This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Endoscopic Therapy of Early Cancer in Barretts Esophagus (NCT00217087), a randomized phase 2 study. The primary outcome is Level of Dysplasia on Histology at 12 Months.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00217087 |
| Phase | Phase 2 |
| Condition | Early Stage Esophageal Adenocarcinoma, Barrett Esophagus |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 73 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Mayo Clinic |
| Results posted | Yes |
2. Clinical Question
The study concerns patients with early esophageal adenocarcinoma or Barrett esophagus who were described as ineligible for surgical or radiological therapy. Its clinical question is whether endoscopic removal of the cancer is sufficient treatment, or whether adding photodynamic therapy is needed. The registry describes the standard method for treating this type of cancer as surgical removal of the esophagus, while the study explores an endoscopic approach for the population described.
Population
Patients with early-stage esophageal adenocarcinoma or Barrett esophagus, described in the study summary as ineligible for surgical or radiological therapy.
Intervention
Endoscopic mucosal resection with photodynamic therapy. Photodynamic therapy is described as treatment with red light and sodium porfimer.
Comparator
Endoscopic mucosal resection, performed at endoscopy if indicated, without the addition of photodynamic therapy as described for the comparison group.
Primary question
At 12 months after therapy, what level of dysplasia is found on histology, and how does the registry characterize that outcome across the treatment groups?
The primary outcome concerns dysplasia in Barrett’s esophagus, assessed through review of specimens by two expert gastrointestinal pathologists. The record does not reduce the outcome to a single treatment contrast. Consequently, the clinical question can be described from the study design, but the registry information does not support a single numerical estimate of the difference between the treatment approaches.
3. Trial Design
This was a randomized, phase 2, parallel-group study with no masking. The registry lists Mayo Clinic as the sponsor and records enrollment of 73 participants. The study status is completed; the recorded start was 2005-09 and the primary completion was 2012-06.
The treatment groups were endoscopic mucosal resection and endoscopic mucosal resection with photodynamic therapy. The arm description for endoscopic mucosal resection says the procedure would be performed at endoscopy if indicated. The photodynamic therapy group is described as receiving endoscopic mucosal resection with photodynamic therapy. The study summary identifies photodynamic therapy as treatment involving red light and sodium porfimer.
Random allocation is intended, in general, to reduce systematic differences between treatment groups at the point of assignment. The record does not describe how the random sequence was generated, how assignments were concealed, or whether any restrictions were used in allocation. It also does not report masking, consistent with the listed masking status of none. The record does not say whether pathologists reviewing specimens knew participants’ assigned groups.
The study was intended for patients described as ineligible for surgical or radiological therapy. This eligibility context matters when interpreting the scope of the findings: the study question is framed around endoscopic treatment in that group, rather than as a direct comparison with surgery or radiological therapy. The registry record does not report the detailed eligibility criteria, the allocation procedures, or baseline characteristics by treatment group. Those details therefore cannot be used to assess how closely the groups were balanced or how broadly the findings might apply.
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.
Before assignment: We intended to recruit 100 patients with early cancer and were able to recruit a total of 124 patients in this single center randomized trial. A total of 73 patients could actually be randomized due to inability to completely remove the cancer, finding evidence of high risk of metastasis, or refusing randomization to photodynamic therapy.
Overall Study
| Stage | Endoscopic Mucosal Resection | Photodynamic Therapy |
|---|---|---|
| STARTED | 36 | 37 |
| COMPLETED | 25 | 17 |
| NOT COMPLETED | 11 | 20 |
Reasons for not completing this period:
| Reason | Endoscopic Mucosal Resection | Photodynamic Therapy |
|---|---|---|
| decided to have esophagectomy | 1 | 2 |
| completed less than 12 months return | 10 | 18 |
Analysis population for the primary outcome, as defined in the registry: 4 participants in the photodynamic therapy group completed at least 3 but less than 12 months follow up post therapy, so they were not included in this 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.
| Characteristic | Unit | Endoscopic Mucosl Resection | Photodynamic Therapy | Total |
|---|---|---|---|---|
| Participants analysed | 36 | 37 | 73 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 13 | 12 | 25 |
| Age, Categorical: >=65 years | Participants | 23 | 25 | 48 |
| Sex: Female, Male: Female | Participants | 3 | 6 | 9 |
| Sex: Female, Male: Male | Participants | 33 | 31 | 64 |
| Region of Enrollment: United States | participants | 36 | 37 | 73 |
6. Primary Endpoint
The registry lists the primary outcome as Level of Dysplasia on Histology at 12 Months, measured over 12 months post therapy.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | paricipants |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled “Level of Dysplasia on Histology at 12 Months.” It concerns the presence and/or level of dysplasia in Barrett’s esophagus, determined from specimens reviewed by two expert gastrointestinal pathologists. The stated timeframe is 12 months after therapy. Histology provides an assessment of tissue characteristics; in this study, the endpoint focuses on dysplasia rather than a patient-reported measure or a time-to-event outcome.
Assessing dysplasia can describe the tissue findings after treatment and is relevant to the study’s question about the extent of endoscopic treatment. The registry record, however, does not specify the categories used to classify dysplasia, the rules for resolving disagreement between pathologists, or whether the review was blinded to treatment assignment. It therefore does not establish how classification decisions were standardized beyond noting the two expert reviewers.
The record states that 4 participants in the photodynamic therapy group completed at least 3 but less than 12 months of follow-up after therapy and were not included in this analysis. That is important when interpreting the endpoint: the described primary analysis does not include those participants, and their 12-month histology is not described in the record. The outcome is presented as having several categories or time points and is not reduced to a single comparison. Thus, the endpoint definition is available, but a single estimate of the treatment contrast is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies histological dysplasia at 12 months as the primary outcome, but it does not provide a single summary comparison for that outcome. The recorded outcome has several categories or time points and is not reduced to one comparison. No category-specific treatment contrast, confidence interval, or p-value is available in the record. As a result, the primary outcome cannot be interpreted as a single estimated difference between endoscopic mucosal resection and endoscopic mucosal resection with photodynamic therapy.
This absence of a single estimate is not evidence that the treatments had equal outcomes, nor does it establish that one approach had better histological findings. It means that the registry record does not offer a single numerical result that answers the comparative question. Category-level results, the way any categories were combined, and the uncertainty around such results are not reported in the registry record.
The safety information is presented separately as counts of participants with serious and other adverse events in each group. For serious adverse events, the registry records 1 of 36 participants at risk in the endoscopic mucosal resection group and 4 of 37 in the photodynamic therapy group. For other adverse events, the record lists 3 of 36 and 21 of 37, respectively. These are descriptive counts. They do not by themselves show whether the difference between groups is statistically distinguishable from chance, and they do not explain the severity or clinical meaning of the events classified as “other.” No inferential comparison of these safety counts is reported in the registry record.
The listed serious-event terms include “heart attack resulting in death” at 5.4%, “Renal failure - Sepsis” at 2.7%, and “Respitory Failure / Sepsis” at 2.7%. The registry does not state the denominators or additional details behind these percentages in the information described. The overall deaths value is not reported in the registry record; it should not be interpreted as zero.
Randomization is a useful design feature for comparative interpretation, but its value depends on how assignment was implemented and how participants were analyzed. Those details are not reported in the registry record. The outcome follow-up exclusion in the photodynamic therapy group also means that the primary endpoint does not include every participant described as enrolled. Without a single primary-outcome estimate, a stated analysis population, and details of missing-data handling, the registry record supports a description of design and selected event counts, not a conclusive comparative estimate.
9. Statistical Methods Explained
The registry identifies the study as randomized, parallel-group, and unmasked. It does not report the statistical analysis plan, the statistical tests or models used, or a numerical primary-outcome contrast. The interpretation below therefore separates general statistical principles from methods that can be attributed to this particular trial.
What does randomization contribute?
In general, random allocation is used to make treatment assignment less dependent on participants’ characteristics. If implemented as intended, it can support a fairer comparison by reducing systematic selection of particular participants into a particular group. Randomization does not guarantee that groups will have identical characteristics, especially in a study with limited enrollment. It also does not eliminate bias that can arise after allocation, such as differences in follow-up, outcome assessment, or decisions about which participants enter an analysis.
For this trial, the registry records randomization but does not describe sequence generation, allocation concealment, stratification, or other allocation details. It also does not provide baseline characteristics by group. Those omissions mean that the precise randomization procedure and the observed balance of participant characteristics cannot be assessed from the registry record.
Why does the unmasked design matter?
In general, masking can reduce the influence of knowledge about treatment assignment on care, reporting, and outcome assessment. The listed masking status is none. The primary outcome is based on histology reviewed by two expert gastrointestinal pathologists, but the registry does not report whether the reviewers were masked to assignment. Expert review can be relevant to outcome assessment, but expertise alone does not establish that assessment was independent of knowledge about treatment or that a specific procedure was used to settle differing assessments.
How should a multi-category outcome be understood?
The primary outcome concerns the level of dysplasia on histology, and the registry’s analysis description indicates that it has several categories or time points rather than a single comparison. General statistical interpretation depends on how such categories are defined and what treatment contrast is intended. A comparison might focus on the full distribution across categories or on a prespecified distinction between categories. Different choices address different questions and can lead to different summaries. The registry record does not report category definitions or a single contrast, so it is not possible to identify which summary would be most appropriate or to interpret an unreported effect estimate.
For an outcome with multiple categories, a simple count in one category does not describe the complete distribution. Readers would need the category-specific results and an explicit comparative method to understand how the groups differed overall. The record does not give those details for the primary endpoint. No test statistic or model should be inferred from the study’s randomized design alone.
What does uncertainty mean?
General statistical uncertainty describes how much a result might vary across comparable studies because participants are a sample rather than the entire population of interest. A confidence interval is one way to express uncertainty around an estimated effect: it gives a range of values compatible with the data under the method’s assumptions. A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under a statistical model; it is not a measure of the size or clinical importance of an effect. Neither a confidence interval nor a p-value for the primary treatment comparison is reported in the registry record.
Small event counts can make estimates imprecise. For safety outcomes, the counts are useful descriptions, but formal comparative interpretation requires an analysis and an account of uncertainty. The registry does not provide a confidence interval, p-value, or other inferential analysis for the serious or other adverse-event counts. It is therefore not appropriate to turn the listed counts into a claim about a statistically established difference.
Why can over-dispersion matter?
General explanation: for count outcomes, some statistical models assume that the variability in counts is determined by the mean. If the observed variability is greater than that assumption allows, the data are over-dispersed relative to the model. In that situation, standard errors may be too small if over-dispersion is ignored, making uncertainty appear less than it is. Model choice should reflect the outcome structure and the observed variability. The registry record does not identify the primary outcome as a count model analysis or report whether over-dispersion was assessed, so this general issue should not be mistaken for a method used in the trial.
What can be said about the analysis?
The registry lists 3 outcome measures and 3 analyses, but the information recorded does not provide enough detail to reconstruct the primary analysis. The record does not report the model, covariates, significance threshold, handling of repeated or multiple assessments, or the analysis population. It also does not report an interim-analysis plan or a sample-size justification. These are not details that can be deduced from the fact of randomization or from the number of recorded outcome measures.
For the endpoint, the record specifically excludes 4 participants in the photodynamic therapy group who completed at least 3 but less than 12 months of follow-up. That exclusion is stated, but the record does not explain the broader missing-data strategy or how participants with incomplete information were handled for other outcomes. In general, complete-case analysis can be biased if inclusion is related to outcome or treatment in a way that is not accounted for. Imputation and other approaches also require assumptions. No such approach is identified in the registry record.
Overall, the design and endpoint can be described, but the inferential methods and primary-outcome estimate cannot be reconstructed from the registry record. Statistical conclusions should remain limited to information explicitly recorded, with the endpoint results and their uncertainty treated as unreported rather than inferred.
10. Multiplicity, Missing Data and Analysis Populations
The record lists 3 outcome measures and 3 analyses. Multiple outcomes or analyses can raise a multiplicity issue: in general, when several hypotheses are tested, the chance of obtaining at least one apparently notable result can increase if the testing strategy is not prespecified or adjusted. The appropriate response depends on which outcomes are primary, which comparisons are confirmatory, and how the analyses are related. The registry record does not report a multiplicity strategy, an adjustment method, or how the listed analyses map to the outcome measures. The primary outcome is specified, but the record does not give a single comparative result for it.
For missing data, the record states that 4 participants in the photodynamic therapy group had at least 3 but less than 12 months of follow-up after therapy and were not included in the 12-month histology analysis. It does not report why those participants lacked the stated follow-up, whether any outcome information was available for them, or whether an alternative analysis addressed their absence. It also does not describe missingness for other outcomes.
The registry record does not report whether the primary analysis followed an intention-to-treat principle, used a per-protocol population, or used another analysis population. It does not describe imputation, sensitivity analyses, or assumptions about missing outcome data. These omissions matter because analysis-population decisions can affect which randomized participants contribute to a treatment comparison, while different assumptions about missing outcomes can lead to different interpretations.
The record also does not report an interim-analysis plan or a sample-size justification. Those features should not be inferred from the trial’s phase or enrollment. Without the analysis plan, multiplicity handling, and a clear account of the analysis population, it is not possible to assess whether the reported endpoint analysis followed prespecified procedures or how robust it would be to alternative missing-data assumptions.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Endoscopic Mucosl Resection | 1 | 36 | 2.8% |
| Photodynamic Therapy | 4 | 37 | 10.8% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 3% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Endoscopic Mucosl Resection | 3 of 36 |
| Photodynamic Therapy | 21 of 37 |
Most frequent serious adverse event terms
| Event term | Organ system | Endoscopic Mucosl Resection | Photodynamic Therapy |
|---|---|---|---|
| heart attack resulting in death | Cardiac disorders | 1 of 36 | 2 of 37 |
| Renal failure - Sepsis | Renal and urinary disorders | 0 of 36 | 1 of 37 |
| Respitory Failure / Sepsis | Respiratory, thoracic and mediastinal disorders | 0 of 36 | 1 of 37 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Endoscopic Mucosl Resection | Photodynamic Therapy |
|---|---|---|---|
| Photosensitivity | Skin and subcutaneous tissue disorders | 0 of 36 | 12 of 37 |
| Dysphagia | Gastrointestinal disorders | 0 of 36 | 6 of 37 |
| Bleeding | Gastrointestinal disorders | 1 of 36 | 1 of 37 |
| Dehydration | General disorders | 1 of 36 | 1 of 37 |
| Atrial fibrilation | Cardiac disorders | 1 of 36 | 0 of 37 |
| Pain | Gastrointestinal disorders | 0 of 0 | 1 of 37 |
Serious events with the highest arm-level rate: heart attack resulting in death (5.4%), renal failure - sepsis (2.7%), respitory failure / sepsis (2.7%).
The registry lists serious adverse events and other adverse events separately. In the endoscopic mucosal resection group, 1 of 36 participants at risk had a serious adverse event and 3 of 36 had an other adverse event. In the photodynamic therapy group, 4 of 37 participants at risk had a serious adverse event and 21 of 37 had an other adverse event. These are recorded participant counts with their at-risk group sizes; they are not a statistical test of a treatment difference.
The registry also lists serious-event terms and percentages: “heart attack resulting in death” at 5.4%, “Renal failure - Sepsis” at 2.7%, and “Respitory Failure / Sepsis” at 2.7%. The record does not provide denominators or further context for these term-level percentages in the information described. The overall deaths entry is not reported in the registry record, which is different from reporting no deaths. The event label that mentions death should be read as a listed term, not as a substitute for an overall deaths result.
The record does not define the “other” adverse-event category or give event-level descriptions for those counts. It also does not report a comparative safety analysis or uncertainty estimates. Accordingly, the figures describe what the registry records, but they do not establish the cause, relative risk, or statistical significance of differences between groups.
12. What the Result Does, and Does Not, Mean
The trial asks a focused comparative question: whether endoscopic mucosal resection alone, or with photodynamic therapy, is associated with different histological dysplasia findings at 12 months for the population described. The registry identifies the design as randomized and records the primary endpoint and the review of specimens by two expert gastrointestinal pathologists. It also records exclusions from the endpoint analysis for 4 participants in the photodynamic therapy group whose follow-up was at least 3 but less than 12 months.
However, the primary outcome is not reduced to a single comparison, and the registry record does not report category-specific estimates or uncertainty for that outcome. It therefore does not establish whether the treatment groups had similar or different histological findings, nor how precise any such difference might be. An absent single estimate should not be interpreted as evidence of no effect or as evidence in favor of either group.
The safety information gives participant counts for serious and other adverse events and lists selected serious-event terms. These figures can be described as recorded, but the registry does not provide an inferential comparison, definitions for the “other” category, or the overall deaths result. The counts alone do not establish that treatment caused an event or that an observed difference is statistically reliable.
The study’s design also does not make it a direct comparison with surgery or radiological therapy. The study summary frames the participants as ineligible for those approaches and compares endoscopic treatment strategies. The registry record does not support extending the findings beyond that described study question, and it does not provide enough outcome information for a conclusion about comparative efficacy or safety.
The result that can be stated most precisely is therefore about the available registry information: the study was completed, its primary endpoint was defined, and the record includes selected safety counts, but a single primary treatment-effect estimate is not reported. That distinction separates what the study set out to assess from what the registry record makes available for statistical interpretation.
13. Why This Trial Matters Statistically
This trial is statistically notable because it combines a randomized comparison with a primary outcome that is described in terms of dysplasia level rather than a single binary result. Such outcomes can contain information across multiple categories. In general, reducing a multi-category outcome to one contrast requires a clear definition of the comparison and a statistical method suited to that question. Without the reported categories and analysis, readers cannot tell how the primary endpoint was summarized or what treatment contrast was intended.
The study also illustrates why design labels are not a substitute for analysis details. Randomization supports a comparative design, but the registry record does not describe the allocation procedure, the analysis population, or missing-data handling. The stated exclusion of 4 participants from the 12-month endpoint analysis is relevant to interpreting the population contributing to that outcome. These details shape how far a reader can take the results, even when the broad design is clear.
Finally, the safety record distinguishes serious events from other events, but provides counts without a reported comparative analysis. Statistical interpretation requires attention to both the size of an estimate and its uncertainty; event counts alone do not quantify either in a complete way. The overall deaths value is not reported in the registry record, and the serious-event term percentages lack stated denominators in the information described.
The statistical importance of this record is therefore not a claim about which intervention is preferable. It is the distinction between a well-defined research question and the limited numerical result available for evaluating it. A registry can describe the intent, design, endpoint, and selected safety findings while still leaving the principal comparative estimate and its precision unreported.
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 statistical interpretation is that the primary endpoint is not presented as a single treatment comparison. The record names histological dysplasia at 12 months but does not give the category-level findings, an effect estimate, or an uncertainty measure. The treatment contrast therefore cannot be quantified from the registry information described.
For the primary endpoint, 4 participants in the photodynamic therapy group with at least 3 but less than 12 months of follow-up were excluded from the analysis. The reason for incomplete follow-up and the handling of missing data are not reported in the registry record. The analysis population for the trial is also not specified. It is consequently unclear how the endpoint analysis relates to all enrolled participants or to the original randomized groups.
The record does not describe the randomization procedure, allocation concealment, baseline characteristics, or whether the pathologists were masked to treatment assignment. Although two expert gastrointestinal pathologists reviewed specimens, the record does not explain how disagreements were handled or whether a prespecified classification procedure was used. Those omissions limit assessment of allocation and outcome-assessment bias.
Additional limitations include the absence of a reported statistical analysis plan, multiplicity strategy, sample-size justification, interim-analysis plan, and inferential safety comparisons. The “other” adverse-event category is not defined in the information described, and the overall deaths value is not reported in the registry record. Finally, the study population is described as ineligible for surgical or radiological therapy. The registry record does not provide detailed eligibility criteria or enough comparative outcome information to assess how results would apply outside that stated population.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Endoscopic Therapy of Early Cancer in Barretts Esophagus — NCT00217087.
- Registry record last updated 2015-12-24; status last verified 2015-11.
- Results first posted 2015-09-25.
- 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.
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18. Record Summary
The registry record describes a completed, randomized, unmasked, parallel-group phase 2 study sponsored by Mayo Clinic, with enrollment of 73. The recorded start was 2005-09 and primary completion was 2012-06. The comparison was endoscopic mucosal resection versus endoscopic mucosal resection with photodynamic therapy in patients described as ineligible for surgical or radiological therapy.
The primary outcome was level of dysplasia on histology at 12 months after therapy, based on specimen review by two expert gastrointestinal pathologists. The record excludes 4 participants in the photodynamic therapy group from that endpoint analysis because their follow-up was at least 3 but less than 12 months. The endpoint is not reduced to a single comparative result.
Serious and other adverse-event counts are recorded by group, along with selected serious-event terms. A single primary-outcome effect estimate, uncertainty measure, detailed analysis plan, and overall deaths result are not reported in the registry record.