Capecitabine + Irinotecan Followed by Combined Modality Capecitabine and Radiation in Locally Advanced Rectal Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Capecitabine + Irinotecan Followed by Combined Modality Capecitabine and Radiation in Locally Advanced Rectal Cancer (NCT00216086), a na phase 2 study. The primary outcome is Pathological Complete Response (pCR) Rate.

2. Clinical Question

3. Trial Design

This was a phase II, single-group study of a treatment sequence for locally advanced rectal cancer. The registry lists enrollment as 22 and the study status as terminated. The recorded start was 2005-05, and primary completion was recorded as 2008-05. These registry fields describe the study record; they do not establish how many participants completed treatment or contributed to the primary endpoint.

The planned sequence began with preoperative capecitabine and irinotecan, followed by combined-modality capecitabine and radiation. The intervention list also includes endoscopic ultrasound, neoadjuvant chemotherapy, preoperative radiation, surgery, and adjuvant chemotherapy. The record’s brief summary describes investigation of this preoperative approach and its relationship to response and local recurrence. It also describes planned investigation of whether TS, TP, DPD, and carboxyesterase expression correlated with objective response. Results for those biomarker questions are not reported in the registry record.

The record describes one investigational treatment group, rather than a randomized or controlled design. Allocation is listed as NA, and masking is listed as none. This design can describe outcomes observed among participants receiving the study regimen, but it cannot by itself separate treatment effects from other explanations for an outcome. There is no concurrent control arm for a like-for-like comparison.

The listed primary endpoint is pathological complete response rate, measured as a percentage of patients. The registry specifies a 95% confidence interval and a 36-month timeframe. The outcome description defines pathological response in terms of complete and non-complete response among evaluable patients, but does not provide a reported result. The registry record also lists local and distant disease recurrence rates, clinical response rate, and disease-free survival as secondary outcomes. Their estimates and analysis details 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

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Pathological Complete Response (pCR) Rate, measured over 36 months.

The primary endpoint is titled pathological complete response rate, abbreviated pCR rate. It is intended to describe the proportion of evaluable patients whose surgical pathology showed a complete response after the planned preoperative treatment sequence. Pathology assesses tumor tissue rather than relying only on changes visible on imaging or on symptoms, making it a distinct way to characterize response after preoperative therapy.

The registry describes the endpoint as a percentage of patients, with a 95% confidence interval and a 36-month timeframe. Its protocol description refers to complete and non-complete pathological response among all evaluable patients. The purpose of reporting a proportion is to make the frequency of complete pathological response interpretable in the assessed group. A confidence interval would convey the uncertainty around that estimated proportion; it would not guarantee that the estimate applies to other populations or treatment settings.

The registry record does not report the observed pCR rate, the number of evaluable patients, or the confidence interval. Enrollment of 22 is recorded, but that does not establish how many participants were evaluable for this endpoint. The endpoint’s planned definition and timeframe therefore should not be mistaken for a posted outcome. Without the result and analysis population, the primary response rate cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods can only be interpreted to the extent that the registry record describes them. It identifies a percentage endpoint and a planned 95% confidence interval, but does not report an analysis method, the number of evaluable patients, an endpoint estimate, or interval limits. No inferential analysis results are posted in the registry record. The explanations below describe general statistical ideas relevant to the stated endpoint; they are not claims about methods actually used in this trial.

What does a response percentage describe?

In general, a response percentage is a proportion: the number of people meeting an outcome definition relative to a specified analysis group. For this trial, the stated endpoint concerns pathological complete response among evaluable patients. The denominator matters because enrollment, treatment receipt, surgery, and evaluable pathology are not necessarily identical populations. A complete report would make clear who was considered evaluable and how participants without an assessable pathology result were handled. Those details are not reported in the registry record.

The protocol description mentions complete and non-complete pathological response. That definition identifies the kinds of response classification relevant to the endpoint, but it does not disclose the observed counts or the rule used for participants whose response could not be assessed. Without both an outcome definition and the actual analysis population, a reported percentage could not be fully reconstructed or evaluated for potential bias.

What does a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimate, reflecting that an observed proportion from a study group is only an estimate of an underlying response frequency. A narrower interval indicates greater statistical precision under the method’s assumptions; a wider interval indicates more uncertainty. It does not account automatically for bias from selection, missing outcomes, measurement, or study design. It also does not turn a single-group study into a comparative trial.

The registry identifies a 95% confidence interval as the planned precision measure, but does not provide the interval or the method used to calculate it. No numerical interpretation of precision is possible from the posted record. The stated confidence level should not be confused with a probability that the particular study result is correct, nor should it be read as a guarantee about results in other patient groups.

What does the single-group design allow?

In general, a single-group study estimates outcomes among people who receive the studied intervention. Its findings can describe the observed experience of that group, subject to outcome ascertainment and missing-data limitations. In the absence of a concurrent control group, the study does not directly estimate a between-group treatment contrast. Changes in disease status may reflect the intervention, participant characteristics, clinical care, or other factors that a controlled design might help distinguish.

Here, the registry lists one investigational treatment group, allocation as NA, and masking as none. It does not list an alternative treatment group. Thus, any reported response proportion would be descriptive rather than a randomized comparison. The registry record does not report adjustment methods or other analyses that would address differences from an external comparison population.

What role would analysis choices play?

General considerations include prespecifying the endpoint, defining the analysis population, and reporting the handling of participants without assessable outcomes. These choices can affect the estimate and its interpretation. The record names the primary endpoint and its planned timeframe, but does not report whether all prespecified analyses were completed, whether the analysis population was defined in a statistical plan, or whether any adjusted analysis was performed.

The trial’s brief summary also describes an interest in correlations between TS, TP, DPD, and carboxyesterase expression and objective response. In general, analyses of multiple biomarkers or outcomes raise questions about multiplicity: when many relationships are examined, the chance of observing an apparently notable association by chance can increase. The registry record does not report the analysis procedures, number of tests conducted, or any multiplicity adjustment. No biomarker association result is available in the record.

Finally, statistical precision is not the same as clinical importance. A proportion and its interval, if reported, would quantify the observed response and its uncertainty, but interpretation would also depend on the population, endpoint definition, follow-up, and the study’s uncontrolled design. Since the primary estimate and the supporting analysis details are not reported in the registry record, those judgments cannot be made from this record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary pathological complete response endpoint and several secondary outcomes: local and distant disease recurrence rates, clinical response rate, and disease-free survival. It also describes planned investigation of associations between TS, TP, DPD, and carboxyesterase expression and objective response. The registry record does not report a statistical analysis plan, the number of comparisons performed, or a method for controlling multiplicity. It is therefore not possible to determine whether any adjustment was planned or used, or how exploratory findings were distinguished from confirmatory findings.

Multiplicity matters in general because examining several outcomes or biomarker associations creates multiple opportunities for chance findings. An adjustment can change the evidential threshold or otherwise account for repeated testing, but the appropriate approach depends on the analysis plan and aims. No results or multiplicity procedures are reported for this study, so no claim about statistical significance across outcomes or biomarkers can be assessed.

The record does not state how missing endpoint observations were handled, how many participants were evaluable, or whether the primary analysis used an intention-to-treat, per-protocol, or other population. The enrollment of 22 is not enough to establish the denominator for the response endpoint. The record also does not report participant flow through treatment, surgery, or follow-up, or the extent and reasons for missing data. These omissions matter because an analysis restricted to evaluable participants can differ from one that includes all enrolled participants under a prespecified missing-outcome rule.

Whether interim analyses were planned or conducted, and whether any stopping rules or analysis populations were prespecified, is not reported in the registry record. These matters should not be inferred from the terminated status.

11. Safety Results

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

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cardiac general - other (specify, __) (4.5%), diarrhea (4.5%), dizziness (4.5%), dyspnea (shortness of breath) (4.5%), edema: head and neck (4.5%).

The registry safety summary lists one single-group assignment, with 22 at risk in the serious-event field and 6 affected. In the other-event field it lists 22 at risk and 21 affected. These are the recorded figures for the group; they are not comparative safety estimates because the study has no control arm. The registry does not provide a treatment-versus-control contrast or an estimate of excess risk.

The listed serious adverse event terms each have a reported frequency of 4.5%: cardiac general—other, diarrhea, dizziness, dyspnea, edema of the head and neck, and febrile neutropenia. These term-level percentages should be read as the registry’s reported category frequencies. They do not establish causation or show whether an event was judged related to a particular study treatment. The registry record does not give further event-level context for these entries.

The record does not report a death count in the safety summary. It also does not provide detailed timing, duration, management, or outcomes for the listed events. Because the study is single-group and the safety information is limited, the figures describe recorded events in the study group rather than proving that the regimen caused them or establishing how its safety compares with another approach.

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

The registry record establishes that a phase II, single-group study was designed to investigate a preoperative treatment sequence for locally advanced rectal cancer. Its primary endpoint was pathological complete response rate, expressed as a percentage among evaluable patients, with a planned 95% confidence interval and a 36-month timeframe. The record does not report the response estimate, confidence interval, or analysis denominator. It therefore does not provide the numerical result needed to assess the primary outcome.

Even if an outcome estimate were available, the single-group design would support a description of what was observed among the assessed participants, not a direct comparison with another regimen. Without a randomized or concurrent control group, differences from results in another study could reflect differences in eligibility, clinical practice, outcome assessment, or follow-up as well as treatment. The registry does not report a like-for-like comparison.

The record lists 22 enrolled participants, but does not state how many received each planned treatment component or were evaluable for pathology. Enrollment should not be substituted for an endpoint denominator. The study status is terminated, but the reason for termination and its implications for outcome availability are not reported in the registry record.

The safety fields record affected participants and serious adverse event terms, but they do not establish that an event was caused by treatment or provide a comparative safety assessment. The listed secondary outcomes and biomarker questions likewise have no reported estimates in the registry record. Accordingly, this record describes the research question, design, and limited safety entries; it does not establish the size or precision of a response, comparative benefit, causal effect, or overall risk-benefit balance.

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 specifies pathological complete response rate, its percentage scale, a confidence interval, and a timeframe. Those details indicate what the investigators intended to assess. Without the observed estimate, interval, and analysis denominator, however, readers cannot evaluate the response frequency or its precision.

The single-group design makes the choice of language especially important. An outcome rate in one treatment group is a description of that group, not a treatment contrast. The registry lists no comparator and records allocation as NA. That design feature should shape interpretation even if endpoint results were available; it is not resolved by a confidence interval around a within-group percentage.

The enrollment field and evaluable-patient endpoint also illustrate why denominator reporting matters. The registry records enrollment as 22, while the primary endpoint is described among evaluable patients. The record does not say whether these populations coincide. Clear participant flow and explicit analysis-population definitions are essential for understanding who contributes to an outcome estimate and how missing observations may affect it.

Finally, the listed secondary outcomes and biomarker aims raise general questions about multiplicity and exploratory analysis. The record does not report how those analyses were conducted or interpreted. The statistical lesson is not that the trial found a particular result, but that design, analysis population, outcome reporting, and comparison structure are all needed before an observed percentage can carry a well-supported interpretation.

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 registry record contains no reported result for the primary pathological complete response endpoint. It gives neither an observed percentage nor a confidence interval, and it does not identify the number of evaluable patients. This is the central limitation for interpreting the study’s stated primary question. The recorded enrollment of 22 cannot stand in for an endpoint denominator.

The design is single-group, with allocation listed as NA and masking as none. There is no like-for-like control comparison in the record. As a result, the design would not isolate the effect of the treatment sequence from other influences, even if a response estimate were available.

The study is marked terminated, but the reason for termination is not reported in the registry record. The record does not explain participant disposition, treatment completion, surgery receipt, follow-up completeness, or the handling of missing outcome data. The 36-month timeframe is stated for the primary outcome, but the record does not explain how follow-up was conducted or whether the planned timeframe was completed for participants.

The registry lists secondary outcomes and biomarker questions but does not report their results or analysis details. It also does not report a statistical analysis plan, interim analyses, sample-size justification, or multiplicity procedures. These gaps limit assessment of whether the analyses followed prespecified methods and how results across outcomes would have been interpreted. The safety summary provides group-level affected figures and event-term percentages, without detailed context sufficient to establish causality or compare risks. These limitations concern the information available in the registry record and should not be taken as evidence that unreported methods or results did not exist elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Capecitabine + Irinotecan Followed by Combined Modality Capecitabine and Radiation in Locally Advanced Rectal Cancer — NCT00216086.
• Registry record last updated 2016-06-06; status last verified 2016-04.
• Results first posted 2016-06-06.
• 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 describes a phase II, single-group study of preoperative capecitabine and irinotecan followed by capecitabine with radiation for locally advanced rectal cancer. Enrollment is listed as 22, the status is terminated, and the recorded study dates are 2005-05 to primary completion in 2008-05. The primary outcome is pathological complete response rate, planned as a percentage among evaluable patients with a 95% confidence interval and a 36-month timeframe.

The primary outcome estimate, confidence interval, endpoint denominator, secondary outcome results, and biomarker results are not reported in the registry record. The record has no concurrent comparator. Safety information lists 6 affected in the serious-event field and 21 affected in the other-event field, each with 22 at risk, along with serious adverse event terms reported at 4.5%. The record does not establish event causality or comparative safety.