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 Neoadjuvant Chemoradiation With RHUMAB VEGF (Avastin) for Rectal Cancer (NCT00113230), a non-randomized phase 2 study. The primary outcome is Pathologic Local Tumor Response.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00113230 |
| Phase | Phase 2 |
| Condition | Rectal Cancer |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 25 |
| Arms in the primary outcome | n/a |
| Lead sponsor | M.D. Anderson Cancer Center |
| Results posted | Yes |
2. Clinical Question
Population
Patients presenting with locally advanced rectal cancer. The record describes an intention-to-treat approach and says the data examination was conducted upon enrollment and evaluability of 25 patients.
Intervention
Neoadjuvant treatment with capecitabine, bevacizumab (Avastin, also identified as RHUMAB VEGF) and radiotherapy, followed by surgical resection as described in the primary outcome definition.
Comparator
There is no separate comparison group. The trial is listed as non-randomized and single-group, so the registry record does not support a randomized, like-for-like comparison with another treatment.
Primary question
After neoadjuvant treatment and surgery, what pathologic local tumor response was recorded in the resected primary tumor? The registry record defines response categories but does not report how many participants fell into each category.
The study rationale was that adding bevacizumab to chemoradiation might increase tumor response in locally advanced rectal cancer. That is the hypothesis stated in the registry summary, not a result. The study combined capecitabine, bevacizumab and radiotherapy; because there was no control group, the primary outcome can describe responses observed after the combined regimen but cannot isolate the contribution of any one component.
The primary assessment was specified from baseline to approximately 5 Months, following 28 days of treatment, chemotherapy and surgical resection of the tumor. The endpoint was based on pathology of the resected primary tumor, rather than a comparison of treatment strategies. The clinically relevant statistical question is therefore descriptive: how were the recorded tumors classified after treatment? The category counts needed to answer that question are not reported in the registry record.
3. Trial Design
This is a phase II study with non-randomized allocation, no masking and a single-group model. The intervention group is described as receiving capecitabine, Avastin (bevacizumab/RHUMAB VEGF) and radiotherapy. Enrollment is recorded as 25, and the registry status is completed. The sponsor is M.D. Anderson Cancer Center. The study start is recorded as 2005-02 and primary completion as 2009-01.
With a single group, the design can describe outcomes and adverse events observed among participants receiving the combined regimen. It does not create a concurrent untreated or alternative-treatment group. As a result, any observed response cannot be interpreted as a treatment effect relative to another strategy based on this design alone. Differences from earlier studies, if considered outside this record, would not substitute for random allocation and a concurrent comparator.
The registry defines the primary outcome as pathologic local tumor response among participants, assessed after neoadjuvant and surgical therapy. The outcome description gives three classifications: pathologic complete response, microscopic residual disease and gross residual disease. The record describes an intention-to-treat analysis method and says data examination was conducted upon enrollment and evaluability of 25 patients. It does not report the category counts, a participant flow accounting, or details on how any unevaluable or missing outcomes were handled.
The study is listed as phase II, but the registry record does not report the protocol rationale for the enrollment target or a statistical analysis plan. Randomization procedures are not applicable to the listed single-group, non-randomized design. The record also lists no analyses. Its completion status indicates that the study is recorded as completed, but that status alone does not supply the missing endpoint results or explain how the outcome was analyzed.
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 | Avastin |
|---|---|
| STARTED | 25 |
| COMPLETED | 25 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Intention to treat analysis method. Data examination conducted upon enrollment and evaluability of 25 patients.
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 | Avastin |
|---|---|---|
| Participants analysed | 25 | |
| Age Continuous | years | 51 (34 to 68) |
| Sex: Female, Male: Female | Participants | 12 |
| Sex: Female, Male: Male | Participants | 13 |
| Region of Enrollment: United States | participants | 25 |
6. Primary Endpoint
The registry lists the primary outcome as Pathologic Local Tumor Response, measured over Baseline to approximately 5 Months (Following 28 days of treatment, chemotherapy and surgical resection of tumor).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is pathologic local tumor response, measured as the classification of the resected primary tumor after neoadjuvant and surgical therapy. The registry describes pathology categories: pathologic complete response means no evidence of residual cancer; microscopic residual means no grossly detected disease but evidence of microscopic residual disease; and gross residual disease indicates grossly detectable remaining disease. The assessment is specified from baseline to approximately 5 Months, following 28 days of treatment, chemotherapy and tumor resection.
Pathologic assessment is used to characterize what is found in the tumor specimen after treatment. It differs from an endpoint based on symptoms, imaging alone, time to recurrence or survival. In general, a categorical pathology endpoint can summarize whether residual disease was found and at what stated level, while keeping the categories distinct rather than treating them as interchangeable outcomes.
The registry record does not report the number of participants in any of the response categories. It therefore does not permit a reader to determine the observed distribution of pathologic response or its precision. The endpoint definition is present, but its results are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The available record identifies the primary endpoint and its assessment window, but it does not provide the observed response counts. In particular, it does not report how many resected tumors were classified as pathologic complete response, microscopic residual disease or gross residual disease. Without those counts, the primary result cannot be quantified, and no estimate of the frequency of each category or its uncertainty can be described from this record.
The record reports enrollment of 25 and describes data examination upon enrollment and evaluability of 25 patients. Those statements do not replace outcome data. They also do not establish, by themselves, whether every enrolled participant had an evaluable pathology result or how any missing or unevaluable assessment was treated. Those details are not reported in the registry record.
The single-group design is central to interpretation. Any outcome counts, if available, would characterize participants treated with capecitabine, bevacizumab and radiotherapy in this study. There is no concurrent randomized comparator against which to estimate what would have occurred under another regimen. A single-group result cannot separate the association of the combined treatment with an outcome from other influences, including patient characteristics, tumor features, surgical care or the natural course of disease. This is a general limitation of uncontrolled studies, not a claim about what occurred in this trial.
No effect estimate, confidence interval or hypothesis-test result is reported in the registry record. A confidence interval, in general, describes the statistical precision of an estimate under the assumptions of the method used; without an endpoint estimate and an analysis, there is no interval to interpret. Likewise, the record does not provide a p-value or an inferential comparison. The registry lists no analyses.
Safety information is also limited to registry counts. The serious adverse event figures record zero participants affected among 25 at risk, while the other adverse event figures record one participant affected among 25 at risk. The registry does not list serious adverse event terms in its top-terms field. These counts should be read as the information recorded for this group, not as proof that treatment has no risk or as a comparison with another intervention.
Overall, the record gives the design, treatment components and primary outcome definition, but the key efficacy result is not reported in the registry record. Any conclusion about the observed tumor response or its precision would go beyond the recorded results.
9. Statistical Methods Explained
Statistical interpretation begins by distinguishing the design, the endpoint and the analysis result. This study is recorded as a single-group, non-randomized phase II trial. Its primary endpoint is a categorical pathology outcome after neoadjuvant treatment and surgery. The record identifies these elements but does not report the outcome-category counts, an inferential analysis or a statistical analysis plan. The concepts below are general explanations of how such information is usually interpreted; they are not claims that a particular method was used in this study.
What does a single-group design estimate?
A single-group study can describe outcomes observed among people who received the study regimen. For a categorical endpoint, this might include counts or proportions in each category, accompanied by an uncertainty estimate if the analysis plan specifies one. Such a description answers what was observed in the studied group. It does not estimate a comparative treatment effect unless a suitable comparison is available and the analysis supports that interpretation.
Random assignment is one way to make treatment groups comparable, on average, for measured and unmeasured baseline factors. This study is explicitly listed as non-randomized and single-group, so that protection against confounding from randomization is absent. A response observed after the combined treatment cannot establish what the same participants would have experienced under a different treatment. The effects of capecitabine, bevacizumab and radiotherapy also cannot be disentangled from one another within this design.
How should categorical response be read?
The pathology endpoint uses three defined categories. In general, a categorical outcome is interpreted by retaining its categories and their definitions. Collapsing categories can change the scientific question, and any such grouping should be prespecified and clearly described. The registry does not report a combined-category analysis. Nor does it report the number of tumors in each stated category, so neither the category distribution nor a summary based on it can be reconstructed from the record.
When a study reports a count in a category, a corresponding proportion can describe the fraction of the analyzed group represented by that category. Precision depends in part on the amount of information available and on the statistical method. A confidence interval communicates uncertainty around an estimate; it does not mean that the true value has a specified probability of lying in that particular calculated interval under the usual frequentist interpretation. No interval or underlying response count is reported for this endpoint in the registry record.
What does a confidence interval add?
As a general statistical concept, a confidence interval shows a range of values compatible with the observed data under a specified procedure and assumptions. A narrow interval indicates greater statistical precision than a wide interval, but neither width nor position alone resolves design bias or establishes causality. For a single-group response endpoint, an interval around the observed response frequency would describe uncertainty in that group; it would not create a comparator or show what would have happened under another regimen.
The record does not report an interval or an effect estimate for pathologic response. It also does not report a significance test. The absence of these statistics means there is no inferential result to interpret; it is not evidence that an analysis found no effect. The registry lists zero analyses.
What can planning illustrations say?
Sample-size illustrations based on an observed effect are planning exercises, not results from a new trial. The record describes the assumptions for such illustrations as a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. The record also specifies that these illustrations are not the trial's own design. For time-to-event outcomes, such illustrations concern total events; for other outcomes, the stated convention is participants per arm.
In general, a planning illustration estimates the sample size needed to detect a chosen effect under stated assumptions. It does not show that a study had a given probability of finding a result after it has been completed, and it is not observed power. Such calculations depend on the target effect, allocation, test assumptions and outcome model. Since this study is single-group, an equal-allocation two-arm illustration is not a description of its enrollment design. The registry does not report the study's own sample-size justification or a power calculation as part of its design.
Why can outcome distributions matter?
For a binary outcome, methods often model the chance of an event. For a categorical endpoint with more than two possible classifications, the analysis must account for the categories and the way they relate to the scientific question. General choices can include separate category frequencies or a model for category probabilities, but the appropriate approach depends on prespecification, data structure and sample size. None of these approaches should be attributed to this trial without a reported statistical plan or results.
Over-dispersion is a general concern when observed variability exceeds what a chosen statistical model assumes. If a model assumes observations are less variable than they really are, its uncertainty estimates can be too small and its tests can be misleading. Whether over-dispersion is relevant depends on the outcome and model. The registry record does not report a model for the primary endpoint, so there is no basis to say that over-dispersion was assessed or present in this analysis.
Interpretation therefore rests on a clear boundary: the registry defines the outcome and study structure, but it does not report the response results or analysis details needed to assess an effect estimate, its precision or model assumptions.
10. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when several outcomes, comparisons, subgroups or repeated tests are analyzed. Testing many questions can increase the chance of at least one apparently noteworthy result even when no corresponding effect exists. General strategies include prespecifying a primary question, adjusting inference for multiple tests, or treating additional analyses as exploratory. The appropriate strategy depends on the trial's analysis plan and the questions it was designed to answer.
The registry identifies pathologic local tumor response as the primary outcome and lists one outcome measure. It lists zero analyses. That does not establish whether additional analyses were performed outside the registry entry, whether there were secondary outcomes in a protocol, or whether any multiplicity adjustment was planned. Those details are not reported in the registry record. No adjustment method should be inferred from the single listed primary outcome.
The record describes an intention-to-treat analysis method and says data examination was conducted upon enrollment and evaluability of 25 patients. Intention-to-treat generally refers to analyzing participants according to their assigned group, regardless of adherence or treatment received. In a single-group study without randomized assignment, the exact operational meaning still depends on the protocol and analysis rules. The registry does not report how the method was implemented, how missing pathology assessments were treated, or whether all enrolled participants contributed to the primary endpoint analysis.
Missingness can affect both the number of observations used and the interpretation of results. In general, complete-case analysis, imputation and sensitivity analyses rely on different assumptions. The record does not report the number or reasons for missing or unevaluable primary outcomes, any imputation method, or sensitivity analyses. Therefore, the extent to which missing data could influence an endpoint estimate cannot be assessed from the registry record.
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 |
|---|---|---|---|
| Avastin | 0 | 25 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 4% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Avastin | 1 of 25 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Avastin |
|---|---|---|
| Amyloidosis | Blood and lymphatic system disorders | 1 of 25 |
The registry records serious adverse event figures for the Avastin group: 25 participants at risk and zero affected. For other adverse events, it records 25 at risk and one affected. The serious-event list contains no top serious adverse event terms. These are counts as entered in the record; they are not comparative estimates and do not establish how the event experience differs from another treatment.
A count of zero affected means that the registry records no participants with a serious adverse event in this group for the reported safety information. It does not prove that the underlying risk is zero. In general, an observed count can be compatible with a range of possible event frequencies, especially when information is limited. A precise uncertainty statement would require a specified method and fuller reporting. No such interval is reported in the registry record.
The record does not describe the adverse-event collection window, severity grading rules, event definitions, follow-up completeness or how repeated events in one participant were handled. It therefore cannot answer whether the counts cover all relevant periods or provide a detailed safety profile. The single-group design also gives no concurrent control for comparing adverse-event counts. The figures should be interpreted narrowly as the safety counts registered for this treatment group.
12. What the Result Does, and Does Not, Mean
The registry record establishes that this was a completed phase II, non-randomized, single-group study of neoadjuvant capecitabine, bevacizumab and radiotherapy in locally advanced rectal cancer. It identifies pathologic local tumor response after treatment and surgery as the primary endpoint, and it defines three pathology categories. It also records enrollment of 25 and gives limited adverse-event counts for the Avastin group.
What the record does not establish is the observed response result. The number of participants with pathologic complete response, microscopic residual disease or gross residual disease is not reported in the registry record. No primary endpoint estimate, confidence interval, p-value or analysis result is reported. Thus, the record cannot support a quantitative statement about how often any response category occurred or how precisely that frequency is known.
Even if category counts were available, a single-group study would describe outcomes among those treated rather than provide a randomized comparison with another treatment. It could not by itself establish that the combined regimen caused an observed response or determine which component contributed to it. These are design limits, not judgments about the clinical value of the regimen.
The safety figures likewise have a narrow meaning: zero participants are recorded as affected by a serious adverse event among 25 at risk, and one is recorded as affected by another adverse event among 25 at risk. They do not establish absence of risk, characterize every possible safety outcome or compare risks against another group.
The study rationale states a hypothesis about adding bevacizumab to standard chemoradiation. A hypothesis is not a finding. Without the endpoint counts and fuller analysis information, the registry record supports a description of the trial design and outcome definition, but not a conclusion about the magnitude, precision or causal interpretation of tumor response.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the distinction between a clearly named endpoint and a reported endpoint result. The registry defines pathologic local tumor response and describes how the tumor specimen is classified, yet it does not report the counts in those categories. An outcome definition is necessary for interpretation, but it cannot substitute for the data needed to estimate an outcome.
The study also illustrates the inferential limits of a single-group design. Such a design can document what was observed among treated participants, but it does not supply the concurrent counterfactual comparison needed to attribute differences to treatment. The regimen combines capecitabine, bevacizumab and radiotherapy, so even a reported response distribution would not separate the contribution of each component.
The registry's description of an intention-to-treat method highlights another statistical issue: analysis labels need operational detail. Readers need to know which participants were included, how evaluability was determined and how missing outcomes were handled. The record does not provide those details for the primary endpoint. Without them, it is difficult to assess how closely the analyzed population corresponds to the intended population.
Finally, the limited safety counts show why denominators, ascertainment periods and event definitions matter. Counts can be reported without enough information to judge completeness or compare risks. These limitations do not make the record uninformative; they identify which conclusions the record can support and which remain 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 principal limitation for interpretation is that the registry does not report the primary endpoint counts. Although the response categories and assessment window are defined, the observed distribution and any estimate of precision are unavailable. The registry also lists zero analyses, and does not report a statistical analysis plan, hypothesis test, confidence interval or effect estimate for the primary endpoint.
The single-group, non-randomized design has no concurrent comparator. It can describe outcomes in the treated group but cannot support a randomized comparison or isolate treatment effects from other influences. Because the intervention includes capecitabine, bevacizumab and radiotherapy, the design also cannot identify the separate contribution of each component.
The record states an intention-to-treat analysis method and describes examination upon enrollment and evaluability of 25 patients, but it does not explain the inclusion rules, participant flow, missing outcome handling or sensitivity analyses. It is therefore not possible to assess the consequences of missing or unevaluable pathology results from the registry record alone.
Safety reporting is limited to counts of affected participants and does not describe event definitions, collection windows, severity grading, follow-up completeness or repeated events. The record contains no top serious adverse event terms. It also does not report the study's sample-size justification or its own statistical design assumptions. Planning illustrations based on observed effects are separate from the trial's design and cannot fill those gaps.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Neoadjuvant Chemoradiation With RHUMAB VEGF (Avastin) for Rectal Cancer — NCT00113230.
- Registry record last updated 2012-08-07; status last verified 2012-07.
- Results first posted 2009-11-13.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry describes a completed phase II trial of neoadjuvant capecitabine, bevacizumab (Avastin/RHUMAB VEGF) and radiotherapy for locally advanced rectal cancer. It is listed as non-randomized, unmasked and single-group, with enrollment of 25. The recorded study start is 2005-02 and primary completion is 2009-01; the sponsor is M.D. Anderson Cancer Center.
The primary outcome is pathologic local tumor response in the resected primary tumor, assessed from baseline to approximately 5 Months after treatment and surgery. The defined categories are pathologic complete response, microscopic residual disease and gross residual disease. The registry describes an intention-to-treat method but does not report the category counts or a primary analysis result.
Safety figures record zero serious adverse events among 25 at risk and one other adverse event among 25 at risk. The record does not provide further event details or a comparator. Its design and outcome definitions are documented, but the primary response result and important analysis details are not reported in the registry record.