Comparative Study of Gemcitabine,Cisplatin and Radiation Versus Cisplatin and Radiation in Cancer of the Cervix: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparative Study of Gemcitabine,Cisplatin and Radiation Versus Cisplatin and Radiation in Cancer of the Cervix (NCT00191100), a randomized phase 3 study. The primary outcome is Number of Participants With Progressive Disease or Death Due to Any Cause at 3 Years.

2. Clinical Question

The clinical question is whether these two treatment strategies differ in the occurrence of progression or death during follow-up. This is a comparison of assigned treatment strategies, not an isolated test of gemcitabine: the experimental strategy also includes adjuvant chemotherapy, while the comparator does not. The registry describes a randomized, parallel-group comparison with no masking. Random assignment is intended to make treatment groups comparable on average, but it does not eliminate uncertainty in observed results or resolve limitations in how outcomes are reported. Without the primary event counts, an estimated difference between groups, or an uncertainty interval, the registry record does not permit an assessment of the direction, size, or precision of the primary comparison.

3. Trial Design

The record describes a phase 3 randomized, parallel-group study of treatment strategies for cancer of the cervix. Enrollment was 515. The registry lists the study as completed, with a start in 2002-05 and primary completion in 2008-04. Masking is listed as none. These design details identify the broad structure of the comparison, but do not provide the full protocol or the results needed to interpret its primary outcome.

One group received concurrent gemcitabine and cisplatin with pelvic radiation and brachytherapy, followed by adjuvant gemcitabine and cisplatin. The other received cisplatin with pelvic radiation and brachytherapy, without adjuvant therapy. The record’s brief summary describes the intended allocation as half to each strategy, but it does not give the number assigned to each group. The experimental arm description is truncated during its adjuvant dosing details; a complete dosing schedule is not reported in the registry record.

The primary analysis population is described as intention-to-treat: all randomized participants are included and analyzed according to their assigned treatment. This approach preserves the randomized comparison even if participants do not complete the assigned treatment, although the record does not provide details about adherence or treatment changes. The primary outcome was the number with progressive disease or death from any cause by 3 years. The follow-up description includes tumor assessments during treatment and later follow-up, but the timing and completeness of outcome ascertainment for individual participants are not reported.

The record lists secondary outcomes covering progression or death at other time points, local failure, tumor response, and death from any cause. It does not report the protocol’s allocation procedure, allocation concealment, eligibility criteria beyond the disease stage in the official title, or the statistical analysis plan. The primary outcome results by arm are not reported in the registry record, so the randomized design can be described but its principal treatment comparison cannot be quantified from the available record.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intention-to-treat population includes all randomized participants. Participants were analyzed according to treatment they were randomly assigned.

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 Number of Participants With Progressive Disease or Death Due to Any Cause at 3 Years, measured over Tumor assessments at baseline, weekly during chemoradiation & brachytherapy, on Day 1 of adjuvant Cycles 1&2 for Arm A, at the 30-day post-study visit, every 4/6 months for 12/48 months of the short/long post-study follow-up periods respectively.

The primary endpoint concerns participants with progressive disease or death from any cause by 3 years. The registry explains that the original outcome was progression-free survival probability at 3 years, with progression-free survival defined as time from baseline to progressive disease or death from any cause. Because probability is not an accepted measure type in the registry format, the record presents the number of participants still progression-free and at risk, along with the cumulative number who experienced an event. The registry entries available for this analysis identify the event-count endpoint, but do not include those group-specific counts.

As a general statistical concept, progression-free survival combines disease progression and death into a single event definition. This can capture clinically important deterioration even when death has not occurred, while including death from any cause avoids treating death as though it were simply an unobserved future progression. A fixed-time event count is easier to understand as a number of people with an event by the stated time, but it does not by itself show when events occurred or how long each participant was observed.

Time-to-event analyses generally use event timing and censoring information to estimate survival probabilities. Censoring means that an event has not been observed by the end of a participant’s available follow-up; it does not establish that the event will never occur. The record describes follow-up assessments but does not provide participant-level timing, censoring details, or an estimated progression-free survival probability. The endpoint is therefore identifiable conceptually, but its reported results cannot be interpreted quantitatively from the record details available.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization assigns participants to treatment groups by chance rather than by a clinician’s selection. As a general statistical principle, random assignment can reduce systematic differences between groups at the time of allocation, including differences that were not measured. It does not guarantee identical groups in a particular trial, and its value depends on the assignment process being implemented as intended. The record says the trial was randomized but does not report how the sequence was generated or whether allocation was concealed before assignment.

The design is parallel: participants were assigned to one of the treatment strategies and followed in that group. The record lists no masking. In an unmasked study, participants and study staff may know the assigned strategy. General considerations include the possibility that knowledge of assignment affects treatment delivery, follow-up, reporting, or outcome assessment. The registry record does not describe procedures to reduce such effects or state whether outcome assessors were masked separately.

The primary analysis population is intention-to-treat. In general, this means analyzing participants according to their randomized assignment, regardless of treatment completion or changes after allocation. It maintains the comparison created by randomization and estimates the effect of assignment to a strategy rather than the effect among only those who fully adhered. The record does not provide details about adherence, crossover, treatment discontinuation, or how any such events were handled in the reported results.

The endpoint began as progression-free survival probability at 3 years. Progression-free survival is a time-to-event measure: it uses the time from baseline until progressive disease or death from any cause. The record states that it instead presents counts of participants still progression-free and at risk and cumulative counts with an event, because probability is not an accepted measure type in the registry format. A cumulative count alone is not an estimated probability. General interpretation requires knowing who was eligible for assessment at each time point, how much follow-up was available, and how incomplete follow-up was treated. Those details and the group-specific primary counts are not reported in the registry record details.

In time-to-event analysis, censoring occurs when a participant’s event time is not observed during available follow-up. Standard survival methods can use the time observed before censoring, subject to assumptions about the relationship between censoring and event risk. If people with incomplete follow-up differ systematically in their prospects for an event, estimates may be biased. The record does not state the censoring rules, provide reasons for incomplete follow-up, or report the number remaining under observation at outcome assessments. No conclusion about those assumptions is possible from the listed endpoint definition alone.

The record includes planning assumptions for sample-size illustrations: a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. It also distinguishes planning quantities as participants per arm for outcomes other than time-to-event outcomes, and total events for time-to-event outcomes. These are planning illustrations based on an observed effect, not observed power and not evidence that the trial was designed using those assumptions. The trial’s own sample-size justification and statistical plan are not reported in the registry record. No numerical illustration results are included in the registry record for this interpretation.

As a general concept, a confidence interval describes a range of effect estimates compatible with the data under a statistical model and procedure. Its width reflects statistical precision; it is not a guarantee that the true effect lies inside a particular interval. A significance test addresses compatibility with a null hypothesis under its assumptions, but a p-value does not measure the size or clinical importance of an effect. The record details available do not include a primary effect estimate, confidence interval, or p-value, so none can be interpreted for this trial.

The record lists a binary outcome kind and describes the primary measure as a count of participants with an event. For counts and proportions, the denominator and the definition of the analysis set matter: the same count can have different meanings in groups of different sizes or with different follow-up. For time-to-event outcomes, event timing and censoring are also essential. General statistical explanations cannot replace those missing trial results or establish the analysis used by the sponsor.

10. Multiplicity, Missing Data and Analysis Populations

The record lists several outcomes in addition to the primary endpoint, including local failure, tumor response, death from any cause at various time points, and progression or death at various time points. It also indicates six outcome measures and six analyses. When a study assesses multiple outcomes or time points, the chance of at least one apparently unusual result can increase if every comparison is treated as though it were the only one. General statistical approaches may define a primary comparison in advance, adjust for multiple testing, or interpret secondary analyses as exploratory. The registry record does not report a multiplicity strategy or identify how conclusions across outcomes were controlled.

The primary outcome description specifies an intention-to-treat population containing all randomized participants, analyzed by assignment. This identifies the intended analysis population for the primary outcome, but it does not explain how missing endpoint assessments were handled. The number of participants with unavailable outcome data, reasons for missingness, imputation methods, and sensitivity analyses are not reported in the registry record.

Missing outcome information can affect interpretation if participants who are not assessed have different event risks from those who remain observed. As a general concept, analysis methods for incomplete follow-up rely on assumptions about why information is missing. A complete-case analysis, an imputation approach, or a time-to-event method with censoring would each require details to understand its assumptions. The record details available do not identify which methods were used.

The registry’s description of assessment timing does not establish that every participant had complete follow-up through 3 years. Group-specific numbers at risk and the handling of censoring are not reported in the registry record. Likewise, the statistical plan for the primary and secondary analyses is not reported. These gaps limit assessment of whether missing data or repeated testing could materially affect the reported interpretation.

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

The trial record defines a randomized comparison between a combined gemcitabine, cisplatin, and radiation strategy followed by adjuvant chemotherapy and a cisplatin-and-radiation strategy without adjuvant therapy. Its primary outcome concerns progressive disease or death from any cause by 3 years. These details clarify the intended question and the event definition, but they do not reveal the primary result.

The primary event counts for each group, any effect estimate, and any measure of uncertainty are not reported in the registry record details available. Thus, the record as described does not establish whether one strategy had more or fewer events, how large any difference was, or how precisely a difference was estimated. A randomized design is a strength for comparing assigned strategies, but design alone is not a result.

The endpoint count should not be treated as a probability or as a complete description of event timing. The registry explains that progression-free survival probability was the original outcome and that the presented measure was changed to counts. Without group-specific counts, denominators, follow-up information, and censoring details, the primary endpoint cannot be translated into a comparative risk estimate from the registry entries.

Adverse-event counts are listed, as are several serious adverse-event terms with percentages. The record does not provide the denominators or detailed definitions needed to interpret these entries as comparative rates. Counts of participants affected also do not, by themselves, describe severity, duration, recurrence, or attribution. These listings should therefore be read as registry entries, not as a complete comparative safety analysis.

In general, a treatment comparison requires more than knowing which groups were assigned and what outcomes were planned. It requires the observed results, the analysis method, and enough information about follow-up and missingness to judge uncertainty and potential bias. Those elements are not reported in the registry record details available for the primary outcome. No conclusion about the relative clinical effects of the strategies follows from the information presented.

12. Why This Trial Matters Statistically

This trial illustrates an important distinction between a clearly described research question and an interpretable result. The registry names two treatment strategies, specifies randomization and an intention-to-treat population, and defines a primary event involving progression or death. Those features help readers understand what the study intended to compare. But without primary outcome results, the central statistical comparison remains unquantified.

The record also illustrates how the format used to register an outcome can differ from the clinical estimand of interest. The original endpoint was progression-free survival probability at 3 years, a time-to-event summary. The record explains that counts were entered instead because probability is not an accepted measure type. Counts can be useful, but only when their denominators, follow-up context, and treatment-group results are available. An event count alone does not convey the probability of remaining progression-free.

It is also a useful case for distinguishing study design from study analysis. Randomization and intention-to-treat analysis are relevant design and population features, while the statistical plan, handling of censoring, missing data, and multiplicity determine how the collected data are analyzed and interpreted. The statistical analysis plan is not reported in the registry record. Readers therefore cannot assess whether the analyses followed a prespecified approach or how uncertainty was quantified.

Finally, adverse-event participant counts and selected serious-event terms show why raw counts require context. Without denominators and clear definitions, counts do not support a fair comparison of event frequency between groups. The same principle applies to efficacy outcomes: a number becomes meaningful through its population, time frame, event definition, and analysis. The registry record provides some of that framework, but not the primary outcome results needed to evaluate the main comparison.

13. 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 main limitation for interpreting this trial from the registry record is that the primary outcome counts by group and the corresponding comparative estimate are not reported in the registry record. This prevents assessment of the direction, magnitude, and precision of the primary finding. The record states that the original endpoint was progression-free survival probability at 3 years but describes counts as the registered measure, so the outcome format does not directly provide a probability estimate.

Important analysis details are also absent. The statistical analysis plan, sample-size justification, allocation procedure, allocation concealment, multiplicity handling, and missing-data methods are not reported in the registry record. Although the primary population is described as intention-to-treat, details about follow-up completeness, censoring, adherence, treatment changes, and withdrawals are not available. The record’s assessment schedule does not by itself establish complete outcome ascertainment.

The experimental arm’s dosing description is truncated during the adjuvant treatment details. The record therefore does not provide a complete schedule for that strategy. Eligibility criteria beyond the cervical cancer stage range in the official title are not reported in the registry record. These omissions limit the precision with which the treatment strategies and trial population can be characterized.

Safety interpretation is limited by the absence of denominators for the listed participant counts and by the lack of detailed adverse-event definitions and follow-up context. The presence of serious-event terms and percentages does not supply a full comparative safety analysis. No numerical primary outcome result is available to balance against those safety entries.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Comparative Study of Gemcitabine,Cisplatin and Radiation Versus Cisplatin and Radiation in Cancer of the Cervix — NCT00191100.
• Registry record last updated 2009-08-11; status last verified 2009-08.
• Results first posted 2009-05-25.
• 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.

17. Record Summary

This completed phase 3 randomized, parallel-group trial enrolled 515 participants with cancer of the cervix. It compared gemcitabine, cisplatin, and radiation followed by adjuvant gemcitabine and cisplatin with cisplatin and radiation without adjuvant therapy. The record lists no masking.

The primary endpoint was the number of participants with progressive disease or death from any cause by 3 years. The record explains that progression-free survival probability was the original outcome, but counts were presented instead. The primary counts by group and a comparative effect estimate are not reported in the registry record details available for interpretation.

The record lists secondary outcomes and adverse-event entries, but does not provide the statistical analysis plan, missing-data methods, or multiplicity strategy. These omissions, alongside the unavailable primary results, limit quantitative interpretation of the trial comparison.