Chemotherapy and Pelvic Radiation Therapy With or Without Additional Chemotherapy in Treating Patients With High-Risk Early-Stage Cervical Cancer After Radical Hysterectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Chemotherapy and Pelvic Radiation Therapy With or Without Additional Chemotherapy in Treating Patients With High-Risk Early-Stage Cervical Cancer After Radical Hysterectomy (NCT00980954), a randomized phase 3 study. The primary outcome is Disease-free Survival (Percentage of Participants Alive Without Disease).

2. Clinical Question

The comparison isolates the question of adding chemotherapy after concurrent cisplatin and pelvic radiation within this trial’s treatment strategies. It is not a comparison of chemoradiotherapy with no treatment, nor does it test radiation alone: both arms include concurrent chemotherapy and pelvic radiation. The population is specifically described as high-risk and early-stage, after radical hysterectomy, so the findings and reporting should be interpreted in that clinical context rather than assumed to apply to other cervical cancer settings.

3. Trial Design

The registry identifies this as a phase III randomized study with a parallel-group design and no masking. Participants were assigned to one of two treatment strategies: cisplatin with pelvic radiation, or that chemoradiotherapy followed by carboplatin and paclitaxel. The registry lists enrollment of 236 and marks the study as completed. It gives a start date of 2009-09 and a primary completion date of 2023-12-14.

In the chemoradiotherapy strategy, the radiation options are standard external beam radiation therapy or intensity-modulated radiation therapy to the pelvis, with optional brachytherapy boost. Cisplatin is given concurrently. In the additional-chemotherapy strategy, the registry describes paclitaxel and carboplatin after chemoradiotherapy, starting 4-6 weeks later, with treatment continuing in the absence of disease progression or unacceptable toxicity. Some treatment-description text is incomplete in the registry record, so details not fully stated there should not be inferred.

Randomization can reduce systematic differences between groups at the point of assignment, while a parallel design follows the assigned groups as separate treatment strategies. Lack of masking means the registry lists no masking; the extent to which participants, clinicians, or outcome assessors were aware of treatment assignment is not further detailed in the registry record. The record does not report the allocation ratio or the method used to generate or conceal assignments.

The primary endpoint is disease-free survival, analyzed using Kaplan-Meier estimates and a log-rank test according to the registry description. Analysis was planned after disease or death had been reported for 50 participants. This statement describes a planned event threshold, not confirmation that the threshold was reached or that an analysis was conducted at that time. A statistical analysis plan, detailed sample-size justification, and interim-analysis procedures are not reported in the registry 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: Eligible participants

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.

Population: Eligible participants

6. Primary Endpoint

The registry lists the primary outcome as Disease-free Survival (Percentage of Participants Alive Without Disease), measured over From randomization to first failure (local, regional, or distant metastases failure or death due to any cause) or last follow-up. Maximum follow-up at the time of analysis was 12.8 years. The 2- and 4-year DFS estimates are reported..

The primary endpoint is disease-free survival (DFS), reported as the percentage of participants alive without disease. The registry defines the event as the first local, regional, or distant metastases failure, or death from any cause. Time is measured from randomization until the first such event or the participant’s last follow-up. Participants without a recorded event by last follow-up are treated as censored in the stated analysis.

DFS combines recurrence or metastases and death into a time-to-event outcome. It therefore captures both whether an event occurs and when it occurs, rather than treating every participant’s follow-up as though it ended at the same time. The registry specifies Kaplan-Meier estimates and a log-rank comparison, with estimates planned at 2 and 4 years. Maximum follow-up at the time of analysis is described as 12.8 years, but the registry record does not report the numerical DFS estimates, their confidence intervals, or the log-rank result.

As a general statistical point, a time-to-event endpoint can make use of differing follow-up durations while accounting for censoring, provided the assumptions behind the analysis are reasonable. It is important to distinguish a Kaplan-Meier estimate from a simple fraction of participants who experienced an event: the estimate incorporates event timing and censoring. The registry’s description identifies the endpoint and planned method, but does not provide enough outcome information to quantify the between-group difference or its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a time-to-event analysis for DFS. The endpoint clock starts at randomization and ends at the first listed disease failure or death from any cause. When no event is recorded before last follow-up, the participant’s time is censored at that follow-up. This definition makes the event rule explicit, although detailed rules for assessing and confirming each disease failure are not reported in the registry record.

What does Kaplan-Meier estimation do?

In general, Kaplan-Meier estimation uses the observed event times to estimate the probability of remaining free of the defined event over time. Participants who are censored contribute information up to their last known follow-up, rather than being treated as if they had an event or remained event-free indefinitely. This is useful when participants have different follow-up durations. The approach relies on assumptions, including that censoring is not systematically related to the future event risk in a way that invalidates the estimate. The registry record does not report diagnostic checks or additional details about censoring.

The registry says that DFS estimates at 2 and 4 years are reported. Those are time-specific summaries of the estimated DFS curve, not necessarily the observed proportion of all randomized participants known to be alive without disease at those exact times. Their interpretation depends on the numbers remaining under observation and the event and censoring patterns. Neither the estimates nor the corresponding numbers at risk at those times are reported in the registry record.

What does the log-rank test compare?

In general, the log-rank test compares the event experience over follow-up between groups, using the timing of events and the participants still at risk at each event time. It tests whether the observed separation between the groups’ event patterns is compatible with a common underlying event distribution under the test’s assumptions. It does not, by itself, express the size of a clinically meaningful difference. The registry names the log-rank test but does not report its test statistic, p-value, or the result.

A log-rank test is most straightforward to interpret when the relative event pattern between groups is reasonably stable over time. If the groups’ event patterns change in relation to one another during follow-up, a single overall test can be harder to summarize. The registry record does not report an assessment of this feature or an alternative primary analysis.

How should the confidence interval be understood?

The primary outcome description lists a 90% confidence interval. In general, a confidence interval communicates uncertainty around an estimate under the statistical model and procedure used: narrower intervals indicate greater precision, while wider intervals indicate less precision. It does not give the probability that a particular fixed treatment effect is true. Because the registry record does not include the DFS estimates or their intervals, the precision of the primary result cannot be evaluated.

The endpoint is labeled as a percentage of participants alive without disease, but the stated Kaplan-Meier method estimates DFS over time. That distinction matters: the estimate accounts for event times and censoring, and should not be replaced by a simple event count or crude percentage. The registry record does not report all details needed to reproduce the analysis, such as the exact analysis dataset, handling of protocol deviations, or further model specifications.

What can the adverse-event counts tell readers?

In general, adverse-event counts describe how many participants were recorded with an event under the specified collection rules. Counts are not equivalent to rates when follow-up time may differ, and they do not account for baseline differences or other covariates. The record gives at-risk and affected counts by group, plus death counts, but does not describe in this summary the event-collection window, exposure adjustment, or whether repeat events are counted once per participant or by occurrence. No rate, risk difference, or other derived comparison is calculated.

The registry also lists selected serious-event terms with percentages. Without the denominator, group assignment, and event-aggregation rules for that listing, the figures cannot be interpreted as arm-specific risks. They are descriptive entries in the record. A fuller safety interpretation would require the underlying definitions and reporting structure, which are not reported in the registry record.

Finally, a planning illustration based on an observed effect is not the same as the trial’s original design justification or an observed-power calculation. The registry record does not report the trial’s sample-size justification or detailed statistical plan. The primary outcome is described as having several categories or time points and is not reduced to one comparison in the posted results, so no single recalculated comparison should be substituted for the sponsor’s analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary DFS outcome and multiple secondary outcomes. These include overall survival, patient-reported measures of neurotoxicity, diarrhea, and cervical cancer symptoms at 12 months, adverse events by highest grade, and exploratory associations involving tumor molecular signatures, serum and plasma factors, and genetic variants. When a study evaluates several outcomes or time points, the chance of at least one apparently notable finding can increase if each is tested separately without a prespecified strategy for controlling multiplicity. This is a general statistical concern, not a claim about the conclusions of this trial.

The registry record does not report whether multiplicity was controlled, which outcomes were included in any formal testing hierarchy, or how the secondary outcomes were intended to support inference. It also does not report a detailed statistical analysis plan or identify which analyses were confirmatory versus exploratory. The listed secondary outcomes should therefore be understood as registered outcomes, not as evidence that each was analyzed or that a particular multiplicity procedure was used.

The primary outcome description says analysis was to occur after disease or death was reported for 50 participants. Whether this event threshold was reached, whether interim analyses were planned or conducted, and whether any statistical adjustment was made for interim looks are not reported in the registry record.

The record describes eligible participants as the primary-outcome population, but does not report whether the analysis followed an intention-to-treat principle, how participants with missing outcome information were handled, or whether additional per-protocol or safety populations were used. Detailed missing-data procedures, reasons for missingness, and sensitivity analyses are also not reported in the registry record. These omissions limit assessment of how completely the analyses preserve the randomized comparison and how robust the estimates are to incomplete follow-up.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: diarrhea (5.0%), urinary tract infection (4.0%), anemia (3.0%), constipation (3.0%), ileus (2.0%).

The registry lists serious adverse-event counts by treatment group. In the cisplatin/radiation group, 107 participants are listed as at risk and 14 as affected by serious adverse events. In the group receiving cisplatin/radiation followed by carboplatin/paclitaxel, 101 are listed as at risk and 25 as affected. For other adverse events, the corresponding counts are 107 at risk and 103 affected in the first group, and 101 at risk and 99 affected in the second. The listed death counts are 17 and 13.

These entries are counts, not adjusted estimates of comparative safety. The registry record does not describe in this summary the observation window, handling of repeat events, or whether categories overlap. It also does not state how deaths are related to adverse events or to DFS failures. The selected serious-event terms are reported with percentages, but an arm-specific breakdown and denominator for those percentages are not given in the listing. They should not be interpreted as treatment-group rates.

In general, safety comparisons require consistent definitions, follow-up, and ascertainment in both groups. The counts alone do not establish that one strategy has greater or lesser risk, and they do not describe the severity distribution beyond the serious-event designation and the separate listed outcome of highest adverse-event grade.

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

The registry record establishes the question the trial set out to address: whether adding carboplatin and paclitaxel after cisplatin with pelvic radiation changes DFS compared with cisplatin and pelvic radiation alone in the registered population. It also specifies the endpoint definition, the planned time-specific estimates, and the named statistical methods. Those details clarify what outcome and comparison were intended.

The record does not report the DFS estimates, confidence intervals, or log-rank result. As a result, it does not show how large a difference was observed, which group had the higher estimated DFS, or how precise the estimates were. The presence of a completed status, a planned event threshold, or adverse-event counts cannot fill that gap. No conclusion about the effectiveness of either strategy follows from the information reported in the registry record.

Even when numerical results are available, a statistical comparison and its clinical interpretation are different questions. A p-value, if reported, would address compatibility of the data with a statistical null model under the chosen test; it would not by itself describe the size or importance of a difference. Estimates and confidence intervals are needed to understand effect size and precision, while interpretation also depends on the population, endpoint, follow-up, and study conduct. The registry record does not provide the primary estimate needed for that assessment.

The safety entries are likewise descriptive. They list affected participants, participants at risk, and deaths, but do not supply enough information for adjusted or time-based comparisons. They cannot by themselves establish a causal difference in harms between the randomized groups.

These limits concern what is reported in the registry record, not necessarily what may be available in other study documents. The record does not report a publication, a detailed analysis plan, or the underlying outcome data. The appropriate reading is therefore that the trial’s design and registered outcomes can be described, while its primary comparative result cannot be quantified from this record.

13. Why This Trial Matters Statistically

This trial raises a clear statistical comparison within a defined treatment sequence: both randomized groups receive concurrent cisplatin and pelvic radiation, while one group also receives subsequent carboplatin and paclitaxel. That structure makes the added chemotherapy the principal strategy difference described by the registry. It also means that conclusions, if supported by complete results, would pertain to this comparison and this registered population, rather than to radiation or chemotherapy in isolation.

DFS is a time-to-event endpoint, which requires attention to both event timing and follow-up. Kaplan-Meier estimation and the log-rank test are methods designed for this kind of outcome. Their use makes the definitions of failure, censoring, follow-up, and analysis population important to interpretation. The registry states the event definition and intended methods, but the lack of numerical estimates and analysis details prevents a reader from assessing the result’s magnitude, precision, or robustness.

The trial also illustrates why a registered endpoint and a completed status are not substitutes for posted outcome statistics. Without the estimated DFS values and their confidence intervals, readers cannot judge how much uncertainty surrounds the comparison. Without the test result, they cannot assess the stated inferential comparison. Without fuller safety definitions, the adverse-event counts remain descriptive and cannot be treated as comparable rates.

Statistically, the record is useful for identifying the population, treatment strategies, endpoint, and intended analysis. It is incomplete for evaluating the trial’s primary comparative finding. That distinction helps keep design information separate from evidence about outcomes, and prevents a methods description or a list of event counts from being mistaken for a quantified treatment 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 central limitation for interpreting this trial from the registry record is that the primary DFS estimates and between-group comparison result are not reported. The stated 2- and 4-year estimates, 90% confidence intervals, and log-rank result cannot be examined. Maximum follow-up at the time of analysis is reported as 12.8 years, but the record does not provide the distribution of follow-up or numbers at risk over time.

The primary analysis is described for eligible participants, but the exact analysis population and handling of all randomized participants are not stated. The record does not report how missing follow-up, protocol deviations, treatment discontinuation, or crossover, if any, were handled. The event-trigger statement refers to disease or death reported for 50 participants, but whether the threshold was reached and how it related to the reported analysis are not established by the registry information.

Further design and analysis details are also absent, including the randomization procedure, allocation ratio, concealment method, sample-size justification, interim-analysis procedures, and detailed statistical plan. The treatment descriptions are incomplete in places, and the record does not provide full operational definitions for the outcome and safety assessments.

The safety summary lists at-risk and affected counts and deaths, but does not explain the event-observation period, repeat-event handling, overlap among categories, or the denominator and group breakdown for the selected serious-event percentages. These limitations constrain comparative interpretation. They do not establish that the trial methods were inadequate; they identify details that are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Chemotherapy and Pelvic Radiation Therapy With or Without Additional Chemotherapy in Treating Patients With High-Risk Early-Stage Cervical Cancer After Radical Hysterectomy — NCT00980954.
• Registry record last updated 2025-12-31; status last verified 2025-09.
• Results first posted 2024-11-06.
• 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.

18. Record Summary

NCT00980954 is a completed randomized phase III parallel-group trial with no masking, listed for high-risk early-stage cervical cancer after radical hysterectomy. The registry reports enrollment of 236 and compares cisplatin with pelvic radiation against the same chemoradiotherapy followed by carboplatin and paclitaxel.

The primary endpoint is DFS, defined from randomization to first local, regional, or distant metastases failure, death from any cause, or last follow-up. Kaplan-Meier estimation and a log-rank comparison are described, with planned estimates at 2 and 4 years. Maximum follow-up at the time of analysis is reported as 12.8 years. The primary estimates and comparison result are not reported in the registry record.

Safety entries include serious and other adverse-event counts and deaths by group, alongside selected serious-event terms and percentages. The registry record does not give enough detail to treat these entries as adjusted or arm-specific rates. Multiplicity procedures, detailed missing-data methods, and the full statistical analysis plan are not reported.