Magnetic Seed Localisation of Breast Cancers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Magnetic Seed Localisation of Breast Cancers (NCT02635737), a na na study. The primary outcome is Migration of Sentimark Device.

2. Clinical Question

In practical terms, the study asks whether magnetic seed placement can be undertaken and whether the marker remains acceptably positioned over the stated follow-up interval. It also lists secondary outcomes relating to initial placement accuracy, marker position and depth, detectability, and host response. Without reported outcome estimates, the record does not establish how often migration occurred or how the other feasibility measures turned out.

3. Trial Design

This was a completed, single-site, single-arm, unblinded safety and feasibility cohort study of magnetic marker seeds for localising breast tumours. The registry lists enrollment of 29 and the Sentimark device as the intervention. Its arm description specifies device placement in women having mastectomy surgery.

The registry lists the allocation as NA, masking as NONE, and phase as NA. The single-group model means there is no parallel control group in the record. The study can describe the experience of the treated cohort, but it cannot directly estimate a between-group treatment contrast. The lack of masking also means the record does not describe blinded assessment.

The study start date is 2016-07-06, the primary completion date is 2017-05-03, and the status is COMPLETED. These dates describe the registry record; they do not supply the timing or completeness of individual participants’ assessments.

The primary outcome is titled “Migration of Sentimark Device,” with a timeframe of 1-4 weeks from placement. The listed secondary outcomes cover accuracy of initial placement, the percentage of magnetic markers within the target area, marker depth, the number of seeds detectable on the Sentimag detector, and host response to the implanted seed device. The registry lists 8 outcome measures overall, but does not give results for these outcomes in the registry record for this analysis.

The record lists 0 analyses. It does not report the protocol details, sample-size justification, interim analyses, or a statistical analysis plan. The enrollment figure should therefore be read as the recorded study enrollment, not as evidence about the rationale for the planned size or the precision of an unreported result.

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: migration of seed

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.

Population: Females having mastectomy surgery

6. Primary Endpoint

The registry lists the primary outcome as Migration of Sentimark Device, measured over 1-4 weeks from placement.

The primary endpoint concerns migration of the Sentimark magnetic seed after placement. The registry describes the measure as the percentage of Magseed migrating >10mm and gives a timeframe of 1-4 weeks from placement. Its description refers to migration between mammograms and to clip position >40mm from the target lesion.

Migration is relevant to a localisation device because the marker is intended to indicate the target area for surgical excision. Measuring whether the marker changes position can therefore contribute to an assessment of placement feasibility and marker stability. This is a general explanation of why a migration endpoint may be used; it does not establish that the device did or did not remain in position in this study.

The registry record uses a percentage as the stated unit, while the listed parameter is NUMBER. It does not provide an operational definition explaining how the percentage or number was calculated, nor does it state the observed value, numerator, denominator, or uncertainty estimate. It also does not clarify how the reference to clip position relates to the migration threshold. Those details are not reported in the registry record.

Because no primary endpoint result is reported, the endpoint description alone cannot show how common migration was, whether the stated threshold was met, or how precisely the outcome was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods that can be described are limited by the registry record. It identifies a single-group cohort design and lists 0 analyses. No inferential method, uncertainty estimate, or model for the primary endpoint is reported. The explanations below are general statistical context, not claims about methods used in this study.

What does a single-group design estimate?

A single-group study records outcomes among participants receiving the intervention. For a binary outcome such as whether migration crosses a specified threshold, an analysis could describe the observed event count and the proportion of participants with the event. That description would summarize the cohort, but it would not estimate a difference from a control treatment. A comparison with another group requires suitable comparative data and a design and analysis that address how the groups were formed.

In this record, there is no reported primary endpoint count or percentage, so even a descriptive estimate cannot be assessed. The stated unit is a percentage, but the parameter is listed as NUMBER. Without the operational definition and underlying observations, the relationship between the intended measure and a possible analysis remains unclear.

Why does a confidence interval matter?

In general, a confidence interval expresses the uncertainty around an estimated quantity under the assumptions of the statistical method. For a proportion, it can show how much uncertainty remains around the observed event frequency. A point estimate alone does not convey that precision. The registry record reports no confidence interval for migration, and the registry entries do not provide the event count or denominator needed to interpret one.

A confidence interval would not resolve all design limitations. It can describe uncertainty about a cohort estimate, but it cannot create a control group or remove bias arising from unblinded assessment, incomplete follow-up, or outcome classification. Those issues need to be considered alongside the estimate and the way the data were collected.

What does the timeframe tell the reader?

The primary outcome timeframe is 1-4 weeks from placement, and the description refers to migration between mammograms. A defined follow-up window is important because an outcome rate depends on when and how it is assessed. However, the record does not specify the schedule for individual assessments, whether every participant had observations throughout that window, or how participants with missing assessments were handled. Those details are not reported in the registry record.

For general context, if follow-up varies or participants are observed for different lengths of time, methods that account for time at risk may sometimes be appropriate. If the outcome is instead assessed at a defined visit, a proportion-based analysis may be used. The registry record does not identify which approach, if any, was planned or performed, so neither can be attributed to this study.

How should the record's analysis count be read?

The record lists 0 analyses. This does not supply a p-value, effect estimate, or model output, and it does not establish whether investigators conducted analyses outside the registry record. It means no analysis results are available in the registry entries assessed. The registry does not report an adjustment strategy, handling of repeated measures, covariate selection, or a statistical plan.

General statistical interpretation also depends on how an endpoint is defined before data are examined. The migration description includes a threshold and references mammograms and clip position, but the record does not explain adjudication or measurement procedures. If outcome classifications are uncertain, consistent criteria and assessment procedures are important for limiting measurement variation. This is a general consideration, not evidence that measurement problems occurred in this study.

The record's planned enrollment and observed enrollment should also be distinguished. Enrollment of 29 is recorded, but the sample-size justification is not reported in the registry record. No conclusion about statistical power or the adequacy of the study size follows from enrollment alone. A planning calculation based on an assumed effect would be an illustration, not observed power or a result of the trial.

Finally, the single-group design and unblinded status influence the scope of interpretation. Descriptive safety and feasibility findings can be useful in characterising the study cohort, but comparative claims require evidence beyond a single treated group. Since the migration estimate and analysis are not reported, there is no quantitative primary outcome result to interpret for precision, statistical significance, or clinical importance.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures, including the primary migration outcome and secondary measures related to placement accuracy, marker location and depth, detectability, and host response. It lists 0 analyses. No analysis plan is reported, including any approach to multiple outcomes, outcome hierarchy, or adjustment for multiple testing.

In general, when several outcomes are examined, the chance of at least one apparently unusual result can increase if each is tested separately without accounting for multiplicity. The appropriate approach depends on the scientific aims and the planned hierarchy of outcomes. The registry record does not say whether any outcomes were treated as exploratory, whether formal hypothesis tests were planned, or whether multiplicity adjustment was intended. No conclusion about such adjustment can be drawn from the number of listed outcomes alone.

Missing-data handling is also not reported in the registry record. The registry entries do not state how many participants had primary endpoint assessments, whether any observations were unavailable, or how missing outcome data were handled. The enrollment of 29 should not be taken as proof that all participants contributed complete endpoint data.

The analysis population is not specified. The record does not describe whether results were intended for all enrolled participants, those with successful device placement, those with available follow-up, or another group. This matters because the set of participants included in an analysis can affect the estimate and its interpretation.

Without a reported protocol or statistical analysis plan, it is not possible to determine whether the listed outcomes, follow-up window, analysis population, and missing-data procedures were prespecified. These omissions limit reproducibility and make it difficult to assess whether the recorded outcomes reflect all planned analyses.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists the Sentimark Device Placement group with 29 at risk for serious events and 0 serious events reported. It also lists 29 at risk for other events and 0 other events reported. The record lists 0 deaths. These figures describe what is entered for this group; they are not a comparative safety estimate because the study has no control group.

An event count of 0 in a cohort does not prove that an event is impossible or that the intervention has no risk. In general, safety counts need to be interpreted with the amount and duration of follow-up, the event definitions, the completeness of reporting, and the way events were collected. Those details are not reported in the registry record.

The registry entries do not list any top serious-event terms. That should be read as absence of listed terms in this record, not as a complete account of all symptoms, complications, or non-serious experiences. The registry record does not give further event-level descriptions or explain whether every event category was actively assessed.

Accordingly, the figures support a narrow description: the listed group has 0 serious events and 0 other events recorded, with the stated at-risk counts. They do not establish comparative safety or rule out uncommon or unrecorded events.

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

The study record documents an investigation of Sentimark placement in women having mastectomy surgery for breast cancer. Its stated purpose is to examine safety and feasibility, with migration of the device as the primary outcome. The record also identifies secondary measures addressing placement, position, detectability, and host response.

What the record does not provide is the primary endpoint result. There is no reported migration count or percentage, no uncertainty interval, and no analysis. Therefore, the record cannot show how often migration exceeding the stated threshold occurred or how precisely that frequency was estimated. The absence of a result should not be interpreted as a zero migration rate or as evidence that the endpoint was met.

The adverse-event entries describe 0 serious events, 0 other events, and 0 deaths for the listed group, with 29 at risk in each event category. Those entries are relevant descriptive safety information, but they do not establish that all possible events were absent, nor do they compare the device with another approach. Event definitions and follow-up completeness are not reported.

The single-group, unblinded design can provide cohort experience but cannot provide a randomized comparison. It does not establish whether outcomes would differ under another localisation method or with no magnetic seed placement. In general, comparative claims require an appropriate comparator and analysis; neither is present in the registry description.

The record is therefore most informative about the study’s design and intended outcomes, rather than the magnitude or precision of a clinical result. It identifies the question being investigated, but the outcome information available does not answer that question quantitatively. The missing estimates and methods should be kept distinct from the recorded adverse-event counts and from the fact that the study status is COMPLETED.

13. Why This Trial Matters Statistically

This study raises a practical measurement question: whether a magnetic seed used to localise a breast tumour remains sufficiently close to its intended target during the stated follow-up period. A migration endpoint translates that concern into an outcome that can, in principle, be counted or expressed as a proportion. The registry’s definition and results would be needed to evaluate that measure fully.

Statistically, the record illustrates why an endpoint label is not a substitute for an estimate. The stated migration threshold and timeframe identify what investigators intended to assess, but the missing result prevents evaluation of frequency and precision. Without a numerator, denominator, or uncertainty interval, readers cannot judge how informative the cohort observations are about migration.

The single-group design also defines the scope of what can be learned. A cohort can describe device placement and record adverse events, while a comparison against another strategy would require comparative data. Keeping those questions separate avoids treating a feasibility study as evidence of comparative effectiveness.

The registry lists multiple secondary outcomes and 0 analyses. That makes transparent reporting of prespecified outcomes, analysis populations, and missing-data methods particularly important. Such details help readers distinguish outcomes that were planned from those that were selected after data collection and understand which observations contributed to each result.

The available safety figures offer a descriptive account for the recorded group, but their interpretation depends on follow-up and event ascertainment details that are not reported. In this way, the record shows both the value and the limits of registry information: design and endpoint descriptions orient the reader, while outcome estimates and methods are needed for a statistical assessment of the study’s findings.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpretation is that the registry record does not report the primary migration result or results for the listed secondary outcomes. Without outcome estimates, counts, or uncertainty measures, the study’s feasibility findings cannot be assessed quantitatively.

The primary endpoint description is not fully operationalized in the record. It labels the unit as a percentage while listing the parameter as NUMBER, and it refers both to migration between mammograms and to clip position >40mm from the target lesion. The record does not explain how those descriptions are combined, how measurements were adjudicated, or how a participant was classified as having migration.

The design is single-group and unblinded, with no control comparison. These features prevent a direct comparative estimate and can make outcome assessment more susceptible to expectations, depending on how the endpoint was measured. The registry does not describe assessor procedures or quality-control methods.

The follow-up window is reported as 1-4 weeks from placement, but the record does not state whether follow-up was complete for all participants or how variable timing was addressed. Missing-data methods and the analysis population are not reported. The enrollment of 29 alone does not establish how many participants contributed to each outcome.

The registry lists 8 outcome measures and 0 analyses, but does not report a statistical analysis plan, multiplicity strategy, or sample-size justification. These omissions limit evaluation of prespecification, precision, and the handling of multiple outcomes. The safety entries are also limited by the absence of event definitions and ascertainment details. These constraints mean the registry description is not a substitute for a complete report of methods and results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Magnetic Seed Localisation of Breast Cancers — NCT02635737.
• Registry record last updated 2021-01-15; status last verified 2021-01.
• Results first posted 2021-01-15.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes a completed, single-site, single-arm, unblinded safety and feasibility cohort study of Sentimark magnetic seed placement for breast cancer localisation. Enrollment was 29. The study began on 2016-07-06, reached primary completion on 2017-05-03, and is listed as COMPLETED.

The primary outcome concerns device migration, with a stated threshold of >10mm and a timeframe of 1-4 weeks from placement. Secondary outcomes address placement accuracy, marker position and depth, detectability, and host response. The registry lists 8 outcome measures and 0 analyses.

The listed adverse-event figures are 0 serious events, 0 other events, and 0 deaths; 29 are listed at risk for each event category. No primary endpoint result, outcome analysis, sample-size justification, or analysis plan is reported in the registry record.