GA-68 DOTA-TOC of Somatostatin Positive Malignancies: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for GA-68 DOTA-TOC of Somatostatin Positive Malignancies (NCT02177773), a na phase 1, phase 2 study. The primary outcome is Number of Lesions as Determined by Gallium Ga 68-DOTA-TOC Positron Emission Tomography (PET) Imaging.

2. Clinical Question

3. Trial Design

The registry classifies this as a phase I/II, single-group study with no masking. Allocation is recorded as not applicable. The listed study agent is gallium Ga 68-DOTA-TOC, with PET imaging and either computed tomography or magnetic resonance imaging as the associated procedures. The study description allows PET/CT or PET/MRI; it does not describe random assignment between those imaging options.

The registry lists enrollment as 300. The study began on 2014-06-23, and the primary completion date is 2017-08-07. Its status is terminated. The record says that, after the study agent was approved by FDA for the indication, the decision was made not to continue the investigation or use resources to analyze collected data to assess effectiveness. Thus, the record includes an intended comparison of imaging measures but does not report an effectiveness analysis.

The primary outcome description refers to assessing lesions in specified body regions and comparing imaging findings within patients. A secondary outcome concerns change in clinical stage determined by conventional imaging and redetermined by gallium Ga 68-DOTA-TOC PET imaging. The registry lists four outcome measures, but does not report analyses for them. It does not report a separate control arm, a masking procedure, or an allocation scheme beyond the single-group classification and allocation marked not applicable.

This design can describe paired imaging assessments, but it is not a randomized trial of one treatment against another. Since effectiveness analyses were not reported, the design details alone cannot establish the diagnostic performance of the imaging approach. Further details about recruitment, the number receiving each imaging option, or why the study was formally terminated are not reported in the registry record beyond the explanation concerning approval and the decision not to analyze the collected data.

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

Analysis population for the primary outcome, as defined in the registry: Since the study agent was approved for the indication by FDA it was decided not to continue investigation and waste resources to analyze data collected to see if the agent is effective for the indication.

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 Lesions as Determined by Gallium Ga 68-DOTA-TOC Positron Emission Tomography (PET) Imaging, measured over 1 day.

The primary outcome is titled as the number of lesions determined by gallium Ga 68-DOTA-TOC PET imaging. Its description gives additional detail: the five largest lesions in each of eight body regions are to be assessed for short and long axis size and maximum standardized uptake value on conventional imaging and gallium Ga 68-DOTA-TOC PET imaging. Reader confidence that each lesion represents metastasis is also to be recorded on a scale from 1, benign, to 5, malignant.

The description then specifies comparing the number of positive body regions between conventional imaging and PET/CT, and comparing reader confidence for paired lesions. This means the stated title and the detailed measurement description do not point to only one simple measure: lesion measurements, positive body regions, and reader confidence are all described. The record does not clarify how these components were combined or identify a single summary measure beyond the title.

These measures are intended to characterize what the imaging detects and how readers classify lesions. Comparing paired findings can account for the fact that the two imaging assessments concern the same patient or lesion. However, the registry does not report the resulting measurements or an analysis. The clinical meaning of any difference, including its precision, therefore cannot be assessed from the reported record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome description specifies paired comparisons. A paired design means that the observations being compared are linked, rather than treated as if they came from unrelated groups. In this study, the described comparison is between conventional imaging and gallium Ga 68-DOTA-TOC PET imaging. Pairing can be useful because characteristics shared by the same patient may affect both imaging assessments. The statistical analysis then focuses on within-pair differences rather than comparing unrelated patient groups.

What does the paired t-test assess?

The registry description names a paired t-test for comparing the number of positive body regions identified by conventional imaging and gallium Ga 68-DOTA-TOC PET/CT. General explanation: this test evaluates the average of the paired differences. Its usual interpretation relies on the paired differences being reasonably compatible with the test’s distributional assumptions. The test does not itself establish that a measure is clinically meaningful, and a result would need to be interpreted alongside an estimate of the difference and its uncertainty.

The record says the Wilcoxon signed-rank test would be used if the data appeared not to be normally distributed. General explanation: this is a rank-based method for paired differences. It uses the ordering and signs of the differences rather than relying on the same normality assumption as the paired t-test. It can be a useful alternative when the distributional assumptions for the paired t-test are not suitable, but it still requires valid paired observations and an appropriate interpretation of the differences. The registry does not state how normality would be assessed or what decision rule would determine which test was used.

How is reader confidence compared?

The description also specifies the Wilcoxon signed-rank test for reader confidence ratings on paired lesions. Confidence is recorded on an ordinal scale from 1, benign, to 5, malignant, with intermediate categories described as likely benign, indeterminant, and likely malignant. General explanation: ordinal ratings have a meaningful order, but the spacing between adjacent categories is not necessarily equal. A rank-based paired method can reflect the ordered nature of such data without treating every step in the scale as an identical numerical interval. The registry does not report the reader ratings or the results of this planned comparison.

The lesion measurements have a separate descriptive role. The plan includes short and long axis size and maximum standardized uptake value for selected lesions on both imaging approaches. These measurements may characterize findings, while the described inferential comparisons focus on positive body regions and reader confidence. The record does not specify a statistical test for every listed measurement, nor does it explain whether the outcome title, lesion measurements, region counts, or confidence ratings would take priority if their findings differed.

Why does the paired structure matter?

General explanation: treating paired observations as independent can discard the connection between measurements and can misrepresent uncertainty. A paired analysis preserves that connection by analyzing the difference within each pair. This approach is distinct from a comparison of independent treatment arms. Here, the registry identifies a single-group design and describes comparisons between imaging assessments, rather than randomization to an imaging method and a control method.

The methods described are plans in the registry record; no test statistic, p-value, effect estimate, confidence interval, or outcome-specific analysis is reported. Therefore, the statistical method names cannot be used to infer whether a comparison was statistically significant or what its direction might have been. The record lists zero analyses, and says the collected data were not analyzed for effectiveness after the decision to stop further investigation following FDA approval for the indication.

The sample-size assumptions included in the record concern planning illustrations computed from an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The record also distinguishes time-to-event planning as a total number of events and other planning as participants per arm. Those assumptions do not describe this single-group imaging study’s own design, and no sample-size illustration values are included in the registry record. Such planning values, when available, are not observed power and do not replace an analysis of collected outcomes.

General explanation: over-dispersion is a situation in which the variability in data is greater than assumed by a model. If present, standard errors based on an overly restrictive variance assumption may be too small, making uncertainty appear less than it is. The registry does not specify an over-dispersion model for this study, and the listed paired tests are not evidence that over-dispersion was evaluated. More broadly, selecting a test requires matching the method to the data structure, measurement scale, assumptions, and analysis question; the registry gives some intended methods but not a completed analysis plan or results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures. The primary outcome description includes several related measurements and comparisons: lesion size and uptake, positive body regions, and reader confidence. A secondary outcome concerns change in clinical stage after reassessment with gallium Ga 68-DOTA-TOC PET imaging. When several outcomes or comparisons are considered, there is a general statistical issue of multiplicity: the chance of finding an apparently notable result can increase if many tests are performed. An analysis plan may address this by defining a primary comparison, adjusting for multiple testing, or treating additional results as exploratory.

Any multiplicity approach for this study is not reported in the registry record. The record does not describe a hierarchy among the measurements in the primary outcome description, an adjustment procedure, or a prespecified approach to interpreting multiple tests. Since effectiveness analyses are not reported, there are no posted results from which to assess whether multiplicity affected interpretation.

Missing-data procedures are also not reported in the registry record. It does not state how incomplete scans, unpaired observations, unreadable images, or missing lesion assessments would have been handled. The enrollment figure does not establish the number of evaluable observations for each measure, and outcome-specific denominators are not reported.

The analysis populations are not reported in the registry record. There is no description of whether analyses would include all enrolled participants, only those completing both imaging approaches, or another defined group. The record lists zero analyses and says the collected data were not analyzed for effectiveness. As a result, neither the handling of missing data nor the composition of any analysis population can be evaluated from the posted information.

11. 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 0% reporting threshold.

The registry reports a DOTATOC Imaging group with 300 participants at risk in the serious adverse event category and 0 affected. It also reports 300 at risk in the other adverse event category and 0 affected. The listed number of deaths is 0, and no top serious adverse event terms are listed.

These are the figures recorded for the study, not an estimate of risk compared with a control group. The study is single-group, and the record does not provide a randomized safety comparator. The figures should therefore be read as registry-reported counts, not as evidence that the imaging procedure or agent has no risk. The record does not explain the completeness of adverse-event collection, the observation period used for these counts, or whether the entries capture every event among all participants.

General explanation: an at-risk count describes the group included in a reported safety category, while an affected count describes participants recorded as having an event in that category. The registry does not provide event terms for serious events. These safety entries do not answer the separate imaging-effectiveness question, and they do not provide detail about event severity beyond the serious and other categories shown.

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

The registry record documents a phase I/II, single-group investigation of gallium Ga 68-DOTA-TOC PET imaging, with PET/CT or PET/MRI described as imaging options. It sets out a plan to assess lesions, positive body regions, and reader confidence, and to compare selected findings with conventional imaging. It also lists a secondary outcome concerning clinical-stage change. These details show what the investigators intended to measure, not what the study found.

The record marks the trial terminated and states that the study agent had been approved by FDA for the indication, after which the decision was made not to continue the investigation or use resources to analyze collected data for effectiveness. No primary outcome results or analysis are reported. Thus, the record does not establish whether the imaging agent improved lesion detection, produced different region counts, changed reader confidence, or altered clinical stage.

The lack of analyzed results should not be interpreted as a null finding. No result is reported that could support a conclusion of no difference, equivalence, or benefit. Nor can the study’s diagnostic accuracy, precision, or generalizability be judged from its enrollment field alone. The record does not provide outcome estimates, uncertainty intervals, analysis populations, or the number of evaluable paired observations.

General explanation: an imaging comparison may show a difference in what is detected without establishing that the difference changes diagnosis or care. Conversely, a lack of statistical evidence for a difference, if it had been reported, would not by itself prove that the methods were equivalent. Those interpretations require appropriate estimates, uncertainty, definitions, and study design. Here, the registry record does not report an effectiveness analysis from which to make such assessments.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of the difference between a measurement plan and an analyzed result. The registry gives a detailed description of the imaging assessments and names paired statistical tests. Yet it also says the collected data were not analyzed for effectiveness. A method listed in a protocol description is not evidence that an analysis was completed, and it cannot supply a result that the registry does not report.

The study also illustrates why the design structure matters. The trial is classified as single-group, while the described comparison is between imaging assessments within patients or lesions. This is not a randomized comparison of separate groups. Paired methods are appropriate to consider for linked observations, but the registry does not report estimates or uncertainty that would let readers judge the magnitude or precision of any imaging difference.

Another statistical issue is outcome definition. The primary outcome title refers to number of lesions, while its description discusses lesion characteristics, number of positive body regions, and reader confidence. A clear hierarchy and explicit analysis population help readers understand which measure answers the main question and how additional measures contribute. Those details and completed analyses are not reported in the registry record.

Finally, the recorded termination context matters when interpreting absent results. The registry says the agent was approved for the indication and the study was not continued to analyze collected data for effectiveness. This explains why the record does not provide those analyses; it does not turn the missing results into evidence for or against the imaging approach. Statistical interpretation must distinguish what a study planned to measure from what it actually reports.

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.

Several limitations follow directly from the registry record. It reports no effectiveness analyses, so there are no estimates or uncertainty measures for the primary outcome or secondary clinical-stage outcome. Although enrollment is listed as 300, outcome-specific denominators and the number of participants with paired, evaluable imaging are not reported in the registry record.

The primary outcome title and its detailed description cover multiple measurement types. The title refers to number of lesions, while the description includes lesion size and uptake, positive body regions, and reader confidence. The record does not clarify which measure was the principal summary or how any measures would be prioritized. It also does not report how missing or incomplete imaging data would be handled, which analysis population would be used, or whether multiplicity would be addressed.

The design is single-group, unmasked, and has allocation recorded as not applicable. It therefore does not provide a randomized control-arm comparison. The registry describes conventional imaging as the paired reference for specified assessments, but does not provide details about its selection or timing beyond the comparison described. Further information about patient characteristics, image-reader procedures, and the number receiving PET/CT versus PET/MRI is not reported in the registry record.

The study is marked terminated, and the registry says data were not analyzed for effectiveness after approval of the study agent for the indication. The reason beyond that stated explanation, and the consequences for completeness of data collection, are not reported in the registry record. These limits mean that neither the planned statistical approach nor the listed enrollment can resolve the unanswered effectiveness questions.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: GA-68 DOTA-TOC of Somatostatin Positive Malignancies — NCT02177773.
• Registry record last updated 2019-11-12; status last verified 2019-10.
• Results first posted 2019-11-12.
• 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.

18. Record Summary

The registry describes a phase I/II, single-group study of gallium Ga 68-DOTA-TOC PET imaging for somatostatin receptor positive malignancies. Patients are described as receiving the agent intravenously before PET/CT or PET/MRI. The primary outcome concerns lesions and includes planned paired comparisons with conventional imaging; the secondary outcome concerns clinical-stage change.

The record lists enrollment as 300 and status as terminated. It states that, after FDA approval of the agent for the indication, the investigation was not continued and collected data were not analyzed for effectiveness. No effectiveness results or analyses are reported. The registry safety entries report 0 affected in both the serious and other adverse event categories and 0 deaths, with 300 at risk in each category.