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
INTERLACE is a phase 3 randomized trial evaluating induction chemotherapy followed by chemoradiation as first line treatment for locally advanced cervical cancer.
| Feature | INTERLACE |
|---|---|
| Condition | Cervical Cancer |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None |
| Primary purpose | Treatment |
| Lead sponsor | University College, London |
| Status | Active, not recruiting |
| Start date | 2012-11-08 |
| Primary completion date | 2026-02 |
2. Clinical Question
Population
Patients with locally advanced cervical cancer.
Intervention
Induction chemotherapy using paclitaxel and carboplatin followed by chemoradiation.
Comparator
Chemoradiation treatment without the induction chemotherapy sequence.
Primary question
Does induction chemotherapy plus chemoradiation improve overall survival compared with the comparator approach?
3. Trial Design
Randomization
500 participants
Treatment
Two parallel arms
Follow-up
Outcome assessment
Analysis
Overall survival
Randomized allocation.
No masking.
Two treatment groups.
Paclitaxel, carboplatin, radiotherapy, and cisplatin.
4. Primary Endpoint
| Endpoint | Definition / Time Frame |
|---|---|
| Overall Survival | 5 years |
5. Planned Analysis
The registry identifies overall survival as the primary endpoint with a time frame of 5 years. Overall survival is typically analyzed as a time-to-event endpoint, where the event is death from any cause and patients without an observed event at the analysis cutoff contribute follow-up information through censoring.
Time-to-event analysis
Common statistical approaches for overall survival include Kaplan-Meier estimation to describe survival over time, log-rank testing to compare randomized groups, and Cox proportional-hazards modeling to estimate relative treatment effects.
6. Statistical Methodology
Overall survival as a time-to-event endpoint
Overall survival differs from a simple proportion because each participant contributes information over a period of observation. Some participants may still be alive when follow-up ends, creating censored observations.
S(t) = Probability of surviving beyond time t
The Kaplan-Meier estimator uses observed event times to estimate survival while retaining information from censored participants.
Hazard ratios
If a Cox proportional-hazards model is used, the hazard ratio summarizes the relative event rate between randomized groups over the analyzed follow-up. A hazard ratio below 1 indicates a lower estimated hazard in the treatment group; it does not directly represent the percentage of patients who survive or the absolute number of deaths prevented.
Randomization
Randomization creates the framework for comparing treatment groups while reducing systematic differences in measured and unmeasured baseline characteristics.
7. Statistical Methods Explained
Why is overall survival analyzed differently from a simple response rate?
Overall survival includes both the timing of events and censoring. A response rate measures whether an event occurred by a defined assessment, while survival analysis evaluates the distribution of time until the event occurs.
What does Kaplan-Meier estimation contribute?
Kaplan-Meier methods allow researchers to estimate survival probabilities over time when not every participant has experienced the event by the analysis cutoff.
Why is randomization important?
Randomization allows the treatment groups to be compared under a design intended to balance prognostic factors between groups.
What does a confidence interval represent?
A confidence interval describes uncertainty around an estimated treatment effect. It reflects statistical precision rather than the range of outcomes experienced by individual patients.
Why does follow-up duration matter?
Time-to-event outcomes depend on how long participants are observed. Longer follow-up can provide additional information about events occurring later after treatment.
8. Limitations
- No posted statistical analyses: The ClinicalTrials.gov record does not report formal statistical analyses or effect estimates for the primary endpoint.
- Time-to-event interpretation: Overall survival analyses depend on follow-up duration, censoring patterns, and the assumptions of the selected statistical model.
- Registry information: Trial registration provides design and endpoint information but may not contain the complete statistical analysis plan.
9. Why This Trial Matters Statistically
| Concept | How it appears in INTERLACE |
|---|---|
| Randomization | Randomized parallel-group phase 3 design |
| Time-to-event analysis | Overall survival measured over 5 years |
| Censoring | Participants without observed events at analysis contribute follow-up information |
| Hazard modeling | Potential framework for comparing survival distributions |
| Clinical trial design | Two-arm treatment comparison |
10. Sources
- ClinicalTrials.gov: NCT01566240
- PubMed: 39419054