MR-Guided Laser Interstitial Thermal Therapy in Treating Patients With Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for MR-Guided Laser Interstitial Thermal Therapy in Treating Patients With Prostate Cancer (NCT01792024), a na na study. The primary outcome is Number of Participants With Undetectable Cancer on MRI-guided Biopsy of Ablation Zone Following Treatment.

2. Clinical Question

The study examined a local tissue finding after treatment: whether biopsy of the treated zone detected cancer at the specified follow-up. That question is narrower than whether participants had cancer elsewhere in the prostate, whether cancer returned later, or whether treatment changed longer-term outcomes. Those broader questions are not captured by the primary endpoint as described.

The registry also lists secondary outcomes concerning cancer found in the treatment zone, adverse events related to treatment, and urinary and sexual function during the year following treatment. The functional outcomes were to be assessed using the International Prostate Symptom Score and the Sexual Health Inventory in Men. The registry record does not report numerical results for these outcomes.

Because the design is single-group and unmasked, the central question is descriptive: what outcomes were recorded among participants treated with this approach? Without a concurrent comparator, the study cannot by itself establish how those outcomes differ from what would have happened under another treatment or no treatment. The missing primary result also means the stated question cannot be answered from the registry record.

3. Trial Design

The registry identifies this as a completed, single-group study with enrollment of 27 participants. Its title describes a Phase II evaluation, while the phase field is recorded as NA. Allocation is also recorded as NA, and masking is listed as none. The named treatment group is Treatment (LITT); no separate control group is described.

Participants in the treatment group underwent magnetic resonance imaging-guided laser thermal therapy using the Visualase Thermal Therapy device. The registry lists magnetic resonance imaging as a procedure and Visualase Thermal Therapy as a device. The study concerns Stage I Prostate Cancer and Stage II Prostate Carcinoma. More detailed information about eligibility, the treatment procedure, or how participants were selected is not reported in the registry record.

The primary endpoint was assessed at 3 months after ablation. It was the number of participants with no cancer detected on MRI-guided biopsy of the ablation zone. Secondary outcomes included cancer on biopsy of the treatment zone, treatment-related adverse events, and urinary and sexual function during the year following treatment, assessed with named questionnaires.

The registry reports 5 outcome measures and 0 analyses. The primary endpoint result and numerical results for the listed secondary outcomes are not reported in the registry record. Statistical methods used to analyze the outcomes, including any adjustment or modeling strategy, are not reported in the registry record.

The study dates recorded are a start date of 2013-01-28 and a primary completion date of 2015-09-16; the status is completed. A completed status indicates the registry's status for the study, not that results for every listed outcome are available in the record. The single-group structure is important when interpreting the results: observations after treatment can describe this treated group, but do not provide a direct randomized comparison.

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 Number of Participants With Undetectable Cancer on MRI-guided Biopsy of Ablation Zone Following Treatment, measured over At 3 months after ablation.

The primary endpoint counts participants with no cancer detected on MRI-guided biopsy of the ablation zone at 3 months after ablation. It is a binary outcome at the participant level: each assessed participant either meets the stated criterion or does not. The registry labels the endpoint as a count of participants, rather than a continuous measurement such as a score.

A biopsy-based endpoint can provide a direct assessment of whether cancer was found in sampled tissue from the treated zone at the stated follow-up. The endpoint is used to describe a treatment-related tissue finding at a defined location and time. It does not, by itself, describe cancer status across the entire prostate or establish what would have happened without treatment.

Interpretation depends on knowing both the count meeting the criterion and the number of participants whose biopsy outcome was assessed. The registry record does not report the primary endpoint result, the number assessed for this endpoint, or details about how missing or indeterminate biopsy findings were handled. Therefore, the endpoint's observed frequency and its precision cannot be evaluated from the registry record.

The stated assessment time is 3 months after ablation. Findings at that time do not establish longer-term status. The registry lists other outcomes, including a measure of cancer in the treatment zone and functional outcomes over the year following treatment, but their numerical results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

A participant-level binary endpoint classifies each assessed participant according to whether a specified event or condition is present. Here, the primary outcome is framed as the number of participants with no cancer on MRI-guided biopsy of the ablation zone at 3 months after ablation. A complete analysis would ordinarily make clear how many participants met the criterion and how many had an evaluable biopsy. Neither result is reported in the registry record.

What does a count show?

A count communicates how many participants met a definition. A count alone does not communicate the frequency in the group unless its denominator is also clear. For a binary outcome, a proportion can be informative, and an interval estimate can show statistical uncertainty around that estimate. These are general statistical concepts; the registry record does not report a primary outcome proportion or confidence interval. No new estimate can be reconstructed from the reported enrollment alone because the number with an assessed biopsy result is not stated.

A confidence interval is a way to express the uncertainty of an estimate under a specified statistical method. It is not a guarantee that the true value lies inside the interval, nor does it address sources of bias such as missing assessments or selection into the study. For a study with one group, an interval around an outcome frequency would describe uncertainty about that group's outcome under the analysis assumptions. It would not create a comparison group or establish a treatment effect relative to another option.

Why does the design matter?

The registry describes a single-group study and lists no masking. In a randomized comparison, assignment to groups is intended to make the groups comparable on average, while a concurrent control helps distinguish treatment-associated outcomes from outcomes that may occur for other reasons. Neither feature is available as a between-group comparison in this design. This does not prevent descriptive reporting, but it limits causal interpretation. The registry record does not report a comparative effect estimate.

Masking can reduce the influence of knowledge of treatment assignment on aspects of care, assessment, or reporting. The record lists masking as none. The extent to which this could affect any particular outcome depends on how it was assessed and recorded; further assessment procedures are not reported in the registry record. The primary endpoint includes biopsy assessment, but no additional details about assessment procedures or interpretation are reported.

What can sample-size planning say?

In general, sample-size planning asks how many observations would be needed to detect a specified effect under chosen assumptions. The registry record does not report the study's own sample-size justification. The planning assumptions associated with the posted sample-size illustrations describe 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. Those are planning assumptions, not evidence that this single-group trial was designed with two arms or followed that allocation plan. The record's design is single group, and no trial-specific sample-size justification is reported.

For time-to-event outcomes, the stated planning convention is a total number of events using the Schoenfeld approach; for other outcomes, it is participants per arm. These are general planning conventions rather than observed trial outcomes. The primary endpoint described in the registry is a participant count at a specified follow-up, not a time-to-event endpoint. The registry record does not report a time-to-event primary analysis.

Planning illustrations based on a fraction of an observed effect depend on an effect estimate being available and on assumptions about the analysis and comparison. They do not measure the probability that the completed study found a statistically significant result, and they are not observed power. No primary endpoint effect estimate is reported in the registry record. Therefore, a trial-specific interpretation of planning quantities cannot be grounded in the posted primary result.

How should adverse-event counts be read?

Safety summaries often distinguish serious events from other events and may count either participants or events, depending on the registry definition. The record gives numbers at risk and numbers affected in the serious and other categories. The serious category lists 2 affected among 27 at risk; the other category lists 20 affected among 27 at risk. The record also lists 0 deaths. The exact event-counting conventions and any details about repeated events are not reported in the registry record, so these numbers should be read in the categories as posted, not expanded into unreported event-level summaries.

In general, safety counts are descriptive. They do not by themselves establish whether an event was caused by treatment, how its risk compares with another treatment, or how precise a comparative difference would be. A one-group study can report events observed in its participants, but causal attribution and comparative safety require information beyond these counts. The registry record does not report a control-group safety comparison.

Finally, the registry lists 5 outcome measures and 0 analyses. An outcome listing defines what investigators intended to assess; it is not an analysis result. No statistical method for the primary endpoint, no missing-data method, and no analysis population are reported in the registry record. In general, such information is necessary to judge how observations were selected, how incomplete outcomes were handled, and how reported estimates should be interpreted. In this record, those details and the primary numerical result are unavailable.

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 (LITT)")
n      <- c(27)
events <- c(26)
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 (LITT)  27  26  96.3  81.0  99.9  81.7  99.3  81.7  99.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 5 outcome measures: the primary biopsy endpoint and secondary outcomes covering cancer in the treatment zone, adverse events, and urinary and sexual function. It lists 0 analyses. The outcome list shows that more than one outcome was intended for assessment, but the registry record does not report how these outcomes were analyzed or whether any were designated as confirmatory beyond the stated primary endpoint.

When several outcomes or statistical tests are examined, the chance of at least one apparently unusual result can increase if each is interpreted in isolation. Statistical approaches can address this issue by defining a hierarchy of tests or adjusting interpretation for multiple comparisons. This is a general statistical consideration, not a description of the study's methods. Any multiplicity strategy is not reported in the registry record.

The primary result is not reported, and numerical results for the secondary outcomes are also not reported. The registry record does not provide participant counts for each outcome, analysis estimates, confidence intervals, or test results. It also does not explain whether all listed outcomes were assessed in all participants.

Missing-data handling is not reported in the registry record. In general, incomplete outcome data can affect both the estimate and its interpretation, especially when the availability of a measurement is related to a participant's outcome or follow-up. For the biopsy endpoint, the number with an evaluable result and the handling of missing or indeterminate biopsies are not reported.

The analysis populations are not reported in the registry record. It is therefore unclear from the entry which participants were included in any outcome analysis, whether the analysis was based on all enrolled participants, or how deviations from the planned treatment or assessment were handled. These omissions limit assessment of the statistical conclusions independently of the missing numerical outcome results.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: bleeding per rectum (3.7%), fever (3.7%).

The registry lists 2 under serious adverse events among 27 participants at risk. It lists 20 under other adverse events among 27 at risk and records 0 deaths. These are descriptive safety figures for the Treatment (LITT) group. They do not provide a comparison with an untreated group or another intervention.

Bleeding per rectum and fever are each listed as serious adverse event terms at 3.7%. The registry record does not provide further event-level detail in the information, such as timing, duration, recurrence, or severity beyond the serious classification. It also does not report a comparison that would show whether the listed events occurred more or less often under another treatment.

Serious and other adverse-event categories should be kept distinct when interpreting the counts. The registry's category labels do not, by themselves, establish cause. Although the listed secondary outcome refers to adverse events related to treatment, the safety summary alone cannot establish a causal effect or quantify comparative risk. The figures describe what the registry reports for the treated group, not a treatment-versus-control contrast.

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

The study's stated primary question is specific: how many participants had no cancer detected on biopsy of the ablation zone at 3 months after ablation? The registry record identifies the intended endpoint and the single-group treatment approach, but it does not report the primary result. As a result, readers cannot determine from this record how many participants met the endpoint or how precisely that outcome was estimated.

The record also does not provide numerical results for the listed secondary outcomes. It describes assessment of cancer in the treatment zone, treatment-related adverse events, and urinary and sexual function during the year following treatment. Those outcome descriptions indicate what was intended to be observed, but do not show the findings.

Even with a reported outcome count, the single-group design would support a description of what was observed among treated participants rather than a randomized estimate of differences between treatments. There is no separate comparator group in the registry design. A treated-group result alone cannot distinguish the contribution of treatment from other influences on an outcome, and it cannot establish how the result compares with another approach.

The primary endpoint is a biopsy finding in the ablation zone at a particular follow-up. It does not by itself measure cancer status throughout the prostate, long-term outcomes, or urinary and sexual function. Those are distinct questions, and the registry lists separate outcomes for some of them. Their results are not reported in the registry record.

The posted safety figures describe events recorded in the treatment group, including 2 under serious adverse events, 20 under other adverse events, and 0 deaths. These figures should not be interpreted as a comparative safety estimate or as proof of causation. The registry record does not report the analysis details needed to assess the precision of safety estimates or the handling of repeated events.

Accordingly, the registry supports a description of study design, enrollment, intended outcomes, and posted safety counts. It does not supply the primary efficacy result, analysis estimates, or a comparison that would support a causal treatment contrast. The absence of a reported result should not be mistaken for either a favorable or an unfavorable finding.

14. Why This Trial Matters Statistically

This trial is statistically notable for the gap between a clearly defined primary endpoint and the absence of its numerical result in the registry record. The endpoint specifies the population-level question, the tissue location, the assessment method, and the timing: participants with no cancer on MRI-guided biopsy of the ablation zone at 3 months after ablation. Those details make the intended measure interpretable in principle, but without the result and its denominator, readers cannot evaluate the observed outcome.

The single-group structure also illustrates why design and analysis answer different questions. Outcome counts can describe what happened among participants who received the intervention. A randomized comparison is needed to estimate how outcomes differ between assigned treatment strategies while reducing some sources of confounding. The registry lists no separate comparator group, so the study design does not yield that kind of contrast.

Enrollment of 27 is relevant context for the scale of the study, but enrollment alone does not establish how much information is available for a particular endpoint. The number with an evaluable biopsy, the outcome count, and an interval estimate are not reported in the registry record. Without these, neither the estimated frequency nor its statistical precision can be assessed.

The entry also lists multiple outcome measures but no analyses. This makes the distinction between prespecified measurement and reported statistical evidence especially important. Naming an outcome does not reveal its result, how missing observations were handled, or whether multiple outcomes were considered together. Those analysis details are not reported in the registry record.

These features matter for statistical literacy: a completed study record, a defined endpoint, and a list of safety findings are not substitutes for a reported primary estimate and its uncertainty. Readers can identify what the study intended to measure and the limits imposed by its design, while recognizing that the efficacy result remains unavailable in the 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 direct limitation of the registry information is that the primary endpoint result is not reported. The number of participants with no cancer detected on biopsy of the ablation zone, the number with an evaluable biopsy, and any estimate of uncertainty are not reported in the registry record. Without these, the central outcome cannot be described quantitatively.

The study is single group and has no separate comparison group in the listed design. Consequently, its observations cannot provide a randomized between-group treatment contrast. The registry record does not report a comparator, a control-group outcome, or a comparative effect estimate.

Enrollment was 27, but enrollment is not necessarily the same as the number assessed for every outcome. The registry record does not report outcome-specific denominators, participant flow, missing-data handling, or analysis populations. This is particularly relevant to the biopsy endpoint and to the listed functional outcomes over the year following treatment.

The entry reports 5 outcome measures and 0 analyses. Analysis methods, any multiplicity strategy, and statistical estimates are not reported in the registry record. The sample-size justification is not reported in the registry record. The phase field is NA, although the study title describes a Phase II evaluation; further detail about the intended statistical design is not reported.

The primary endpoint is limited to a biopsy finding in the ablation zone at 3 months after ablation. It does not by itself cover disease outside that zone, longer-term outcomes, or the separate functional outcomes listed in the record. The registry record does not report numerical results for those secondary outcomes. These limitations arise from the study design and the information reported in the registry entry; they do not establish what the unreported results were.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: MR-Guided Laser Interstitial Thermal Therapy in Treating Patients With Prostate Cancer — NCT01792024.
• Registry record last updated 2018-03-13; status last verified 2018-02.
• Results first posted 2018-03-13.
• 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

NCT01792024 is a completed, single-group study of MR-guided laser interstitial thermal therapy for prostate cancer, with enrollment of 27. The title describes a Phase II evaluation; the phase and allocation fields are recorded as NA, and masking is listed as none. Participants underwent magnetic resonance imaging-guided laser thermal therapy using the Visualase Thermal Therapy device.

The primary endpoint was the number of participants with no cancer on MRI-guided biopsy of the ablation zone at 3 months after ablation. The registry lists 5 outcome measures and 0 analyses, but does not report the primary endpoint result or numerical results for the secondary outcomes. Safety information lists 2 under serious adverse events, 20 under other adverse events, and 0 deaths. Bleeding per rectum and fever are each listed among serious adverse event terms at 3.7%.

The design supports description of the treated group but does not include a like-for-like control comparison. Statistical methods, missing-data handling, analysis populations, and a sample-size justification are not reported in the registry record.