Nab-Paclitaxel in Treating Older Patients With Locally Advanced or Metastatic Breast Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nab-Paclitaxel in Treating Older Patients With Locally Advanced or Metastatic Breast Cancer (NCT01463072), a na phase 2 study. The primary outcome is Percent of Participants With Grade 2-5 Toxicity Using National Cancer Institute Common Toxicity Criteria Version 4.0.

2. Clinical Question

The study also lists response according to Response Evaluation Criteria in Solid Tumors, median progression-free survival, and a Cancer-specific Geriatric assessment as secondary outcomes. These measures address different questions: tumor response, time until progression or death as defined by the study, and geriatric assessment. Their inclusion does not change the primary focus on toxicity. Results for those outcomes are not reported in the registry record.

3. Trial Design

This is a phase II, single-group study sponsored by City of Hope Medical Center. Its title and official title identify nab-paclitaxel treatment in patients 65 and older with locally advanced or metastatic breast cancer. Enrollment was 40. The registry lists no allocation to treatment arms and no masking; the study is therefore not a randomized, blinded comparison.

Participants received nab-paclitaxel intravenously over 30 minutes on days 1, 8, and 15. Treatment cycles were scheduled every 28 days, continuing in the absence of disease progression or unacceptable toxicity. Laboratory biomarker analysis and questionnaire administration are also listed as interventions. Further details of how those activities were conducted are not reported in the registry record.

The primary completion date is 2017-05-17, and the study status is active, not recruiting. The registry lists a start date of 2012-06-20. These dates describe the record’s study timeline; they do not establish that all outcome data have been posted or that the study has a final results report.

The primary outcome is the percentage of participants with grade 2-5 toxicity, assessed with National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. The description says that rates and associated 95% exact Clopper and Pearson binomial confidence limits will be estimated for treatment-attributed grade 2 or higher toxicities. The specified timeframe is during and after treatment, up to 2.5 years.

The registry lists seven outcome measures and three analyses, but the details and results of all of them are not reported in the registry record. The protocol, eligibility criteria beyond the population description, treatment modifications, and a detailed statistical analysis plan are also not reported. No control arm is listed, so the design can describe outcomes among treated participants but does not provide a like-for-like control comparison.

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

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 Percent of Participants With Grade 2-5 Toxicity Using National Cancer Institute Common Toxicity Criteria Version 4.0, measured over During and after treatment, up to 2.5 years.

The primary endpoint is the percentage of participants who experience grade 2-5 toxicity attributed to treatment. Toxicity is to be graded using National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0. The endpoint description specifies grade 2 or higher toxicities, with observation during and after treatment, up to 2.5 years. The registry says that the rate and 95% exact Clopper and Pearson binomial confidence limits will be estimated.

This type of endpoint is used to describe the frequency of a defined safety outcome in the study population. A percentage communicates how common the recorded event was among participants included in the analysis; the accompanying confidence interval describes the statistical uncertainty around that estimate. It does not establish that a treatment caused every event, and attribution depends on the study’s assessment and definitions. Further details about attribution and the analysis population are not reported in the registry record.

The endpoint is not itself a measure of tumor response or time to disease progression. Those outcomes are listed separately as secondary measures, along with a geriatric assessment. The registry record does not report the primary endpoint’s observed percentage, the interval limits, or the number of participants with the endpoint. Consequently, the endpoint’s numerical result and its precision cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary safety outcome as a percentage of participants with grade 2-5 toxicity and specifies estimation of rates and 95% exact Clopper and Pearson binomial confidence limits for treatment-attributed grade 2 or higher toxicity. This discussion explains the statistical ideas relevant to that description. The observed estimate and interval are not reported in the registry record.

What a participant-level percentage describes

For a binary outcome, each participant is classified according to whether the defined event occurred during the stated assessment window. The proportion with the event describes the observed frequency within the group being analyzed. It is important that the event definition, attribution rules, and analysis population are clear: changing any of these can change which participants count as having the outcome. The registry record names the toxicity grading system and timeframe, but does not report detailed rules for attribution or the analysis population.

Why report a confidence interval?

A confidence interval expresses uncertainty around an estimate. A point estimate alone can appear more definitive than the data warrant, particularly when the number of observations is limited. The interval gives a range of values compatible with the data under the method’s assumptions; it is not a guarantee that the true rate lies within that particular interval. It also does not describe the range of individual participants’ experiences.

The registry specifies a 95% exact Clopper and Pearson interval for the binomial rate. This is an exact method for a binary outcome, based on the binomial model. “Exact” refers to the method’s coverage properties under that model, not to perfect knowledge of the underlying event rate. The registry does not report the interval limits, so neither its width nor the amount of uncertainty in the study’s estimate can be assessed.

How the grading threshold shapes the outcome

Adverse events are graded by severity under the named criteria. An endpoint defined as grade 2 or higher excludes events below that threshold, whereas an endpoint including all grades would count a broader range of events. This choice makes the outcome specific to the protocol’s threshold; it does not summarize every possible adverse event. The title refers to grade 2-5 toxicity, and the outcome description refers to treatment-attributed grade 2 or higher toxicities. The registry does not clarify any further distinctions in how these descriptions were operationalized.

Attribution is also consequential. An event can occur during a study without being attributed to the study treatment. The registry states that the primary endpoint concerns toxicity attributed to treatment, but does not report the attribution process, who made those assessments, or whether attribution was independently reviewed. These details matter when interpreting the endpoint as a treatment-related safety measure.

What a single-group design can estimate

A single-group design can estimate the frequency of outcomes observed among participants receiving the study regimen. Without a concurrent comparison group, it cannot directly estimate how outcomes would differ under another treatment or under no study treatment. This limitation applies even if an event count or percentage is available. The registry identifies no comparator and no randomized allocation, so the intended interpretation should be descriptive rather than a between-group treatment effect.

General statistical principle: random variation is only one source of uncertainty. Participant selection, event classification, incomplete follow-up, and measurement can also affect an estimate. A confidence interval based on a binomial model addresses sampling uncertainty under its assumptions; it does not resolve these other sources of uncertainty. The registry record does not report enough detail to assess all of them.

Why the numerical result matters

To interpret a safety endpoint, readers need the observed rate, its confidence interval, the number of participants included in the analysis, and clarity about outcome ascertainment and follow-up. The registry record gives the planned method and a stated timeframe but does not report the endpoint estimate or interval. It also does not report whether every enrolled participant contributed complete endpoint data. Thus, the statistical method can be described, but the result and its precision cannot be evaluated from the registry entry.

The secondary outcomes use different statistical structures. Response is listed as a response criterion, while median progression-free survival is a time-to-event measure and the geriatric assessment is another distinct outcome. Methods for analyzing or summarizing these secondary outcomes are not reported in the registry record. General methods for time-to-event data can account for participants who have not experienced an event by the end of observed follow-up, but whether and how such methods were used in this study is not reported.

Neither the listed count of analyses nor the number of outcome measures establishes how statistical testing was planned. The registry record does not report a full statistical analysis plan, inferential testing procedures, or a strategy for handling multiple outcomes. Accordingly, no claims about statistical significance or adjustment for multiple testing can be made from the available 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("Treatment (Nab-paclitaxel)")
n      <- c(40)
events <- c(36)
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  Treatment (Nab-paclitaxel)  40  36  90.0  76.3  97.2  76.9  96.0  76.9  95.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures and three analyses. It identifies the primary toxicity endpoint and lists response, median progression-free survival, and Cancer-specific Geriatric assessment as secondary outcomes. The detailed definitions, estimates, and analysis methods for the outcomes are not reported in the registry record.

When a study examines multiple outcomes, there can be more than one opportunity to observe an apparently notable result by chance. General statistical practice may address this issue through prespecified outcome hierarchies or adjustments to testing, depending on the study’s aims. The registry record does not report whether any such strategy was specified or used. It also does not report interim analyses or a detailed statistical analysis plan; these should not be assumed.

Missing data can affect a participant-level percentage if participants lack outcome assessments or follow-up. The registry record does not report the number of participants with missing toxicity assessments, how missing observations were handled, or whether the primary analysis included all enrolled participants. It also does not describe the analysis populations for the secondary outcomes. Therefore, the 40 enrolled participants should not automatically be assumed to be the denominator for every outcome.

The primary outcome timeframe extends during and after treatment, up to 2.5 years. The registry does not provide participant-level follow-up completeness or detail how events after treatment were captured. For the listed progression-free survival outcome, censoring rules and the time origin are not reported in the registry record. These omissions limit assessment of outcome ascertainment and of how missing follow-up may have affected estimates.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: nausea (10.0%), vomiting (10.0%), diarrhea (5.0%), dehydration (5.0%), dyspnea (5.0%).

The registry’s adverse-event entry lists 14 participants affected by serious adverse events among 40 at risk. It lists 40 participants affected by other adverse events among 40 at risk, and reports 35 deaths. These are separate registry entries and should not be treated as interchangeable measures. The record does not establish that serious adverse events, other adverse events, and deaths share the same definitions, observation windows, or attribution rules.

The serious adverse-event terms listed are nausea at 10.0%, vomiting at 10.0%, diarrhea at 5.0%, dehydration at 5.0%, dyspnea at 5.0%, and anemia at 2.5%. These percentages are reported as registry values; the record does not give additional event-level detail or explain whether an individual participant could contribute to more than one term. They should not be added together or interpreted as a total event rate.

The adverse-event counts do not provide the missing primary endpoint estimate. The primary endpoint is treatment-attributed grade 2-5 toxicity, with its description specifying grade 2 or higher toxicity. The adverse-event listing does not show how its categories align with that endpoint. The record also does not report causes or treatment attribution for the 35 deaths, so those deaths cannot be attributed to nab-paclitaxel on the basis of this entry alone.

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

The registry record establishes that a phase II, single-group study enrolled 40 participants to receive nab-paclitaxel for locally advanced or metastatic breast cancer in an older population. It specifies a primary safety endpoint, a grading framework, an observation window, and a planned exact binomial confidence interval. These design and methods details describe the intended evaluation, but they do not disclose the primary outcome result.

The posted record does not report the percentage of participants with the primary toxicity endpoint or its 95% confidence interval. It therefore does not show the observed frequency of treatment-attributed grade 2 or higher toxicity as defined for the primary outcome, or how precisely that frequency was estimated. The adverse-event listing provides separate counts and terms, but its connection to the primary endpoint is not fully explained.

The record also lists tumor response, median progression-free survival, and a geriatric assessment as secondary outcomes, without reporting their numerical results. Those entries identify outcomes of interest; they do not establish what participants experienced or how those outcomes compare with any alternative.

Because there is no comparator group, the study design cannot by itself isolate a treatment effect from other influences. It can be a source of descriptive information about enrolled participants and recorded events, but it does not support a randomized comparison. No conclusion that nab-paclitaxel does or does not work, or that it caused particular adverse events or deaths, follows from the registry information alone.

The record’s status is active, not recruiting, and its primary completion date is 2017-05-17. Those registry entries do not replace outcome estimates or a full report. The most defensible reading is that the registry describes a single-group safety-focused study and lists some adverse-event information, while leaving the primary endpoint result, its precision, and several key analysis details unreported.

14. Why This Trial Matters Statistically

This study illustrates a common statistical distinction between a study’s planned question and the results needed to answer it. The registry identifies a specific primary safety endpoint: the percentage of participants with treatment-attributed grade 2 or higher toxicity, assessed with a named grading system and a stated timeframe. It also specifies an exact binomial confidence interval. Yet the primary estimate and interval are not reported in the registry record. Knowing the planned method is not equivalent to knowing the result.

The single-group design also makes the scope of interpretation important. A study can describe observed toxicity among participants receiving a regimen, but without a comparator it cannot directly quantify how that experience differs from another treatment group. Statistical precision around a single-group rate, if reported, would not remove this design limitation.

The registry includes additional outcomes for response, progression-free survival, and geriatric assessment. These represent distinct clinical and statistical questions. Their inclusion highlights why outcome-specific definitions, analysis methods, and results matter: a toxicity percentage, a response measure, and a time-to-event summary cannot be interpreted as though they were the same type of evidence. The results and methods for these secondary measures are not reported in the registry record.

The adverse-event information further illustrates why counts need context. Serious adverse events, other adverse events, and deaths are listed, but the record does not fully explain their relation to the primary toxicity endpoint or provide details on attribution and timing. Statistical interpretation depends not only on the numbers but also on how events were defined, measured, and analyzed.

For biostatistical reading, the central lesson is to distinguish documented design and method from unavailable estimates. A planned confidence interval describes an intended approach; it cannot convey the observed rate or its uncertainty when its limits are absent. Likewise, a listed outcome name does not establish its finding. This record makes the missing result and analysis details as important to note as the study design itself.

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 interpretation is that the registry record does not report the observed primary endpoint percentage or its 95% confidence interval. Without these, the primary safety estimate and its precision cannot be evaluated. Although the adverse-event entry lists counts and terms, the registry does not explain how those data map to the primary endpoint of treatment-attributed grade 2 or higher toxicity.

The study has no comparator group, no allocation, and no masking. Its findings therefore cannot provide a randomized comparison with another treatment. The record also does not report eligibility criteria in detail beyond the population description, the analysis population, or whether all enrolled participants had complete outcome follow-up.

Methods for assigning treatment attribution, handling missing outcome assessments, and capturing events through the stated timeframe are not reported in the registry record. Neither a detailed statistical analysis plan nor methods for the secondary outcomes are reported. The record does not state how any multiplicity, interim analyses, or censoring issues were handled; those methods should not be inferred.

Although the record lists 35 deaths, it does not give causes, timing, or attribution. The adverse-event entry also lacks detail about event-level overlap and the definitions used for the separate categories. These omissions limit interpretation of the safety information and prevent attributing the listed events to the treatment from the registry entry alone.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Nab-Paclitaxel in Treating Older Patients With Locally Advanced or Metastatic Breast Cancer — NCT01463072.
• Registry record last updated 2026-11-03; status last verified 2026-10.
• Results first posted 2022-07-26.
• 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

NCT01463072 is a phase II, single-group study sponsored by City of Hope Medical Center. It enrolled 40 participants and studied nab-paclitaxel in patients 65 and older with locally advanced or metastatic breast cancer. The regimen was intravenous treatment over 30 minutes on days 1, 8, and 15, with cycles every 28 days in the absence of progression or unacceptable toxicity.

The primary outcome was the percentage of participants with grade 2-5 toxicity, with the description specifying treatment-attributed grade 2 or higher toxicity and planned 95% exact Clopper and Pearson binomial confidence limits. The timeframe was during and after treatment, up to 2.5 years. The observed primary result and interval are not reported in the registry record.

Response, median progression-free survival, and Cancer-specific Geriatric assessment are listed as secondary outcomes. The adverse-event entry lists 14 participants with serious adverse events, 40 with other adverse events, and 35 deaths, without enough detail to establish attribution or how these entries relate to the primary endpoint. The study status is active, not recruiting; the primary completion date is 2017-05-17.