Finasteride in Treating Patients With Stage II Prostate Cancer Who Are Undergoing Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Finasteride in Treating Patients With Stage II Prostate Cancer Who Are Undergoing Surgery (NCT00438464), a randomized phase 2 study. The primary outcome is Comparison of Biomarkers Between Treatment Arms: Percentage Change of Tumor Cells Exhibiting Detectable Staining Within Gleason Grade 3 (GG3) Biomarker Subgroups at Prostatectomy.

2. Clinical Question

The trial focused on tissue effects observed after a short preoperative treatment period. The registry describes biomarker expression in tissue microarrays derived from the dominant tumor focus, and it identifies the percentage of tumor cells exhibiting detectable staining as the measurement of interest. The listed markers are vascular epithelial growth factor (VEFG), estrogen receptor beta (ERβ), androgen receptor (AR), SRD5A2, UBE2C, and cleaved caspase 3.

The primary outcome was intended to compare these tissue measurements between randomized treatment arms at prostatectomy. It was not described as a measure of survival, recurrence, symptoms, or long-term clinical outcomes. The registry record does not report numerical primary-outcome results, so it does not establish the magnitude or precision of any between-arm difference in these staining measures.

3. Trial Design

This was a randomized, double-masked, parallel-arm phase II trial sponsored by the National Cancer Institute. The registry lists an enrollment of 204 and identifies stage II prostate cancer and adenocarcinoma of the prostate as the conditions studied. Participants were assigned to finasteride or placebo before planned prostatectomy. The treatment descriptions specify finasteride 5 mg once daily or placebo once daily for 4-6 weeks, followed by prostatectomy.

The study examined tissue effects of preoperative treatment. Its primary outcome concerned percentage change in tumor cells with detectable staining for biomarker subgroups at prostatectomy, with tissue taken from the dominant tumor focus. The registry also lists pathologic outcomes involving Gleason score and grade, TNM stage, resection margins, lymph node status, cancer foci, and tumor zonal origin. These are distinct from longer-term patient outcomes; the listed primary outcome is a laboratory and pathology measure.

The registry reports a primary completion date of 2012-04 and a status of completed. Its primary-outcome description states that 62 finasteride participants and 68 placebo participants had a qualifying tumor specimen with GG3 or GG4. It also refers to a total of 183 enrolled participants in both arms. Those figures describe the tissue-analysis context, while the overall enrollment field reports 204. The registry record does not explain the relationship between these counts, and they should not be treated as interchangeable denominators.

The record identifies a non-parametric Wilcoxon rank-sum test for p values. It does not report a detailed statistical analysis plan, allocation procedures beyond randomization, or the concealment process. Such details 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: Of the 210 participants recruited, 204 were randomized to the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Of total 183 enrolled participants in both arms, 62 Finasteride and 68 Placebo participants respectively had a qualifying tumor specimen with GG3 or GG4. Differences in number (N) of tissue specimens (tumor foci) is based on feasibility of subgroup participants' radical prostatectomy samples analyzed.

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 includes participants who were randomized to arms and received assigned treatment.

6. Primary Endpoint

The registry lists the primary outcome as Comparison of Biomarkers Between Treatment Arms: Percentage Change of Tumor Cells Exhibiting Detectable Staining Within Gleason Grade 3 (GG3) Biomarker Subgroups at Prostatectomy, measured over At prostatectomy following maximum 6 week treatment period.

The primary endpoint concerns percentage change in tumor cells exhibiting detectable staining for biomarkers within Gleason grade 3 (GG3) biomarker subgroups at prostatectomy. The registry describes molecular marker expression assessed using tissue microarrays derived from the dominant tumor focus. Staining was scored from 0 to 10, with a higher score representing greater tumor-cell involvement. The listed candidate markers are VEFG, ERβ, AR, SRD5A2, UBE2C, and cleaved caspase 3.

This endpoint provides a tissue-level measure of biological characteristics after the preoperative treatment period. General statistical context: a biomarker measurement can help characterize a biological response, but it is not automatically a measure of a patient-centered clinical benefit. Interpretation depends on the assay, the tissue sampled, the scoring approach, and whether the observed difference is clinically meaningful.

The registry names percentage change as the primary outcome, but its detailed description also states that staining is scored on a 0-to-10 scale. Numerical arm-specific endpoint results, percentage changes, uncertainty intervals, and the exact denominator for each marker are not reported in the registry record. The endpoint’s value therefore cannot be interpreted quantitatively from the record alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record describes a randomized, double-masked, parallel-group design. Randomization is intended, in general, to make treatment assignment independent of participants’ measured and unmeasured baseline characteristics on average. Masking is intended to reduce the influence of treatment knowledge on behavior, care, assessment, or interpretation. These design features support a comparative treatment study, but the registry record does not describe the exact randomization procedure, allocation concealment, or who remained masked.

What does the endpoint measure?

The primary outcome concerns the percentage change in tumor cells with detectable staining within GG3 biomarker subgroups at prostatectomy. The registry’s assay description refers to tissue microarrays built from 0.6-mm biopsy cores representing tumor grades and scores, and says that the dominant tumor focus was used for the molecular marker analysis. Staining scores range from 0 to 10, with higher scores indicating more tumor-cell involvement. The listed markers are VEFG, ERβ, AR, SRD5A2, UBE2C, and cleaved caspase 3.

The wording of the outcome title and its detailed description does not provide numerical results or a marker-by-marker analysis population. Although the title refers to percentage change, the record does not state the observed percentage changes. The exact rules used to derive each percentage-change value are not reported in the registry record. The record also does not clarify how missing or unevaluable tissue was handled for each marker.

Why use medians and ranges?

The endpoint is described using a median and full range. A median is the middle value after observations are ordered. It is less sensitive than a mean to extreme values and can be useful when measurements are skewed or have outliers. The full range reports the smallest and largest observed values, but it does not show how observations are distributed between those extremes. In general, a range can be especially sensitive to extreme observations and is not a substitute for a confidence interval.

The registry identifies the Wilcoxon rank-sum test as the basis for p values. General statistical context: this non-parametric test compares the ranks of observations across two independent groups. It does not require the measurements to follow a normal distribution in the same way as a conventional two-sample t test. Its interpretation is most directly about differences in distributions; interpreting it solely as a test of medians requires additional assumptions about the shape of those distributions. The record does not report the test statistics, p values, or any assumptions used to interpret the test.

How should p values and uncertainty be read?

General statistical context: a p value describes how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the test’s assumptions were correct. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. A confidence interval, when reported, conveys a range of effect estimates compatible with the data and model at the stated confidence level. No confidence intervals for the primary outcome are reported in the registry record, so precision cannot be assessed directly.

The registry identifies 24 outcome measures and 33 analyses. When researchers conduct many tests, the chance of observing one or more nominally small p values by chance can increase. General approaches to this issue include prespecifying a primary comparison, adjusting for multiple testing, or treating secondary findings as exploratory. The registry record does not report which approach, if any, was used for these analyses. It does not report an interim-analysis plan or a complete statistical analysis plan.

What can the planning assumptions tell us?

The record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is specified as a fraction of the observed effect. For non-time-to-event outcomes, such illustrations are expressed as participants per arm for 80% power or other stated power levels. They are planning calculations, not observed power and not evidence that the study had a particular chance of detecting an effect after the results were known. No numerical planning values are reported in the record details, and the record does not state that these assumptions were the trial’s original design justification.

General statistical context: power calculations depend on assumptions about the target effect, variability, significance level, and analysis. If the observed effect is used as a planning input after a trial, the resulting illustration is not an independent assessment of how well the completed trial was designed. The registry does not report the original sample-size justification, target effect, or planned power.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 24 outcome measures and 33 analyses, including the primary biomarker endpoint and multiple pathologic outcomes. It does not report a testing hierarchy, a multiplicity adjustment, or which analyses were designated confirmatory versus exploratory. When many outcomes or subgroup comparisons are examined, the chance of at least one apparently unusual result can rise. General statistical context: prespecifying a primary question and accounting for multiple comparisons can help control this issue, but the registry record does not state how it was addressed.

The primary-outcome description reports qualifying specimens with GG3 or GG4 for participants in both arms and says that tumor-foci counts varied according to feasibility of the prostatectomy samples. It does not provide marker-specific analysis denominators or explain how missing, inadequate, or unevaluable specimens were handled. The record also does not describe an intention-to-treat analysis, a per-protocol population, or a missing-data method. These analysis-population details are not reported in the registry record.

The overall enrollment field reports 204, while the primary-outcome description refers to 183 enrolled participants and identifies 62 finasteride and 68 placebo participants with qualifying specimens. The record does not reconcile those figures. They should be understood as differently described counts, not as a basis for calculating an unreported analysis fraction or total.

No numerical primary-outcome estimates or p values are reported, so multiplicity cannot be evaluated against actual findings. The registry record also does not report interim analyses, stopping rules, or a detailed statistical analysis plan. These omissions limit assessment of selective reporting and the intended interpretation of the many listed analyses.

11. Safety Results

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

Other (non-serious) adverse events

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

For Arm I (Finasteride), the registry reports 89 participants at risk for serious adverse events and 0 participants affected. For Arm II (Placebo), it reports 94 participants at risk for serious adverse events and 0 participants affected. The registry also reports 89 and 94 participants, respectively, at risk for other adverse events, with 0 affected in each arm. The death counts are not reported in the registry record.

These figures describe the adverse-event entries in the registry, not a complete account of every possible safety outcome. A reported count of 0 affected means that no events were entered for that category in these fields; it does not establish that no symptoms or harms occurred, or that the treatments are free of risk. The record does not provide event definitions, severity details beyond the serious-versus-other categories, follow-up duration for these counts, or participant-level exposure information.

General statistical context: when no events are recorded, the data still do not show that the underlying event risk is exactly zero. The precision of a safety comparison depends on the number followed, duration, ascertainment, and event definitions. The registry record does not provide enough information to quantify that uncertainty or to compare safety risks comprehensively.

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

The trial addressed a focused preoperative question: whether finasteride, compared with placebo, was associated with differences in tumor-cell staining for selected biomarkers in prostatectomy tissue. The design was randomized, double-masked, and parallel-group, and the registry describes treatment for 4-6 weeks before surgery. This is a study of tissue biomarkers at prostatectomy rather than a direct test of long-term clinical outcomes.

The primary-outcome description identifies the tissue assay, scoring direction, candidate markers, and a Wilcoxon rank-sum test for p values. But numerical results for the primary outcome are not reported in the registry record. Without arm-specific values, effect estimates, p values, or confidence intervals, the magnitude, direction, and precision of any biomarker difference cannot be determined from this record.

General statistical context: a difference in a laboratory marker can support a biological interpretation, but a marker difference is not automatically evidence of a change in symptoms, recurrence, survival, or other patient-centered outcomes. Such conclusions would require relevant clinical endpoints and adequate follow-up. The registry’s listed pathologic characteristics provide additional outcome categories, but their numerical results are not included in the registry record described for this analysis.

The tissue-analysis population also requires care in interpretation. The registry reports qualifying specimens for a subset of participants and notes that specimen counts depended on feasibility. It reports an overall enrollment of 204 while the primary-outcome description refers to 183 enrolled participants; the relationship between those counts is not explained. These details prevent a clear account of the analysis population from the registry record alone.

The appropriate conclusion is therefore limited: the registry documents a randomized phase II study designed to compare preoperative finasteride and placebo using tissue biomarkers and pathology outcomes. It does not provide the numerical primary results needed to say whether the groups differed, how large any difference was, or how precisely it was estimated. The record cannot establish clinical benefit or lack of benefit from the biomarker information alone.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it combines randomized treatment assignment with a tissue-based endpoint measured at surgery. The design aims to compare biomarker staining after a short course of preoperative treatment, while the assay evaluates tumor tissue from prostatectomy specimens. Such a study can examine biological effects in a setting where tissue is available for laboratory analysis.

The endpoint also illustrates why clear measurement definitions matter. The registry describes staining scores from 0 to 10, higher values indicating greater tumor-cell involvement, and characterizes the primary outcome as percentage change. The exact derivation of that change and the marker-specific analysis denominators are not reported in the registry record. Understanding how scores become an endpoint is essential for interpreting effect estimates and comparing results across measures.

Specimen availability is another important statistical feature. The record states that participants with qualifying specimens formed the tissue-analysis population and that the number of tumor foci depended on sample feasibility. Analyses based on available specimens may not represent every randomized participant. A transparent account of specimen exclusions, missing measurements, and analysis populations would help readers assess how representative the tissue findings are.

Finally, the registry lists many outcomes and analyses but does not describe multiplicity handling or provide numerical primary results. This highlights the importance of distinguishing the primary hypothesis from secondary and exploratory analyses, reporting effect estimates with uncertainty, and explaining missing-data decisions. These principles are broadly relevant to trials that test multiple biomarkers in tissue subgroups.

The study’s statistical importance lies in its design and measurement questions, not in a result that can be established from the registry record: the numerical treatment comparisons are not reported, so no conclusion about the observed biomarker effects can be drawn.

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.

Numerical results for the primary endpoint are not reported in the registry record. There are no arm-specific medians or ranges, percentage-change estimates, p values, or confidence intervals available in the record details. This prevents assessment of effect direction, magnitude, and precision, and precludes a statistical comparison based on the registry information alone.

The primary-outcome description refers to 183 enrolled participants, while the enrollment field reports 204. It also states that 62 finasteride participants and 68 placebo participants had qualifying tumor specimens with GG3 or GG4. The record does not explain how these counts relate to each other or to the analysis for each marker. It notes that tumor-foci counts varied based on feasibility of the prostatectomy samples, but does not give marker-specific denominators or detailed specimen-exclusion rules.

The endpoint description calls the measure percentage change while also describing a staining score from 0 to 10. The formula used to derive percentage change, the handling of baseline measurements, and the exact scoring and aggregation procedures are not reported in the registry record. The record identifies the Wilcoxon rank-sum test for p values but does not provide test statistics or explain how its results were interpreted for the endpoint.

The registry lists multiple outcome measures and analyses but does not report a multiplicity strategy or a testing hierarchy. It also does not describe missing-data methods, a complete analysis-population definition, interim analyses, or the original sample-size justification. These omissions limit evaluation of the analysis plan and of how robust the findings would be to alternative assumptions. The adverse-event fields report no affected participants in the listed categories, but definitions and follow-up details are not reported.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Finasteride in Treating Patients With Stage II Prostate Cancer Who Are Undergoing Surgery — NCT00438464.
• Registry record last updated 2016-03-09; status last verified 2015-06.
• Results first posted 2016-03-09.
• 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

The registry describes NCT00438464 as a completed, randomized, double-masked, parallel-group phase II trial sponsored by the National Cancer Institute. It studied patients with stage II prostate cancer undergoing prostatectomy, comparing finasteride 5 mg once daily with placebo once daily for 4-6 weeks before surgery. The enrollment field reports 204, and the primary completion date is 2012-04.

The primary outcome concerned percentage change in tumor-cell staining for biomarkers in GG3 subgroups at prostatectomy. The registry describes a median and full range and identifies the Wilcoxon rank-sum test for p values. It also lists pathology outcomes and reports 24 outcome measures and 33 analyses.

Numerical primary-outcome results, uncertainty estimates, and detailed analysis-population and missing-data methods are not reported in the registry record. The safety fields list 0 affected participants for serious and other adverse events in each arm; death counts are not reported in the registry record. The documented design and outcome definitions are therefore clearer than the trial’s numerical findings in this record.