Merits of Performing a Modified Template Retroperitoneal Lymph Node Dissection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Merits of Performing a Modified Template Retroperitoneal Lymph Node Dissection (NCT00751140), a na na study. The primary outcome is Number of Participants With Pathologically Proven Lymph Node Metastasis.

2. Clinical Question

The study’s stated objective is to assess whether lymph node dissection can detect occult nodal metastasis in this patient population and provide diagnostic information. The registry description notes potential therapeutic benefits for patients with isolated nodal metastases, but the primary endpoint itself concerns pathological detection. It does not directly measure survival, recurrence, or the effect of surgery on those outcomes.

The primary endpoint timeframe is up to 4 years. The record describes the target population as patients treated with open or laparoscopic nephroureterectomy for upper tract urothelial cancer. The listed condition is cancer of the urinary tract. The study does not provide a randomized or concurrent untreated comparison, so the clinical question is descriptive: whether and how often node-positive disease was identified among those who underwent the procedure.

3. Trial Design

This is a completed, prospective, single-arm study of lymph node dissection at the time of nephroureterectomy. The arm description characterizes it as a two-stage phase II study, while the phase field is recorded as NA. The registry lists the intervention as a lymph node dissection procedure and describes nephroureterectomy with bladder cuff excision, performed by an open or laparoscopic approach.

Enrollment was 20. The registry record gives a start date of 2008-09 and a primary completion date of 2012-04. Masking is listed as none, and allocation is listed as NA. These fields do not describe a randomized comparison. There is one intervention group, so there is no control arm against which to estimate a relative treatment effect.

The primary outcome is the number of participants with pathologically proven lymph node metastasis, with a timeframe of up to 4 years. The record identifies all evaluable participants as the primary endpoint population and notes that one participant was excluded after histopathological review found a benign angioma. A secondary outcome is mean lymph node count. The registry lists two outcome measures overall, but the secondary outcome result is not reported in the registry record.

The study is marked completed, but completion status does not by itself establish that every planned analysis or outcome result is available in the registry. No detailed protocol, analysis plan, sample-size justification, or explanation of the two-stage design is reported in the registry record. The study’s stated purpose is to evaluate detection of occult nodal disease and provide diagnostic information, rather than to estimate a randomized between-group contrast.

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: All evaluable participants. On histopathological review, one patient had a benign angioma and was excluded from the final data analysis.

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 Pathologically Proven Lymph Node Metastasis, measured over Up to 4 years.

The primary endpoint counts participants with pathologically proven lymph node metastasis identified at radical nephroureterectomy and modified retroperitoneal lymph node dissection. It is a binary participant-level outcome summarized as a number: each evaluable participant either had pathologically confirmed nodal metastasis or did not. The endpoint is not a count of metastatic nodes, nor does it quantify survival or treatment benefit.

Pathological confirmation is relevant to the study’s stated diagnostic question because it identifies nodal disease through tissue assessment. The registry describes the intended use of the procedure as detecting occult nodal metastasis in patients with upper urinary tract urothelial carcinoma. Such a finding can provide information about disease status, but the endpoint alone does not establish whether detection changes subsequent management or improves clinical outcomes.

The timeframe is up to 4 years, and the endpoint population is all evaluable participants. One participant with a benign angioma was excluded from the final data analysis after histopathological review. The registry record does not report the number of evaluable participants who had pathologically proven metastasis, so the primary endpoint result cannot be interpreted from the posted record. The outcome’s unit is participants, and the registry lists its parameter as a number.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a binary outcome at the participant level, reported as a number of participants with pathological lymph node metastasis. For each evaluable participant, the underlying status is positive or negative. A count can describe how many participants met the endpoint, but interpretation also requires a clear analysis population and, when a rate is intended, an appropriate denominator. The registry describes the population as all evaluable participants and notes one exclusion following histopathological review.

What does a single-group endpoint count tell us?

In a single-group study, an endpoint count describes what was observed among participants who received the intervention. It does not estimate a difference between intervention and control groups. A control comparison can help separate an intervention-associated outcome from other explanations, while a descriptive count alone cannot do that. This distinction is especially important when interpreting an outcome that may be affected by participant characteristics, disease extent, surgical approach, or how participants are selected for surgery. These are general considerations; the registry record does not report adjusted analyses addressing them.

How should precision be assessed?

General statistical interpretation considers both an estimate and its uncertainty. A confidence interval is a range calculated using a specified method that conveys the precision of an estimate. Wider intervals indicate less precision, while narrower intervals indicate greater precision, given the method and assumptions. The registry record does not report a primary endpoint count, confidence interval, or p-value. As a result, neither the magnitude nor the precision of the primary endpoint can be evaluated from the posted result information.

The outcome is a participant count rather than a time-to-event endpoint. Although the endpoint timeframe is up to 4 years, no time-to-event result or survival analysis is reported in the registry record. The record also lists mean lymph node count as a secondary outcome, but gives no result or variability measure for that outcome. A mean describes an average, and interpretation of a mean generally benefits from information about spread, such as a standard deviation or confidence interval; those details are not reported in the registry record.

What do the planning illustrations represent?

The sample-size planning illustrations are described as based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not a description of the actual single-group study design. They should not be read as evidence that the trial had those two arms, or as a justification recorded in the trial protocol.

In general, a planning calculation estimates the sample size needed under chosen assumptions about the effect, statistical error rates, allocation, and analysis method. It is prospective: it asks what sample size might be needed for a future study under those assumptions. It is not observed power, which is not a useful substitute for reporting the estimate and its uncertainty after a study. The registry record does not report the trial’s own sample-size justification or the numerical assumptions used in its original design.

Why does the two-arm assumption matter?

Equal allocation between two arms is not aligned with the registry’s single-group design. The planning illustrations therefore represent hypothetical comparisons rather than a direct description of this study. A normal approximation is a general method that relies on the behavior of an estimator being adequately approximated by a normal distribution. For binary outcomes and small samples, the quality of that approximation can depend on the event frequency and method. The registry record does not describe a trial-specific analysis method or provide enough endpoint results to assess such assumptions for the primary outcome.

The registry does not list analyses. It does not report whether the primary endpoint was analyzed only descriptively, whether any confidence interval was planned, or whether adjusted or exploratory analyses were intended. Those details are not reported in the registry record, so the available description supports a design-level explanation but not a reconstruction of the statistical analysis.

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("Lymph Node Dissection at Time of Nephroureterectom")
n      <- c(19)
events <- c(1)
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  Lymph Node Dissection at Time of Nephroureterectom  19  1  5.3  0.1  26.0  0.9  24.6  1.2  24.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and identifies the number of participants with pathologically proven lymph node metastasis as the primary endpoint. Mean lymph node count is listed as a secondary outcome. The registry record does not report a multiplicity strategy, such as how interpretation would account for testing more than one outcome or conducting multiple analyses. It also lists zero analyses, so there are no analysis results or analysis-specific details to review.

Multiplicity is a general statistical concern when several outcomes or hypotheses are tested: repeated testing can increase the chance of at least one apparently notable finding. Whether and how to address that issue depends on the prespecified analysis plan. No such plan is reported in the registry record, so it is not possible to determine whether adjustment, a hierarchy of outcomes, or another approach was planned.

For missing data, the record identifies one participant excluded from final data analysis after histopathological review found a benign angioma. It does not explain how other unavailable or incomplete observations, if any, were handled. The number of participants included in the final primary endpoint analysis is not stated as a separate result. The registry record does not report an intention-to-treat or per-protocol definition, nor does it describe imputation or sensitivity analyses.

The record’s population description—“all evaluable participants”—and the exclusion note give some information about endpoint eligibility, but they do not fully define the analysis population. Further details about missing outcomes, exclusions beyond the stated participant, and the handling of participants without evaluable pathology are not reported in the registry record.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: chylous leak requiring surgical exploration - grade iiib (5.3%).

The registry lists 19 participants at risk for serious events, with one participant affected. It also lists 19 participants at risk for other events, with eight participants affected. These are counts within the single intervention group, not comparisons with a control group. The record separately identifies “Chylous leak requiring surgical exploration - Grade IIIb” among the top serious event terms and gives 5.3% for that term.

These categories should be read as registry-reported safety summaries. Seriousness and severity are related but distinct concepts in general: seriousness usually refers to regulatory or clinical consequences, while a grade describes severity. The record provides the event term and grade, but it does not supply a narrative describing the course or outcome of that event. The percentage is quoted as recorded; it should not be treated as a comparative risk estimate.

The registry lists deaths as null. This does not establish a zero death count; deaths are not reported in the registry record. The safety observation period and detailed rules for attributing events to the procedure are also not reported in the registry record. With no comparator arm, these data describe reported events in the study group and cannot establish whether event frequency differed from another approach.

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

The study asks whether modified template retroperitoneal lymph node dissection performed with nephroureterectomy can identify pathological nodal metastasis in patients with upper urinary tract urothelial carcinoma. Its primary endpoint is suited to describing detection of node-positive disease among evaluable participants. The registry record does not report the primary endpoint count, however, so the central diagnostic result cannot be stated from the posted results.

Even if the endpoint count were available, a single-group count would answer a limited question: what was observed in this cohort. It would not establish how often nodal metastasis would have been found under a different surgical strategy, nor would it isolate the effect of dissection from the clinical characteristics of participants or the operation. The design has no like-for-like control group.

The stated rationale discusses potential diagnostic information and possible therapeutic benefits in patients with isolated nodal metastases. Those are motivations for the research, not outcomes demonstrated by the endpoint. The primary endpoint does not directly measure survival, recurrence, quality of life, or benefit from treatment decisions informed by pathology. Results for those outcomes are not reported in the registry record.

The safety counts offer limited descriptive information about events in the intervention group: one participant is listed as affected by a serious event, and eight by other events, each among 19 at risk. A serious event term is also listed with its grade and recorded percentage. In the absence of a comparator, these observations cannot show whether the procedure raises or lowers event risk relative to another approach.

The appropriate interpretation is therefore bounded by the record: it describes a completed single-group study and its intended diagnostic endpoint, but omits the primary outcome result and detailed analysis information. The record does not support a conclusion about comparative effectiveness or clinical benefit.

14. Why This Trial Matters Statistically

This study is statistically interesting because its central question is about diagnostic yield, while its design is single-group. A participant count can document whether pathological nodal disease was detected in the cohort, but a comparator is needed to estimate a difference between surgical strategies. Keeping those questions distinct prevents a descriptive finding from being interpreted as a comparative treatment effect.

It also illustrates why the denominator and analysis population matter. Enrollment was 20, while the primary endpoint is defined for all evaluable participants and one participant was excluded after histopathological review found a benign angioma. The registry record does not report the final endpoint count or a separate final analysis denominator. Without those pieces, a reader cannot assess the observed frequency or its precision.

The registry’s stated rationale includes both diagnostic information and possible therapeutic relevance. Statistically, these are not interchangeable outcomes. Finding nodal metastasis is a pathology result; demonstrating that the finding improves later decisions or patient outcomes would require relevant outcomes and an analysis capable of addressing those questions. Such results are not reported in the registry record.

Finally, the planning illustrations use hypothetical two-arm assumptions, whereas the trial is described as single-group. This distinction matters because sample-size scenarios depend on the comparison and assumptions being planned. Planning calculations are not observed evidence, and they do not replace reporting the endpoint estimate and its uncertainty. The record’s missing primary result limits what can be learned about the study’s main statistical question.

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 main limitation for interpreting the posted results is that the registry record does not report the primary endpoint count. Without that result, the study’s central question about detection of pathological lymph node metastasis cannot be answered from the record. No confidence interval or p-value is reported for the primary endpoint.

The single-group design has no concurrent comparator. It can describe outcomes among participants receiving lymph node dissection at nephroureterectomy, but it cannot estimate a relative difference versus another surgical approach. The record lists allocation as NA and masking as none. It does not report details of participant selection or provide adjusted analyses that might address differences in clinical characteristics.

The record notes that one participant with a benign angioma was excluded from the final data analysis, but the final analysis denominator and details of any other exclusions or unavailable endpoint observations are not reported. The secondary outcome, mean lymph node count, is listed without a result. The registry also does not report the statistical analysis plan, sample-size justification, multiplicity approach, missing-data methods, or interim analyses.

Safety findings are descriptive and have no comparator. The event observation period and attribution details are not reported, and deaths are not reported in the registry record. These limitations restrict interpretation to the study description and the safety counts that are listed; they do not establish comparative effects or clinical benefit.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Merits of Performing a Modified Template Retroperitoneal Lymph Node Dissection — NCT00751140.
• Registry record last updated 2017-05-30; status last verified 2012-12.
• Results first posted 2013-01-08.
• 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

NCT00751140 is a completed, prospective, single-group study of modified template retroperitoneal lymph node dissection during nephroureterectomy for upper urinary tract urothelial carcinoma. The registry describes open or laparoscopic surgery with bladder cuff excision, enrollment of 20, a start date of 2008-09, and a primary completion date of 2012-04. Masking is listed as none, and allocation is listed as NA.

The primary endpoint is the number of evaluable participants with pathologically proven lymph node metastasis, with a timeframe of up to 4 years. One participant with a benign angioma was excluded from final data analysis. The primary endpoint result and the secondary mean lymph node count result are not reported in the registry record. Safety listings show one participant affected by a serious event and eight affected by other events, among 19 at risk in each category. A serious event term is listed as chylous leak requiring surgical exploration, Grade IIIb, at 5.3%.