Tracking Renal Tumors After Cryoablation Evaluation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Tracking Renal Tumors After Cryoablation Evaluation (NCT01117779), a registered phase not stated study. The primary outcome is Changes in Lesion Size.

2. Clinical Question

3. Trial Design

TRACE was an observational, open-label, single-arm, multi-center registry of people who had undergone renal lesion cryoablation according to their physician’s standard of care. It was sponsored by Boston Scientific Corporation. The registry lists Kidney Neoplasms as the condition and Cryoablation as the device intervention. Enrollment was 246.

The record states that people aged 18 years or older who were considered appropriate candidates for cryoablation could be offered enrollment. Since treatment was part of usual physician care and the registry was not randomized, it was not designed as a like-for-like comparison between treatment groups. The record does not state an allocation method; no control arm is described.

Participants were to be observed for five years from the date of their cryoablation procedure. The primary-outcome timeframe lists baseline and months 6, 12, 24, 36, 48 and 60. The registry start date is 2010-07-09, and primary completion is listed as 2020-11-24. The status is TERMINATED. The reason for termination is not reported in the registry record, and that status alone does not explain whether follow-up was complete for individual participants.

The primary outcome concerned lesion size. Secondary outcomes are listed as Procedure Method Outcomes and Standard of Care Follow-up Procedures. The record lists 11 outcome measures and zero analyses. It does not report a statistical analysis plan or explain how the listed secondary outcomes were analyzed. Because the study has a single arm and the posted record does not give numerical primary-outcome findings, the design and outcome definitions can be described, but a treatment effect cannot be estimated from this 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

Analysis population for the primary outcome, as defined in the registry: Participants for whom cryoablation via GALIL Medical Cryoablation system was performed with available data at the respective time point.

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 Changes in Lesion Size, measured over Baseline and months 6, 12, 24, 36, 48 and 60.

The primary endpoint was change in lesion size, measured as the greatest trans-axial diameter in centimeters. Measurements were specified for baseline and months 6, 12, 24, 36, 48 and 60. At each time point the summary measure was the median, accompanied by the inter-quartile range. The primary-outcome population was participants who had cryoablation using the GALIL Medical Cryoablation system and had data available at the respective time point.

In general, lesion diameter is a direct measurement of lesion dimensions. Following the measure over time can describe how the distribution of lesion sizes changes among participants with available observations. The median conveys the middle of the observed distribution and is less affected by unusually large or small measurements than the arithmetic mean. The inter-quartile range describes the spread of the middle portion of that distribution; it helps readers see whether participants’ measurements cluster closely or vary more widely. These are general interpretations of the statistics, not claims about the registry’s observed values.

The registry record does not report the medians or inter-quartile ranges at baseline or any follow-up point. It also does not report numerical changes from baseline. Therefore, the endpoint definition is available, but the posted record does not allow readers to assess the magnitude, direction, or precision of lesion-size change. The record does not explain how measurements were obtained, who performed them, or whether measurement procedures were standardized across centers; those details are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the median describe?

The median is the middle value when measurements are arranged from smallest to largest. In general, it provides a measure of the center of a distribution without being pulled as strongly as the mean by extreme observations. For TRACE, the registry specified the median greatest trans-axial lesion diameter at baseline and at scheduled follow-up assessments. This describes the center of the observed lesion-size distribution at each time point; by itself, it does not show how each individual participant’s lesion changed.

What does the inter-quartile range add?

The inter-quartile range, or IQR, describes the spread between the lower and upper quartiles of a distribution. In general, it conveys how dispersed the middle half of observed measurements is. Reporting a median with an IQR can be useful when measurements are skewed or include extreme values. The registry specifies this summary, but does not report the actual medians or IQRs, so the observed distribution and its variability cannot be assessed.

How should repeated time points be understood?

The outcome timeframe includes baseline and months 6, 12, 24, 36, 48 and 60. In general, repeated measurements can describe the course of an outcome over time. A comparison of group summaries across visits is not necessarily the same as calculating each participant’s change and summarizing those changes. The record does not state which approach was used for any numerical analysis, and it provides no such analysis results. It also does not report whether all participants were expected to contribute measurements at every visit or how missed visits were treated.

What does the available-data population imply?

The primary-outcome description includes participants treated using the GALIL Medical Cryoablation system who had data available at the respective time point. In general, an available-case summary uses the observations present for a particular assessment. The contributing participants can differ from one assessment to another if data are missing. This can affect comparisons over time if the participants with measurements are not representative of those without them. The record does not provide visit-specific counts, missingness reasons, or an imputation method, so the impact cannot be evaluated.

What can an observational single-arm design estimate?

In general, an observational registry records care without assigning participants to treatment groups through randomization. A single-arm registry can describe characteristics, procedures, outcomes, and safety events among people who received care. It lacks a separate control group for estimating what would have happened under another treatment or without the intervention. Changes over time may also reflect factors beyond the intervention, including differences in participants’ clinical circumstances or follow-up. Those are general considerations; the registry does not report enough detail to quantify such influences.

TRACE is described as observational, open-label, and single-arm, with cryoablation performed according to physician standard of care. Therefore, the primary outcome is framed as change during follow-up, not as a randomized treatment-versus-control contrast. No allocation method is stated, and no control arm is described. The record does not report an adjusted comparison or a causal analysis.

What precision information is missing?

A confidence interval is a statistical range that, under its method and assumptions, expresses uncertainty around an estimate. In general, narrower intervals indicate greater precision and wider intervals indicate less precision. The registry record does not report confidence intervals for lesion size or change. It also does not provide a statistical test, p-value, or model estimate for the primary outcome. As a result, readers cannot use the record to judge the statistical precision or significance of the primary outcome.

The registry lists zero analyses. This means the record does not give a reported analysis result for the listed outcomes. The particular statistical methods intended for analysis, including any model, adjustment variables, or tests, are not reported in the registry record. It would be inappropriate to infer a method from the outcome summary format alone.

How should planning illustrations be read?

Any sample-size planning illustrations associated with the posted results are not observed trial findings and do not establish the study’s original design requirements. The stated planning assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; they set the effect to detect as a stated fraction of the observed effect. The record describes these as planning illustrations computed from the observed effect, not as the trial’s own design. For time-to-event illustrations, the stated quantity is total events; other illustrations are expressed as participants per arm.

In general, sample-size calculations show how a hypothetical study might be planned under chosen assumptions. They are not observed power, and they do not demonstrate that an effect exists or that the registry had a particular level of power. Here, the design itself is single-arm, while the planning assumptions describe equal allocation between two arms. Such illustrations should therefore be understood as hypothetical planning scenarios, not as a description of TRACE’s enrollment design. The registry record does not report a sample-size justification or its own statistical design plan.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures, including Changes in Lesion Size as the primary outcome and Procedure Method Outcomes and Standard of Care Follow-up Procedures as secondary outcomes. It reports zero analyses. The record does not describe a multiplicity strategy, such as whether or how statistical testing across outcomes or follow-up times would be controlled. It also does not report which outcomes, time points, or comparisons were included in an analysis. Without numerical analyses, it is not possible to evaluate the effect of multiple testing on any reported inference.

Missing-data information is also limited. The primary-outcome population consists of participants with available data at the respective time point, but the record does not give the number with measurements at each assessment. Reasons for missing measurements, follow-up completion by visit, and methods for handling missing observations are not reported in the registry record. In general, complete-case summaries can be biased if the chance of having a measurement is related to the outcome or participant characteristics. Whether that concern applies cannot be assessed from the posted record.

The safety group is labelled “ITT Population,” while the primary outcome uses a time-specific available-data definition. The record does not explain the relation between these populations beyond those descriptions. Because the study is observational and single-arm, the ITT label should not be read as evidence of randomized assignment. The registry does not report analysis populations for the secondary outcomes or provide a statistical plan defining how populations were to be selected.

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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: bleeding/hemorrhage, gu (0.8%), other (0.8%), arrhythmia-supraventricular (0.4%), hematoma (0.4%), infection (documented clinically) with grade 3 or 4 anc (0.4%).

The registry reports serious adverse events affecting 11 of 246 participants at risk and other adverse events affecting 33 of 246 participants at risk. It separately reports 26 deaths. These are counts recorded for the group labelled “Kidney Lesions Amenable to Cryoablation [ITT Population].” The record does not explain whether participants could appear in more than one adverse-event category, so the counts should not be added or treated as mutually exclusive.

The listed serious-event terms include BLEEDING/HEMORRHAGE, GU and OTHER, each reported as 0.8%. ARRHYTHMIA-SUPRAVENTRICULAR, HEMATOMA, INFECTION (DOCUMENTED CLINICALLY) WITH GRADE 3 OR 4 ANC, and PAIN are each reported as 0.4%. These are the posted percentages; the registry record does not provide further event-level detail in the information.

These figures describe reported events in the registry. They do not, on their own, establish that an event was caused by cryoablation. The record does not report event timing, duration, individual-level overlap, or a comparator group for interpreting relative safety. The reported deaths should likewise be read as a count, not as evidence about cause or treatment attribution; those details are not reported in the registry record.

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

TRACE describes an observational registry intended to follow people after renal lesion cryoablation. Its primary endpoint is defined as median greatest trans-axial lesion diameter, with an IQR, at baseline and scheduled follow-up through month 60. The record also lists selected adverse-event counts. These details establish what was intended to be measured and identify some reported safety information.

The record does not report numerical primary-outcome values or analyses. It therefore does not show how lesion size changed, how variable the measurements were, or how precisely any change was estimated. No conclusion about the direction or magnitude of lesion-size change can be drawn from the endpoint definition alone. The absence of posted results is not evidence that there was no change; it means the numerical outcome findings are not reported in the registry record.

The study’s single-arm observational design also sets limits on interpretation. A descriptive change over time would not, by itself, show that cryoablation caused the change. There is no control group in the record to provide a direct comparison with another treatment or with no intervention. The record does not report methods that would adjust for other possible explanations.

The reported adverse-event figures are counts and percentages for the stated safety group. They describe what the registry lists, but do not establish causation or allow comparison with another group. The record does not report event-level timing or attribution details. Overall, the registry record supports a description of the study design, planned lesion-size measure, and selected safety counts; it does not provide enough numerical outcome or analysis information to determine an efficacy effect or a comparative safety effect.

13. Why This Trial Matters Statistically

TRACE is statistically informative as an example of how a longitudinal registry can define a clinical outcome without using a randomized comparison. It specifies lesion diameter as a repeated measure and identifies a median and IQR as summaries. This makes the intended outcome construct and summary approach clear, even though the numerical outcome results are not reported.

The record also highlights the importance of distinguishing a planned follow-up schedule from complete observed follow-up. The outcome population is defined by data availability at each time point, but visit-specific counts and missing-data methods are not reported. For longitudinal evidence, those details help readers understand who contributed to each summary and whether the composition of the observed group changed over time. Without them, interpretation of trends would be limited even if summary values were available.

A further statistical lesson is that repeated measurements in a single arm answer a descriptive question, not the same question as a controlled treatment comparison. A baseline-to-follow-up pattern can characterize observations after treatment, but without a comparator it cannot isolate the effect of treatment from other influences. TRACE’s design should therefore guide how any reported change is interpreted.

Finally, the registry lists 11 outcome measures but zero analyses, and gives safety counts without detailed event attribution. This illustrates why outcome definitions, analysis methods, missing-data reporting, and safety context are all needed alongside counts or summary statistics. The registry record makes the intended measurement framework visible, while its absent numerical primary findings prevent readers from assessing the amount and precision of any observed change.

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 main limitation for interpretation is that numerical primary-outcome results are not reported in the registry record. Although the outcome and its scheduled assessments are defined, no median lesion sizes, IQRs, or changes from baseline are available. The record also lists zero analyses, leaving no reported statistical estimates or tests to evaluate.

The study is observational, open-label, and single-arm, with no control group described. Thus, even if descriptive changes were reported, the design would not by itself support a controlled estimate of the effect of cryoablation. The registry states treatment was performed according to physician standard of care, but does not report the treatment details or a standardized procedural protocol.

The primary-outcome population is limited to participants treated using the GALIL Medical Cryoablation system who had data available at the relevant time point. The record does not report how many participants contributed at each visit, how missing measurements were handled, or why data were unavailable. It also does not describe measurement procedures or report whether they were standardized across centers.

The registry is marked TERMINATED, but the reason for termination is not reported in the registry record. The listed primary completion date does not, by itself, establish the completeness of participant follow-up. The safety counts lack details on event timing, attribution, and overlap among categories. Finally, no statistical analysis plan, sample-size justification, or multiplicity approach is reported. These gaps limit assessment of precision, bias, and the scope of any conclusions.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Tracking Renal Tumors After Cryoablation Evaluation — NCT01117779.
• Registry record last updated 2024-01-19; status last verified 2023-04.
• Results first posted 2024-01-19.
• 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

TRACE (NCT01117779) is an observational, open-label, single-arm, multi-center registry of renal lesion cryoablation performed according to physician standard of care. The registry lists enrollment of 246, a start date of 2010-07-09, primary completion on 2020-11-24, and status TERMINATED.

The primary outcome is median greatest trans-axial lesion diameter in centimeters, with an IQR, at baseline and months 6, 12, 24, 36, 48 and 60. The registry record does not report numerical results for this outcome and lists zero analyses. It reports serious adverse events affecting 11 of 246 at risk, other adverse events affecting 33 of 246 at risk, and 26 deaths. Event attribution and the reason for termination are not reported in the registry record.