Study of Modified Docetaxel, Cisplatin, and Fluorouracil (mDCF) in Unresectable or Metastatic Gastric and Gastroesophageal Junction Adenocarcinoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Modified Docetaxel, Cisplatin, and Fluorouracil (mDCF) in Unresectable or Metastatic Gastric and Gastroesophageal Junction Adenocarcinoma (NCT00515411), a randomized phase 2 study. The primary outcome is 6 Month Progression Free Survival (PFS).

2. Clinical Question

3. Trial Design

The registry describes NCT00515411 as a phase II randomized, open-label, parallel-group study sponsored by Memorial Sloan Kettering Cancer Center. It lists 111 participants enrolled and the status as completed. The recorded start date is 2006-10-23, and the primary completion date is 2018-10-26. The study concerned unresectable or metastatic gastric and gastroesophageal junction adenocarcinoma.

Three treatment groups appear in the outcome record. Arm A received modified docetaxel, cisplatin, and fluorouracil with leucovorin. The regimen description specifies repeated treatment every two weeks, with a cycle considered to be six weeks. Arm B received parent DCF with G-CSF support, using Neulasta or Neupogen as described in the registry. Arm C received modified DCF plus trastuzumab and is identified as the treatment for HER2-positive participants. The registry summary says patients with HER2-positive tumors were eligible to receive trastuzumab with chemotherapy.

The design fields identify random allocation, no masking, and a parallel model. The registry does not report the allocation procedure, whether allocation was stratified, or how assignment to the trastuzumab group was handled relative to HER2 status. It also does not report enough detail to determine whether all three arms were intended as direct randomized comparisons under the same eligibility criteria. The designated control is Arm A.

Overall survival is listed as a secondary outcome, but the record summarized for these results does not provide an overall-survival estimate. The record does not report a detailed statistical analysis plan, an enrollment target rationale, or the handling of treatment changes and protocol deviations.

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

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 6 Month Progression Free Survival (PFS), measured over From date of randomization until the date of first documented progression or date of death from any cause, whichever came first, assessed up to 6 months.

The primary endpoint is titled six-month progression-free survival, reported as a percentage of participants. Progression-free survival measures the time from randomization until the first documented disease progression or death from any cause. The registry specifies assessment up to six months and defines progression using RECIST v1.0: an increase in the sum of the longest diameters of target lesions, measurable growth in a non-target lesion, or the appearance of new lesions, or a similar appropriate definition.

A six-month PFS percentage provides a time-specific description of how many participants are estimated to remain free of progression or death through that horizon. It is useful because it combines progression and death into one outcome and gives a clinically interpretable snapshot at a specified follow-up time. It does not describe the full pattern of event timing after six months, nor does it distinguish progression from death.

The registry reports 63% for Arm A, 53% for Arm B, and 73% for Arm C, each with a 95% confidence interval. The measure is titled as a percentage, while the registry also labels its parameter as a mean of a continuous measure. The record does not explain that representation or provide participant-level data. The exact estimator and any censoring rules used to obtain the percentages are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Understanding these results requires separating the endpoint estimate, its uncertainty, and the comparison between groups. A percentage at a fixed time is a summary of the group’s outcome by that horizon. It is not itself a treatment effect. A treatment effect would require an explicit comparison, such as a difference or ratio estimated under a stated method, generally with uncertainty quantified. The registry does not report such a comparison for six-month PFS.

What does the confidence interval convey?

Each 95% confidence interval describes statistical uncertainty in the corresponding group estimate under the method used to calculate it. Wider intervals indicate less precision. They do not give the range of individual participants’ outcomes, and they do not show that each possible value inside the interval is equally plausible. The posted estimates are accompanied by intervals that extend across substantial ranges: 48% to 75% for Arm A, 34% to 69% for Arm B, and 51% to 86% for Arm C. The record does not state the interval calculation method.

Comparing confidence intervals informally is not equivalent to a formal hypothesis test. Overlap does not establish that the treatment groups are the same, and non-overlap is not the only way a difference may be assessed. A formal comparison would need a defined contrast and an analysis method that accounts for the outcome’s time-to-event structure and the trial design. No such comparison is reported for this endpoint.

Why does the time-to-event definition matter?

Progression-free survival is based on time until progression or death, rather than a simple measurement taken once for every participant. In time-to-event analyses, participants who have not experienced an event by their last assessment may be censored: their event time is unknown beyond that point, but they contribute information up to the point they were observed. The registry describes the endpoint’s time origin and event definition, but does not report the censoring rules, estimator, assessment schedule, or number of events. Those details are necessary to reproduce or fully assess a time-to-event estimate.

The registry expresses the primary outcome as a percentage assessed up to six months. It does not specify whether the percentage is a direct observed proportion or an estimate derived from a survival method. These approaches can differ when follow-up is incomplete or varies among participants. The record also labels the parameter as a mean of a continuous measure, which is not readily explained by the endpoint title. This mismatch warrants caution about the statistical representation; the underlying analysis details are not reported in the registry record.

What does randomization contribute?

Random assignment can support fair comparisons by balancing measured and unmeasured factors across groups on average, provided the assignment process is implemented and analyzed appropriately. The registry identifies the study as randomized, but does not report the sequence-generation method, concealment process, allocation ratio, stratification factors, or analysis population. The presence of a randomized design does not by itself resolve whether Arm C is comparable with the other arms, since Arm C is described for HER2-positive participants and includes trastuzumab.

Likewise, the registry’s no-masking designation means the study is open-label, but the record does not explain how knowledge of treatment assignment may have affected assessment or reporting. The progression definition references RECIST v1.0, but independent review or blinding of response assessment is not reported.

How should planning calculations be interpreted?

Any sample-size illustrations associated with these results are planning exercises based on the observed effect, not evidence of the study’s original design or its achieved statistical power. The stated assumptions for such illustrations are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect set to a stated fraction of the observed effect. For time-to-event outcomes, the illustration concerns a total number of events; other illustrations concern participants per arm. These assumptions do not establish that the trial enrolled enough participants for a reliable comparison, and they do not turn a nonsignificant or unreported test into evidence of no difference. The original sample-size justification is not reported in the registry record.

More generally, over-dispersion occurs when observations vary more than a model’s assumed distribution allows. If a model ignores over-dispersion, uncertainty can be understated and tests can appear more decisive than warranted. This is a general statistical consideration, not a reported feature of this trial: the registry does not describe a model for the primary endpoint or report whether over-dispersion was assessed.

10. Multiplicity, Missing Data and Analysis Populations

The study has three treatment groups and lists a primary endpoint, six-month PFS, as well as overall survival as a secondary outcome. When multiple outcomes or multiple group contrasts are examined, the chance of a false-positive finding can increase unless the analysis plan addresses multiplicity. The registry record does not report a multiplicity procedure, a hierarchy of hypotheses, or which comparisons were planned. It also does not report inferential tests for the primary endpoint. Therefore, the posted group estimates should be treated as descriptive, rather than as evidence from a declared set of confirmatory comparisons.

The record does not report whether interim analyses were planned or conducted, whether stopping rules were used, or whether the primary endpoint was changed. These details should not be inferred from the phase, enrollment, or completion status.

Missing outcome data can affect an endpoint estimate, especially when follow-up ends before the assessment horizon or differs among participants. The registry gives the endpoint definition but does not report the amount or pattern of missing data, censoring by arm, reasons for incomplete follow-up, or methods used to address missing observations. It also does not identify whether the primary analysis followed an intention-to-treat, per-protocol, or other analysis population. The numbers reported for each arm do not by themselves reveal how many participants contributed to the six-month estimates.

These omissions limit assessment of bias and reproducibility. They do not establish that missingness or multiplicity caused a problem; the relevant methods and diagnostics are simply not reported in the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: vomiting (32.3%), nausea (29.0%), dehydration (22.6%), pain - abdomen nos (19.4%), diarrhea (19.2%).

The registry lists serious adverse event counts for each treatment group. For Arm A, 26 participants were affected among 54 at risk; for Arm B, 23 among 31; and for Arm C, 13 among 26. These are counts of participants recorded as affected, not event rates adjusted for time on treatment or follow-up. The record also lists deaths of 37, 30, and 22 participants, respectively. It does not state in these fields whether the deaths were caused by treatment, cancer, or another reason, so the death counts should not be interpreted as treatment-related deaths.

The serious adverse event terms with posted percentages include vomiting, 32.3%; nausea, 29.0%; dehydration, 22.6%; pain - abdomen NOS, 19.4%; diarrhea, 19.2%; and fatigue (asthenia, lethargy, malaise), 19.2%. The registry record does not specify the denominator or detailed counting rules for these term percentages in the information. These percentages should therefore be read as registry-reported descriptions, not as comparative risks between groups.

Safety counts do not show event duration, severity beyond the serious classification, timing, recurrence, or exposure-adjusted frequency. The record does not report a causal assessment for each event. Comparisons across arms are also complicated by the different group sizes and by the HER2-positive population described for Arm C. These figures characterize what was recorded; they do not establish that a regimen is safer or less safe than another.

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

The posted results provide descriptive six-month PFS estimates for three regimens in a phase II study. They show that the registry reported 63% for modified DCF, 53% for parent DCF with G-CSF, and 73% for modified DCF with trastuzumab. Each estimate has a 95% confidence interval, and the intervals indicate substantial uncertainty. The registry does not report a formal comparison or treatment-effect estimate, so the results do not establish a statistically supported difference among groups.

The results also do not establish equivalence or noninferiority. Those conclusions require a prespecified margin and an analysis designed to assess whether a difference is sufficiently small. Neither is reported. A numerically higher point estimate does not, on its own, demonstrate a clinically meaningful benefit, and a lower estimate does not prove that a regimen is inferior.

Arm C includes trastuzumab and is described for HER2-positive participants. Consequently, the three values cannot be interpreted as a simple ranking of regimens for one uniform population without further details about eligibility, allocation, and the analysis. The posted results do not supply the information needed to determine how patient characteristics or treatment assignment differed across groups.

The results also do not answer the study summary’s question about whether modified dosing produces fewer side effects while maintaining benefit relative to the standard schedule. The registry provides safety counts, but not a comparative safety analysis or sufficient detail to interpret differences in event risk. Overall survival is listed as a secondary outcome, but an estimate is not reported in the record.

In short, these data describe outcomes observed and recorded for the three groups, with uncertainty around the primary estimates. They do not support medical advice, a definitive treatment ranking, or claims about efficacy, equivalence, or comparative safety.

13. Why This Trial Matters Statistically

This trial illustrates why reading a point estimate separately from its uncertainty and design context can be misleading. Six-month PFS is an interpretable endpoint, but each percentage is an estimate with a confidence interval, not a precise statement of the outcome for every participant. The intervals make the uncertainty visible and discourage over-reading small differences in point estimates.

The three-group structure also raises questions about the comparison being made. Arm A is designated as the control, Arm B uses parent DCF with G-CSF, and Arm C adds trastuzumab for HER2-positive participants. A randomized label is important, but it is not a substitute for knowing the eligibility and allocation procedures or seeing the planned contrasts. This is especially relevant when one group is defined by a tumor marker and receives an additional drug.

The record also demonstrates the importance of complete reporting. A time-to-event endpoint requires information about estimation, censoring, event counts, and analysis populations to support reproducibility and assess possible bias. Those details are not reported for these results. The designation of a secondary overall-survival outcome without a posted estimate further shows why outcome names alone do not provide a complete account of the evidence.

Finally, descriptive safety counts and an efficacy endpoint answer different questions. Neither should be treated as a substitute for a planned comparison, and neither alone establishes the overall balance of benefits and harms. Statistical interpretation depends on the analysis design, precision, comparability of groups, and transparent reporting—not simply on which group has the largest or smallest number.

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 limited methodological detail for interpreting the primary endpoint. It reports percentages and 95% confidence intervals but does not identify the estimator, interval method, censoring rules, number of events, or follow-up distribution. The endpoint is described as a time-to-event measure while the parameter is labeled as a mean of a continuous measure; the record does not explain this mismatch.

The population and group comparability also require caution. Arm C is described as a modified DCF regimen with trastuzumab for HER2-positive participants, while the other groups have different treatment descriptions. The registry does not report the HER2 distribution across arms, the allocation process, or whether the groups were analyzed under a common eligibility framework. It is therefore not possible to treat the three group estimates as straightforward head-to-head comparisons.

The registry does not report baseline participant characteristics, missing-data amounts or handling, analysis populations, prespecified contrasts, multiplicity procedures, interim analyses, or the original sample-size rationale. These omissions constrain assessment of bias, precision, and reproducibility. The adverse-event fields provide counts and selected terms but do not fully describe event attribution, exposure time, or denominators for the listed term percentages.

The reported enrollment and group sizes do not resolve these limitations. The record also lists overall survival as a secondary outcome without posting an estimate in the results. These are limitations of the information available in the registry record; they do not establish that the trial’s analyses were necessarily conducted inadequately.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Modified Docetaxel, Cisplatin, and Fluorouracil (mDCF) in Unresectable or Metastatic Gastric and Gastroesophageal Junction Adenocarcinoma — NCT00515411.
• Registry record last updated 2019-12-10; status last verified 2018-10.
• Results first posted 2019-12-10.
• 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

NCT00515411 is a completed, randomized, open-label, parallel phase II study sponsored by Memorial Sloan Kettering Cancer Center. It enrolled 111 participants with unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma. The recorded start date is 2006-10-23, and the primary completion date is 2018-10-26.

The primary outcome was six-month progression-free survival. Posted estimates were 63% for modified DCF, 53% for parent DCF with G-CSF, and 73% for modified DCF plus trastuzumab, with respective 95% confidence intervals of 48% to 75%, 34% to 69%, and 51% to 86%. Overall survival is listed as a secondary outcome, but an estimate is not reported in the registry record.

The record lists serious adverse event counts and selected event terms, but does not provide a formal comparative analysis. Details about the statistical analysis, missing data, analysis populations, and planned comparisons are not reported in the registry record.