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 Glutamine for the Prevention of Radiation Toxicity in Subjects Conserving Therapy (NCT02012608), a randomized phase 2 study. The primary outcome is Excessive Radiation Toxicity as Defined by Radiation Therapy Oncology Group (RTOG) Acute Scale of Radiation-toxicity Criteria.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02012608 |
| Phase | Phase 2 |
| Condition | Breast Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 14 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Arkansas |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned subjects with breast cancer undergoing breast-conserving therapy and radiation treatment. The registry lists an enrollment of 14, but reports no participants analyzed for the primary outcome and states that no outcome data were collected.
Intervention
The intervention was powdered glutamine taken by mouth at 10.0 grams three times a day for 30 days, for a daily dose of 30 grams.
Comparator
The comparison was powdered dextrose placebo taken by mouth at 8.33 grams three times a day for 30 days, for a daily dose of 25 grams.
Primary question
The study aimed to determine whether glutamine would reduce excessive radiation toxicity, defined as an RTOG Acute scale score of 2 or higher at either the 12-day or 30-day assessment. The registry record contains no primary-outcome results, so it does not provide an estimate of the difference between groups.
3. Trial Design
The registry describes a randomized, double-blind, parallel, two-arm study, listed as Phase 2. The sponsor was the University of Arkansas. The study was single-centered according to its brief summary. The condition listed was breast cancer, and the study concerned subjects undergoing breast-conserving therapy.
The planned comparison was oral glutamine versus powdered dextrose placebo. The glutamine regimen was 10.0 grams by mouth three times a day for 30 days, with a stated daily dose of 30 grams. The placebo regimen was 8.33 grams by mouth three times a day for 30 days, with a stated daily dose of 25 grams. The registry describes both interventions as drugs.
The registry lists an enrollment of 14 and a study status of terminated. The start is recorded as 2014-06 and primary completion as 2019-04. Those registry dates and status do not explain why the study was terminated or how many participants completed the intervention or each assessment. That information is not reported in the registry record.
The primary measure was excessive radiation toxicity on the RTOG Acute scale, assessed at 12 days and 30 days. The record states that no data were collected and that zero participants were analyzed for this outcome. It therefore does not support a comparison of the groups’ primary-outcome results. Details such as the randomization procedure, allocation concealment, adherence, and the intended statistical analysis plan are not reported 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
| Stage | Glutamine | Placebo |
|---|---|---|
| STARTED | 7 | 7 |
| COMPLETED | 4 | 7 |
| NOT COMPLETED | 3 | 0 |
Analysis population for the primary outcome, as defined in the registry: No data displayed because Outcome Measure has zero total participants analyzed and no data was collected.
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 | Glutamine | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 7 | 7 | 14 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 5 | 3 | 8 |
| Age, Categorical: >=65 years | Participants | 2 | 4 | 6 |
| Sex: Female, Male: Female | Participants | 7 | 7 | 14 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): White | Participants | 6 | 6 | 12 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Excessive Radiation Toxicity as Defined by Radiation Therapy Oncology Group (RTOG) Acute Scale of Radiation-toxicity Criteria, measured over 12 days and 30 days.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was excessive radiation toxicity, defined in the registry as an RTOG Acute scale score of 2 or higher at either the 12-day or 30-day assessment. The record says the scale ranges from 0-4 and that 0 is defined as “no change.” It does not give a more detailed interpretation of the individual scores.
Using a threshold turns the scale into a classification of whether a participant met the registry’s definition of excessive toxicity at either assessment. In general, a threshold can make a clinically defined outcome easier to interpret as a yes-or-no event, but it also loses detail about the full range of scores. In general, considering either of two assessment times can capture an event recorded at either time; it does not, on its own, explain how missing assessments would be handled.
The endpoint was intended to assess acute toxicity during radiation treatment. The registry record reports no participants analyzed and no data collected for it, so it gives no event counts or group comparison for the primary endpoint. It also does not report a rationale for selecting the threshold or the two assessment times.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes the question and the planned comparison, but it does not provide an efficacy result. Although the listed enrollment is 14, the primary outcome has zero total participants analyzed and no data were collected. Consequently, there is no posted primary-outcome event count, effect estimate, confidence interval, or statistical test result to interpret.
This absence matters for interpretation. A group comparison requires observed outcome information from the groups. Without it, readers cannot determine how often excessive toxicity occurred, whether the groups differed, or how precisely a difference could be estimated. The lack of results is not evidence that the groups had the same outcome, and it is not evidence that either group had more toxicity. No conclusion about the primary question follows from the missing outcome data.
The safety information is distinct from the primary efficacy outcome. The registry lists 7 participants at risk for serious adverse events in each group and 0 affected in either group. It also lists other adverse events affecting 6 of 7 at risk in the glutamine group and 5 of 7 at risk in the placebo group. These descriptive counts do not replace the missing primary endpoint and do not establish that an event was caused by a study intervention. The registry does not provide detail on the nature or timing of the other adverse events.
The terminated status and the registry dates describe the record’s study status and chronology, but they do not identify the reason for termination, whether the study stopped early relative to its plan, or how termination affected data collection. Such explanations are not reported in the registry record. It would be inappropriate to infer them from the absence of outcome data alone.
Any planning illustration based on an observed effect must be read as a hypothetical planning exercise, not as an observed-power calculation or evidence that the study detected an effect. Here, no primary outcome data are reported from which a result could be assessed. The record also does not provide a sample-size justification or report the statistical plan underlying the study. The appropriate statistical conclusion is therefore limited: the planned comparison is described, but the posted record does not permit an estimate or test of the primary treatment-group difference.
9. Statistical Methods Explained
Interpreting a clinical trial ordinarily requires a clear outcome definition, information about how participants entered each analysis, and a statistical comparison that matches the outcome and design. The registry describes a randomized, double-blind, parallel, two-arm study and defines its primary outcome, but reports no analyzed participants and no collected primary-outcome data. The methods concepts below explain how such a comparison is generally approached; they do not assert that the registry used any unreported procedure.
What does randomization contribute?
In general, randomization assigns participants to study groups using a chance-based process. Its purpose is to reduce systematic differences between groups at the start of a trial, including differences that may not have been measured. Randomization does not guarantee that groups will be identical, especially in a small study, and it does not correct problems that arise after assignment, such as missing outcomes or departures from the planned analysis.
The record identifies the study as randomized but does not report the sequence-generation method, allocation concealment, stratification, or any other implementation details. Those details are not reported in the registry record. The record also describes the study as double-blind, but does not specify who was masked or how masking was maintained. The design labels describe the intended approach; they are not enough to verify how it was carried out.
How is the primary outcome classified?
The registry defines excessive toxicity as an RTOG Acute scale score of 2 or higher at either the 12-day or 30-day assessment. In general, this rule converts scores into a binary outcome: a participant meets the threshold or does not. An analysis could compare the proportion meeting that definition between groups, but the registry does not report outcome counts or an analysis. No such comparison can be reconstructed from the record.
A binary threshold may simplify interpretation, but it discards distinctions among scores on the scale. The registry gives the scale range as 0-4 and defines 0 as “no change”; it does not explain the clinical meaning of each other score. Nor does it report whether the threshold or assessment schedule was prespecified in a protocol or analysis plan. The registry’s endpoint description is available, but the protocol details are not reported in the registry record.
What would an effect estimate and confidence interval mean?
In general, an effect estimate describes the observed contrast between groups on a defined outcome. For a binary outcome, possible measures include a difference in proportions or a relative measure, but selection should follow the analysis plan and the intended interpretation. No effect estimate of any kind is reported for this primary outcome, and the underlying event counts are unavailable.
In general, a confidence interval expresses the uncertainty associated with an estimate under the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, while both the estimated effect and the interval are needed to understand the result. A confidence interval cannot be recovered when the primary outcome data are absent. The registry also gives no confidence level or interval for this outcome.
What does a significance test tell the reader?
In general, a significance test evaluates how compatible the observed data are with a specified null hypothesis under a model. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. Any test also depends on a chosen statistical model and analysis plan. The registry reports no primary-outcome p-value or test statistic, and its analysis plan is not reported in the registry record.
The record’s sample-size assumptions describe a planning illustration using a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. Such assumptions concern a planning calculation; they do not demonstrate that a trial had a particular probability of detecting an effect, and sample-size illustrations are not observed power. No resulting sample-size values or effect estimate appear in the registry record for this analysis. The registry does not report its own sample-size justification.
Why does the assessment schedule matter?
The endpoint counts toxicity if the threshold is met at either assessment. In general, repeated assessments can provide information about outcome occurrence over time, but they also raise analytic questions: whether each time point is analyzed separately, whether the “either time” definition is the sole primary comparison, and how incomplete assessments are treated. The registry’s outcome description supplies the threshold and assessment times but not those analytic details.
The registry indicates that the primary outcome has multiple categories or time points and is not reduced to one comparison. This is important because results from separate time points or categories can represent different questions. Without a stated analysis plan and posted data, readers cannot tell which comparison would have been primary if data had been collected or how any multiplicity would have been addressed.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when more than one hypothesis is tested or when several outcomes, categories, or time points are examined. In general, making many comparisons can increase the chance of obtaining at least one apparently notable result by chance. Statistical plans may address this by identifying a primary comparison in advance or adjusting interpretation for multiple tests. The registry defines a primary outcome assessed at 12 days and 30 days, and indicates that the outcome has multiple categories or time points and is not reduced to one comparison. It does not report a multiplicity strategy or a detailed analysis plan.
The record lists one outcome measure and zero analyses. It reports no primary-outcome data, no test results, and no analysis population beyond stating that zero participants were analyzed for that outcome. Therefore, the record does not show whether all randomized participants were included in an intended analysis, whether analyses were intended to follow assignment, or whether any per-protocol or other population was planned. These details are not reported in the registry record.
Missing-data handling is also not reported. The record explicitly says no data were collected for the primary outcome, which differs from reporting that some outcome values were missing among participants who were assessed. There are no posted data from which to assess incomplete follow-up, reasons for missingness, or the assumptions that an analysis might make about missing outcomes. The status “terminated” does not explain why outcome data were not collected or whether any information was collected outside the registry outcome record.
With no primary-outcome data and no reported analysis, there is no basis to judge whether multiplicity or missingness altered an estimated treatment effect. These are unresolved reporting limitations, not evidence for or against a group difference.
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 |
|---|---|---|---|
| Glutamine | 0 | 7 | 0.0% |
| Placebo | 0 | 7 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Glutamine | 0 of 7 |
| Placebo | 0 of 7 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Glutamine | 6 of 7 |
| Placebo | 5 of 7 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Glutamine | Placebo |
|---|---|---|---|
| skin erythema | Skin and subcutaneous tissue disorders | 3 of 7 | 3 of 7 |
| skin hyperpigmentation | Skin and subcutaneous tissue disorders | 2 of 7 | 2 of 7 |
| anemia | Blood and lymphatic system disorders | 2 of 7 | 0 of 7 |
| fatigue | General disorders | 2 of 7 | 0 of 7 |
| breast pain | Reproductive system and breast disorders | 0 of 7 | 1 of 7 |
| asymptomatic breast edema | Reproductive system and breast disorders | 1 of 7 | 0 of 7 |
| breast fibrosis/fat necrosis | Reproductive system and breast disorders | 1 of 7 | 0 of 7 |
| telangiectasia | Skin and subcutaneous tissue disorders | 1 of 7 | 0 of 7 |
| nausea | Gastrointestinal disorders | 1 of 7 | 0 of 7 |
| hyperkalemia | Blood and lymphatic system disorders | 0 of 7 | 1 of 7 |
The registry lists serious adverse events separately from other adverse events. For serious adverse events, it reports 7 participants at risk in the glutamine group and 7 in the placebo group, with 0 affected in each. It reports 0 deaths in each group. These are the posted counts; they do not establish that no adverse events of any kind occurred.
For other adverse events, the registry lists 7 at risk in each group, with 6 affected in the glutamine group and 5 in the placebo group. The record does not provide the event terms, severity breakdown, timing, or attribution for those other events. It also does not explain the relationship between these safety populations and the population used for the primary outcome, for which no participants were analyzed.
Safety counts are descriptive. They do not, by themselves, show that an event was caused by glutamine or placebo, and the small listed groups provide limited information about uncommon events. The registry’s serious-event counts should be read as counts recorded for the listed groups, not as proof that an intervention is free of risk.
12. What the Result Does, and Does Not, Mean
The registry establishes that a randomized, double-blind study was intended to compare glutamine with placebo for radiation toxicity during breast-conserving therapy. It gives the intervention regimens, defines excessive toxicity using the RTOG Acute scale, and lists the assessment times. It also records an enrollment of 14 and a terminated status.
What the record does not establish is whether glutamine changed the frequency or severity of radiation toxicity. The primary outcome has zero participants analyzed and no data collected. There are no primary-outcome counts, effect estimates, confidence intervals, or significance tests to support a conclusion about the intended comparison. A lack of posted results cannot be interpreted as no difference, and it cannot be interpreted as evidence of benefit or harm.
The safety entries provide descriptive counts for serious and other adverse events, but the registry does not supply details needed to interpret the other events or their relationship to treatment. These counts are not a substitute for the missing efficacy data, and they do not establish causation.
More broadly, the registry record does not report why the study was terminated, the statistical analysis plan, a sample-size justification, or the handling of missing outcome data. Without those details and without collected primary-outcome data, readers cannot assess the planned analysis, estimate its uncertainty, or judge whether the study could answer its stated question. The reliable interpretation is limited to the study design and the information actually recorded; any claim about comparative efficacy would go beyond that information.
13. Why This Trial Matters Statistically
This study illustrates why a trial’s design and outcome definition are not the same as an interpretable treatment-effect result. The registry specifies a randomized comparison, identifies glutamine and placebo regimens, and defines excessive radiation toxicity using a threshold on the RTOG Acute scale at two assessment times. Those details identify the question the study was intended to address.
Statistical interpretation nevertheless depends on observed outcome data. Here, the registry reports zero participants analyzed for the primary endpoint and states that no data were collected. As a result, there is no estimate of the group contrast and no way to quantify its precision. The record cannot establish a null result or a treatment effect.
The distinction between missing results and negative results is central to evidence assessment. A reader should not treat the absence of an analysis as though an adequately estimated difference were close to zero. Nor can the listed enrollment alone establish how many participants contributed usable outcome information. The registry’s status of terminated does not explain why the data are absent.
The case also highlights analytic questions that remain open when a registry gives an endpoint but not an analysis plan. The “either assessment” definition, multiple categories or time points, missing-data handling, and multiplicity strategy can all affect how an outcome should be analyzed. The registry does not report those methods. Statistical transparency requires both a defined question and enough data and analytic detail to evaluate the answer.
Finally, descriptive safety counts should be distinguished from comparative efficacy evidence. They provide some recorded information about affected participants, but do not establish causation or answer the primary question. Together, these features make the record useful for understanding the intended design and the limits of the available results, while leaving the clinical comparison unresolved.
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 most important limitation is the absence of primary-outcome data. The registry states that zero participants were analyzed and that no data were collected for the outcome. No event counts or treatment-effect estimates are available, so the intended comparison cannot be evaluated statistically.
The record lists an enrollment of 14 but does not explain how enrollment relates to the safety denominators, completion of the intervention, or eligibility for outcome assessment. It does not report participant flow, withdrawals, adherence, protocol deviations, or reasons for missing outcome information. These omissions limit understanding of who contributed to each reported measure.
The study is marked terminated, but the reason for termination and its relationship to the planned timeline are not reported in the registry record. The record also does not report the randomization method, allocation concealment, masking details, sample-size justification, statistical analysis plan, or missing-data procedures. The endpoint is defined by a threshold at either of two assessment times, while the record notes that the outcome has multiple categories or time points and is not reduced to one comparison. How that complexity was intended to be handled is not reported.
Safety reporting is limited to group counts. The terms, timing, severity details for other events, and attribution to an intervention are not reported. These limitations mean the safety counts should be interpreted descriptively and cannot fill the gap in primary-outcome results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Glutamine for the Prevention of Radiation Toxicity in Subjects Conserving Therapy — NCT02012608.
- Registry record last updated 2019-05-29; status last verified 2019-05.
- Results first posted 2019-05-29.
- 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 describes a Phase 2, randomized, double-blind, parallel, two-arm study sponsored by the University of Arkansas. It lists breast cancer as the condition, enrollment of 14, a start of 2014-06, primary completion of 2019-04, and status as terminated.
The planned intervention was oral glutamine compared with powdered dextrose placebo. The primary outcome was excessive radiation toxicity, defined as an RTOG Acute scale score of 2 or higher at either the 12-day or 30-day assessment. The registry reports zero participants analyzed and no data collected for this outcome, so no efficacy comparison is available.
For safety, the registry lists 0 serious adverse events and 0 deaths in each group; other adverse events affected 6 of 7 at risk in the glutamine group and 5 of 7 at risk in the placebo group. The record does not provide details sufficient to establish causation or explain termination.