 was the pre-Zometa measure and Scan 3, obtained 1-2 weeks later, was the post-Zometa measure. A decline of at least 15% was defined as a response.

The study also planned to evaluate PSA, bone scan findings and bone turnover markers. These are additional measures, not separate comparison groups. The registry describes the study rationale as evaluating PET change and notes that FMAU PET scans can detect bony metastatic sites in prostate cancer. It does not report the observed PET response or the results for the additional measures. The clinical question can therefore be described from the planned endpoint, but the posted record does not give an answer in the form of an observed response estimate.

3. Trial Design

This completed pilot trial is listed as single-group, with allocation recorded as NA and masking recorded as NONE. Its phase is listed as NA. The registry reports enrollment of 11 participants and identifies the condition as prostate cancer. The sponsor is Barbara Ann Karmanos Cancer Institute. The recorded start is 2010-09, and primary completion is 2013-08.

The listed intervention is zoledronate therapy, a drug intervention, together with PET scanning, a device intervention. The arm is named Zometa & PET Scans. The arm description says that two scans, about 1-2 weeks apart, were obtained over a period of 2 weeks before therapy to confirm reproducibility. It also lists a bone scan within 4 weeks before registration, bone turnover markers and PSA before therapy. The description ends while describing administration of Zometa, so the dosing details are not reported in the registry record.

There is no concurrent control arm in the recorded design. The changes of interest are therefore measured within participants around treatment, rather than contrasted with outcomes in an untreated or differently treated group. Such a design can describe observed changes over the study period, but by itself cannot separate a treatment-associated change from other explanations for change over time.

The registry lists the study as completed. It records four outcome measures: the primary PET response measure and secondary measures concerning PSA, bone scans and bone turnover markers. It does not report the detailed eligibility criteria, the planned analysis populations, the handling of missing observations, or a statistical analysis plan. The record also lists no statistical analyses. Those omissions limit how fully the study conduct and its results can be assessed from this entry.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as PET Response Rate in Metastatic Prostate Cancer Patients Treated With Zoledronate Therapy., measured over Within 3 weeks.

The primary endpoint is the proportion of participants with a PET response within 3 weeks. The protocol definition, as summarized in the registry, classifies a participant as a responder if SUVmean declines by at least 15% between the pre-Zometa and post-Zometa scans. Scan 2 is the pre-Zometa measure; Scan 3, obtained 1-2 weeks later, is the post-Zometa measure.

This endpoint turns a change in a continuous imaging measurement into a binary outcome: each participant either meets the stated response threshold or does not. A proportion is a natural summary for this kind of participant-level response classification. The registry reports a 90% confidence interval as the endpoint’s dispersion measure, but it does not report the observed proportion or the interval limits.

As a general statistical point, a threshold can make a result easier to interpret as a responder count, but it also discards information about how far individual changes fall above or below the cutoff. Participants with changes near the threshold may be classified differently despite having similar measurements. The record does not report the individual scan values or the number meeting the response definition, so neither the underlying distribution of SUVmean changes nor the resulting response proportion can be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information is mainly the endpoint definition and its planned summary. The registry identifies a proportion of participants with response as the primary outcome and names a 90% confidence interval as its dispersion measure. It does not report the resulting proportion, interval limits or statistical analysis details. The explanations below describe general statistical concepts and should not be read as a claim that a particular unreported procedure was used.

What does a response proportion summarize?

The endpoint classifies participants according to whether their measured SUVmean change crosses the protocol threshold. In general, a response proportion summarizes the fraction of an analyzed group that meets a binary definition. Its interpretation depends on the exact response rule, the population included in the analysis, and the availability and handling of the measurements needed to classify each participant. The record states the threshold and scans used, but does not report the analysis population or the number classified as responders.

Converting a measurement change into a yes-or-no outcome is convenient for reporting, but it loses detail. A participant just meeting the threshold and one with a larger decline both count as responses under this definition. A participant just short of the cutoff and one with little or no decline both count as nonresponses. As a general point, this makes it useful to consider the underlying continuous measurements as well as the binary summary. The posted record does not include the SUVmean values needed to do that.

How should a confidence interval be understood?

In general, a confidence interval expresses uncertainty around an estimate under the assumptions of the statistical method used. A wider interval indicates less precision than a narrower interval, all else being comparable. It does not show the range of individual participant responses. The registry names a 90% confidence interval for the primary response rate, but its bounds are not reported, and the interval method is not reported in the registry record. Without an estimate and interval, the precision of the response rate cannot be evaluated.

The confidence level alone does not indicate whether a result is clinically important or whether it supports a causal claim. The endpoint’s 90% interval is a planned way of expressing uncertainty about a proportion; it cannot make up for the absence of a comparison group or missing result. No hypothesis test or p-value for the primary outcome is reported.

What does the scan schedule contribute?

The arm description says two PET scans about 1-2 weeks apart were obtained over a period of 2 weeks before therapy to confirm reproducibility. It then identifies Scan 2 as the pre-Zometa value for the response calculation and Scan 3, 1-2 weeks later, as the post-Zometa value. Repeated pretherapy measurements can, in general, help describe variation in measurement when no treatment has yet been given. But the record does not report the pretherapy scan values or a reproducibility estimate. It is therefore not possible to tell from this entry how much measurement variability was observed or how it related to the response threshold.

The primary timeframe is within 3 weeks. Time windows matter because a measurement can depend on when it is taken. The registry does not report the distribution of actual scan times or how deviations from the described schedule were handled. It also does not report whether all participants had the scans needed to calculate the endpoint.

What analysis choices remain unknown?

The record gives no statistical analysis plan and lists no statistical analyses. The exact method for calculating the confidence interval, handling missing scans, defining the analysis population and accounting for protocol deviations is therefore not reported in the registry record. The record does not say whether an intention-to-treat or another analysis population was used. It would be inappropriate to infer any of these choices from the endpoint description alone.

The study is single-group. General statistical interpretation of a within-participant change does not make it equivalent to a randomized comparison: change over time may have explanations other than the intervention. The study’s stated use of pretherapy scans addresses measurement reproducibility as a design consideration, but it does not provide an untreated control for the post-treatment period.

How do the planning illustrations differ from trial results?

The sample-size illustrations are planning exercises, not observed power and not a description of this trial’s design. The stated assumptions for those illustrations are a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. The actual study is recorded as single-group, so a two-arm illustration should not be read as the trial’s own sample-size justification or as evidence that it had a particular probability of detecting an effect. The trial’s sample-size justification is not reported in the registry record.

In general, sample-size calculations depend on assumptions about the target effect, variability, error rates and design. A planning calculation cannot establish what an observed study result would be, and it cannot replace a reported estimate with its uncertainty. Since no primary response estimate is posted here, there is no observed effect from this registry entry to interpret against those planning illustrations.

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("Zometa & PET Scans")
n      <- c(11)
events <- c(0)
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  Zometa & PET Scans  11  0  0.0  0.0  28.5  -0.0  25.9  0.2  26.5

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies one primary outcome, PET response rate, and three secondary outcome topics: change in PSA, change in bone scans and changes in bone turnover markers. It records four outcome measures overall, but does not report results for the primary or secondary measures. The record does not describe a multiplicity adjustment, a hierarchy among the outcomes beyond the primary designation, or how multiple analyses were to be interpreted. These details are not reported in the registry record.

As a general statistical issue, examining multiple outcomes or multiple analyses can increase the chance of finding an apparently notable result by chance. Whether and how to address that issue depends on the analysis plan and the claims being made. Since the registry lists no statistical analyses and does not describe a multiplicity strategy, no adjustment or testing framework should be assumed.

The record does not report how missing PET scans, PSA measurements, bone scans or bone turnover marker measurements were handled. It also does not state whether missing data occurred. The analysis population for each outcome is not reported in the registry record. Enrollment of 11 is not enough to establish how many participants contributed usable data to any particular endpoint. The posted safety figures have their own at-risk counts, but those do not establish the analysis population for efficacy outcomes.

These gaps matter because response classification requires the measurements specified by the endpoint. General methods for missing outcomes can make different assumptions, and those choices can affect an estimate. Without a reported missing-data approach, participant flow by outcome or analysis population, the completeness and interpretability of the planned efficacy analyses cannot be assessed from the registry entry.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The safety figures list zero participants with a serious adverse event among 11 at risk. The record also lists three participants with other adverse events among 11 at risk. These are participant counts in the single Zometa & PET Scans group, not comparisons between treatment arms. The record lists no serious adverse event terms.

These counts should be read as the safety information posted in the registry, not as a complete account of all possible safety outcomes. The record does not report the observation period for the figures, detailed definitions for the serious and other adverse-event categories, event descriptions for the other adverse events, or whether the same participant could appear in both categories. It also does not provide a comparative safety analysis.

General statistical interpretation of a count from a small, single-group study is limited: the count describes what was recorded among those at risk in this study, but does not estimate a between-group difference. The safety figures do not fill the gap in the unreported PET response results, and they should not be used to infer comparative benefit or harm.

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

This registry entry establishes that a completed pilot trial was designed to assess PET changes after zoledronate therapy in patients with metastatic prostate cancer. It gives the primary response definition: a decline in SUVmean of at least 15% from Scan 2 before Zometa to Scan 3, 1-2 weeks later. It also identifies a 90% confidence interval as the planned measure of uncertainty for the response rate.

What the posted record does not establish is the observed response rate. It does not report how many participants met the threshold, the estimated proportion, or the confidence interval. It also does not report the actual results for PSA, bone scans or bone turnover markers. The endpoint description explains how a response would be defined; it is not evidence that any particular response occurred.

The single-group design also shapes what a result could mean. As a general point, a change observed before and after an intervention is not a direct comparison with what would have happened over the same period without that intervention. The design can describe the study group’s measured changes, but the absence of a control group limits causal interpretation.

The record reports enrollment of 11 and safety counts of zero serious adverse events among 11 at risk and three participants with other adverse events among 11 at risk. Those counts describe the posted safety data and do not provide an efficacy estimate or a comparative safety assessment. No conclusions about treatment effects should be drawn from the design details or safety counts alone.

In short, the registry record makes the study question and planned endpoint interpretable, but leaves the central efficacy result unavailable. A reader can assess the response rule and the study’s broad design, but cannot assess the observed response, its precision, or the secondary outcome findings from this record.

14. Why This Trial Matters Statistically

This trial is statistically notable for the distinction between a clearly defined endpoint and a reported result. The registry specifies the imaging measure, the threshold for response, which scans enter the comparison and the endpoint timeframe. Those details make the planned question understandable. Yet the observed response proportion and its confidence interval are not reported, so the most important statistical summary cannot be evaluated.

The study also illustrates the limits of a single-group before-and-after design. Repeated pretherapy PET scans were described as a way to confirm reproducibility, which recognizes that imaging measurements can vary. In general, repeated measurements can help characterize measurement variation, but they do not provide a concurrent control for changes after treatment. The registry does not report the repeatability findings, leaving that aspect of the planned assessment unresolved.

The binary response definition offers a simple endpoint, but any threshold-based classification compresses a continuous measurement into responder and nonresponder categories. As a general matter, the threshold can aid communication while obscuring how close measurements are to the cutoff and the extent of changes among participants. No individual SUVmean values are posted to complement the binary endpoint.

Finally, the record shows why completion status, enrollment and an outcome definition should not be mistaken for evidence of a study finding. The entry lists a completed study with 11 participants and four outcome measures, but no statistical analyses. The distinction between design information and posted results is essential when judging what can be learned from a registry record.

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 consequential limitation for interpreting this registry entry is the absence of the primary PET response result. The record does not report the response count, the estimated proportion or the planned 90% confidence interval. It also gives no observed results for the secondary outcomes of PSA change, bone scan change and bone turnover marker change. The absence of these results prevents assessment of the direction, magnitude and precision of the measured outcomes.

The study is a pilot with 11 participants and a single-group design. No concurrent control group is recorded, so any change over time would not by itself distinguish treatment-associated change from other influences. The registry’s description of pretherapy scans intended to confirm reproducibility does not include their observed values or a reproducibility result.

Analysis details are also limited. The statistical analysis plan, analysis populations, missing-data handling, protocol-deviation handling and method for calculating the confidence interval are not reported in the registry record. The record does not say whether all enrolled participants contributed to each outcome. The arm description ends before giving the details of Zometa administration, and eligibility criteria are not reported.

The safety record gives participant counts but not event terms for serious events, a detailed account of other events or the observation period. These limitations mean that the registry supports a description of the planned study and the posted safety counts, but not a full assessment of efficacy, precision, analysis conduct or safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: PET Scanning to Evaluate Zoledronate Efficacy in Metastatic Prostate Cancer — NCT01205646.
• Registry record last updated 2019-04-12; status last verified 2019-04.
• Results first posted 2014-06-06.
• 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

This completed, single-group pilot trial evaluated planned PET response measures in patients with metastatic prostate cancer receiving zoledronate therapy. The registry lists enrollment of 11, no masking, and a primary endpoint defined as a decline in SUVmean of at least 15% between the designated pre- and post-Zometa scans. The endpoint timeframe is within 3 weeks, with a 90% confidence interval named as its dispersion measure.

The record also lists secondary outcomes concerning PSA, bone scans and bone turnover markers. It reports zero participants with a serious adverse event among 11 at risk and three with other adverse events among 11 at risk. It does not report the observed primary response, interval limits, secondary outcome results or statistical analyses. The study’s sample-size justification, analysis populations and missing-data methods are not reported in the registry record.