Calcium-41 (41Ca) Chloride Aqueous Solution in Diagnosing Patients With Prostate Cancer and Bone Metastasis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Calcium-41 (41Ca) Chloride Aqueous Solution in Diagnosing Patients With Prostate Cancer and Bone Metastasis (NCT00918645), a na na study. The primary outcome is Number of Patients Whose Samples Were Measured for Pharmacokinetics.

2. Clinical Question

The study concerned whether calcium-41 (41Ca) chloride aqueous solution could be used in evaluating patients with prostate cancer and bone metastasis. Its stated purpose was to study how well the solution worked in diagnosis. The registry lists a pharmacokinetic measurement endpoint and secondary outcomes concerning urinary 41Ca clearance and disease progression or stage. It does not report patient-level results for those outcomes, so the record does not establish whether clearance was associated with progression or stage.

The secondary questions were whether urinary 41Ca clearance correlated with disease progression and whether 41Ca clearance correlated with disease stage. These are questions about measured relationships, not randomized comparisons of treatments. The registry record does not report estimates of either relationship, nor does it give results that would answer the diagnostic-purpose question.

3. Trial Design

NCT00918645 is listed as a single-group study with one named intervention, 41 Ca. The condition entries are metastatic cancer and prostate cancer. The registry lists enrollment of 13, phase NA, allocation NA, and masking NONE. No separate control group is described, so the design does not provide a like-for-like comparator for estimating a between-group effect.

The study is titled “Calcium-41 (41Ca) Chloride Aqueous Solution in Diagnosing Patients With Prostate Cancer and Bone Metastasis”; its official title is “Measurement of Ca Kinetics in Humans With Prostate Cancer-induced Bone Disease.” The sponsor is the University of California, Davis. The listed start is 2009-09, and primary completion is listed as 2013-01. The status is TERMINATED. The registry record does not explain the reason for termination, whether enrollment reached the listed number, or how many participants completed specimen collection.

The primary outcome concerns the number of patients whose samples were measured for pharmacokinetics, with specimen collection described over 18 months. The description refers to pre-dose specimens, urine collected 6 hours after dosing on Day 1, later urine specimens, and blood specimens collected at the same time of day if feasible. However, the outcome population entry states that no data was collected from the specimens. Thus, the listed collection schedule describes the intended measurements, but the record does not document analyzable pharmacokinetic observations.

Two secondary outcomes concern correlations between urinary 41Ca clearance and disease progression or stage. The registry lists three outcome measures in total and zero analyses. A statistical analysis plan, further eligibility details, and an explanation of the terminated status are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: No data was collected from the specimens.

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 Number of Patients Whose Samples Were Measured for Pharmacokinetics, measured over Samples will be collected over 18 months.

The primary endpoint is the number of patients whose samples were measured for pharmacokinetics. It is a count of patients with samples measured, rather than a reported estimate of calcium kinetics, a measure of diagnostic accuracy, or a comparison of clinical outcomes. The unit, parameter, and dispersion are not specified in the registry record.

Pharmacokinetic measurements can describe how a substance is absorbed, distributed, and cleared over time. In general, repeated specimen measurements can help characterize the time course of a measured substance. The registry describes urine and blood collection over 18 months, including pre-dose specimens and a Day 1 urine collection 6 hours after dosing. Those details indicate the intended measurement schedule; they do not establish that the scheduled measurements were completed or analyzed.

The stated purpose was diagnostic, and the secondary outcomes were framed around urinary 41Ca clearance in relation to disease progression and disease stage. A count of patients with measured samples could indicate whether the data needed for pharmacokinetic analysis were obtained, but it would not by itself show diagnostic performance or establish a relationship with disease status. Most importantly, the primary outcome population states that no data was collected from the specimens. No endpoint value or pharmacokinetic result is reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group study, not a randomized comparison. In general, a single-group study can describe measurements among participants who receive the listed intervention, but it does not estimate a contrast against a concurrent control group unless such a group is included. No separate comparator is listed, and allocation is NA. Masking is recorded as NONE. These design entries do not show that a particular statistical model was used; the analysis methods are not reported in the registry record.

What the primary endpoint can measure

The primary endpoint is a patient count: the number whose samples were measured for pharmacokinetics. Counts describe how many observations meet a stated condition. They are distinct from continuous pharmacokinetic values, such as measured concentrations or clearance estimates. The endpoint fields for unit, parameter, and dispersion are empty, and the population description states that no data was collected from the specimens. Accordingly, the record supplies no endpoint count or pharmacokinetic estimate to interpret.

In general, a count may be reported with a clear denominator and definition of what qualifies as measured. The registry record does not explain whether a patient would count after any specimen was measured, after a complete specimen series, or after another criterion. Nor does it state how incomplete specimen collection would affect endpoint status. These details matter because different definitions can produce different counts, even when they refer to the same intended endpoint.

What the secondary questions require

The secondary outcomes concern correlations between urinary 41Ca clearance and disease progression, and between clearance and disease stage. In general, a correlation summarizes the direction and strength of association between measured quantities. Interpreting one requires a definition of each variable, the observations included, the analysis method, and an estimate with suitable uncertainty. The registry record does not report those definitions beyond the outcome titles, any correlation coefficient, or any analysis result. A correlation would describe an association in the analyzed data; it would not on its own establish causation or diagnostic accuracy.

For disease progression, the timing and definition of progression can affect which observations are compared. For disease stage, the coding and timing of stage assessments also matter. Such details are not reported in the registry record. The stated specimen schedule extends over 18 months, but that timeframe does not establish which observations were paired for an analysis or whether follow-up data were available.

Precision and uncertainty

In general, an estimate is more informative when accompanied by an uncertainty interval. A confidence interval describes a range of values compatible with the observed data under the analysis assumptions; it does not guarantee that the true value lies within that range. For a correlation, the interval helps show how precisely the association was estimated. For a count, a denominator and an appropriate uncertainty description help distinguish a small observed count from a reliably estimated rate. The registry record reports no estimates or confidence intervals for the listed outcomes, so precision cannot be assessed.

Small or sparse datasets can make estimates unstable, and incomplete specimen collection can reduce the information available for analysis. The listed enrollment is 13, but the number with measured samples is not reported. It is therefore not possible to assess the effective sample size for the primary or secondary analyses, or to determine whether any estimate would be precise. Over-dispersion is a general concern when count variability exceeds what a chosen count model assumes; the registry does not report a count model or data with which to assess this issue.

Planning assumptions are not analysis results

The record includes a statement that planning illustrations use 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. It also distinguishes total events for time-to-event calculations from participants per arm for other calculations. These are planning assumptions, not evidence that the trial used a two-arm design or carried out those analyses. The actual registry design is single-group, and no analysis results are listed. Sample-size illustrations are hypothetical planning quantities, not observed power or evidence that a planned effect occurred.

In general, a sample-size calculation depends on a specified outcome, target effect, variability assumptions, allocation, and error-rate choices. Its output describes a design under those assumptions. It does not establish the amount of information actually collected, nor does it correct for missing outcome data. Here, no analysis plan or sample-size justification for the trial itself is reported in the registry record. The record’s planning statement cannot be used to infer the protocol, the reason for termination, or what analysis was actually performed.

What can be concluded statistically

The available statistical record is descriptive: it identifies intended endpoints and the study structure, but gives no outcome estimates, uncertainty intervals, or analysis methods. Because the specimen population entry says no data was collected and the analysis count is zero, there is no reported statistical result from which to estimate a pharmacokinetic pattern or relationship with disease status. Any general interpretation of correlation, confidence intervals, count models, or planning calculations explains statistical concepts; it does not fill in the missing trial results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures: the primary pharmacokinetic sample-measurement count and two secondary outcomes concerning relationships between urinary 41Ca clearance and disease progression or disease stage. When several outcomes are examined, multiplicity can increase the chance of at least one apparently notable result arising by chance. In general, investigators may address this by defining a primary outcome, setting an analysis hierarchy, or adjusting inference across outcomes. A multiplicity strategy is not reported in the registry record. Since zero analyses are listed and no outcome results are reported, there are no posted tests to interpret or adjust.

The primary outcome description states that no data was collected from the specimens. The record does not explain whether other data were collected, whether any participants had partial specimen collection, or how missing measurements would be handled. Imputation, complete-case analysis, and other missing-data methods are not reported in the registry record. No analysis population is defined, and the record does not say how the enrolled participants relate to any population eligible for analysis.

The listed enrollment is 13, but the registry does not give the number with usable specimens, the number included in any secondary assessment, or a breakdown of missingness. In general, missing data can affect both precision and the interpretation of an estimate, especially when the reason data are missing is related to participant characteristics or outcomes. The record provides no information to assess that possibility.

The adverse-event entries list zero at risk and zero affected in the serious and other event categories; deaths are not reported in the registry record. Those entries do not resolve the missing outcome information or establish that participants were assessed for adverse events. Reasons for termination and any consequences for data collection or analysis are also not reported.

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

The record establishes that a study was registered to examine calcium-41 chloride aqueous solution in patients with prostate cancer and bone metastasis, with a pharmacokinetic sample-measurement endpoint and two secondary questions about urinary clearance. It also records a single-group design, enrollment of 13, a terminated status, and a specimen collection timeframe of 18 months. These details describe the study’s stated scope and design, not its findings.

The record does not show that the intervention did or did not work as a diagnostic procedure. It contains no reported pharmacokinetic results, no reported correlation with progression or disease stage, and no reported diagnostic-performance measures. The primary outcome population entry says no data was collected from the specimens, and zero analyses are listed. Absence of a reported result is not evidence that a relationship was absent; it means the registry record does not permit that relationship to be evaluated.

The single-group design is not a randomized comparison. Even if an association had been reported, it would not by itself establish a causal effect or demonstrate that the measurement can distinguish disease states accurately. Interpretation of diagnostic use would generally require appropriate validation and an account of measurement performance; such results are not reported in the registry record.

The enrollment entry should not be mistaken for a count of analyzed participants. The record does not specify how many people contributed usable samples or completed the intended schedule. Likewise, the adverse-event entries with zero at risk do not establish that no adverse events occurred among an assessed group. The death field is not reported. Thus, the posted information cannot support a conclusion about safety.

In practical statistical terms, the record is informative about the intended question and the lack of analyzable specimen results documented in the registry, but it does not resolve the scientific question. It cannot establish the size, direction, precision, or clinical meaning of any pharmacokinetic or disease-status relationship.

12. Why This Trial Matters Statistically

This study is statistically notable because its intended diagnostic question depends on measurements and relationships, while the primary endpoint is framed as a count of patients whose samples were measured. Those are related but different questions. A count of measured samples could describe data availability; it would not itself quantify calcium kinetics, show a correlation, or establish diagnostic performance. Clear distinctions among feasibility, measurement, association, and diagnostic accuracy are essential when defining outcomes.

The record also illustrates why design and analysis need to be interpreted together. A single-group study can describe observed measurements, but it has no listed comparator for a between-group contrast. Its secondary correlation questions concern association, not randomized treatment effects. The registry’s planning statement refers to equal allocation between two arms, while the registered design is single-group. Because the statement is explicitly about planning illustrations rather than the trial’s own design, it should not be read as evidence of a hidden comparator or an analysis actually performed.

Missing outcome information is central to the interpretation. The registry states that no data was collected from the specimens and lists zero analyses. Without measurements, there is no estimate whose magnitude or precision can be assessed. This is different from a result showing no association: no association estimate is reported at all.

Finally, the terminated status and the distinction between listed enrollment and analyzed participants matter. The record does not explain why the study was terminated or how much data collection occurred. Statistical interpretation requires knowing the analysis population and the extent of missingness, not just the planned questions. The registry record leaves those matters unresolved, so its value is chiefly in documenting the intended study and the limits of the recorded results.

13. 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 is that the primary outcome population states that no data was collected from the specimens. The registry therefore provides no pharmacokinetic measurements with which to answer the main study question. Although the protocol description outlines specimen timing, it does not establish that specimens were collected, measured, or analyzed according to that schedule.

The record lists enrollment of 13 but does not report how many participants contributed any specimens or how many had data suitable for the secondary outcomes. It also does not define an analysis population or explain whether participants with incomplete collection would be included. The status is TERMINATED, but the reason for termination, extent of follow-up, and effect on data collection are not reported in the registry record.

The single-group design has no separate comparator listed. This limits the design to descriptions of the observed group and prevents a direct between-group comparison. The secondary outcomes concern correlations, but the record does not provide detailed definitions for progression or stage, the timing of those assessments, or the planned correlation methods. No diagnostic accuracy endpoint or result is reported.

The statistical analysis plan, handling of missing data, multiplicity approach, and trial-specific sample-size justification are not reported in the registry record. Zero analyses are listed, and no estimates or uncertainty measures are presented. The planning assumptions that appear in the record are described as illustrations rather than the trial’s own design; they cannot fill these gaps.

Safety interpretation is also limited. The adverse-event entries list zero participants at risk and zero affected, and the death count is not reported. These fields do not establish the size of a safety-assessed population. Taken together, these limitations mean the registry record supports description of the intended study but not an assessment of its pharmacokinetic, diagnostic, or safety findings.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Calcium-41 (41Ca) Chloride Aqueous Solution in Diagnosing Patients With Prostate Cancer and Bone Metastasis — NCT00918645.
• Registry record last updated 2017-12-22; status last verified 2017-12.
• Results first posted 2017-12-22.
• 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.

17. Record Summary

NCT00918645 is a terminated, single-group study sponsored by the University of California, Davis. It concerns calcium-41 chloride aqueous solution in patients with prostate cancer and bone metastasis. The registry lists enrollment of 13, phase NA, allocation NA, and masking NONE. The listed study start is 2009-09, and primary completion is 2013-01.

The primary outcome is the number of patients whose samples were measured for pharmacokinetics, with a stated specimen collection timeframe of 18 months. Two secondary outcomes concern urinary 41Ca clearance in relation to disease progression and disease stage. The primary outcome population states that no data was collected from the specimens, and zero analyses are listed. No outcome estimates, uncertainty measures, analysis plan, or reason for termination are reported in the registry record. The posted record describes the study’s intended questions but does not provide results that answer them.