Transrectal MRI-Guided Biopsy in Identifying Cancer in Patients With Suspected Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Transrectal MRI-Guided Biopsy in Identifying Cancer in Patients With Suspected Prostate Cancer (NCT02501759), a na na study. The primary outcome is Proportion of MRI-guided Biopsies That Demonstrate a Higher Gleason Score Than Contemporaneous TRUS Guided Biopsy.

2. Clinical Question

The clinical question is about whether the MRI-guided biopsy identifies a higher Gleason score than the ultrasound-guided biopsy in the same clinical evaluation. It is not a question about an overall treatment effect, survival, or whether either procedure improves health outcomes. The endpoint compares biopsy findings, and the intended population is restricted to people diagnosed with prostate cancer according to a reference standard.

The study description presents MRI-guided biopsy as a method under evaluation for identifying cancer in patients already scheduled for standard biopsy. Its stated rationale is that MRI may help identify cancer and guide tissue sampling. Those statements describe the motivation for the study, not evidence that MRI-guided biopsy was more accurate or caused less pain in this trial. The registry record does not report the primary endpoint result, so the planned comparison cannot be answered from the posted results.

3. Trial Design

This was a pilot study registered as NCT02501759, titled Transrectal MRI-Guided Biopsy in Identifying Cancer in Patients With Suspected Prostate Cancer. The official title describes it as a pilot study of transrectal multiparametric MRI-guided biopsy in prostate cancer evaluation. The sponsor was OHSU Knight Cancer Institute. The registry lists the study as terminated and reports enrollment of 2. The start date is 2015-05, and the primary completion date is 2016-12-31.

The registry characterizes the study as single group, with allocation listed as NA and masking listed as none. Participants were described as receiving gadodiamide intravenously and undergoing diagnostic multiparametric endorectal MRI. Those with visible lesions were to undergo transrectal MRI-guided biopsy within 2 weeks of diagnostic MRI, followed by TRUS-guided biopsy. The arm description ends before giving further details about the latter procedure, so additional procedural details are not reported in the registry record.

This arrangement is a within-participant diagnostic comparison as described, rather than a randomized comparison between groups assigned to different procedures. The registry does not report a separate control arm or a masking procedure. Its primary endpoint concerned differences in Gleason scores from the two biopsy approaches among patients with cancer identified by the reference standard. The endpoint timeframe was up to 42 days (6 weeks).

The registry lists 3 outcome measures and 0 analyses. It does not report an analysis result for the primary endpoint. Instead, it states that low enrollment left insufficient data to report that outcome. The termination status and small enrollment are important context for reading the record: the trial description identifies a planned method of evaluation, while the posted results do not provide a usable estimate of the primary 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

Analysis population for the primary outcome, as defined in the registry: Due to low enrollment, insufficient data was collected to report this outcome

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 Proportion of MRI-guided Biopsies That Demonstrate a Higher Gleason Score Than Contemporaneous TRUS Guided Biopsy, measured over Up to 42 days (6 weeks).

The primary endpoint was the proportion of MRI-guided biopsies that demonstrated a higher Gleason score than the contemporaneous TRUS-guided biopsy. The intended denominator was patients diagnosed with prostate cancer based on the reference standard. The timeframe was up to 42 days (6 weeks).

This endpoint was chosen to assess whether the MRI-guided procedure identified a higher grade in biopsy samples than the ultrasound-guided procedure in the same diagnostic episode. A higher Gleason score is the comparison of interest as specified by the registry; the endpoint does not, by itself, measure cancer detection in all enrolled participants, accuracy against every possible reference, or a patient health outcome. The registry description states that the proportion would be estimated and that McNemar's test would be used to assess whether MRI-guided biopsies were more likely to yield a higher score.

The outcome is not reported. The registry attributes this to low enrollment and insufficient data. Consequently, there is no reported proportion, uncertainty interval, or test result from which to characterize the size or precision of the planned comparison. The registry record also does not report the number of participants diagnosed with cancer based on the reference standard, the numbers of higher, lower, or equal score pairs, or the way any such pairs would have been handled in the analysis.

In general, a paired biopsy endpoint can make use of the fact that both methods are assessed within the same participant. That design addresses a within-person comparison, but it does not resolve the lack of endpoint observations in this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a planned paired comparison of biopsy scores and names two statistical methods: McNemar's test for the primary question and simple logistic regression for associations between a higher Gleason score and patient characteristics or clinical information. The record lists 0 analyses, and the primary outcome is explicitly not reported because of low enrollment. These methods should therefore be read as planned methods, not as analyses with reported results.

What does a paired comparison mean?

General explanation: when each participant has results from both diagnostic procedures, the observations are paired. The two results from a participant are related, rather than independent measurements from unrelated groups. A paired analysis uses that structure when comparing the procedures. Here, the endpoint was framed around whether the MRI-guided biopsy had a higher Gleason score than the contemporaneous TRUS-guided biopsy among patients diagnosed with cancer based on the reference standard.

The registry does not provide the individual paired scores or counts of pairs in which one procedure yielded a higher score, the other yielded a higher score, or scores were equal. Those details matter to understanding the comparison and cannot be reconstructed from enrollment alone. The record also does not report how equal scores or other data patterns would be represented in the planned endpoint analysis.

Why was McNemar's test named?

General explanation: McNemar's test is used for paired categorical outcomes, focusing on pairs where the two methods disagree. It assesses whether the discordant outcomes favor one method more often than the other under the test's assumptions. In this registry, the planned use was to assess whether MRI-guided biopsies were more likely to yield a higher Gleason score than TRUS-guided biopsy. The registry does not provide a test statistic, p-value, or result, and the endpoint itself is not reported.

The exact categorization and implementation are not reported in the registry record. In particular, it does not give a detailed analysis specification for score ties, missing paired scores, or the handling of participants outside the cancer-diagnosed endpoint population. Those details should not be inferred from the named test alone.

What would logistic regression address?

General explanation: logistic regression models the probability of a binary outcome in relation to one or more explanatory variables. The registry says simple logistic regression would assess the association between a higher Gleason score and patient characteristics and/or clinical information for patients diagnosed with prostate cancer. It does not identify specific characteristics, state how the higher-score outcome would be coded, or report estimates from such a model. Because the registry lists 0 analyses, there is no reported model result to interpret.

Simple logistic regression is a planned association analysis, not evidence that patient characteristics cause a biopsy-score pattern. With very limited enrollment, a model can also be difficult to estimate reliably. That is general statistical context; the registry does not report a model fit, covariate set, or diagnostic assessment.

How should precision and significance be understood?

General explanation: an estimate is more informative when accompanied by a measure of uncertainty, such as a confidence interval. A confidence interval describes a range of values compatible with the observed data under the specified method and assumptions. It is not a guarantee that the true value lies in that particular interval. No interval is reported for the primary outcome, so its precision cannot be assessed.

The registry includes planning assumptions for sample-size illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect specified as a fraction of the observed effect. Those are planning illustration assumptions, not a report of the trial's own design justification. The study is described as single group, and the registry does not report an observed primary effect from which a reportable comparison can be interpreted. The record does not report the protocol's sample-size justification or the basis for the planning assumptions. A planning illustration is not observed power and does not create evidence that the trial did or did not detect an effect.

General explanation: over-dispersion occurs when variation in observed data is greater than a statistical model expects. Accounting for it can be important for some outcome types and models. The registry does not report an over-dispersion assessment or a model for count data; it would not be appropriate to assume one was needed or used for this endpoint.

No interim analyses, stopping boundaries, or other monitoring methods are reported in the registry record. The registry lists no analyses, so the stated methods and planning description do not establish that inferential analyses were performed. Statistical conclusions should remain limited to that distinction between planned methods and reported results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 0 analyses. The primary endpoint is described, but its result is not reported because the registry says low enrollment left insufficient data. Results for the other outcome measures are not detailed in the record summarized for this study, and their definitions and analysis results are not reported.

Multiplicity concerns arise when multiple outcomes or multiple statistical tests are considered. General explanation: examining several outcomes can increase the chance of obtaining an apparently notable result by chance, so a prespecified approach may state which outcome is primary and whether any adjustment or hierarchy will be used. The registry identifies a primary endpoint, but a multiplicity adjustment, testing hierarchy, or broader strategy for the listed outcomes is not reported in the registry record. It is therefore not possible to assess how the planned analyses would have addressed multiplicity.

Missing-data procedures are also not reported. The primary outcome is described as not reportable because of insufficient data, but the record does not specify whether the limitation arose from missing biopsy scores, the number of cancer diagnoses, incomplete paired assessments, or another data issue. No imputation method, complete-case rule, or sensitivity analysis is reported. The reason should not be expanded beyond the registry's statement about low enrollment and insufficient data.

The endpoint description defines its target population as patients diagnosed with prostate cancer based on the reference standard. The record does not report how many enrolled participants belonged to that population or provide a broader analysis-population definition. It also does not report an intention-to-treat or per-protocol population, or detailed rules for inclusion in the primary analysis. No interim-analysis plan is reported.

11. 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.

The safety record lists 2 participants at risk for both serious and other adverse events. It reports 0 participants affected by serious adverse events and 0 affected by other adverse events, with 0 deaths. No serious adverse-event terms are listed.

These are counts from the enrolled study group, not comparative rates from separate randomized groups. The study was single group, and the registry lists masking as none. The figures should be read as the events recorded for this small group during the study, not as evidence that an event could not occur or that one biopsy approach is safer than another.

General explanation: a count of zero in a small group provides limited information about the likelihood of uncommon events. It does not establish that the underlying risk is zero. The record does not report event-specific follow-up details, a comparative safety analysis, or additional context about adverse-event collection. The safety figures therefore describe the registry record but cannot support a broad safety conclusion.

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

The registry record describes a pilot study intended to compare Gleason scores from MRI-guided and contemporaneous TRUS-guided biopsies in patients diagnosed with prostate cancer based on a reference standard. It reports enrollment of 2 and states that low enrollment left insufficient data to report the primary outcome. The principal result is therefore unavailable: the record does not tell readers how often MRI-guided biopsy yielded a higher score, whether the procedures tended to agree, or how uncertain any comparison would be.

The missing outcome is not a finding of no difference. Without a reported estimate, no direction or size of the score comparison can be assigned. Likewise, the absence of a statistical test result is not evidence that a test found no association. The registry lists 0 analyses, so the methods described should be understood as plans rather than completed analyses with interpretable results.

The design also limits the kinds of claims that could follow from the planned endpoint. It compares diagnostic findings from two procedures in the same clinical evaluation, rather than comparing randomized groups on a health outcome. A higher Gleason score on one biopsy is the specified endpoint; it is not, by itself, proof of greater overall accuracy or improved patient outcomes. The brief study description mentions possible advantages as a rationale, but the primary result needed to evaluate the stated comparison is not reported.

The safety counts are similarly narrow: 0 serious adverse events, 0 other adverse events, and 0 deaths are reported among 2 participants at risk. Such counts do not establish comparative safety or rule out events that the study was too small to characterize.

In practical statistical terms, the record is informative about the study question, planned procedures, endpoint, and the reason the primary outcome could not be reported. It does not provide an effect estimate, precision measure, or completed analysis that can resolve the comparison. Conclusions should remain at that descriptive level.

13. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the difference between a well-defined question and an answer supported by analyzable results. The registry specifies a comparative diagnostic question: whether MRI-guided biopsy yielded a higher Gleason score than contemporaneous TRUS-guided biopsy in the endpoint population. It also names a paired test and a regression analysis for associations with patient characteristics. Yet the primary endpoint is not reported, and the registry lists 0 analyses.

A pilot study can be used to explore feasibility or inform later research, but the registry record does not describe a specific feasibility objective or a protocol-based sample-size justification. Its stated reason for the unavailable primary outcome is low enrollment and insufficient data. This makes transparent reporting of the data limitation especially important: readers should distinguish the intended analysis from results that were actually available.

The study also highlights why design and analysis must be read together. Both biopsy procedures were described within a single group, making the planned score comparison paired rather than a randomized contrast between groups. A method appropriate for paired data depends on the pattern of within-participant results, which is not reported. The planned test name alone cannot substitute for those observations.

Finally, the record demonstrates the limits of interpreting zero-event safety counts when enrollment is very small. The reported counts are useful as a record of what was observed, but they cannot characterize uncommon events or establish comparative safety. The statistical value of the record is therefore mainly in clarifying the question, intended analysis, and evidentiary gap—not in estimating comparative diagnostic performance.

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.

The primary limitation is that the registry reports no primary endpoint result. It attributes this to low enrollment and insufficient data, while reporting enrollment of 2. No score comparison, proportion, confidence interval, or test result is available. The number of participants diagnosed with prostate cancer based on the reference standard is not reported, so the size of the primary endpoint population cannot be determined.

The study was terminated, but a detailed reason for termination beyond the low-enrollment statement is not reported in the registry record. Recruitment details, reasons for non-enrollment, and any changes to the study plan are also not reported. The registry lists 0 analyses; whether any additional analyses were conducted outside the posted record is not reported.

The design is described as single group, allocation NA, and masking none. It does not provide a randomized between-group comparison. The endpoint concerns biopsy-score findings, and the record does not report information needed to assess the accuracy of either method beyond the planned reference-standard definition. Details of score handling, ties, missing paired measurements, and analysis-population rules are not reported.

The registry lists 3 outcome measures but does not report a multiplicity strategy, missing-data method, or interim-analysis plan. It also does not report a protocol-based sample-size justification. The planning assumptions described for sample-size illustrations should not be mistaken for the trial's own design rationale or for evidence from an observed treatment effect.

Safety interpretation is limited by the small enrolled group and the absence of a separate comparative arm. The reported adverse-event counts do not establish event rates for a broader population. Further details about event-specific timing and follow-up are not reported.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Transrectal MRI-Guided Biopsy in Identifying Cancer in Patients With Suspected Prostate Cancer — NCT02501759.
• Registry record last updated 2019-04-03; status last verified 2019-03.
• Results first posted 2019-04-03.
• 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

NCT02501759 is a terminated, single-group pilot study sponsored by OHSU Knight Cancer Institute. It examined diagnostic multiparametric endorectal MRI, MRI-guided biopsy for patients with visible lesions, and TRUS-guided biopsy. The registry reports enrollment of 2, a start date of 2015-05, and a primary completion date of 2016-12-31.

The primary endpoint was the proportion of MRI-guided biopsies yielding a higher Gleason score than contemporaneous TRUS-guided biopsy among patients diagnosed with prostate cancer based on the reference standard, assessed up to 42 days (6 weeks). The registry states that low enrollment left insufficient data to report this outcome. It lists 3 outcome measures and 0 analyses.

The safety record reports 0 serious adverse events, 0 other adverse events, and 0 deaths among 2 participants at risk. These counts do not provide a comparative safety estimate. Overall, the record documents the planned question and methods but does not provide a reportable primary comparison.