Metvix PDT in Participant With "High Risk" Basal Cell Carcinoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Metvix PDT in Participant With "High Risk" Basal Cell Carcinoma (NCT00473343), a na phase 3 study. The primary outcome is Percentage of Participants With Histologically Confirmed Patient Complete Response (CR) 3 Months After Last Metvix PDT Cycle.

2. Clinical Question

The study focuses on a participant-level response after treatment. The primary endpoint is not simply the status of an individual lesion: the response definition requires all lesions within a participant to have negative histological findings for nodular basal cell carcinoma. The registry specifies an assessment 3 months after the last Metvix PDT cycle, with the timeframe extending up to 6 months.

The record describes an open, multicenter, Phase III study and lists 102 enrolled participants. It does not identify a randomized or concurrent control group. Consequently, the clinical question represented by the primary endpoint is descriptive: how often the defined response was recorded among the treated participants in the study population. It is not a randomized comparison of Metvix PDT against another treatment or against no treatment.

The endpoint result itself is not reported in the registry record. The record therefore does not establish the observed proportion meeting the response definition, its precision, or how outcomes varied across participants or lesions. The stated question can be identified from the endpoint definition, but its numerical answer cannot be read from the posted registry information.

3. Trial Design

This is an open, multicenter, Phase III, single-group study of photodynamic therapy with Metvix® cream in participants with basal cell carcinoma described as high risk. The registry lists Galderma R&D as sponsor, 102 participants enrolled, and a completed study. The recorded study start is 2000-09 and primary completion is 2006-06.

The intervention arm is named Metvix® PDT. Its description records Metvix® cream 160 mg/g applied for three hours, followed by illumination using non-coherent light at a fluence of 75 J/cm². Further details of the illumination description are incomplete in the registry record. The number and scheduling of treatment cycles, any rules for additional treatment, and other procedural details are not reported in the registry record.

The allocation field is recorded as not applicable, and the study model is single group. There is no separate control arm in the posted design. This means the study can describe outcomes among participants receiving the intervention, but it does not make a direct randomized comparison with an alternative treatment. Because masking is listed as none, the study is open label; the registry does not report masking of participants, investigators, or outcome assessors.

The primary endpoint is a percentage of participants with histologically confirmed patient complete response 3 months after the last treatment cycle, with an endpoint timeframe up to 6 months. The registry defines the primary analysis population as enrolled participants who received at least one dose. It lists six outcome measures and zero analyses. The record does not report the analysis methods used to produce a primary result, an endpoint result, or a statistical plan. Sample-size justification and interim-analysis details are not reported in the registry record.

These design features shape interpretation. The single-group structure supports description of the treated cohort as recorded, but does not isolate an intervention effect from other explanations for outcomes. The open-label design also makes the nature of outcome assessment relevant; the primary outcome includes histological examination, but details about assessor masking or central review 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:

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat analysis set included all the participants enrolled in the study who received at least one dose of study treatment.

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: Intent-to-treat analysis set included all the participants enrolled in the study who received at least one dose of study treatment.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Participants With Histologically Confirmed Patient Complete Response (CR) 3 Months After Last Metvix PDT Cycle, measured over 3 months after last Metvix PDT cycle, up to 6 months.

The primary endpoint is the percentage of participants with histologically confirmed patient complete response 3 months after the last Metvix PDT cycle. The registry gives a timeframe of 3 months after the last cycle, up to 6 months. Patient complete response is defined as 100 percentage of the lesions within a participant having negative findings for nodular basal cell carcinoma on histological examination.

This is a participant-level endpoint built from lesion-level findings. A participant meets the definition only when the stated histological condition applies across that participant’s lesions. This approach gives a single response classification for each participant, rather than treating every lesion as an independent participant. It therefore answers a specific question about complete response across the lesions belonging to a participant.

Histological assessment provides tissue-based evidence for the endpoint definition. In general, a prespecified endpoint helps make the outcome being counted explicit and supports consistent interpretation of what qualifies as a response. The registry’s definition identifies the histological finding and the participant-level requirement, but does not report laboratory procedures, pathology review processes, or how missing or unevaluable lesion assessments were handled.

The endpoint result is not reported in the registry record. No observed percentage, participant count meeting the definition, confidence interval, or statistical test is included in the posted results. The endpoint’s definition and timing can therefore be described, but the rate of complete response and the precision of any estimate cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General: what a participant-level percentage represents. A percentage endpoint expresses the share of participants who meet a stated outcome definition. For this study, the definition concerns histological findings across all lesions within a participant. The participant, rather than each lesion, is the unit represented by the primary percentage. That distinction matters because multiple lesions in the same participant do not constitute independent participants. The registry identifies the definition but does not report the number of participants meeting it or the resulting percentage.

General: uncertainty and confidence intervals. A confidence interval is a range intended to communicate the uncertainty around an estimated quantity under a specified statistical procedure. For a percentage, it helps readers distinguish an estimate that is relatively precise from one compatible with a broader range of underlying values. The interval depends on the estimate, the amount of contributing information, and the method used. No primary confidence interval or method for calculating one is reported in the registry record, so precision cannot be assessed for the primary endpoint.

General: hypothesis tests and p-values. A hypothesis test compares observed data with a stated statistical model or null hypothesis. A p-value describes how unusual the data would be under that null model and its assumptions; it is not the probability that a treatment works, nor does it measure clinical importance. The registry does not report a primary hypothesis test, p-value, or statistical hypothesis. Since there is no control group, the primary endpoint as described is a response proportion, not a randomized between-group contrast.

General: why the analysis population matters. An analysis population determines which participants contribute to an estimate. The registry defines the primary analysis set as all enrolled participants who received at least one dose of study treatment. This is the population description attached to the endpoint. The record does not give a participant flow, the number with endpoint assessments, or the handling of participants without an evaluable histological result. It is therefore not possible to determine from the registry whether the endpoint denominator matched the enrollment count or how missing outcomes affected the analysis.

General: missing outcomes. Missing data can affect a percentage when participants do not have an observed outcome. An analysis must use a stated rule for deciding whether such participants are excluded, counted as nonresponders, or handled by another method. Different rules can yield different estimates. No missing-data rule, imputation method, or account of missing endpoint observations is reported in the registry record. The endpoint result is also absent, so no sensitivity assessment can be made.

General: single-group interpretation. A single-group study can report what happened among enrolled participants receiving the study intervention. It does not, by itself, provide a randomized contrast. Outcomes can reflect multiple influences, and without a concurrent control group the contribution of the intervention cannot be separated from those influences. The study’s allocation is recorded as not applicable, and its model is single group; there is no like-for-like control comparison in the registry record.

General: open-label assessment. In an open-label study, treatment assignment is not masked. Knowledge of assignment can affect some forms of assessment or reporting. Histological confirmation gives the primary endpoint a defined tissue-based component, but it does not establish that assessment was blinded or standardized. The registry does not report assessor masking, central review, or procedures to resolve differing pathology assessments. These missing details limit assessment of how consistently the endpoint was evaluated.

General: multiplicity. Multiplicity arises when several outcomes, time points, or analyses are assessed. When multiple statistical tests are conducted, the chance of at least one apparently notable result can increase unless the analysis plan addresses this issue. The registry lists six outcome measures, including outcomes assessed at different times, but reports zero analyses. A multiplicity strategy, hierarchy of outcomes, or adjustment procedure is not reported in the registry record. There are no posted outcome tests to interpret in light of multiplicity.

General: planning illustrations. Any sample-size illustration based on an observed effect is a planning calculation, not an observed trial outcome and not observed power. The registry’s stated assumptions for such illustrations are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect set as a stated fraction of the observed effect. For time-to-event tables, the stated quantity is the total number of events; for other tables, it is participants per arm. These are hypothetical planning assumptions, not features of the single-group study design. The registry does not report the trial’s own sample-size justification, so the illustration should not be treated as evidence of the original design rationale.

The registry does not report a prespecified statistical analysis plan, model, confidence-interval method, test, covariate adjustment, or interim-analysis approach. Without those details and the missing primary result, the analysis cannot be independently reconstructed or evaluated for agreement with a prespecified plan.

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("Metvix® PDT")
n      <- c(102)
events <- c(82)
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  Metvix® PDT  102  82  80.4  71.4  87.6  71.6  86.9  71.6  86.9

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies six outcome measures and zero analyses. It names the primary participant-level complete-response endpoint and lists secondary outcomes that include lesion complete response, cosmetic outcome assessed by investigators and participants, recurrence among participants in the complete-clearance group, and investigator-assessed cosmetic outcome at later follow-up times. The corresponding numerical results are not reported in the registry record.

When a study examines several outcomes or time points, multiplicity is a concern because repeated statistical testing can make chance findings more likely. A prespecified hierarchy, adjustment procedure, or distinction between confirmatory and exploratory analyses can help explain how multiple results should be interpreted. None of these details is reported in the registry record. Because there are no posted analyses, there are no reported p-values or confidence intervals to assess for multiplicity.

The primary analysis population is defined as enrolled participants who received at least one dose of study treatment. The record does not report how many participants had an evaluable primary endpoint, how many had missing or unevaluable histology, or how such cases were handled. It does not describe imputation, exclusion rules, or sensitivity analyses. These omissions matter because the treatment of missing outcomes can affect a participant-level percentage.

The record also does not report whether secondary outcomes used the same analysis population or how follow-up availability was handled for outcomes assessed after the primary assessment. Thus, the stated population definition clarifies who was intended for the primary analysis, but it does not show how complete the outcome data were or whether all enrolled and treated participants contributed to the posted analyses.

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: angina pectoris (1.0%), burning sensation skin (1.0%), surgical intervention (1.0%), bowen's disease (1.0%), stroke (1.0%).

For the Metvix® PDT group, the registry lists 102 participants at risk for serious adverse events and 10 participants affected. It lists 102 participants at risk for other adverse events and 88 affected. The record also lists 7 deaths. These are counts from a single-group study, not a comparison with another treatment group.

The serious adverse event terms listed with a percentage are Angina Pectoris, Burning sensation skin, Surgical intervention, Bowen's disease, Stroke, and Peripheral vascular disease; each is listed as 1.0%. The registry record does not provide event-level narratives or explain whether participants could contribute more than one event or term. These entries should therefore be read as the posted safety summaries, not as a complete account of each participant’s experience.

Adverse events recorded during a study are not automatically caused by the study intervention. The listed counts do not establish causality, and the record does not give timing, duration, outcome, or attribution for individual events. The death count likewise does not establish a treatment relationship. Because there is no comparator arm, these figures cannot be used to estimate a relative safety difference between treatments.

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

The registry record establishes that a completed, open-label, single-group Phase III study enrolled 102 participants with basal cell carcinoma described as high risk and evaluated Metvix PDT. It defines a primary participant-level outcome based on histological findings across lesions, assessed 3 months after the last treatment cycle, with a stated timeframe up to 6 months. It also records selected safety counts and secondary outcome descriptions.

The record does not report the primary response result, an estimate of its precision, or statistical analyses. Therefore, it does not show how many participants met the complete-response definition or how uncertain an estimated response percentage would be. The endpoint definition alone is not evidence that a particular response rate was observed.

The study’s single-group design also means the record does not provide a randomized comparison with another treatment. Any outcome proportion from the treated group would describe that group under the study conditions; it would not, on its own, quantify the difference attributable to treatment. The open-label design and unreported details about outcome assessment add further uncertainty about how assessments were conducted.

The safety counts describe events recorded for participants in the Metvix® PDT group. Without a control group, event-level detail, or reported causal attribution, they cannot establish whether the intervention caused those events or how its safety compares with another option. The registry record is consequently useful for identifying the study structure, endpoint definition, and posted safety summaries, but it does not provide the outcome evidence needed to estimate the primary response or make a comparative statistical assessment.

14. Why This Trial Matters Statistically

This study illustrates why the design and the availability of results are both essential to statistical interpretation. A precisely defined endpoint can clarify what investigators intended to measure, but it cannot substitute for the observed result. Here, the primary outcome is described in detail at the participant level, including its histological basis and assessment timing, while the response estimate and its uncertainty are not reported in the registry record.

The study also makes the distinction between a response proportion and a comparative treatment effect important. A single-group study can describe the outcomes recorded among its treated participants, but without a concurrent control group it cannot estimate a randomized difference against another approach. This distinction remains even when the study is designated Phase III.

Outcome construction is another relevant statistical feature. The primary response classification depends on findings across a participant’s lesions, so the participant is the unit of the primary percentage. A lesion-level outcome, by contrast, would answer a different question and must account for the fact that multiple lesions can belong to the same participant. The registry lists both participant- and lesion-related outcomes, but does not report their analyses.

Finally, the record shows why safety counts require context. Counts from a treated group can describe what was recorded, but they do not establish causality or comparative risk. Overall, this study’s registry entry supports careful reading of its design and definitions while demonstrating the limits of interpretation when endpoint results, analysis methods, missing-data handling, and a comparator are not reported.

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 most important limitation of the registry record for statistical interpretation is that it does not report the primary endpoint result. There is no response percentage, response count, confidence interval, or test result. The record also lists zero analyses, so the stated endpoint cannot be evaluated against a reported statistical analysis.

The single-group design has no concurrent control arm. It cannot provide a randomized comparison with another treatment, and any outcome observed among participants would not by itself isolate the intervention’s contribution. The open-label design adds a potential source of assessment influence. Although histological examination forms part of the primary definition, masking of assessors and central pathology review are not reported in the registry record.

Participant flow and endpoint completeness are not described. The primary population is defined as enrolled participants who received at least one dose, but the number with evaluable histology, the number missing an endpoint assessment, and the handling of missing outcomes are not reported. Without these details, the denominator and possible influence of missing data cannot be assessed.

The registry also does not report the statistical plan, confidence-interval method, analysis model, multiplicity approach, sample-size justification, or interim-analysis details. The intervention description does not give complete procedural information, and longer-term outcome results are not reported. These gaps prevent evaluation of how analyses were planned, how follow-up was completed, and whether reported findings would align with prespecified methods.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Metvix PDT in Participant With "High Risk" Basal Cell Carcinoma — NCT00473343.
• Registry record last updated 2023-01-05; status last verified 2021-06.
• Results first posted 2023-01-05.
• 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

The registry describes an open, multicenter, Phase III, single-group study of Metvix® photodynamic therapy in participants with high-risk basal cell carcinoma. Galderma R&D is listed as sponsor; 102 participants were enrolled. The recorded study start is 2000-09, primary completion is 2006-06, and status is completed.

The primary endpoint is the percentage of participants with histologically confirmed patient complete response 3 months after the last treatment cycle, with a timeframe up to 6 months. The primary analysis population includes enrolled participants who received at least one dose. The primary result and statistical analyses are not reported in the registry record.

The safety record lists 10 participants with serious adverse events, 88 with other adverse events, and 7 deaths. There is no comparator arm, and the record does not establish causality for these events. Sample-size justification, missing-data handling, and a statistical analysis plan are not reported in the registry record.