Pilot Study of Abbreviated Chemotherapy Based on Positron Emission Tomography (PET) Scan in Hodgkin's Lymphoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pilot Study of Abbreviated Chemotherapy Based on Positron Emission Tomography (PET) Scan in Hodgkin's Lymphoma (NCT00901303), a non-randomized na study. The primary outcome is 36-Month Progression-free Survival Rate.

2. Clinical Question

The study asked whether progression-free survival at 36 months could be assessed among patients with Hodgkin lymphoma who had a complete metabolic response, shown by a negative FDG-PET scan after one cycle of ABVD, and then received abbreviated ABVD chemotherapy consisting of three cycles. The registry identifies this as the primary objective, rather than a comparison of abbreviated chemotherapy with a separate control treatment.

This distinction between the planned question and the available evidence is central to interpreting the record. It describes a clinical strategy linking an early imaging response to subsequent treatment duration, but does not report the primary outcome needed to evaluate the strategy. Nor does it report a comparison that could separate outcomes under abbreviated treatment from outcomes under another treatment approach.

3. Trial Design

The registry classifies this as a pilot study with a nonrandomized allocation, no masking, and a single-group model. Its phase is listed as NA. The intervention is ABVD chemotherapy. The study description focuses on patients with Hodgkin lymphoma who have a negative FDG-PET scan after one cycle and then receive three cycles of abbreviated ABVD. The registry also lists early-stage and advanced-stage disease groups; it does not describe those groups as randomized treatment arms or as a control comparison.

The record lists enrollment of 6. That entry does not establish how many participants had the required PET response, completed the stated chemotherapy, had follow-up, or were included in any endpoint analysis. Those details are not reported in the registry record. The sponsor is Weill Medical College of Cornell University. The record lists a study start of 2008-10, primary completion of 2010-06, and status as terminated.

Most importantly, the primary outcome description states that data were not collected due to early termination. The record therefore documents a study objective and design, but not an evaluable primary outcome result. It lists one outcome measure and zero analyses. No statistical analysis plan, sample-size justification, interim-analysis plan, or reason for termination beyond the stated early termination is reported in the registry record.

Because the design is nonrandomized and single-group, the study is not a randomized test of abbreviated treatment against a concurrent control. Comparisons between the early-stage and advanced-stage labels would also not be a like-for-like treatment comparison based on the registry information. The posted tables, plots, and sample-size section should therefore be read in the context of a small pilot record without collected primary endpoint data, rather than as evidence from a completed comparative efficacy analysis.

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

Analysis population for the primary outcome, as defined in the registry: Data was not collected due to early termination of the study.

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 36-Month Progression-free Survival Rate, measured over 36 months.

The primary endpoint is the 36-month progression-free survival rate. The registry defines progression-free survival as the length of time from study intervention to disease progression or death, and identifies the relevant timeframe as 36 months. The intended population is patients with Hodgkin lymphoma who had a negative FDG-PET scan after one ABVD cycle and then received abbreviated chemotherapy.

In general, a time-to-event endpoint describes how long it takes for a specified event to occur. Progression-free survival combines disease progression and death into the event definition, so the endpoint captures time until either event rather than describing only one of them. Such endpoints can be useful when the timing of events matters and when participants may have differing follow-up. Those are general properties of time-to-event outcomes, not a description of the analysis used in this study.

The registry does not report the number of progression or death events, an estimated progression-free survival rate, a confidence interval, or an analysis method. It explicitly states that data for the primary measure were not collected because of early termination. Consequently, the endpoint definition is available, but its observed value and precision are not. Details such as censoring rules, how progression was assessed, and the handling of incomplete follow-up are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record supports a limited methods discussion. It gives the study's broad design classifications, intervention, endpoint definition, and stated reason the primary endpoint data are unavailable. It does not report an inferential analysis of the primary outcome. The explanations below describe general statistical concepts and distinguish them from methods actually documented for this study.

What does the design classification imply?

The record labels the allocation nonrandomized, the masking none, and the model single-group. In general, random allocation is used to create treatment groups whose observed and unobserved characteristics are less systematically tied to treatment assignment. Without randomization, a comparison between groups can reflect differences in the people assigned to them as well as differences in treatment. Here the registry does not describe a randomized comparator. The early-stage and advanced-stage labels should not be read as randomized arms or as a control group.

Masking concerns whether participants, clinicians, or outcome assessors know the assigned treatment. The record's classification is none; it does not give further details about who knew what or how outcomes were assessed. The registry does not report procedures for reducing assessment bias. These general design concepts do not establish that bias occurred; they identify what the design description does and does not document.

How should the primary endpoint be understood?

The endpoint is progression-free survival, defined in the record as time from study intervention to disease progression or death, with a stated timeframe of 36 months. In general, time-to-event data retain information about when an event occurs, rather than reducing the observation to a simple event/no-event label at one point. A survival analysis may also account for participants whose event has not been observed by the end of their available follow-up, using censoring rules. The registry does not report whether or how censoring was used in this study, so no particular survival estimator or censoring approach can be attributed to it.

In general, a point estimate summarizes the endpoint under an analysis, while a confidence interval expresses uncertainty around that estimate. A standard error or interval width can help show how much information the data provide. None of these primary endpoint quantities is reported. Because the registry states that primary outcome data were not collected due to early termination, there is no estimate whose uncertainty can be described.

What can be inferred from the analysis fields?

The record lists one outcome measure and zero analyses. This distinguishes having a defined outcome from having an analyzed outcome. A registry can describe what investigators intended to measure even when no result was collected or posted. In this case, the endpoint definition and timeframe do not imply that a survival curve, rate estimate, statistical test, or model was produced. The analysis method is not reported in the registry record.

For general context, a statistical test evaluates how compatible observed data are with a specified null hypothesis under assumptions. A p-value is not an effect size and does not measure the probability that a treatment works. The registry provides no primary endpoint test or p-value to interpret. It also does not report adjusted or unadjusted analyses, covariates, or an analysis population. No model choice can be inferred from the endpoint being time-to-event.

What does the sample-size section represent?

The sample-size section is identified as a planning illustration computed from an observed effect, rather than the trial's own design. Its stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event tables, the section refers to total events, while other tables refer to participants per arm. These are features of the planning illustration, not evidence that this single-group pilot used those assumptions to plan enrollment.

In general, a sample-size calculation asks how much information might be needed to detect a specified effect under assumed design and analysis conditions. Its result depends on those assumptions and is a planning quantity, not an observed outcome. Such an illustration is not observed power, and it does not establish what the trial could detect after it ended. The registry does not report the trial's own sample-size justification. Further, because the primary outcome data were not collected, the posted record does not supply a trial-specific observed effect on that endpoint for interpretation. The section's calculations should be treated according to their stated illustrative purpose.

What methods remain unknown?

The registry record does not report the planned handling of missing data, the definition of analysis populations, multiplicity procedures, interim analyses, or a detailed statistical analysis plan. It also does not report the methods for determining progression, the approach to follow-up, or how participants who did not complete treatment would have been handled. These omissions prevent reconstruction of a planned or completed endpoint analysis. They should not be filled in by assuming customary practice.

In general, over-dispersion matters when observed variability exceeds what a statistical model assumes; ignoring it can make uncertainty estimates too small. That concept is not linked to a reported analysis: no count model or over-dispersed outcome analysis is described. Likewise, no recalculated estimate can replace the absent primary data. A simple recalculation from posted summary statistics would require relevant summary statistics, and none for the primary endpoint is reported.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, identifies progression-free survival at 36 months as primary, and lists zero analyses. It does not report a multiplicity plan. In general, multiplicity arises when several outcomes, time points, subgroups, or statistical tests are evaluated; without an analysis plan, readers cannot determine how any resulting multiple comparisons would have been handled. The record does not provide a set of analyzed comparisons to assess.

The primary endpoint data were not collected due to early termination. This is different from having collected outcome data and then omitting some observations from an analysis. The record does not describe individual missingness, the amount or pattern of incomplete follow-up, or any method for addressing missing data. It therefore does not support a judgment about whether missingness was related to prognosis or how it might affect an estimate.

The analysis population is not reported in the registry record. In particular, it does not say whether any planned population was defined by enrollment, treatment receipt, PET response, or follow-up availability. The enrollment listing of 6 alone does not identify an endpoint denominator. The entry also does not report an intention-to-treat or per-protocol analysis.

These omissions matter because multiplicity, missing-data assumptions, and analysis-population definitions can affect interpretation even when outcome estimates are available. Here, the issue is more fundamental: the registry says the primary outcome data were not collected, and no analyses are listed. Statistical adjustments cannot be inferred, and there is no primary estimate on which to apply or evaluate them.

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

This record establishes that investigators proposed a pilot study of PET-guided abbreviated ABVD chemotherapy in Hodgkin lymphoma. The clinical question concerned 36-month progression-free survival among patients who had a negative FDG-PET scan after one ABVD cycle and then received three cycles of abbreviated ABVD. It also establishes that the registry classifies the study as nonrandomized and single-group, lists enrollment of 6, and records the study as terminated.

It does not establish the observed progression-free survival rate. The registry explicitly says that primary endpoint data were not collected because of early termination. There is no reported event count, effect estimate, confidence interval, or analysis to show how the endpoint behaved. Thus, the record neither demonstrates a favorable result nor demonstrates an unfavorable one. It leaves the primary question unanswered in the posted results.

It also does not establish a treatment effect relative to another regimen. No randomized comparator is described, and the early-stage and advanced-stage labels are not a like-for-like control comparison. Any apparent distinction between those groups would not, on the available information, isolate the effect of treatment. The registry supplies no reported group outcome analysis in any case.

In general, a small enrollment can limit the amount of information available, but enrollment alone is not enough to quantify precision or power. Here the main limitation is that the primary outcome data were not collected. The sample-size section is described as a planning illustration, not as the study's own design or observed power. It should not be used to imply that the trial achieved a particular ability to detect an effect.

The adverse-event fields also require care. The posted stage groups list zero at risk and no serious adverse terms. Those entries do not amount to evidence that there were no adverse events among treated participants, because the record does not list participants at risk in those fields or provide a meaningful adverse-event analysis. Readers should distinguish empty or uninformative registry fields from observed zero events.

In sum, this is a record of a proposed clinical question and a terminated pilot, not a result establishing the endpoint or a comparative treatment conclusion. Its statistical value lies in documenting the design and the limits of the available results.

12. Why This Trial Matters Statistically

The study is statistically notable because its primary question depends on the relationship between an early biomarker assessment and a later clinical outcome. The registry describes selection by a negative FDG-PET scan after one ABVD cycle, followed by abbreviated chemotherapy, and asks about progression-free survival at 36 months. That structure makes clear what the investigators intended to measure, even though the record does not contain the outcome data needed to answer it.

It also illustrates why a defined endpoint is not the same as an analyzed endpoint. The record gives a time-to-event definition and timeframe, but reports that data were not collected after early termination. Without observed events and follow-up, there is no rate estimate or measure of precision. That distinction is fundamental when interpreting trial registries: design details can remain visible even when the results are unavailable.

The classification as nonrandomized and single-group is another important statistical feature. A clinical strategy can be described without supporting a causal comparison. The stage labels do not create a randomized control, and the record does not provide a like-for-like comparison. Keeping that distinction explicit prevents descriptive design information from being mistaken for evidence of comparative effect.

Finally, the sample-size section's stated role as a planning illustration shows why statistical displays need context. Illustrative calculations are not a trial's observed power, actual enrollment target, or clinical outcome. This record offers a useful example of how a pilot's intended question, posted design, and available evidence can diverge: the registry describes the first two, while the primary outcome data are absent.

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 most direct limitation is the absence of primary outcome data. The registry states that progression-free survival data were not collected due to early termination. As a result, there is no endpoint estimate, event count, confidence interval, or analysis to evaluate. No interpretation of the 36-month progression-free survival outcome can be made from this record.

The record lists enrollment of 6, but does not report how many participants met the PET-response criterion, received the stated abbreviated regimen, or contributed follow-up. Nor does it describe follow-up duration for individual participants, censoring, progression assessment, or the analysis population. These gaps prevent readers from determining the denominator or reconstructing a time-to-event analysis.

The design is nonrandomized and single-group, with no masking. The record does not describe a concurrent randomized control comparison. Although early-stage and advanced-stage groups are listed, they do not provide a like-for-like control comparison as described in the record. Any causal interpretation would therefore be unsupported, quite apart from the missing primary endpoint data.

Additional limitations include the absence of a reported statistical analysis plan, sample-size justification for the trial, interim-analysis plan, multiplicity procedures, or missing-data methods. The registry lists zero analyses. The adverse-event entries show zero participants at risk in the displayed groups and no serious adverse terms, which is insufficient to establish the absence of adverse events. The record does not give a reason for termination beyond stating that it occurred early and that the primary data were not collected.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Pilot Study of Abbreviated Chemotherapy Based on Positron Emission Tomography (PET) Scan in Hodgkin's Lymphoma — NCT00901303.
• Registry record last updated 2018-08-31; status last verified 2018-08.
• Results first posted 2018-08-31.
• 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 registry entry describes a pilot study of PET-guided abbreviated ABVD chemotherapy for Hodgkin lymphoma. Its primary question was 36-month progression-free survival among patients with a complete metabolic response, shown by a negative FDG-PET scan after one ABVD cycle, who then received three cycles of abbreviated ABVD.

The study is classified as nonrandomized, unmasked, and single-group; its phase is listed as NA. The registry lists enrollment of 6, a study start of 2008-10, primary completion of 2010-06, and status as terminated. Early-stage and advanced-stage groups are listed, but not as a like-for-like control comparison.

The primary outcome description states that data were not collected because of early termination. The record lists one outcome measure and zero analyses, and does not report an endpoint estimate or analysis. The sample-size material is identified as a planning illustration rather than the trial's own design.