Avoiding Growth Factor During Paclitaxel Treatment in Breast Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Avoiding Growth Factor During Paclitaxel Treatment in Breast Cancer (NCT02698891), a na phase 2 study. The primary outcome is Rate of Paclitaxel Treatment Completion Within 7 Weeks.

2. Clinical Question

The clinical question is principally one of feasibility and safety: whether the planned paclitaxel course can be delivered on schedule under a strategy that avoids routine growth-factor prophylaxis. It is not a comparative efficacy question about cancer outcomes. The study description places the paclitaxel course within a dose-dense doxorubicin/cyclophosphamide and paclitaxel regimen recommended for early stage breast cancer, but the primary endpoint is limited to treatment completion within the specified timeframe.

The safety criteria describe circumstances in which Neulasta could be administered: a prior episode of fever and neutropenia, or an active infection for which the decision was at the provider’s discretion. Thus, the question concerns a conditional strategy, rather than an absolute prohibition on Neulasta. The registry record does not report how often the criteria were met, how often Neulasta was ultimately used, or the primary endpoint result. Without those results and a concurrent control group, the record cannot establish how completion or safety would compare with routine prophylaxis.

3. Trial Design

This is a phase 2, single-group study sponsored by Dana-Farber Cancer Institute. The registry record lists 127 participants as enrolled, describes the study as completed, and gives a start date of 2016-04-07 and primary completion in 2020-12. The condition is early stage breast cancer.

The intervention description focuses on the paclitaxel portion of a dose-dense doxorubicin/cyclophosphamide and paclitaxel regimen. Paclitaxel is described at 175 mg/m² by IV once every 2 weeks for 4 cycles, with one cycle defined as 2 weeks. The study tested omitting routine Neulasta (pegfilgrastim) during those cycles, while allowing its use under the stated safety criteria. The registry arm description also mentions Neulasta 6 mg subcutaneously on day 2 of a cycle, approximately 24 hours after chemotherapy, in connection with those criteria.

There is no randomized allocation or masking: allocation is listed as NA, masking as none, and the model as single group. Consequently, the study does not have a like-for-like control arm in the registry record. Its design can describe treatment delivery and events among participants managed under the study strategy, but it cannot isolate the effect of omitting routine growth-factor support from differences that might be present in a separate comparison group.

The registry record lists one primary endpoint and 7 secondary outcomes, including neutropenia, other toxicities, dose reductions, completion of planned chemotherapy, hypersensitivity reactions, treatment delays, and savings when pegfilgrastim is omitted. It lists no posted statistical analyses. Further details of eligibility criteria, implementation of the strategy, and the statistical plan 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:

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: Baseline characteristics given for treated population.

6. Primary Endpoint

The registry lists the primary outcome as Rate of Paclitaxel Treatment Completion Within 7 Weeks, measured over 7 Weeks.

The primary endpoint is the rate of paclitaxel treatment completion within 7 weeks. It is defined as the percentage of participants who completed paclitaxel in that timeframe while omitting Neulasta, subject to the stated safety criteria. The registry record gives the timeframe as 7 Weeks and identifies the measure as a percentage of participants. It specifies a 95% confidence interval as the dispersion measure.

Completion within a prespecified timeframe is a feasibility measure: it captures whether participants can receive the planned treatment course within the intended schedule under the strategy being studied. For a dose-dense regimen, delays or interruptions are relevant to whether the schedule can be delivered as planned. That is the statistical reason this kind of endpoint can address feasibility; the registry record does not give a separate rationale for selecting this particular endpoint or timeframe.

The endpoint is not itself a measure of tumor response, recurrence, or survival. Nor does the measure alone identify why a participant did or did not complete treatment within the timeframe. The secondary outcomes include dose reductions, completion of all planned chemotherapy cycles, and delays by reason, but their results are not reported in the registry record.

No primary endpoint count, percentage, or confidence interval is posted in the record. Therefore, the endpoint definition can be described, but its observed result and precision cannot be assessed. The safety conditions also mean the strategy was conditional: the endpoint description does not imply that Neulasta was never used.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a proportion: participants are classified according to whether they completed paclitaxel within 7 weeks under the study strategy. In general, a proportion describes the share of an analyzed group meeting a defined event criterion. Its interpretation depends on both the event definition and the population included in the denominator. The registry identifies the measure as a percentage of participants, but the analysis population and handling of missing endpoint information are not reported in the registry record.

What does a 95% confidence interval communicate?

In general, a confidence interval describes uncertainty in an estimate under the statistical method used. An interval around a proportion reflects that the observed rate is an estimate of the rate that might be seen in the population represented by the study. A narrower interval indicates greater precision under the method; a wider interval indicates more uncertainty. The registry specifies a 95% confidence interval for the primary endpoint, but reports neither the endpoint estimate nor the interval. Its width, and whether the data are compatible with a broad or narrow range of completion rates, therefore cannot be evaluated.

What can a single-group design estimate?

In general, a single-group study can estimate outcomes observed in participants receiving the study strategy. It does not estimate a randomized between-group contrast because there is no concurrent control group. Comparisons with an external benchmark, historical experience, or a presumed usual-care rate would require details and assumptions that are not reported in the registry record. The study’s allocation is listed as NA, its model as single group, and masking as none. These features make the study suitable for describing observed treatment delivery, but limit conclusions about what caused an outcome or how outcomes differ from routine prophylaxis.

How should binary adverse-event counts be read?

In general, a participant-level event count records how many participants experienced at least one event meeting a definition during the reporting period. It is different from an event count that counts every occurrence, since one participant might have more than one occurrence. The registry lists participants at risk and participants affected for serious and other adverse events. It also lists several serious-event terms with percentages. The record does not give additional detail about whether a participant could contribute to more than one term, how event terms were coded, or the observation window used for each event. The term percentages therefore should be read as the registry’s reported values, not used to reconstruct a participant-level distribution.

In general, adverse-event summaries also depend on the denominator and event definitions. A count among participants at risk does not supply a comparison with another strategy, and the absence of a listed death does not resolve the frequency or severity of nonfatal events. The record reports 0 deaths, but does not provide a comparative risk estimate. It also does not report results for the named secondary toxicity outcomes, so the listed serious-event terms should not be interpreted as a complete summary of all toxicities measured by the study.

What are the sample-size assumptions for the planning illustrations?

The planning illustrations are described as calculations based on the observed effect, rather than as the trial’s own design justification. Their stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not results from participants and not observed power. In general, a planning calculation asks what sample size might be needed under chosen assumptions. It does not establish that a study had a particular probability of detecting an effect after the data have been observed.

Those assumptions describe a two-arm planning comparison, whereas the clinical study is recorded as single group. The record does not report a trial-specific sample-size justification or a randomized comparator. The observed primary endpoint result is also not reported, so the effect-based planning assumptions cannot be evaluated against a reported endpoint estimate. The planning illustrations should therefore be kept separate from interpretation of the trial’s observed outcomes.

What analyses are documented?

The registry lists 8 outcome measures and 0 analyses. A named endpoint is not the same as a posted analysis: the outcome description states what was intended to be measured, while an analysis would report how the data were handled and what estimate was obtained. The record does not report the statistical method used to calculate the primary confidence interval, any hypothesis test, model adjustment, or analysis population. It also does not report an interim analysis plan or whether any interim analyses occurred. Those details are not reported in the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Paclitaxel")
n      <- c(125)
events <- c(112)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Paclitaxel  125  112  89.6  82.9  94.3  83.0  93.8  83.0  93.8

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures: the primary completion endpoint and secondary outcomes covering neutropenia, other toxicities, dose reductions, chemotherapy completion, hypersensitivity reactions, delays, and savings. Assessing several outcomes can raise a multiplicity question: in general, the more statistical claims made across outcomes, the greater the chance that some apparent findings may occur by chance if each is tested separately. Whether that concern applies to formal claims depends on which outcomes were treated as confirmatory, what analyses were planned, and whether any adjustment or hierarchy was used.

Those details are not reported in the registry record. It lists 0 analyses, and gives no results for the secondary outcomes. The record does not report any multiplicity adjustment, prespecified testing sequence, or distinction between confirmatory and exploratory analyses. No conclusion about the handling of multiple comparisons can therefore be drawn.

Missing-data methods and analysis populations are also not reported in the registry record. The primary endpoint is defined as completion within 7 weeks, but the record does not state how participants with incomplete follow-up, missing treatment dates, withdrawal, or other unavailable endpoint information were handled. It does not identify an intention-to-treat, per-protocol, or other analysis population. These omissions matter because the denominator and rules for classifying missing outcomes can affect a reported percentage.

The record does not report whether an analysis plan specified interim looks, stopping rules, or other adaptations. It also does not report a protocol-level rationale for the sample size. These should not be inferred from the fact that the study is completed or from the planning assumptions used for illustrations.

12. 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: febrile neutropenia (0.8%), peripheral motor neuropathy (0.8%), pneumonitis (0.8%), neutrophil count decreased (0.8%).

The registry reports the Paclitaxel group with 127 participants at risk for serious adverse events and 4 participants affected. It reports 127 at risk for other adverse events and 63 affected. Deaths are listed as 0. These figures describe the posted safety counts for the single group; they are not risk differences or comparisons with routine pegfilgrastim prophylaxis.

The record’s most frequently listed serious-event terms are febrile neutropenia, peripheral motor neuropathy, pneumonitis, and neutrophil count decreased, each reported as 0.8%. Those term-level values are not a substitute for the overall serious-event count. The registry does not give further information on overlap between terms, event duration, severity details beyond the serious-event classification, or the timing of events in relation to treatment cycles.

In general, adverse-event counts require attention to the population at risk, event definitions, and observation period. The registry provides counts at risk and affected, but does not report a comparative group or detailed event-level data. These figures can describe events recorded in this group; they cannot establish a causal relationship or quantify how safety would differ under another treatment strategy.

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

The study addresses a practical treatment-delivery question: whether a dose-dense paclitaxel course can be completed within the specified timeframe when routine Neulasta support is omitted, while allowing use under stated safety criteria. Its single-group design can describe what happened among participants treated under that approach. The registry’s enrollment of 127 and its reported safety counts supply context about the study, but do not answer the primary question on their own.

The primary endpoint result is not reported in the registry record. Consequently, it is not possible to say from the registry whether completion within 7 weeks was common or uncommon, or to assess the precision of the estimate. The absence of a reported endpoint result is not evidence that participants did or did not complete treatment. It is a limitation of the available record.

Even with a reported completion rate, a single-group result would not establish how completion compares with a strategy using routine pegfilgrastim. Without a concurrent control group, differences from other settings could reflect participant characteristics, clinical practice, or other factors, rather than the growth-factor strategy alone. The study is not described as a randomized comparison, and the record does not report an external comparator.

The safety counts are descriptive, not proof that the strategy caused or prevented any event. The record lists serious adverse events in 4 participants, other adverse events in 63 participants, and 0 deaths among the reported group. It does not provide comparative safety estimates or the results of the named secondary outcomes. The criteria for Neulasta use also mean that the strategy allowed exceptions; the record does not report how frequently those exceptions occurred.

The appropriate interpretation is therefore bounded: the registry describes a completed phase 2 feasibility and safety study and defines the primary measure, but does not post the primary endpoint result or analyses. It cannot support a conclusion about comparative effectiveness, comparative safety, or the reliability of omitting routine prophylaxis across other populations or treatment settings.

14. Why This Trial Matters Statistically

Statistically, this study illustrates the distinction between defining an endpoint and reporting an estimate for it. The registry specifies a clinically interpretable feasibility measure—completion of paclitaxel within 7 weeks—and identifies a 95% confidence interval as its measure of precision. Without the estimate and interval, readers can understand what the study intended to quantify but cannot assess the observed rate or its uncertainty.

The single-group design also clarifies the boundary between descriptive evidence and comparative evidence. A study can document treatment delivery and adverse events within a defined group, yet cannot provide a randomized contrast when no concurrent control arm is included. This matters particularly when the question concerns omission of supportive treatment: observed outcomes under the strategy do not reveal what outcomes would have been under routine use of that support.

The record names multiple secondary outcomes, which highlights the need for transparent analysis plans and clear reporting of how outcome-specific conclusions are made. The registry lists no analyses, and does not report how multiplicity, missing outcomes, or analysis populations were handled. These are not peripheral details: they help readers understand which results were planned, how denominators were formed, and how much inferential weight to place on individual findings.

Finally, the planning assumptions should be distinguished from the clinical study design. The illustrations use assumptions for a two-arm calculation, while the clinical study is single group. Such planning calculations are not observed power and do not replace a trial-specific design justification. This distinction helps prevent sample-size illustrations from being mistaken for evidence of a treatment effect or for a description of how the study was conducted.

15. 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 the registry record is that it does not report the primary endpoint estimate or its 95% confidence interval. Although the endpoint is defined and the study is listed as completed, the registry does not provide the result needed to assess the completion rate or its precision. It also lists no analyses, so the statistical methods used for the endpoint cannot be verified from the record.

The single-group design has no concurrent comparator. It can describe treatment completion and adverse events in the enrolled group, but cannot directly estimate a difference from routine pegfilgrastim prophylaxis. The registry also records no masking. That design does not invalidate descriptive outcomes, but it limits comparative interpretation.

The study strategy is conditional rather than an absolute omission of Neulasta: the description permits use after a prior episode of fever and neutropenia, and provider discretion in the presence of active infection. The record does not report how many participants met these criteria or received Neulasta. Therefore, exposure to the strategy cannot be characterized fully from the posted information.

Further trial-specific details—including eligibility criteria beyond the stated condition, missing-data handling, analysis populations, multiplicity procedures, and the trial’s sample-size justification—are not reported in the registry record. Secondary outcome results are also not reported. The adverse-event summary offers limited event-level detail and no comparative safety estimates. These limitations constrain interpretation to the study description and the counts that are actually posted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Avoiding Growth Factor During Paclitaxel Treatment in Breast Cancer — NCT02698891.
• Registry record last updated 2022-05-06; status last verified 2022-04.
• Results first posted 2022-05-06.
• 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.

19. Record Summary

NCT02698891 is a completed phase 2, single-group study sponsored by Dana-Farber Cancer Institute. It enrolled 127 participants with early stage breast cancer and examined whether the paclitaxel portion of a dose-dense regimen could be delivered without routine pegfilgrastim prophylaxis, with Neulasta permitted under stated safety criteria.

The primary endpoint was the percentage completing paclitaxel within 7 weeks, with a 95% confidence interval specified. The registry record does not report the endpoint estimate or its interval and lists 0 analyses. It reports 4 participants with serious adverse events, 63 with other adverse events, and 0 deaths in the Paclitaxel group. No concurrent comparison group is described, so the record supports descriptive reading of the reported information, not a randomized comparison.