Nab-paclitaxel and Gemcitabine Hydrochloride Followed by Radiation Therapy Before Surgery in Treating Patients With Pancreatic Cancer That Can Be Removed by Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nab-paclitaxel and Gemcitabine Hydrochloride Followed by Radiation Therapy Before Surgery in Treating Patients With Pancreatic Cancer That Can Be Removed by Surgery (NCT02427841), a na phase 2 study. The primary outcome is R0 Resection Rate Defined as Macroscopically Complete Tumor Removal With Negative Microscopic Surgical Margins by Pathologic Assessment.

2. Clinical Question

3. Trial Design

This completed phase 2 study enrolled 20 participants and used a single-group design. Allocation is recorded as not applicable, and masking is recorded as none. These features mean that the recorded design does not include random assignment or a masked treatment comparison. The study was sponsored by OHSU Knight Cancer Institute. The recorded start date is 2016-01-21, and primary completion is recorded as 2019-11-12.

The treatment strategy was intended to be given before surgery. The registry describes preoperative nab-paclitaxel and gemcitabine, followed by chemoradiation and surgery. It specifies intravenous administration of both drugs on days 1, 8, and 15, with treatment repeating every 28 days for 2 courses in the absence of disease progression or unacceptable toxicity. The recorded regimen description then begins to state when treatment after chemotherapy starts, but ends before specifying the full schedule. The remaining treatment details are not reported in the registry record.

Interventions listed include fluorouracil, gemcitabine, nab-paclitaxel, image-guided and intensity-modulated radiation therapy, conventional surgery, and laboratory biomarker analysis. The intervention list does not establish which specific components each participant received, or the sequence and delivery details beyond the arm description. Those details are not reported in the registry record.

A single-group design can describe outcomes observed during a treatment strategy, but it does not offer a randomized concurrent group for separating treatment effects from other explanations. The primary endpoint uses a reference rate of 0.37 rather than a control arm. The registry record does not report the rationale for that reference, a sample-size justification, or further design details. The enrollment figure is not itself a measure of endpoint precision; precision depends on the outcome data, which 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.

Before assignment: 20 participants enrolled who agreed to participate in the study following completion of the informed consent process. 19 started is the number of participants who were assigned to each Arm/Group. One subject withdrew prior to treatment resulting in a total of 19 subjects enrolled and started treatment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Efficacy evaluable population is those who have received at least one administration of study drug and have at least one efficacy evaluation. Efficacy evaluable participants who fail to go onto surgery are counted as R0 failures (part of the denominator)

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 R0 Resection Rate Defined as Macroscopically Complete Tumor Removal With Negative Microscopic Surgical Margins by Pathologic Assessment, measured over At the time of surgery.

The primary endpoint is the R0 resection rate at the time of surgery. R0 resection is defined in the registry as macroscopically complete tumor removal with negative microscopic surgical margins by pathologic assessment. The rate is intended to represent the percentage of participants meeting that definition in the stated efficacy population.

This endpoint captures a surgical and pathology outcome rather than a direct comparison of treatment groups. Including participants who do not proceed to surgery as R0 failures in the efficacy-evaluable population makes failure to reach surgery part of the endpoint denominator, according to the registry description. The record also describes the rate as being calculated among participants who initiate study drug. Its population definition additionally requires at least one efficacy evaluation; the registry record does not explain the relationship between these two descriptions further.

A confidence interval communicates uncertainty around an estimated rate: narrower intervals indicate greater precision, while wider intervals indicate less precision. The registry specifies a 95% confidence interval, but the interval and observed R0 rate are not reported in the registry record. The endpoint is used to assess whether the treatment strategy was associated with a rate exceeding the stated reference of 0.37. A result for that test is also not reported in the registry record, so the endpoint’s observed magnitude and precision cannot be characterized.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a binary outcome at the participant level: R0 resection or not, according to the registry definition. A binary endpoint records whether an event or condition is present, rather than a continuously measured quantity. The rate is the proportion of the defined analysis population meeting the endpoint, expressed in the registry as a percentage of participants. The actual proportion and denominator are not reported in the registry record.

What does the confidence interval contribute?

A confidence interval gives an estimate together with an indication of its sampling uncertainty. If the same study process were repeated under the assumptions of the interval method, the method is designed to produce intervals that cover the underlying parameter at the stated confidence level over repeated studies. This interpretation concerns the procedure, not a probability attached to the particular interval after it has been calculated. The registry specifies a 95% confidence interval for the R0 rate, but does not report its limits. Without those limits, the estimated rate’s precision cannot be assessed.

For a proportion, precision is influenced by the amount of outcome information and by how the observed outcomes are distributed. The total enrollment of 20 does not establish the analysis denominator, because the efficacy-evaluable definition requires study-drug administration and an efficacy evaluation. The record does not report the number meeting those criteria. It also does not report the number with R0 resection, so neither the estimate nor the interval can be reconstructed from the record.

How should the specified test be read?

The registry describes a 2-sided binomial test and says it will determine whether the R0 resection rate is significantly greater than 0.37 at a 10% significance level. A binomial model is commonly used for counts of successes among a fixed number of observations when each observation is classified into one of two outcome categories and the model’s assumptions are appropriate. In this study, the success category corresponds to R0 resection under the endpoint definition. A test evaluates how compatible the observed data are with a specified reference assumption; it does not measure the size or practical importance of an effect.

The wording combines a 2-sided test with a question about whether the rate is greater than the reference. The registry record does not provide more detail about how this test was operationalized. It does specify the reference value and significance level, but not the observed test result or p-value. The test’s conclusion therefore cannot be stated. Statistical significance, even if reported, would not alone show the estimate’s precision, establish causality, or resolve limitations arising from the single-group design.

Why distinguish the analysis population from enrollment?

Enrollment describes the number of participants entered into the study, while an endpoint analysis uses the participants defined for that analysis. The primary description identifies participants who received at least one administration of study drug and had at least one efficacy evaluation. It further states that efficacy-evaluable participants who do not proceed to surgery count as R0 failures. That rule places failure to reach surgery within the endpoint assessment rather than treating those participants as successful resections. The number in the efficacy population and the number who did not proceed to surgery are not reported in the registry record.

The endpoint description also says the R0 rate is measured among those who initiate study drug. The registry does not explain whether this phrase is intended to be identical to the efficacy-evaluable definition or how participants without an efficacy evaluation are handled. This distinction matters because changing who is counted in the denominator can change a rate. No alternative analysis population or sensitivity analysis is reported in the registry record.

What can the planning assumptions say?

Planning calculations are not observed outcomes and do not show the probability that a completed study has detected an effect. The record’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. It also distinguishes total events for time-to-event planning from participants per arm for other planning calculations. The record is a single-group study, so the two-arm planning assumptions do not describe its recorded treatment allocation. No numerical planning results or sample-size justification are reported in the registry record. Such calculations should not be interpreted as observed power.

More broadly, statistical methods depend on how outcomes, analysis populations, and missing observations are defined. The registry record gives a primary endpoint definition and a test description, but does not report enough outcome data or analytic detail to reproduce the analysis. Further details on interim analyses, adjustments, or other statistical procedures are not reported in the registry record. General statistical concepts can clarify what the stated methods are intended to do, but they cannot supply the missing study results.

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 (Chemotherapy, Chemoradiation Therapy, S")
n      <- c(19)
events <- c(8)
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 (Chemotherapy, Chemoradiation Therapy, S  19  8  42.1  20.3  66.5  23.1  63.7  23.1  63.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the R0 resection rate as the primary outcome and describes a test for it. It also lists secondary outcomes concerning toxicity, overall survival at the 2 Year and One Year time points, relapse-free survival at One Year from surgical resection, and response by RECIST 1.1. The record does not report a multiplicity adjustment or a plan for controlling the chance of false-positive findings across multiple outcomes. It also does not report whether secondary outcomes were treated as confirmatory or exploratory. Without those details and results, findings across outcomes cannot be interpreted as a coordinated family of tests.

The primary outcome description specifies an efficacy-evaluable population and counts participants in that population who do not proceed to surgery as R0 failures. The number analyzed and the outcome counts are not reported in the registry record. The record does not report how missing endpoint assessments, withdrawals, or other departures from the stated population definition were handled. It does not provide sensitivity analyses for alternate missing-data assumptions.

Details about missing data matter because the endpoint denominator and the classification of participants can affect the estimated rate. Counting failure to proceed to surgery as an R0 failure is explicitly described for efficacy-evaluable participants, but the record does not state how participants without an efficacy evaluation were handled. Further rules for missing data are not reported in the registry record.

The record also does not report interim analyses, stopping rules, or additional analysis populations. These omissions do not establish that such procedures were or were not used; they mean those details are not reported in the registry record. The reported primary analysis description should therefore be interpreted narrowly, without assuming unreported procedures.

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 4% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: fascial dehiscene (5.3%), abdominal wall soft tissue infection (5.3%), intractable nausea, vomiting, abdominal pain (5.3%), dehydration (5.3%), gda bleed/cardiac arrest (5.3%).

The adverse-event record lists 19 participants at risk in the treatment group for serious adverse events and 3 participants affected. For other adverse events, it lists 19 at risk and 16 affected. The record also lists 13 deaths. These are separate registry figures; the record does not explain their timing, causes, relationship to treatment, or overlap with the event categories. The counts should not be treated as evidence that treatment caused an event or death.

The listed serious adverse-event terms each have a reported value of 5.3%: Fascial Dehiscene; Abdominal wall soft tissue infection; Intractable Nausea, vomiting, abdominal pain; Dehydration; and GDA Bleed/Cardiac arrest. The registry does not provide further event-level detail in these entries, such as severity, timing, duration, or participant-level overlap. The listed terms should be read as registry-reported serious-event categories, not as a complete clinical narrative.

At-risk and affected counts answer different questions: the former gives the listed group size considered at risk, while the latter gives the number recorded as affected. The record does not report enough detail to determine whether all participants had the same observation period or how event collection was conducted. Safety figures are descriptive and do not, on their own, establish comparative risk, especially in a single-group study without a concurrent control group.

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

The registry record describes a phase 2, single-group study of preoperative nab-paclitaxel and gemcitabine followed by chemoradiation and surgery. Its primary endpoint is a pathologically assessed R0 resection rate, with participants in the efficacy-evaluable population who do not proceed to surgery counted as failures. The planned comparison is against a reference rate of 0.37 using a 2-sided binomial test at a 10% significance level, with a 95% confidence interval specified.

Those design and analysis details describe what the study set out to assess; they are not the result. The observed endpoint rate, denominator, confidence interval, and test result are not reported in the registry record. Accordingly, the record does not establish whether the rate exceeded the reference, or how precisely it was estimated. Secondary outcome results are also not reported in the registry record.

Even if the endpoint result were available, a single-group study would not provide a randomized comparison with another treatment strategy. An observed rate could describe outcomes among the study participants under the recorded study approach, but would not by itself show what would have happened to comparable participants under a different approach. The reference value in the test is not a concurrent control group.

The safety entries describe recorded counts and event terms, but do not establish causation. The record does not provide details needed to interpret timing, attribution, or overlap among event categories. Overall, the registry record supplies information about the study design, endpoint definition, and some safety counts, while leaving the central efficacy result and several analytic details unreported.

14. Why This Trial Matters Statistically

This study illustrates why a clinical result needs more than a named endpoint and a planned test. The R0 resection definition identifies a clinically interpretable surgical outcome, and the stated confidence interval would communicate how precisely its rate was estimated. But neither the rate nor its interval is reported in the registry record. Without the observed estimate, readers cannot assess the magnitude or precision of the primary outcome.

The analysis population also matters. The record specifies that efficacy-evaluable participants who do not proceed to surgery count as R0 failures, so the endpoint is not restricted to participants who ultimately undergo surgery. At the same time, the number meeting the efficacy-evaluable definition is not reported. The distinction between enrollment and the analysis denominator is essential for understanding what a percentage represents.

The study’s single-group structure is another central statistical feature. Testing against a reference value can address whether the observed rate is compatible with that benchmark under the stated method, but it does not create a randomized control group. This distinction helps separate evidence about an observed rate from evidence about a comparative treatment effect.

Finally, registry descriptions and results serve different purposes. Design details identify the question and intended analysis; numerical results are needed to evaluate the evidence. Here, the available record supports a careful description of the planned endpoint and some safety counts, but it does not support a conclusion about the primary efficacy result. Recognizing that boundary is a fundamental part of statistical interpretation.

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 primary limitation for interpreting efficacy is that the observed R0 resection rate, its confidence interval, the analysis denominator, and the test result are not reported in the registry record. The primary endpoint description defines an efficacy-evaluable population, but its size is also not reported. This prevents assessment of the estimate, its precision, and the test conclusion.

The study uses a single-group design and has no randomized concurrent comparator described. The reference value of 0.37 is part of the planned test, not a control arm. The registry record does not report the rationale for that reference value. As a result, the design cannot provide a like-for-like randomized comparison of treatment strategies.

The treatment description is incomplete: it specifies chemotherapy administration and says treatment after chemotherapy begins 3-6 weeks later, but does not give the remainder of that schedule. The interventions list includes several treatment and procedure types, but does not provide complete participant-level treatment exposure. Further eligibility characteristics, baseline characteristics, and treatment adherence information are not reported in the registry record.

For safety, the record lists at-risk and affected counts, deaths, and serious-event terms, but does not report timing, attribution, event duration, or participant-level overlap. For statistical interpretation, multiplicity procedures, missing-data handling beyond the stated failure rule, interim analyses, and further analysis details are not reported in the registry record. These limitations restrict what can be concluded from the record; they do not establish what procedures may have been used but left unreported.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Nab-paclitaxel and Gemcitabine Hydrochloride Followed by Radiation Therapy Before Surgery in Treating Patients With Pancreatic Cancer That Can Be Removed by Surgery — NCT02427841.
• Registry record last updated 2023-09-06; status last verified 2023-08.
• Results first posted 2021-01-14.
• 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

This completed phase 2 study enrolled 20 participants and used a single-group, unmasked design. It evaluated preoperative nab-paclitaxel and gemcitabine followed by radiation-based treatment and surgery for pancreatic cancer described as borderline resectable or node-positive. The primary endpoint was the R0 resection rate at surgery, defined by macroscopically complete tumor removal and negative microscopic margins.

The registry specifies a 95% confidence interval and a 2-sided binomial test against 0.37 at a 10% significance level. Participants in the efficacy-evaluable population who did not proceed to surgery were counted as R0 failures. The observed primary rate, its interval, analysis denominator, and test result are not reported in the registry record. Safety entries list 3 participants with serious adverse events and 16 with other adverse events among 19 at risk in each category, alongside 13 deaths; additional interpretation details are not reported.