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 Prospective Randomized Trial Comparing Gastrectomy, Metastasectomy Plus Systemic Therapy Versus Systemic Therapy Alone: GYMSSA Trial (NCT00941655), a randomized phase 3 study. The primary outcome is Overall Survival in Patients With Limited Metastatic Gastric Carcinoma: Arm I.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00941655 |
| Phase | Phase 3 |
| Condition | Gastric Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Cancer Institute (NCI) |
| Results posted | Yes |
2. Clinical Question
Population
Adults diagnosed with gastric cancer were eligible according to the registry summary. The record describes the clinical context as gastric cancer with limited metastatic disease, and the primary outcome title refers to patients with limited metastatic gastric carcinoma. Enrollment was 15. The registry record does not give a fuller baseline description of the enrolled population or enough information to determine how closely participants represented other groups with gastric cancer.
Intervention
The intervention arm is titled Surgery + HIPEC + Systemic Chemotherapy. Its description includes gastric resection, metastasectomy, heated intraperitoneal chemotherapy, and systemic treatment. The brief summary describes removal of tumors followed by chemotherapy. These descriptions differ in detail, so the registry record does not support assuming that every procedure or timing detail in the summary was implemented identically for each participant.
Comparator
The comparator is titled Systemic Chemotherapy Alone. Its arm description lists irinotecan, oxaliplatin, leucovorin, and 5-Fluorouracil. The brief summary also describes the four-drug systemic regimen. The trial is recorded as randomized, with parallel groups and no masking.
Primary question
The primary outcome is titled overall survival in patients with limited metastatic gastric carcinoma in Arm I. It is defined as time from the first day of treatment to death, with a timeframe of 12 weeks up to 3 years. The registry record does not report a comparative overall-survival estimate for the two arms. It therefore does not establish from the posted results whether the surgery-based strategy differed from systemic chemotherapy alone on this endpoint.
3. Trial Design
GYMSSA is recorded as a Phase 3, randomized, parallel-group trial with no masking. The registry lists enrollment as 15 and status as completed. The recorded start date is 2009-07-22, and primary completion is recorded as 2011-07-14. The sponsor is the National Cancer Institute (NCI).
The planned comparison was a strategy involving surgery, HIPEC, and systemic chemotherapy versus systemic chemotherapy alone. The surgery arm description includes gastric resection, metastasectomy, and heated intraperitoneal chemotherapy. The chemotherapy-only arm description specifies irinotecan, oxaliplatin, leucovorin, and 5-Fluorouracil. The brief summary describes initial assessment with examination, blood tests, imaging, and laparoscopy, then assignment to treatment strategies. However, the registry record does not report detailed participant flow, allocation procedures, concealment, adherence, treatment changes, or reasons for any departures from assigned treatment.
The record reports adverse-event group sizes of 8 for Surgery + HIPEC + Systemic Chemotherapy and 7 for Systemic Chemotherapy Alone. Those group counts align with the listed enrollment, but the record does not provide a flow account explaining how participants entered, remained in, or were analyzed within each group. Randomization can support a fair comparison when allocation and follow-up are well conducted, but it does not by itself address small-sample imprecision, missing outcome data, or deviations after assignment.
Although the primary outcome is an overall-survival measure, the registry lists a specific outcome description for Arm I and provides no comparative effect estimate. Details such as a prespecified statistical analysis plan, sample-size justification, interim analyses, and handling of censoring are not reported in the registry record. The available information therefore supports describing the trial design and the posted outcome details, but not reconstructing a full randomized comparison.
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 | Surgery + HIPEC + Systemic Chemotherapy | Systemic Chemotherapy Alone |
|---|---|---|
| STARTED | 8 | 7 |
| COMPLETED | 3 | 2 |
| NOT COMPLETED | 5 | 5 |
Reasons for not completing this period:
| Reason | Surgery + HIPEC + Systemic Chemotherapy | Systemic Chemotherapy Alone |
|---|---|---|
| received some chemo, 4 and 9 cycles | 1 | 0 |
| not meet criteria for chemo foll surgery | 4 | 0 |
| progressed while on chemo | 0 | 2 |
| refused further treatment | 0 | 1 |
| withdrew consent | 0 | 1 |
| non-compliant | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Patient #7 - alive 14 months at time of study closure; patient 11 alive 12 months at time of study closure; patient 15 expired following surgery.
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 | Surgery + HIPEC + Systemic Chemotherapy | Systemic Chemotherapy Alone | Total |
|---|---|---|---|---|
| Participants analysed | 8 | 7 | 15 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 8 | 6 | 14 |
| Age, Categorical: >=65 years | Participants | 0 | 1 | 1 |
| Age, Continuous | years | 45.73 (SD 14.88) | 52.94 (SD 11.67) | 49.33 (SD 13.44) |
| Sex: Female, Male: Female | Participants | 2 | 4 | 6 |
| Sex: Female, Male: Male | Participants | 6 | 3 | 9 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 5 | 0 | 5 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 3 | 7 | 10 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 1 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 7 | 6 | 13 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
| Region of Enrollment: United States | Participants | 8 | 7 | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Overall Survival in Patients With Limited Metastatic Gastric Carcinoma: Arm I, measured over 12 weeks up to 3 years.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Months |
| Endpoint classification | not reduced to a single comparison |
The primary outcome is titled overall survival in patients with limited metastatic gastric carcinoma in Arm I. The registry defines it as the time between the first day of treatment and the date of death, with a timeframe of 12 weeks up to 3 years. Overall survival is a time-to-event endpoint: it concerns both whether death occurred and how long participants were followed before the event or the end of observation. In general, this endpoint is useful because it measures time to death directly, rather than relying on an intermediate change in disease status.
The posted population description gives brief status notes for three people: patient #7 was alive 14 months at study closure; patient 11 was alive 12 months at study closure; patient 15 expired following surgery. These notes are not a complete survival analysis. The registry does not report a median, survival probability, hazard ratio, confidence interval, comparison between arms, or a complete account of deaths and follow-up times. It also does not report how censoring was handled or whether the described people represent all participants in Arm I.
Consequently, the outcome definition is clear, but the posted information does not quantify an overall-survival difference between the randomized strategies. The few individual status notes should not be treated as a substitute for a group-level time-to-event estimate.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record identifies a randomized comparison, but it does not provide a usable comparative estimate for the primary outcome. Overall survival is defined as time from the first day of treatment to death, and the listed timeframe is 12 weeks up to 3 years. For Arm I, the record includes brief status notes for patient #7, patient 11, and patient 15. It does not report a group-level survival estimate for Arm I or a corresponding primary-outcome result for the systemic-chemotherapy-alone arm.
Without an effect estimate and a measure of its uncertainty, readers cannot assess the direction or precision of a between-arm difference in overall survival. A confidence interval, when reported, describes the range of values compatible with the data under the analysis assumptions; it is not a guarantee that the true effect lies within that range. No confidence interval or inferential comparison is reported in the registry record. A p-value is also not reported for the primary outcome. The absence of such statistics is not evidence that the treatments had identical outcomes.
The adverse-event listings offer descriptive safety information, but they do not resolve the missing primary comparison. Serious adverse events are recorded for 8 of 8 participants in the surgery-based arm and 1 of 7 in the systemic-chemotherapy-alone arm. Non-serious adverse events are recorded for 8 of 8 and 5 of 7, respectively. The record also lists 7 deaths in each arm. It does not specify in these group summaries whether the deaths were caused by treatment, occurred during a particular follow-up interval, or were included in the primary endpoint analysis. The serious-event counts therefore should not be read as causal estimates.
Enrollment was 15, so estimates from this trial would be expected in general to be vulnerable to substantial uncertainty, particularly for outcomes that depend on the timing of events. That is a general statistical consideration, not a trial-specific estimate of precision. The record provides no sample-size justification or uncertainty interval that would quantify it. Likewise, randomized allocation is a design feature, not proof that all potential sources of bias were eliminated. No details are reported about allocation concealment, loss to follow-up, adherence, or analysis populations.
The defensible reading is limited: the registry records a completed randomized trial and posts several outcome and safety entries, but does not report a comparative primary-outcome analysis. The entries cannot establish whether one strategy was superior, equivalent, or inferior on overall survival.
9. Statistical Methods Explained
The registry describes a randomized, parallel-group study with no masking. These design labels explain how a trial comparison is intended to work, but they do not supply the missing outcome analysis. In a randomized trial, participants are assigned to treatment strategies by chance; this can reduce systematic differences between groups at the point of assignment. A parallel design means the groups follow their assigned strategies rather than crossing over between them as part of the planned comparison. No masking means treatment assignment was not concealed from participants or relevant study personnel in the manner denoted by the registry field. The record does not describe who knew assignments or whether outcome assessors were masked.
What does an overall-survival analysis usually estimate?
In general, time-to-event analysis uses the time from a defined starting point until an event such as death. Participants without an observed event by their last known follow-up are often treated as censored: their follow-up contributes information up to that point, but their eventual event time is unknown. This requires clear follow-up definitions and assumptions about censoring. The registry defines the starting point and event, but the handling of censoring, follow-up completeness, and analysis method is not reported in the registry record.
Common summaries for survival outcomes include survival probabilities at specified times, a median survival time, or a relative event-rate measure such as a hazard ratio. A confidence interval expresses statistical uncertainty around an estimate. These are general statistical tools, not results reported for GYMSSA. The registry does not give a comparative survival estimate, confidence interval, or p-value. Individual status notes are insufficient to reconstruct these statistics, because they do not provide complete participant-level follow-up information.
Why is the randomized comparison not recoverable from the posted endpoint?
The primary outcome entry is identified as Arm I and gives several individual status notes rather than a summarized comparison between arms. The registry lists no analyses. Without corresponding outcome information for both randomized groups and a defined analysis, a contrast cannot be interpreted. The trial's randomized label does not permit readers to infer a treatment effect from enrollment or from the design description alone.
In general, intention-to-treat analysis compares participants according to their randomized assignments, while per-protocol approaches focus on participants who followed specified treatment requirements. These approaches answer different questions and may produce different estimates if treatment deviations occur. The analysis population used for the GYMSSA primary outcome is not reported in the registry record. Nor are treatment adherence, crossover, or exclusions described sufficiently to identify an analysis approach.
How should the adverse-event counts be understood?
The record gives group-level counts for participants at risk and affected by serious and non-serious adverse events. These are descriptive counts. They do not by themselves measure the severity, duration, recurrence, or causal relationship of events to assigned treatment. General safety comparisons also require consistent event definitions, observation periods, and reporting practices across groups. Those details are not reported in the registry record.
Over-dispersion is a general statistical issue that arises when count outcomes vary more than a simple model expects. In that situation, standard errors from an overly restrictive model can be too small. The record does not report a count model, participant-level event counts, or an analysis of event rates, so it is not possible to assess over-dispersion or to infer that a count-model analysis was performed.
Finally, a sample-size calculation is a planning exercise, not evidence of the precision achieved in a completed study. The record does not report a trial-specific sample-size justification or a statistical analysis plan. Any planning illustration based on a posted effect would not be the trial's original design calculation and would not represent observed power. The posted information does not support adding such a calculation to the interpretation of this primary endpoint.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 11 outcome measures, including overall survival, disease-free survival, adverse events, surgical measures, and quality-of-life parameters. When a study examines several outcomes, multiplicity is a general concern: repeated statistical testing can increase the chance of finding at least one apparently noteworthy result by chance. Prespecified outcome hierarchies, adjustment procedures, or a clear distinction between primary and exploratory outcomes can help readers understand how findings should be interpreted. The registry record does not report a multiplicity strategy or a detailed statistical analysis plan.
The primary outcome entry describes overall survival for Arm I, but the registry lists no analyses and gives no comparative primary-endpoint estimate. The record does not explain how the listed outcomes were prioritized in analysis, whether any were assessed at multiple time points, or whether subgroup analyses were planned. These items are not reported in the registry record; they should not be inferred from the outcome titles alone.
Missing-data handling is also not reported. The record does not provide a participant-flow account, the completeness of follow-up, reasons for missing observations, or the method used to address missing outcomes. This does not establish that data were missing; it means that the registry does not describe their extent or handling.
The analysis population is not reported in the registry record. It is therefore unclear whether the primary outcome was analyzed by randomized assignment, by treatment received, or using another population definition. These distinctions matter because excluding participants or reclassifying them after randomization can affect comparability. The posted information does not permit evaluation of those choices.
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 |
|---|---|---|---|
| Surgery + HIPEC + Systemic Chemotherapy | 8 | 8 | 100.0% |
| Systemic Chemotherapy Alone | 1 | 7 | 14.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Surgery + HIPEC + Systemic Chemotherapy | 7 of 8 |
| Systemic Chemotherapy Alone | 7 of 7 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Surgery + HIPEC + Systemic Chemotherapy | 8 of 8 |
| Systemic Chemotherapy Alone | 5 of 7 |
Most frequent serious adverse event terms
| Event term | Organ system | Surgery + HIPEC + Systemic Chemotherapy | Systemic Chemotherapy Alone |
|---|---|---|---|
| Hemoglobin | Blood and lymphatic system disorders | 4 of 8 | 0 of 7 |
| Platelets | Blood and lymphatic system disorders | 3 of 8 | 0 of 7 |
| Fatigue (asthenia, lethargy, malaise) | General disorders | 2 of 8 | 0 of 7 |
| Febrile neutropenia | Infections and infestations | 2 of 8 | 0 of 7 |
| Neutrophils/granulocytes (ANC/AGC) | Blood and lymphatic system disorders | 2 of 8 | 0 of 7 |
| Obstruction, GI:Small bowel NOS | Gastrointestinal disorders | 2 of 8 | 0 of 7 |
| Pleural effusion (non-malignant) | Respiratory, thoracic and mediastinal disorders | 2 of 8 | 0 of 7 |
| Weight loss | General disorders | 2 of 8 | 0 of 7 |
| Albumin, serum-low (hypoalbuminemia) | Metabolism and nutrition disorders | 1 of 8 | 0 of 7 |
| Bilirubin (hyperbilirubinemia) | Metabolism and nutrition disorders | 1 of 8 | 0 of 7 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Surgery + HIPEC + Systemic Chemotherapy | Systemic Chemotherapy Alone |
|---|---|---|---|
| AST, SGOT (serum glutamic oxaloacetic transaminase) | Metabolism and nutrition disorders | 6 of 8 | 0 of 7 |
| CPK (creatine phosphokinase) | Metabolism and nutrition disorders | 4 of 8 | 0 of 7 |
| Nausea | Gastrointestinal disorders | 2 of 8 | 2 of 7 |
| Neuropathy: sensory | Nervous system disorders | 2 of 8 | 2 of 7 |
| Neutrophils/granulocytes (ANC/AGC) | Blood and lymphatic system disorders | 4 of 8 | 0 of 7 |
| Hemoglobin | Blood and lymphatic system disorders | 2 of 8 | 1 of 7 |
| ALT, SGPT (serum glutamic pyruvic transaminase) | Metabolism and nutrition disorders | 2 of 8 | 0 of 7 |
| Diarrhea | Gastrointestinal disorders | 0 of 8 | 2 of 7 |
| Fatigue (asthenia, lethargy, malaise) | General disorders | 0 of 8 | 2 of 7 |
| Pain:Abdomen NOS | Gastrointestinal disorders | 1 of 8 | 1 of 7 |
Serious events with the highest arm-level rate: hemoglobin (50.0%), platelets (37.5%), fatigue (asthenia, lethargy, malaise) (25.0%), febrile neutropenia (25.0%), neutrophils/granulocytes (anc/agc) (25.0%).
The registry records serious adverse events in 8 of 8 participants in Surgery + HIPEC + Systemic Chemotherapy and 1 of 7 in Systemic Chemotherapy Alone. It records non-serious adverse events in 8 of 8 and 5 of 7, respectively. These are the posted participant counts, not adjusted comparisons or estimates of treatment-caused risk.
The record lists serious-event terms with percentages: Hemoglobin, 50.0%; Platelets, 37.5%; Fatigue (asthenia, lethargy, malaise), 25.0%; Febrile neutropenia, 25.0%; Neutrophils/granulocytes (ANC/AGC), 25.0%; and Obstruction, GI:Small bowel NOS, 25.0%. The registry does not make clear in these term listings which group or denominator each percentage represents. The percentages should therefore be read as reported, not converted into event counts or used to compare arms.
The death counts are 7 in each arm. The record does not specify cause, timing, attribution to treatment, or how these deaths relate to the primary endpoint entry. Seriousness and treatment-relatedness are different concepts; the available group summaries do not establish that an event was caused by an assigned strategy.
12. What the Result Does, and Does Not, Mean
The registry record establishes that GYMSSA was a completed, randomized, parallel-group Phase 3 trial comparing surgery with HIPEC and systemic chemotherapy against systemic chemotherapy alone. It also records enrollment of 15 and reports group-level adverse-event entries. These details describe the study and its posted data; they do not provide a comparative estimate of overall survival.
The primary endpoint is defined, but the result is not reported as an arm-to-arm analysis. The brief notes about three people in Arm I do not provide a complete survival profile, and the registry does not report a survival estimate, confidence interval, or p-value. As a result, the posted record cannot establish that either strategy improved, worsened, or had the same overall survival compared with the other strategy.
Similarly, the adverse-event counts are not proof of a causal difference in harms. The registry does not report event attribution, observation windows for the group summaries, or an adjusted safety analysis. The listed deaths also cannot be interpreted as treatment-related from the information recorded.
These limits are particularly important when reading a small randomized trial. Randomization is valuable for reducing bias, but a design feature cannot replace outcome data or quantify uncertainty. The registry record does not describe the analysis population, missing-data approach, or protocol deviations needed to judge how completely the posted results reflect the randomized comparison.
The appropriate conclusion is about the availability of evidence in this record: it documents the trial design and selected outcome information, while leaving the main comparative survival question unanswered in the posted results. Absence of a reported comparison is not evidence of no difference, and it does not establish equivalence.
13. Why This Trial Matters Statistically
This trial is statistically important to read as a distinction between a randomized design and a reported treatment-effect estimate. Random allocation can create a sound basis for comparing strategies, but readers still need outcome data for both groups, a defined analysis, and a measure of uncertainty. The registry identifies the randomized comparison but does not report a comparative overall-survival result.
The issue is especially visible because the primary outcome is time to death, yet the posted primary-outcome details are limited to a few status notes for Arm I. A time-to-event endpoint normally requires follow-up information across participants and a method for accounting for those whose event time is not observed during follow-up. Without these elements, a reader cannot judge the estimated difference or its precision.
The safety entries provide a second statistical lesson. Counts of participants with adverse events are useful descriptive information, but interpretation depends on event definitions, follow-up, and attribution. Percentages for listed serious-event terms do not specify an evident denominator in the term list. Treating those percentages as direct between-arm comparisons would go beyond the record.
Finally, a trial can list several outcomes without reporting how multiplicity, missing data, or analysis populations were addressed. These are not merely technical details: they affect how confidently outcome patterns can be interpreted. For GYMSSA, those methods are not reported in the registry record. The record therefore illustrates why design labels, endpoint definitions, and safety counts should be kept separate from evidence of a comparative effect.
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 has important limitations for interpreting this specific trial. Although it identifies overall survival as the primary outcome, it provides no comparative estimate between the randomized arms. The primary entry is labeled for Arm I and includes brief notes about patient #7, patient 11, and patient 15; it does not give a complete group-level survival analysis or corresponding result for the other arm.
The record does not report a confidence interval, p-value, survival probability, median, hazard ratio, or a full accounting of deaths and follow-up. It also does not describe censoring or the analysis population. These omissions prevent assessment of the magnitude and precision of any primary-endpoint effect, not merely its statistical significance.
Enrollment is listed as 15, and the adverse-event summaries identify groups of 8 and 7. The record does not provide detailed participant flow, baseline characteristics, follow-up completeness, adherence, treatment changes, or reasons for exclusions. It is therefore not possible to assess balance at baseline or determine how deviations from randomized assignment may have affected the posted results.
The safety information is also limited. The record provides counts of participants with serious and non-serious adverse events, deaths by group, and percentages for several serious-event terms, but does not report event timing, treatment attribution, recurrence, or the denominator for the term percentages. The regimen descriptions also vary in detail between the brief summary and the arm descriptions. These limitations leave substantial uncertainty about implementation and outcome interpretation; they do not establish that any unreported problem occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Prospective Randomized Trial Comparing Gastrectomy, Metastasectomy Plus Systemic Therapy Versus Systemic Therapy Alone: GYMSSA Trial — NCT00941655.
- Registry record last updated 2019-11-13; status last verified 2019-11.
- Results first posted 2013-07-11.
- 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
GYMSSA (NCT00941655) is recorded as a completed Phase 3 randomized trial with a parallel design and no masking. It compared Surgery + HIPEC + Systemic Chemotherapy with Systemic Chemotherapy Alone for gastric cancer. Enrollment was 15. The record lists the start date as 2009-07-22 and primary completion as 2011-07-14.
The primary outcome is overall survival in Arm I, defined as time from the first day of treatment to death, with a timeframe of 12 weeks up to 3 years. The record includes brief status notes for three people but no comparative primary-outcome estimate or listed analysis. It also reports serious and non-serious adverse-event counts and deaths by group, without enough detail for causal safety comparisons.
Important details—including the analysis population, missing-data handling, multiplicity approach, and statistical analysis plan—are not reported in the registry record. The available information describes the trial and selected results but does not answer the comparative overall-survival question.