Thoracoscopic Sentinel Lymph Node Biopsy in Patients With Stage I or Stage II Breast Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Thoracoscopic Sentinel Lymph Node Biopsy in Patients With Stage I or Stage II Breast Cancer (NCT00450723), a na na study. The primary outcome is Success Rate in Removing Sentinel Lymph Nodes by Thoracoscopy.

2. Clinical Question

The clinical question is procedural and descriptive: it concerns whether the approach can identify and remove the targeted internal mammary sentinel nodes in this patient group. It is not a randomized treatment comparison, and the listed primary outcome is not a measure of cancer control, survival, or quality of life. The record’s stated purpose is to study how well thoracoscopic sentinel lymph node biopsy finds sentinel lymph nodes located between the breasts. The registry does not report a numerical success rate, so it is not possible to determine from this record how often the procedure met its stated objective.

3. Trial Design

The registry identifies NCT00450723 as a completed clinical trial sponsored by the University of Miami. The title is “Thoracoscopic Sentinel Lymph Node Biopsy in Patients With Stage I or Stage II Breast Cancer,” and the official title is “Thoracoscopic Internal Mammary Sentinel Node Biopsy.” The condition is Breast Cancer. The recorded start is 2004-05, primary completion is 2011-01, and status is COMPLETED. Phase is listed as NA.

The design is single group, with enrollment of 39 participants. Allocation is listed as NA and masking as NONE. These entries describe a study without a separate randomized control arm; they do not establish details of the surgical protocol or how outcomes were assessed. The registry also lists a sentinel lymph node biopsy arm, but its description is blank. It therefore does not explain how participants entered the arm or whether everyone received the same set of procedures.

Interventions listed in the record include isosulfan blue and technetium Tc 99m sulfur colloid, as well as axillary lymph node dissection, surgery, sentinel lymph node biopsy, and thoracoscopic surgery. These entries identify interventions associated with the study but do not establish which participants received each one, the dose or timing of either agent, or the sequence of procedures. Those details are not reported in the registry record.

The registry lists 3 outcome measures and 0 analyses. The primary outcome is the number of participants with successful removal of sentinel lymph nodes by thoracoscopy, with a timeframe of 5 years. The record does not report a result for this endpoint, an analysis population, or an analysis method. Thus, the design and objective can be described, but the central outcome cannot be quantified from the registry entry. The absence of a comparator also means the design cannot estimate a relative effect against another approach.

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:

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 Success Rate in Removing Sentinel Lymph Nodes by Thoracoscopy, measured over 5 years.

The primary endpoint is titled “Success Rate in Removing Sentinel Lymph Nodes by Thoracoscopy.” Its unit is participants and its parameter is NUMBER, so it is framed as a count rather than a continuous measurement. The clinical purpose is to assess whether thoracoscopic biopsy can locate and remove sentinel lymph nodes in the internal mammary region, described in the trial summary as nodes located between the breasts.

A procedural success endpoint can be useful because it addresses whether a diagnostic procedure reaches its immediate technical objective. In general, a count of participants meeting a defined success criterion can communicate how often that objective was achieved in the study group. Interpretation depends on the criterion being explicit: the record does not define what counted as successful removal, how unsuccessful or indeterminate attempts were classified, or how the outcome was verified.

The registry lists the endpoint timeframe as 5 years. That label alone does not clarify the assessment schedule or whether it refers to the period during which the outcome was collected. The registry record does not report the endpoint count, denominator used in its analysis, or a success estimate. Although enrollment is 39, the endpoint’s analyzed population is not stated. Accordingly, the endpoint’s intended meaning can be described, but its observed frequency and precision cannot be evaluated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

General statistical principle: a single-group study describes outcomes among participants who receive or undergo the studied procedure. It can estimate an observed frequency if the outcome count and its denominator are reported, but it does not by itself estimate a contrast with a separate control group. Here, the registry lists a single-group model and no allocation. The primary endpoint result is not reported, so even a descriptive success frequency cannot be recovered from the entry.

A comparator matters when the question is whether outcomes differ between approaches. Without a concurrent comparison group, observed outcomes can reflect the study procedure as well as participant characteristics, clinical decisions, measurement practices, and other factors. This is a general limitation of non-comparative designs, not a claim that any particular source of bias occurred in this study. The record does not report a comparator or a method for adjusting for differences in patient characteristics.

What does a count endpoint mean?

The primary endpoint uses participants as its unit and NUMBER as its parameter. A count can be the numerator of a rate when paired with a clearly defined eligible population. To interpret a rate, readers need to know which participants were eligible for assessment, which had an observed outcome, and how success was classified. The registry does not report those details or the endpoint result. The listed enrollment of 39 should not automatically be taken as the endpoint denominator.

General statistical principle: an estimate is more informative when its uncertainty is reported as well as its central value. A confidence interval describes a range of values compatible with the data and statistical model at a stated confidence level. It helps distinguish a precisely estimated frequency from one with substantial uncertainty. No confidence interval or primary endpoint estimate is reported in the registry record, so endpoint precision cannot be assessed.

What is the role of an outcome definition?

General statistical principle: outcome definitions support consistent classification across participants. For a procedural success endpoint, the protocol or registry might specify what constitutes successful localization and removal, how failed attempts are handled, and whether confirmation is required. Without a stated definition, readers cannot judge whether the endpoint is reproducible or compare its meaning with outcomes from other studies. The record gives the endpoint title but does not report its operational definition.

The registry lists a timeframe of 5 years. A timeframe label is not a complete description of measurement. It does not by itself specify when assessment occurred, whether the endpoint was measured once or repeatedly, or how the timeframe relates to the procedure. Those details are not reported in the registry record.

How should analysis methods be read?

General statistical principle: a statistical analysis plan identifies the outcome calculation, the population included, the handling of missing observations, and any uncertainty estimates or tests. These choices affect what a result represents. The registry lists 0 analyses and does not report an endpoint analysis method. It is therefore not possible to determine whether the sponsor used a particular estimator, whether adjustments were planned, or how any unobserved outcomes were addressed.

The record also lists 3 outcome measures. Multiple outcomes can serve different purposes, such as describing procedural performance and monitoring safety. When several statistical tests are conducted, the chance of at least one apparently unusual result can increase if no multiplicity approach is used. This is a general statistical concern, not evidence that multiple testing occurred or that a particular adjustment was warranted in this study. The registry does not report a multiplicity plan or analysis details.

Why does over-dispersion matter in some studies?

General statistical principle: over-dispersion occurs when observed variability exceeds what a chosen statistical model expects. If it is ignored, standard errors may be too small and uncertainty intervals too narrow. This concept is relevant to some count or clustered data analyses, but the registry does not report an analysis model for this endpoint. The outcome is described as a participant count, and there is no basis in this entry for claiming that over-dispersion was assessed or present.

How should sample-size calculations be interpreted?

General statistical principle: a sample-size calculation depends on assumptions about the outcome, the effect of interest, variability, significance level, power, and study design. A planning illustration is not an observed result and does not show the probability that the completed study found a real effect. In particular, observed power is not a substitute for reporting an effect estimate and its uncertainty.

The registry does not report the trial’s sample-size justification, a planned success rate, or an analysis for the primary endpoint. The sample-size assumptions listed for planning illustrations describe hypothetical two-arm calculations based on an observed effect, with equal allocation, a two-sided significance level of 0.05, and a normal approximation. Those assumptions do not describe this single-group design and cannot establish the trial’s original design rationale. Since the primary outcome effect is not reported, no observed-effect-based planning illustration can resolve the absence of an endpoint result. The trial’s own sample-size justification is not reported in the registry record.

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("Sentinel Lymph Node Biopsy")
n      <- c(34)
events <- c(31)
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  Sentinel Lymph Node Biopsy  34  31  91.2  76.3  98.1  77.0  97.0  76.9  96.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 0 analyses. It does not identify a multiplicity strategy, such as a prespecified hierarchy of outcomes or an adjustment for multiple statistical tests. General statistical principle: when many hypotheses are tested, interpreting isolated p-values without regard to multiplicity can make chance findings more likely. That concern is relevant only if inferential tests were performed; the registry does not report whether they were, or what role any secondary outcomes had.

The primary outcome is named, but the record does not report a primary endpoint result, analysis population, or statistical analysis method. It also does not report the number of participants with a missing or unevaluable primary outcome, reasons for missingness, or a method for handling missing observations. These omissions prevent assessment of whether the endpoint estimate, if calculated, would represent all enrolled participants or a selected subset.

Enrollment is 39, while safety risk sets are recorded as 34 for both serious and other adverse events. These are different registry entries and do not establish the denominator for the primary endpoint. The record does not explain the difference between enrollment and safety risk sets, and it does not report the primary analysis denominator. No assumption should be made about participant exclusions, withdrawals, or outcome completeness.

Analysis populations such as an intention-to-treat population or a per-protocol population are not reported in the registry record. Because the design is single group, the meaning of such populations would depend on the study’s procedures and eligibility rules, which are not described in sufficient detail. The endpoint analysis population and missing-data approach remain unknown.

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 5% reporting threshold.

The registry records a single arm for safety, with 34 participants at risk for serious adverse events and 0 affected. For other adverse events, it also records 34 at risk and 0 affected. These are participant counts in the registry’s safety fields; they should be read as recorded, rather than as a complete account of all possible harms or as a measure of the primary endpoint.

The record does not list top serious adverse event terms. It also does not explain the adverse-event definitions, ascertainment window, severity grading, relatedness assessment, or whether events were collected actively or passively. These details are not reported in the registry record. The reported counts therefore cannot answer questions about the nature, timing, or attribution of adverse events.

Deaths are listed as null, which means a death count is not reported in the registry record. Null should not be converted into a numerical count or interpreted as a statement that no deaths occurred. The safety risk set is 34, whereas total enrollment is 39; the record does not explain that difference. The safety figures should not be extrapolated to participants outside the stated risk set.

In general, a zero count in a recorded category is an observation within the stated population and recording framework. Its interpretation depends on complete ascertainment and a clear definition of the event. The registry entry does not provide enough detail to evaluate those conditions or to estimate safety-event uncertainty.

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

The record establishes that the University of Miami sponsored a completed, single-group study of thoracoscopic internal mammary sentinel lymph node biopsy in patients with stage I or stage II breast cancer. It records enrollment of 39 participants and names successful removal of sentinel lymph nodes by thoracoscopy as the primary outcome. It also lists procedural and tracer interventions and safety counts for 34 participants at risk.

The registry does not report the primary outcome result. Consequently, it does not show how many participants had successful removal, how often the procedure met the endpoint definition, or how precise an estimated success rate would be. The outcome definition and analysis denominator are also absent. These omissions prevent a statistical assessment of the central question the study set out to examine.

The design does not include a separate comparator group. Thus, the record cannot establish a relative difference between thoracoscopic biopsy and another procedure or diagnostic strategy. A single-group outcome, even if reported, would describe the study participants and would not on its own show what would have happened to comparable patients under a different approach.

The endpoint concerns a procedural objective. It is not itself a reported measure of whether cancer treatment was improved, whether recurrence changed, or whether survival or quality of life differed. Those outcomes are not presented as results in this record. The listed safety counts are likewise limited to the categories and risk sets entered and do not fill the gap in the primary endpoint result.

The appropriate reading is therefore narrow: the registry documents the study’s objective and broad design, but does not provide enough outcome or analysis information to judge the measured procedural success. It neither demonstrates success nor demonstrates failure. It also does not support a comparative treatment conclusion or a claim about broader clinical outcomes.

14. Why This Trial Matters Statistically

This study raises a practical statistical question that is easy to lose in a procedural description: what exactly counts as successful localization and removal, and how is that success quantified? A clear endpoint definition and denominator are essential for interpreting a procedural success rate. The registry names the endpoint and its unit, but does not report the definition or result. This makes the distinction between the study’s stated objective and the evidence available in the registry especially important.

The single-group design also illustrates the boundary between descriptive and comparative evidence. A study can document experience with a procedure, but a comparator is needed to estimate how outcomes differ from an alternative approach under a comparative design. The registry describes no separate comparator and no allocation. Therefore, the design information does not support a relative-effect estimate.

Statistical precision matters alongside the observed count. In general, a success estimate should be interpreted with its denominator and uncertainty interval, particularly when the study population is limited. The registry reports enrollment of 39, but does not provide the primary endpoint count, analysis denominator, or confidence interval. Those omissions prevent readers from judging both the magnitude and precision of the outcome.

The record also shows why registry completeness matters. It lists 3 outcome measures and 0 analyses, and the primary outcome has no reported result. Without an analysis population, missing-data account, or method, readers cannot reconstruct how the endpoint was evaluated. The safety entries are useful as recorded counts, but their risk set and missing detail do not substitute for a reported efficacy or performance outcome.

Statistically, the central lesson is not a conclusion about the procedure. It is that a study objective and a completed status do not make an unreported endpoint interpretable. Clear definitions, denominators, analysis methods, and results are needed to distinguish a measured finding from an intended 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 most direct limitation is that the registry does not report the primary endpoint result. Without a success count, denominator, or uncertainty estimate, the study’s stated procedural question cannot be answered from this record. The endpoint definition is also not reported, so even a numerical count would require more information to establish what was classified as success.

The single-group design has no separate comparator, and the registry lists allocation as NA. It therefore cannot support a randomized comparison with another approach. The record does not describe the sample characteristics beyond the breast cancer stage range in the title and summary, so the extent to which the enrolled group represents a broader patient population cannot be assessed.

The registry reports enrollment of 39 but does not state how many participants contributed to the primary endpoint analysis. The safety fields list 34 at risk, without explaining the difference from enrollment. Reasons for missing or unevaluable outcomes, withdrawals, exclusions, and analysis populations are not reported. The record also does not describe the protocol for the procedures or the endpoint assessment in enough detail to evaluate reproducibility.

Although 3 outcome measures are listed, analyses are recorded as 0. Statistical methods, multiplicity handling, sample-size justification, and the treatment of missing data are not reported in the registry record. The timeframe for the primary endpoint is listed as 5 years, but its assessment schedule and meaning are not clarified. Safety reporting is limited: no serious or other adverse events are recorded among 34 participants at risk, top serious event terms are absent, and deaths are null rather than reported as a count. These limitations restrict interpretation of both procedural outcomes and safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Thoracoscopic Sentinel Lymph Node Biopsy in Patients With Stage I or Stage II Breast Cancer — NCT00450723.
• Registry record last updated 2017-02-07; status last verified 2016-12.
• Results first posted 2013-04-05.
• 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

NCT00450723 is a completed, University of Miami-sponsored, single-group study of thoracoscopic internal mammary sentinel lymph node biopsy in patients with stage I or stage II breast cancer. The record lists enrollment of 39, phase NA, allocation NA, and masking NONE. It records a start of 2004-05 and primary completion of 2011-01.

The primary outcome is titled “Success Rate in Removing Sentinel Lymph Nodes by Thoracoscopy,” with participants as the unit and a timeframe of 5 years. Its result, definition, analysis denominator, and statistical method are not reported in the registry record. The entry lists 3 outcome measures and 0 analyses, and no separate comparator group.

For safety, 34 participants are listed at risk for serious adverse events and 34 for other adverse events, with 0 affected in both categories. Deaths are null, and top serious adverse event terms are not listed. The registry record describes the study objective and broad design but does not report the primary outcome needed to assess procedural success.