Upper Extremity Lymphatic Mapping for Breast Cancer Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Upper Extremity Lymphatic Mapping for Breast Cancer Patients (NCT00717886), a na na study. The primary outcome is Number and Prevalence of Metastases of Blue Nodes in the ALND Specimen (Nodes Draining the Breast)..

2. Clinical Question

3. Trial Design

This is a completed pilot study listed under the title Upper Extremity Lymphatic Mapping for Breast Cancer Patients. The official title describes it as a pilot study. The sponsor is Memorial Sloan Kettering Cancer Center. The registry record lists a start date of 2008-06, a primary completion date of 2009-10, and enrollment of 13. The phase and allocation are listed as NA.

The study model is single-group, with no masking. The arm description refers to patients with documented axillary metastases and Stage II breast cancer. It says that technetium sulfur colloid was injected beneath the skin of the upper extremity on the side of the breast cancer approximately 3 hours before surgery. The intervention entry names isosulfan blue dye and labels its type as radiation. Because the record does not reconcile these entries, the mapping procedure should be described using the stated details rather than assuming how the materials were used together.

The study rationale is that axillary lymph node dissection removes lymph nodes under the arm to examine them for cancer cells. The registry summary says that usually about 12 to 15 nodes are removed and identifies lymphedema, described as fluid build-up in the arm, as a common side effect. It frames mapping as a way to investigate whether nodes draining the arm can be identified separately from those draining the breast. The possibility of leaving arm-draining nodes is presented as a future research rationale, not as a tested clinical benefit in this study.

A single-group pilot can describe what was observed in the enrolled group, but it cannot by itself provide a randomized comparison against a control group. The record does not report a control arm, randomization, or masking. It is marked completed, but no endpoint analysis is posted in the registry 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

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 Number and Prevalence of Metastases of Blue Nodes in the ALND Specimen (Nodes Draining the Breast)., measured over 2 years.

The primary endpoint is titled Number and Prevalence of Metastases of Blue Nodes in the ALND Specimen (Nodes Draining the Breast). Its unit is participants, and its parameter is listed as a number. The stated timeframe is 2 years. In context, the endpoint is intended to describe whether the mapped blue nodes found in the axillary lymph node dissection specimen contained metastases.

This endpoint addresses the study’s mapping question: whether nodes identified as draining the arm may also be involved in drainage from the breast, as indicated by metastases in the specimen. Such information is relevant to the study’s stated rationale for investigating whether arm-draining nodes might be distinguished from nodes that need to be examined during cancer surgery. It does not, on its own, measure lymphedema or establish that preserving any node changes the risk of that condition.

The registry record lists one outcome measure but provides no numerical endpoint result or analysis. It therefore does not report the number or prevalence of participants with metastases in the mapped blue nodes. The endpoint description also does not specify a detailed operational definition, such as exactly how a blue node was classified or how missing pathology findings were handled; those details are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a single-group study and lists no outcome analyses. Statistical methods can help explain what would be needed to interpret the stated endpoint, but the record does not report that those methods were used. No model, adjustment strategy, hypothesis test, confidence interval, or missing-data method is reported in the registry record.

What does the endpoint count?

The primary endpoint is framed as the number and prevalence of metastases of blue nodes in the axillary lymph node dissection specimen, with participants as the unit. A binary participant-level outcome would ordinarily indicate whether a participant met a defined criterion, such as having at least one relevant mapped node with metastasis. A count outcome would instead record a number of nodes or events. The registry lists the parameter as NUMBER and the unit as participants, but does not define the participant-level classification or give a count. That ambiguity makes it difficult to know precisely how the title’s reference to number and prevalence was operationalized.

For a binary outcome, an estimated prevalence is based on the number of participants meeting the endpoint definition relative to the number with evaluable endpoint information. The numerator and denominator are both needed to interpret such an estimate. Neither is reported for the primary endpoint, and the enrollment figure alone does not establish the endpoint denominator. No prevalence can therefore be reconstructed from the posted record.

Why does uncertainty matter?

A point estimate describes the observed frequency in the analyzed group, while a confidence interval conveys the range of values reasonably compatible with the data under the interval’s statistical assumptions. The interval’s width reflects both the amount of information and the variability in the data. In a pilot study, an estimate can be imprecise even when it is useful for describing feasibility or generating a research question. Because the registry record gives no endpoint estimate or interval, its precision cannot be evaluated.

A confidence interval would not remove the design limitations. For a single-group study, it would describe uncertainty about the group’s observed endpoint rate, not a treatment contrast against a control. It also would not establish whether preserving mapped nodes changes a later outcome such as lymphedema. That is a different question from whether metastases were present in the mapped nodes.

What can a single-group design establish?

In a single-group study, investigators can describe the characteristics and outcomes recorded for the participants who were studied. Without a comparator, observed findings cannot distinguish the effect of the mapping procedure from other factors that may affect the outcome. Random allocation is not listed, and there is no like-for-like control comparison in the registry record. The design should therefore be read as exploratory rather than as a controlled test of a clinical strategy.

Masking is listed as none. The record does not describe whether outcome assessment was blinded or how pathology findings were classified. In general, clear outcome definitions and consistent assessment are important because they reduce ambiguity in classifying participants. The specific procedures used for this endpoint are not reported in the registry record.

How should planning calculations be read?

The registry record includes general assumptions for planning illustrations: 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. It states that participant figures for ordinary outcomes are per arm, while time-to-event illustrations refer to total events. These are planning assumptions, not a description of this trial’s design: the study itself is single-group and no allocation is listed. The record does not give the underlying observed endpoint effect or any planning illustration values here, so no sample-size result can be interpreted from the posted trial details. Such calculations are not observed power and should not be mistaken for evidence that the completed study had a particular probability of detecting an effect.

In general, planning calculations depend on assumptions about the outcome, target effect, error rate, allocation, and statistical method. If those assumptions do not match the eventual design or endpoint, the calculated sample size may not answer the study’s actual question. The registry record does not report the study’s own sample-size justification or protocol-based calculation.

What does over-dispersion mean in general?

Over-dispersion arises when observed variability is greater than a statistical model assumes. For count outcomes, a simple model may understate uncertainty if the data vary more than its assumptions allow. Methods that account for extra variability can produce more realistic uncertainty estimates. This is a general concept, not a reported feature of this study. The registry endpoint is listed in terms of participants, and no count distribution, variance estimate, or model is reported, so over-dispersion cannot be assessed for this endpoint.

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("Upper Extremity Lymphatic Mapping for Breast Cance")
n      <- c(9)
events <- c(0)
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  Upper Extremity Lymphatic Mapping for Breast Cance  9  0  0.0  0.0  33.6  -0.0  29.9  0.3  30.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and 0 analyses. It does not report an analysis population, a statistical analysis plan, or a method for handling missing endpoint data. These omissions constrain interpretation: the record does not say which enrolled participants were included in the primary analysis or whether any participants lacked evaluable mapping or pathology findings.

Multiplicity refers to the interpretive problem that can arise when many outcomes, time points, subgroups, or statistical tests are examined. Considering many possible findings can increase the chance of highlighting an apparently notable result by chance. The registry record lists a single outcome measure, but it does not provide an analysis plan or describe whether additional outcomes, subgroups, or unregistered analyses were considered. It is therefore not possible to determine whether any multiplicity adjustment was planned or needed.

The primary endpoint has a stated timeframe of 2 years, but the record does not explain how that timeframe relates to endpoint assessment or follow-up. It also does not describe how participants with incomplete follow-up, unavailable specimens, or indeterminate node findings would be handled. Those procedures are not reported in the registry record.

For a transparent interpretation, an analysis population should be defined, missingness should be described, and the endpoint denominator should be reported alongside the outcome count. None of these details is available for the primary endpoint. Consequently, there is no basis for assessing whether the endpoint findings, if any were collected, represent all enrolled participants or a subset.

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.

The registry record lists one safety group, titled Upper Extremity Lymphatic Mapping for Breast Cancer Patients. For serious adverse events, 9 participants are listed as at risk and 0 as affected. For other adverse events, 9 are listed as at risk and 0 as affected. The record lists no top serious-event terms.

These are posted counts, not proof that no adverse events occurred outside the recorded categories or observation period. The record does not describe the event collection method, the safety follow-up period, or the criteria used to classify events. Deaths are listed as null, which means the registry record does not report a death count; null should not be interpreted as zero.

The safety at-risk count is 9, while overall enrollment is 13. The registry record does not explain this difference, so the safety denominator should not be assumed to include every enrolled participant. No percentage or rate should be inferred without a clearly defined denominator and follow-up information. These adverse-event counts also do not address the primary metastasis endpoint or the study’s future-facing question about lymphedema.

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

The record supports a limited description of the study: it was a completed, single-group pilot of upper-extremity lymphatic mapping in breast cancer patients, with a stated endpoint concerning metastases in blue nodes found in the axillary lymph node dissection specimen. The study rationale links this mapping question to the possibility of distinguishing nodes that drain the arm, which might be relevant to future work on reducing lymphedema. That rationale is not itself an outcome finding.

The record does not report the primary endpoint result. It therefore does not establish the frequency of metastases in mapped blue nodes, and it cannot show how precisely that frequency was estimated. It also does not report a lymphedema outcome or compare a node-preservation approach with a usual-care or control group. No conclusion about the effect of preserving mapped nodes follows from the posted endpoint description.

Likewise, the absence of a comparator prevents a controlled estimate of differences between study strategies. The single-group design can describe observations within the studied group if results are available, but it does not isolate the effect of mapping from other influences. The record does not report randomization, masking, a statistical analysis, or a sample-size justification.

The safety entries report 0 serious events and 0 other events among 9 participants at risk, with deaths not reported. These counts describe what is entered in the registry and should be interpreted in light of the unreported denominator discrepancy and event-collection details. They do not establish an overall safety profile.

In short, the registry record documents a pilot question and study design, rather than a quantifiable primary result. It can motivate further evaluation of lymphatic mapping, but the posted information does not answer whether mapped nodes were free of metastases or whether mapping can reduce lymphedema.

14. Why This Trial Matters Statistically

This study illustrates a common statistical distinction between a clinically motivated research question and an interpretable estimate. The idea is to identify arm-draining nodes and determine whether they also show metastases in the axillary lymph node dissection specimen. The registry record states why that question could matter for future research, but it does not post the endpoint count or an estimate of prevalence. Without those results, readers cannot judge the observed frequency or its precision.

The study’s single-group pilot design is also important. A pilot can document an exploratory procedure and generate information for later research, but a single group does not provide a controlled contrast. Even a clearly reported endpoint estimate would describe the mapped group, not establish what would have happened under a different strategy. The distinction prevents an observational finding from being treated as evidence of a comparative benefit.

Denominators are essential to this interpretation. The record gives overall enrollment as 13 and the safety at-risk count as 9, but it does not report the endpoint denominator or explain the difference in safety counts. A result is only interpretable when readers know how many participants contributed data and how the outcome was defined. A numerator without a matching denominator, or an enrollment figure used in place of an analysis population, can misstate precision.

Finally, the intervention entries are not fully aligned: one names isosulfan blue dye, while the arm description names technetium sulfur colloid injection. That ambiguity is relevant to reproducibility and interpretation. The case therefore underscores how statistical reporting depends on clear intervention definitions, endpoint rules, analysis populations, and uncertainty estimates—not only on a clinically compelling rationale.

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 registry record is that it does not report a primary endpoint result, despite listing one outcome measure. There is no endpoint numerator, denominator, estimate, confidence interval, or analysis. The record also lists 0 analyses. As a result, neither the endpoint frequency nor its precision can be assessed.

The study is single-group, with allocation listed as NA and no comparator described. It cannot provide a randomized comparison or separate the mapping procedure’s contribution from other influences. The registry record does not report a protocol-based sample-size justification, interim analyses, or a statistical analysis plan. Those details should not be inferred from the general planning assumptions listed in the record.

The participant-level outcome definition is not fully specified. Although the endpoint refers to the number and prevalence of metastases of blue nodes and uses participants as the unit, the record does not explain how participants were classified or how multiple nodes, uncertain pathology, or missing specimens were handled. The timeframe of 2 years is listed, but its relationship to endpoint assessment is not explained.

The registry also gives inconsistent intervention detail: the intervention entry names isosulfan blue dye and labels its type as radiation, while the arm description refers to technetium sulfur colloid injection. The record does not explain the relationship between these details. This limits clarity about the procedure being evaluated.

For safety, the at-risk count is 9 while enrollment is 13, and the record gives no explanation. Deaths are null rather than reported as a count. Event definitions, ascertainment, and follow-up are not described. These limitations mean the posted safety counts should be read as registry entries, not as a complete account of risk.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Upper Extremity Lymphatic Mapping for Breast Cancer Patients — NCT00717886.
• Registry record last updated 2015-11-20; status last verified 2015-10.
• Results first posted 2015-11-20.
• 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

NCT00717886 is a completed pilot study titled Upper Extremity Lymphatic Mapping for Breast Cancer Patients. The sponsor is Memorial Sloan Kettering Cancer Center. The record lists enrollment of 13, a start date of 2008-06, and primary completion on 2009-10. Phase and allocation are listed as NA; the study model is single-group and masking is listed as none.

The arm description concerns patients with documented axillary metastases and Stage II breast cancer, and describes technetium sulfur colloid injection into the ipsilateral upper extremity approximately 3 hours before surgery. The intervention entry separately names isosulfan blue dye. The primary endpoint concerns metastases of blue nodes in the axillary lymph node dissection specimen, with a stated timeframe of 2 years. No primary endpoint analysis is reported in the registry record.

Safety entries list 0 serious events and 0 other events among 9 participants at risk; deaths are not reported. The record does not explain the safety denominator or reconcile the intervention descriptions.