This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record.
1. Trial at a Glance
SUCCESS C was a phase 3 randomized parallel-group trial evaluating adjuvant treatment approaches in patients with breast cancer. The registry identifies disease-free survival after randomization as the first primary objective.
| Feature | SUCCESS C |
|---|---|
| Condition | Breast Cancer |
| Phase | Phase 3 |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None |
| Primary purpose | Treatment |
| Lead sponsor | Philip Hepp |
| Sponsor type | Other |
2. Clinical Question
The primary clinical question was whether disease-free survival after randomization differed between patients receiving a combination of 5-FU/Epirubicine/Cyclophosphamide followed by Docetaxel and patients receiving Docetaxel/Cyclophosphamide.
Population
Patients with breast cancer enrolled in the phase 3 randomized study.
Intervention
Drug-based intervention including docetaxel-based adjuvant treatment strategies.
Comparator
Docetaxel/Cyclophosphamide comparator regimen as specified in the registry primary objective.
Primary question
Does the randomized treatment comparison affect disease-free survival after randomization over 60 months?
3. Trial Design
Drug-based intervention
- Drug-based intervention
- Docetaxel-based adjuvant treatment evaluation
Lifestyle-based intervention
- Lifestyle-based behavioral intervention
- Included as a study intervention category
4. Primary Endpoint
| Endpoint | Definition | Time Frame |
|---|---|---|
| Disease-free survival after randomisation | The first primary objective is to compare disease free survival after randomisation in patients treated with a combination of 5-FU/Epirubicine/Cyclophosphamide followed by Docetaxel vs. Docetaxel/Cyclophosphamide | 60 months |
5. Planned Analysis
The registry identifies disease-free survival after randomization as the primary endpoint. Disease-free survival is a time-to-event endpoint, where analysis typically evaluates the time from randomization until a disease-related event or another prespecified event defined by the study protocol.
Common statistical approaches for this type of endpoint include Kaplan-Meier estimation to describe disease-free survival over time, comparison of randomized groups using a log-rank test, and estimation of treatment effects using a Cox proportional-hazards model.
6. Statistical Methodology
Time-to-event analysis
Disease-free survival is analyzed as a time-to-event outcome. Unlike a simple proportion measured at one point, survival analysis incorporates both event timing and censoring. Patients without a recorded event at their last follow-up still contribute information up to that time.
The survival function describes the probability that the event time exceeds a specified time point.
Kaplan-Meier estimation
The Kaplan-Meier estimator is commonly used to display disease-free survival curves. It estimates the probability of remaining event-free while accounting for patients whose follow-up ends before an event occurs.
Cox proportional-hazards model
A Cox model is commonly used to estimate the relative hazard between randomized groups. The resulting hazard ratio summarizes the relative event rate over the analyzed follow-up period.
A hazard ratio is not the same as an absolute risk reduction and does not describe the outcome of every individual participant.
7. Statistical Methods Explained
Why is disease-free survival analyzed as a time-to-event endpoint?
Patients may experience events at different times, and some participants may not have an event before the end of follow-up. Time-to-event methods preserve information from both event timing and censoring.
Why is randomization important in this design?
Random allocation helps balance known and unknown factors between treatment groups, allowing differences in outcomes to be interpreted as comparisons between assigned strategies.
Why would Kaplan-Meier curves be useful?
Kaplan-Meier curves provide a visual description of how disease-free survival changes over time and allow investigators to account for incomplete follow-up.
Why might a Cox model be used?
A Cox model allows estimation of a hazard ratio while accounting for the timing of events rather than only counting whether events occurred.
Why should a hazard ratio not be interpreted as a percentage of patients benefiting?
The hazard ratio describes a relative event rate under a statistical model. It does not directly indicate the proportion of patients who experience benefit.
8. Limitations and Interpretation Issues
- No posted efficacy estimates: The registry does not report outcome estimates, confidence intervals, or p-values for the primary endpoint.
- Endpoint definition: Disease-free survival depends on the protocol definition of qualifying events and censoring rules.
- Follow-up interpretation: A 60-month endpoint frame describes the planned observation period, not an individual patient's outcome duration.
- Randomized comparisons: The interpretation of treatment effects depends on adherence to the randomized design and prespecified statistical methods.
- Multiple study interventions: The registry lists both drug-based and lifestyle-based intervention categories.
9. Why This Trial Matters Statistically
SUCCESS C illustrates several important principles in randomized clinical-trial statistics: treatment allocation, parallel-group design, time-to-event endpoints, and the importance of prespecified endpoint definitions.
| Concept | How it appears in SUCCESS C |
|---|---|
| Randomization | Patients were assigned in a randomized study design. |
| Parallel design | The registry identifies a parallel-group design with 3 arms. |
| Time-to-event analysis | The primary endpoint is disease-free survival after randomization. |
| Censoring | Relevant for participants without observed events during follow-up. |
| Hazard-based methods | Cox modeling is a common framework for disease-free survival comparisons. |
10. Primary Sources
- ClinicalTrials.gov: NCT00847444.
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11. Record Summary
SUCCESS C is a phase 3 randomized breast cancer trial designed around a disease-free survival comparison after randomization. The registry defines the primary endpoint and study design, while the publicly available record does not report statistical outcome estimates for the primary endpoint.