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 Chemotherapy & Erlotinib in Treating Patients w/ Esophageal or Gastroesophageal Cancer That Cannot Be Removed by Surgery (NCT00539617), a na phase 2 study. The primary outcome is Progression Free Survival (PFS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00539617 |
| Phase | Phase 2 |
| Condition | Esophageal Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 7 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of California, San Francisco |
| Results posted | Yes |
2. Clinical Question
Population
The registry record describes patients with unresectable or metastatic cancer of the esophagus or gastroesophageal junction. Its brief summary characterizes the disease as esophageal or gastroesophageal cancer that cannot be removed by surgery. The listed condition is esophageal cancer. The recorded enrollment is 7, but that figure alone does not establish how many participants contributed data to any particular outcome.
Intervention
The study evaluated a combination of erlotinib and FOLFOX6. The listed drugs are erlotinib, 5-fluorouracil, leucovorin, and oxaliplatin. The regimen description specifies oral erlotinib once daily on days 1-56, and intravenous FOLFOX6 components on days 1, 15, 29, and a further day or days not specified in the recorded description. The complete schedule is not reported in the registry record.
Comparator
There was no separate comparator group. The registry classifies the study as a single-group, non-randomized study with no masking. Consequently, the record does not support a like-for-like comparison with another treatment group, and any change observed during treatment could not be separated from other influences using a concurrent control.
Primary question
The primary endpoint was progression-free survival, defined as time from enrollment into the run-in period to objective tumor progression assessed using RECIST. The registry planned to report the proportion with progression-free survival and evaluate the endpoint with Kaplan-Meier curves, a median, and a 95% confidence interval. However, the record explicitly states that no progression-free survival data were collected. It therefore does not answer whether, or to what extent, the regimen was associated with progression-free survival in this study.
3. Trial Design
This was a phase II, single-group study sponsored by the University of California, San Francisco. The registry describes the study as a single-arm evaluation of Tarceva plus FOLFOX6 in patients with unresectable or metastatic cancer of the esophagus or gastroesophageal junction. Allocation is listed as not applicable, and masking as none. There was no concurrent control arm, so the design was not a randomized comparison.
The registry lists enrollment of 7. The study start date is 2007-10-05, and the primary completion date is 2011-05-12. Its status is terminated. The reason for termination is not reported in the registry record, so the status should not be taken as evidence for any particular reason or outcome.
The treatment description includes oral erlotinib once daily on days 1-56. FOLFOX6 is described as intravenous oxaliplatin over 2 hours, intravenous leucovorin over 2 hours, and intravenous fluorouracil over 46-48 hours on days 1, 15, 29, and a further day or days not included in the recorded description. The registry record does not provide a complete dosing schedule in the available arm description.
The primary outcome was progression-free survival, with a timeframe listed as up to 2 years. Objective response rate and time to progression are listed as secondary outcomes. The registry lists 3 outcome measures, but reports 0 analyses. It also states that no progression-free survival data were collected. Details on whether data were collected for the secondary outcomes are not reported in the registry record.
A single-group phase II design can describe outcomes among people enrolled in the study, but without a concurrent comparator it cannot establish how those outcomes compare with another treatment or with what would have occurred without the regimen. The registry record does not report a statistical analysis plan, the reason for termination, or a sample-size justification for the trial itself.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: This trial has a pre-enrollment phase in which patients have their tissue tested for Kras and EGFR mutations to determine eligibility for the treatment trial. There is also a run-in phase with Erlotinib followed by a post-treatment biopsy. After this, the main treatment phase begins.
Pre-screening Period
| Stage | FOLFOX and Erlotinib |
|---|---|
| STARTED | 7 |
| COMPLETED | 4 |
| NOT COMPLETED | 3 |
Run-In Period
| Stage | FOLFOX and Erlotinib |
|---|---|
| STARTED | 4 |
| COMPLETED | 3 |
| NOT COMPLETED | 1 |
Treatment Period
| Stage | FOLFOX and Erlotinib |
|---|---|
| STARTED | 3 |
| COMPLETED | 3 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: No data was collected for progression free survival
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 | FOLFOX and Erlotinib |
|---|---|---|
| Participants analysed | 7 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 7 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 54 (SD 12) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 7 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 6 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 |
| Race (NIH/OMB): White | Participants | 4 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 2 |
| Region of Enrollment: United States | participants | 7 |
6. Primary Endpoint
The registry lists the primary outcome as Progression Free Survival (PFS), measured over Up to 2 years.
| 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 progression-free survival (PFS). The registry defines PFS as the duration from enrollment into the study run-in period to objective tumor progression determined using Response Evaluation Criteria in Solid Tumors (RECIST). The planned timeframe was up to 2 years. The registry says the proportion of patients with PFS would be reported and evaluated using Kaplan-Meier survival curves, with a median survival and 95% confidence interval.
In general, a time-to-event endpoint records how long it takes for a specified event to occur. PFS is used in clinical research to describe the time until documented progression under a defined assessment rule. Kaplan-Meier methods are generally used when participants may have different lengths of follow-up or when an event has not occurred by the last available observation. The method can account for such incomplete event times under its assumptions; it does not turn missing endpoint data into observed outcomes.
For this study, the registry explicitly states that no PFS data were collected. Thus, despite the endpoint definition and planned method, there is no PFS estimate, median, confidence interval, or survival curve reported in the registry record. The endpoint specification describes what the study intended to measure, not an observed result. It is not possible to infer progression-free survival from the listed enrollment, treatment schedule, status, or adverse-event information.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central statistical finding is the absence of primary-outcome data. Progression-free survival was designated as the primary endpoint, but the registry record states that no data were collected for it. Accordingly, it provides no estimate of the PFS distribution, no median PFS, and no 95% confidence interval. The intended Kaplan-Meier analysis cannot be interpreted as a completed analysis or as evidence about the endpoint.
The record lists enrollment of 7 and marks the study terminated. Neither fact supplies an outcome estimate. Enrollment describes the recorded study size; it does not establish how many participants had evaluable follow-up for a specific endpoint. Termination describes study status, but the reason is not reported in the registry record. It would be inappropriate to infer a reason for termination or to treat termination itself as a result about the regimen.
The design also limits what any within-study observations could establish. This was a single-group study with no randomized comparator. In general, outcomes in a single group can be described, but changes over time may reflect influences other than the intervention, including the course of the disease, participant differences, or other care. Without a concurrent comparison group, the registry cannot estimate a treatment contrast or attribute an outcome to the combination.
Objective response rate and time to progression are listed as secondary outcomes. The registry record does not present their results in the registry record recorded for this analysis, and it reports 0 analyses. Their inclusion in the outcome list should not be mistaken for evidence that an estimate was reported or that a particular result was observed. Details of endpoint-specific analysis populations and missing-data handling are not reported in the registry record.
The serious adverse-event information is descriptive. The group entry lists 4 participants at risk and 4 affected for serious adverse events, and separately lists 4 at risk and 4 affected for other adverse events. The record also lists 3 deaths and terms with percentages. These figures do not provide a controlled estimate of risk, establish causality, or identify the timing and relationship of each event to treatment. The registry record does not report further details needed to interpret these events in context.
Planning illustrations based on an observed effect are not results from a new randomized comparison and are not the trial's design justification. The stated assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power. With no PFS data reported and no comparator in this study, they should not be read as evidence that the trial established a treatment effect.
9. Statistical Methods Explained
The registry specifies a time-to-event primary endpoint and names Kaplan-Meier curves, a median, and a 95% confidence interval as the planned method of evaluation. The registry also states that no PFS data were collected. The statistical concepts below explain the stated methods in general; they do not imply that an analysis was completed for this study.
What does a time-to-event endpoint represent?
In general, a time-to-event endpoint measures the duration from a defined starting point until a defined event. Here, the registry defines the starting point as enrollment into the run-in period and the event as objective tumor progression assessed with RECIST. A clear start point and event rule are necessary for consistent interpretation: changing either can change the meaning of the endpoint. The registry's definition does not supply individual event times, assessment dates, or follow-up records.
Time-to-event methods are useful when follow-up duration can differ among participants. Some participants may have an event observed during follow-up, while others may not have an event recorded before their last observation. In general, the latter observations are censored at the last known time under the method's assumptions; censoring is not itself evidence that an event did or did not occur later. The registry record does not report the individual follow-up information or censoring details for this study.
What does Kaplan-Meier estimation do?
In general, the Kaplan-Meier method estimates the probability of remaining free of the specified event over time, while incorporating event and censoring times. It can be presented as a survival curve. The curve's interpretation depends on the endpoint definition, the observed event and censoring information, and the assumptions about censoring. A curve cannot be reconstructed from an enrollment figure alone. Because the record says no PFS data were collected, there is no reported PFS curve to interpret for this study.
What does a median and confidence interval convey?
In general, the median time-to-event is the time by which the estimated event-free proportion reaches the halfway point, when the data allow that point to be estimated. A confidence interval expresses statistical uncertainty around an estimate under the method used; it is not a guarantee that the true value lies within the interval. Its width depends on the amount and distribution of information, including observed events and follow-up. The registry's plan names a median and 95% confidence interval, but it reports no PFS data and therefore supplies no numerical median or interval.
A confidence interval would also need to be interpreted in relation to the study design. In a single-group study, it would describe uncertainty around that group's estimated outcome, not the difference between the regimen and a comparator. No comparator group is listed in this registry record. Thus, even if a single-group estimate had been reported, it would not by itself quantify a comparative treatment effect.
Why do over-dispersion and model choice matter in general?
General statistical note: for count outcomes, over-dispersion means that the observed variability exceeds what a simple model assumes. If a model ignores over-dispersion, uncertainty can be understated and inferences may appear more precise than warranted. Choosing an appropriate model requires knowing the outcome type, data structure, and analysis plan. The registry record does not report an analysis model for the secondary outcomes, so no claim about over-dispersion or a particular count model is justified for this study.
What do the planning assumptions mean?
The planning assumptions describe illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They specify that the effect to detect is a stated fraction of the observed effect. For time-to-event calculations, the total number of events is the planning quantity; for other calculations, the stated quantity is participants per arm. These are general design-planning concepts and are not observed outcomes or observed power.
The planning assumptions do not establish that this single-group study was designed as a two-arm trial. The record lists no randomized comparison and does not report a trial sample-size justification. The observed effect used for planning and any numerical planning results are not reported in the registry record. No calculation can substitute for the missing primary endpoint data or create a treatment comparison absent from the study design.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists progression-free survival as the primary outcome and objective response rate and time to progression as secondary outcomes. It lists 3 outcome measures and 0 analyses. Multiple outcomes can raise multiplicity concerns when several hypotheses are tested, because interpreting each test without accounting for the testing strategy can affect the overall chance of a false-positive finding. The registry record does not report a multiplicity adjustment, a hierarchy among secondary outcomes, or a statistical analysis plan. It is therefore not possible to determine how multiplicity was intended to be handled.
The primary endpoint has a more fundamental limitation: the registry states that no progression-free survival data were collected. This means there is no reported PFS analysis to assess for multiplicity or precision. The presence of secondary outcomes in the registry does not establish that their data or analyses are available; their results are not reported in the registry record.
Missing-data methods and analysis populations are also not reported in the registry record. The absence of PFS data is specifically described as no data collected, not as a particular pattern of missing observations. The record does not say whether participants were analyzed according to an intention-to-treat, per-protocol, safety, or other population definition. It also does not provide endpoint-specific numbers analyzed, reasons for absent data, follow-up completeness, or any imputation method.
In general, the analysis population and missing-data approach matter because they determine which observations contribute to an estimate and how incomplete follow-up is handled. Without those details, readers cannot assess potential selection or attrition effects for the stated outcomes. The recorded enrollment should not be substituted for an endpoint-specific analysis denominator.
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 |
|---|---|---|---|
| FOLFOX and Erlotinib | 4 | 4 | 100.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| FOLFOX and Erlotinib | 3 of 4 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| FOLFOX and Erlotinib | 4 of 4 |
Most frequent serious adverse event terms
| Event term | Organ system | FOLFOX and Erlotinib |
|---|---|---|
| Dehydration | Gastrointestinal disorders | 2 of 4 |
| Aspiration | Respiratory, thoracic and mediastinal disorders | 1 of 4 |
| Chest Pain | Cardiac disorders | 1 of 4 |
| Constipation | Gastrointestinal disorders | 1 of 4 |
| Hemoglobin | Blood and lymphatic system disorders | 1 of 4 |
| Pneumonia | Infections and infestations | 1 of 4 |
Most frequent non-serious adverse event terms
| Event term | Organ system | FOLFOX and Erlotinib |
|---|---|---|
| Fatigue | General disorders | 4 of 4 |
| Acne | Skin and subcutaneous tissue disorders | 3 of 4 |
| Diarrhea | Gastrointestinal disorders | 3 of 4 |
| Nausea | Gastrointestinal disorders | 3 of 4 |
| Neutrophil | Blood and lymphatic system disorders | 3 of 4 |
| Peripheral sensory neuropathy | Nervous system disorders | 3 of 4 |
| Vomiting | Gastrointestinal disorders | 3 of 4 |
| Abdominal Pain | Gastrointestinal disorders | 2 of 4 |
| Anorexia | Gastrointestinal disorders | 2 of 4 |
| Constipation | Gastrointestinal disorders | 2 of 4 |
Serious events with the highest arm-level rate: dehydration (50.0%), aspiration (25.0%), chest pain (25.0%), constipation (25.0%), hemoglobin (25.0%).
The registry lists a group titled FOLFOX and Erlotinib. For serious adverse events, it records 4 participants at risk and 4 affected; for other adverse events, it also records 4 at risk and 4 affected. It lists 3 deaths. These are descriptive registry figures, not a comparison between treatment groups, because the study had a single group.
The listed serious adverse-event terms include dehydration at 50.0%, and aspiration, chest pain, constipation, hemoglobin, and pneumonia, each at 25.0%. These percentages describe the entries in the registry record; they do not establish severity beyond the record's classification, timing, duration, or cause. The record does not report whether an event was judged related to treatment, how events were counted when a participant experienced more than one, or how the listed percentages were calculated.
Serious adverse events, other adverse events, and deaths are distinct registry summaries and should not be combined into a single count. The record does not establish whether the participants represented in these summaries overlap, and it does not provide a comparator for estimating relative risk. These figures cannot by themselves determine whether an event was caused by the regimen or how safety would compare with another treatment.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a phase II, single-group study of erlotinib plus FOLFOX6 was conducted in the setting of unresectable or metastatic esophageal or gastroesophageal junction cancer. It identifies PFS as the primary endpoint and specifies a RECIST-based definition and a planned Kaplan-Meier approach. It also lists objective response rate and time to progression as secondary outcomes.
It does not provide a PFS result. The record explicitly says no PFS data were collected, so there is no primary-outcome estimate to interpret for duration, precision, or uncertainty. The listed enrollment of 7 cannot fill that gap. Nor does the study status of terminated explain why the study ended; the reason is not reported in the registry record.
The single-group design means there is no concurrent treatment comparison. In general, a descriptive outcome among participants in one group is not equivalent to an estimate of what the same population would have experienced under a different treatment. The record therefore does not support a causal conclusion about the effect of the combination. The secondary outcomes are listed, but their results are not reported in the registry record.
The safety entries provide limited descriptive information, including adverse-event categories, listed terms, and deaths. They do not establish treatment causation or comparative safety. The registry record does not report details such as event timing, treatment relationship, or the overlap among event categories.
In short, the registry describes the study question, design, planned endpoint, and some safety entries, but it does not supply the primary endpoint data needed to answer the main clinical question. The record supports neither a conclusion that the regimen improved outcomes nor a conclusion that it did not. The absence of a reported estimate is a limitation of the available record, not evidence for either direction of effect.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of the difference between an endpoint plan and an endpoint result. The registry gives a PFS definition, a timeframe of up to 2 years, and a planned Kaplan-Meier evaluation with a median and 95% confidence interval. Yet it also states that no PFS data were collected. A method named in a protocol or registry entry does not itself produce an estimate; event and follow-up data are necessary.
The single-group design also makes the role of a comparator clear. In general, a single-arm study can describe outcomes within its enrolled group, but it cannot directly estimate a difference against a concurrent control group. This matters when translating a clinical question about a regimen into a statistical question: the design determines which comparisons can be estimated, independent of the sophistication of a planned analysis.
The record also illustrates why enrollment should not be confused with endpoint-specific information. It lists enrollment of 7, while providing no PFS data or analysis. Enrollment does not reveal how many participants had evaluable observations, how much follow-up was available, or how an endpoint estimate would have been calculated.
Finally, the safety summaries and the primary endpoint serve different purposes. Adverse-event entries can describe reported harms, but they do not substitute for a missing efficacy endpoint or establish comparative effects. The terminated status is likewise not an outcome, and its reason is not reported in the registry record.
These distinctions are useful when reading clinical trial records: separate study design from analysis, planned methods from observed data, and descriptive summaries from comparative evidence. In this record, that separation prevents overinterpreting a planned PFS analysis or the limited safety figures.
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 reports no progression-free survival data, despite naming PFS as the primary outcome. It therefore provides no primary endpoint estimate or uncertainty interval. The listed enrollment of 7 does not identify an endpoint-specific analysis population or establish how much follow-up was available.
The study is single-group, with no randomized comparator and no masking. Any outcomes that might have been observed in the group could not be directly compared with a concurrent control in this design. The record does not report an external comparison or a plan for adjusting for differences between groups.
The study status is terminated, but the reason for termination is not reported in the registry record. The arm description gives only a partial schedule, ending after the FOLFOX6 days listed as 1, 15, 29,. The full schedule is not reported in the registry record. Treatment exposure, adherence, and discontinuation details are also not reported in the registry record.
Although objective response rate and time to progression appear as secondary outcomes, their results are not reported in the registry record. The record lists 0 analyses. It does not report a statistical analysis plan, multiplicity approach, analysis populations, missing-data methods, endpoint-specific follow-up, or sample-size justification for the trial.
The safety information is limited to the registry's group-level figures, listed terms, percentages, and deaths. Details about timing, relatedness, event counting, and overlap between summaries are not reported in the registry record. These limitations restrict interpretation of both the clinical outcomes and the safety descriptions.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Chemotherapy & Erlotinib in Treating Patients w/ Esophageal or Gastroesophageal Cancer That Cannot Be Removed by Surgery — NCT00539617.
- Registry record last updated 2020-03-23; status last verified 2020-03.
- Results first posted 2012-10-12.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry record describes a phase II, single-group study of erlotinib plus FOLFOX6 for unresectable or metastatic cancer of the esophagus or gastroesophageal junction. It lists enrollment of 7, identifies progression-free survival as the primary outcome, and gives objective response rate and time to progression as secondary outcomes. The primary endpoint was defined using objective tumor progression assessed with RECIST, with a planned Kaplan-Meier evaluation.
The study is marked terminated. The registry explicitly states that no PFS data were collected and lists 0 analyses. The reason for termination and results for the secondary outcomes are not reported in the registry record. The safety entry lists serious and other adverse-event summaries, terms, percentages, and 3 deaths, without a comparator group.
Because the primary endpoint data are absent and the design has no control group, the record does not establish a comparative treatment effect. Its treatment description and endpoint plan define the study question, but they do not supply the missing outcome evidence.