Alcohol and Breast Cancer (ABC) Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Alcohol and Breast Cancer (ABC) Trial (NCT05423730), a randomized na study. The primary outcome is Blood Levels of Total Estradiol Concentration.

2. Clinical Question

The trial randomized participants to an exposure sequence: white wine followed by white grape juice, or white grape juice followed by white wine. The central statistical question is therefore about the measured hormone outcome under the two exposure conditions in this crossover study. It is not a comparison of breast cancer outcomes, recurrence, or survival; those are not the primary endpoint reported in the registry record.

The primary measure was total estradiol concentration on a log scale, in pg/mL. The registry describes measurements at the beginning and end of each three-week period, with the post-period estimate adjusted for the level at the beginning of that period. Six additional hormone outcomes were posted as secondary outcomes. The clinical question is consequently narrow: it concerns a short-term laboratory measure in the described study population and does not by itself address longer-term outcomes or other populations.

3. Trial Design

The Alcohol and Breast Cancer (ABC) Trial, NCT05423730, is listed as a randomized, single-masked, crossover study with phase recorded as NA. It enrolled 23 participants and is marked completed. The listed sponsor is Beth Israel Deaconess Medical Center. The registry lists a start date of 2022-09-01 and a primary completion date of 2023-07-31.

Participants were randomized to one of two sequences: white wine followed by white grape juice, or white grape juice followed by white wine. Each exposure period was described as three weeks of one daily serving. The endpoint description specifies 5 ounces for white wine and 6 oz for white grape juice, with a two-week washout period before each drinking period. This sequence structure is the defining feature of the crossover design: the study describes both exposures within each randomized sequence rather than assigning participants only to one exposure for the entire study.

The research procedures described in the registry include a screening visit, four study visits with blood draws, and ten weekly phone calls and online questionnaires. The arm descriptions are truncated in the registry record, so further procedural detail is not reported in the registry record. The identity of the masked party, details of allocation concealment, and the randomization method are not reported in the registry record.

The primary endpoint results list 20 participants for White Wine and 20 for White Grape Juice. These are the posted endpoint group counts; they do not establish from the registry record how many participants contributed paired measurements or why the endpoint counts differ from enrollment. The analysis population and participant flow are not reported in the registry record. The study is explicitly described as a pilot, but a formal sample-size justification is 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: Twenty-three participants consented to participate. Two participants drank too much to be eligible for the trial, and one declined to participate. All twenty women who were randomized completed the trial and are included in the analyses.

Overall Study

Analysis population for the primary outcome, as defined in the registry: We imputed values for estradiol below the lower limit of detection (0.5 pg/mL ) at one-half of that value. No other hormones fell below that value.

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 Blood Levels of Total Estradiol Concentration, measured over 3 Weeks.

The primary endpoint is blood levels of total estradiol concentration, measured on a log scale in pg/mL. Estradiol is one of the sex hormones the study set out to examine in postmenopausal women with ER+ breast cancer receiving aromatase inhibitor therapy. As a laboratory measure, it offers a direct way to describe hormone levels during the exposure periods. It is not a clinical outcome such as cancer progression or survival.

For each exposure, blood levels were measured at the beginning and end of three weeks of daily consumption. The registry describes estimates following the three weeks as adjusted for the blood level at the beginning of the drinking period. This adjustment aims to account for the starting measurement when describing the post-period level. The endpoint description also states that a two-week washout period preceded each drinking period.

Estradiol values below the lower limit of detection, 0.5 pg/mL, were imputed at one-half of that value. The registry states that no other hormones fell below that limit. How this imputation entered the statistical analysis beyond that description is not reported in the registry record.

The registry lists six secondary hormone outcomes: free estradiol concentration, free estradiol index, estrone concentration, DHEAS, testosterone, and sex hormone binding globulin (SHBG). The primary endpoint remains a short-term biomarker comparison, and its results should be interpreted within that scope.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry reports a continuous primary endpoint and lists exposure-specific estimates as least-squares means with 95% confidence intervals. A continuous measure can take a range of numerical values, rather than being limited to categories such as event or no event. A least-squares mean is generally a model-based estimate of an average, potentially adjusted for terms included in the model. Which model terms were used for these estimates is not reported in the registry record, so the exact adjustment beyond the stated baseline blood level should not be inferred.

What does the confidence interval express?

In general, a confidence interval communicates uncertainty around an estimate under the assumptions of the analysis. A 95% confidence interval is not a guarantee that the true value lies inside the particular interval. It gives a range of values that are compatible with the data and the method’s assumptions. The endpoint-specific intervals and the comparison interval answer different questions: the first describe uncertainty around each exposure estimate, while the latter describes uncertainty around the reported contrast.

The reported comparison has a 95% confidence interval from -49.75 to 57.20 around a mean difference in final values of -11.12. The interval spans zero, and the registry does not report a p-value. The comparison scale and method are not reported in the registry record. Since the exposure-specific endpoint is on a log scale while the reported contrast is labelled as a mean difference in final values, readers should not assume the values are directly interchangeable or derive a contrast from the exposure-specific estimates.

Why does the crossover structure matter?

In general, crossover studies can use within-participant comparisons because participants receive more than one exposure. Measurements from the same participant may be correlated, so analyses commonly need to account for that dependence. Period effects, sequence effects, and carryover can also be relevant considerations in crossover designs. The registry identifies the design as crossover and describes randomized sequences with a washout period. It does not report the comparison model or whether the analysis accounted for within-participant correlation, period, sequence, or carryover. Those details should not be assumed.

The washout period is part of the described design, but its adequacy for preventing carryover is not established by the registry information. In general, a washout is intended to separate exposure periods; the registry record does not provide an analysis of whether residual effects remained. This is a design and analysis question, not a conclusion that carryover occurred.

How should a log-scale endpoint be read?

In general, a logarithmic scale represents values in a transformed form and can affect how differences are interpreted. The registry reports the endpoint unit as log scale, pg/mL, and describes baseline-adjusted estimates after each exposure period. It does not report the log transformation details or a back-transformation for the estimates. Therefore, the posted values should be retained on the stated scale rather than converted into another scale or given a ratio interpretation that the record does not specify.

The endpoint description notes that values below the lower limit of detection, 0.5 pg/mL, were imputed at one-half of that value. In general, values below an assay’s detection limit are not observed as exact concentrations, and substituting a value can affect estimates, particularly when such observations are numerous. The number of affected estradiol measurements is not reported in the registry record. The registry states that no other hormones fell below that limit.

What cannot be assessed from the posted analysis?

The registry lists a mean difference in final values and a confidence interval, but the comparison method is not specified. It also does not report the analysis population, handling of other missing measurements, or a statistical analysis plan. No p-value is posted for the primary comparison. Without those details, the exact inferential procedure, assumptions, and planned status of the reported analysis cannot be established from the registry record.

The study lists seven outcome measures and seven analyses, including the primary endpoint and six secondary hormone outcomes. In general, testing multiple outcomes can increase the chance of at least one apparently notable result if each is assessed separately. Whether any multiplicity adjustment or outcome hierarchy was planned or used is not reported in the registry record. The posted primary result should therefore be interpreted as the reported endpoint estimate, not as evidence that a family of outcomes was controlled under a stated statistical plan.

10. Analyses Reported by the Sponsor

The registry reports a comparison labelled mean difference in final values: -11.12, with a 95% confidence interval from -49.75 to 57.20. It does not report the statistical method or a p-value for that comparison. The registry separately gives least-squares mean estimates for each exposure on the primary endpoint’s log scale, with baseline adjustment described for levels after three weeks.

A separate unadjusted recalculation of the two-arm comparison is not available from the posted summary statistics: the registry record indicates that values are missing or not estimable for that continuous two-arm comparison. Accordingly, no independently recalculated contrast should be substituted for the reported result. The available information also does not permit a precise reconciliation between the mean-difference label and the baseline-adjusted log-scale estimates. No discrepancy is flagged in the registry record, but the details needed to reproduce the reported comparison are not reported in the registry record.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures and seven analyses. The primary outcome is total estradiol concentration; six secondary outcomes cover other hormone measures. When several outcomes are assessed, multiplicity is a statistical concern: in general, the chance of at least one apparently unusual result can rise when multiple tests are considered separately. The registry record does not report whether the outcomes were arranged in a hierarchy, whether an adjustment for multiple comparisons was planned or used, or whether the primary endpoint alone was treated as confirmatory. No multiplicity procedure should be assumed.

For the primary endpoint, the registry explicitly describes one imputation rule: estradiol values below the lower limit of detection, 0.5 pg/mL, were imputed at one-half of that value. It also states that no other hormones fell below that limit. The number of estradiol observations affected by this rule is not reported in the registry record. The treatment of other missing endpoint values, if any, and the reasons for missingness are not reported in the registry record.

Enrollment was 23, while the primary endpoint lists 20 participants for each exposure. The registry does not explain the relationship between these figures, identify the analysis population, or report participant-level completion and exclusion details. Because the design is crossover, the two exposure counts alone do not establish the number of participants with complete paired measurements.

In general, missing-data decisions can affect an estimate when missingness is related to participant characteristics or measured outcomes. The registry information does not allow assessment of that possibility or of any sensitivity analysis. The statistical analysis plan, interim analyses, and sample-size justification are not reported in the registry record.

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.

The posted safety figures list 20 participants at risk in each exposure group. For White Wine, the registry reports zero serious adverse events, zero other adverse events, and zero deaths. For White Grape Juice, it also reports zero serious adverse events, zero other adverse events, and zero deaths. No top serious-event terms are listed.

These figures are counts in the registry record, not evidence that risk is absent. The study is a pilot with a limited number of participants, and the safety counts describe the recorded experience in these groups. They do not establish what might occur in a larger population or over a different duration.

The registry does not report further detail about adverse-event definitions, collection procedures, severity grading beyond the serious/other categories, or how safety information was attributed across crossover periods. These details are not reported in the registry record. The zero counts should be read narrowly as the posted event counts, rather than as a general safety conclusion about either exposure.

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

The posted result addresses a specific question: blood total estradiol levels after three weeks of daily white wine compared with levels after three weeks of daily white grape juice in postmenopausal women with ER+ breast cancer taking aromatase inhibitors. It is a short-term laboratory endpoint in a randomized crossover pilot study. The reported comparison is -11.12, with a 95% confidence interval from -49.75 to 57.20, and no p-value is reported.

The confidence interval spans zero and includes a broad range of possible values. This means the estimate is imprecise as a description of the contrast. It does not establish that the exposures have identical effects, and it does not establish that one exposure produces a reliable difference. The registry does not report an equivalence margin or a statistical method for the comparison. No conclusion beyond the posted estimate and its uncertainty is warranted from those details.

The result does not answer whether either exposure changes cancer risk, recurrence, or survival. Those are not the primary outcomes reported. Nor does a three-week hormone measurement establish longer-term effects. The registry’s population is specific, and the results should not be generalized from the record to people outside the described study population.

The trial is described as a pilot, and the registry does not report a sample-size justification. Its enrollment and endpoint counts therefore provide context for the scale of the study but do not establish the precision that investigators intended to achieve. The reported estimate and interval are the appropriate basis for describing statistical uncertainty; a claim that the study was adequately powered or that a null finding demonstrates no effect is not supported by the registry record.

Overall, the posted data provide a numerical estimate of the primary hormone comparison but leave important interpretive details unspecified, including the comparison model, analysis population, and handling of any missing values beyond the stated below-detection imputation. The result should be understood as a limited, short-term biomarker finding with substantial uncertainty, not as a clinical recommendation or a conclusion about treatment benefit.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how design and reporting details shape interpretation. Its randomized crossover structure gives each participant sequence exposure to white wine and white grape juice, and the registry describes a washout period between the exposure periods. In general, crossover designs can make within-participant comparisons useful, while requiring care about correlated measurements, period effects, and carryover. The registry record does not state how the reported comparison handled those considerations.

The endpoint is also reported in more than one statistical form: exposure-specific least-squares means on a log scale with baseline adjustment, and a mean difference in final values with a confidence interval. Without the method and scale details for the comparison, these summaries cannot be independently reconciled from the posted record. That distinction illustrates why a clear description of the estimand, model, and scale matters alongside numerical results.

The confidence interval gives an important complement to the central estimate. Rather than treating the point estimate as a definitive answer, readers can see that the comparison is uncertain and compatible with a broad range of values. The absence of a reported p-value does not remove the value of the interval; it makes the reported uncertainty especially important to describe directly.

The record also shows why outcome multiplicity and missing-data reporting matter. Seven outcomes and seven analyses are listed, but the record does not specify multiplicity handling or the analysis population. A stated imputation rule addresses estradiol values below the detection limit, yet the count of affected measurements is not reported. Together, these omissions limit reproducibility and the assessment of robustness.

For clinical researchers and biostatisticians, the study highlights the value of reporting how crossover data were analyzed, which participants contributed to each estimate, and how uncertainty was calculated. Those details are necessary to distinguish what the registry numbers directly show from what would require additional assumptions.

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 registry record leaves the primary comparison method unspecified. It does not state how within-participant correlation, period, sequence, or carryover was handled in the crossover analysis. The reported exposure-specific estimates are described as baseline-adjusted least-squares means, but the model terms beyond that adjustment are not reported in the registry record. The comparison is labelled a mean difference in final values, with no reported method or p-value and no stated scale for that contrast.

The record lists 23 enrolled participants and 20 participants for each primary endpoint exposure group, but does not explain participant flow or identify the analysis population. In a crossover study, group counts do not by themselves reveal how many participants contributed paired data. Reasons for missing measurements, the handling of missing data beyond the below-detection imputation, and any sensitivity analyses are not reported in the registry record.

Estradiol values below 0.5 pg/mL were imputed at one-half of that value, but the number of affected observations and the effect of this rule on the estimates are not reported. The log transformation details and any back-transformation are also not reported in the registry record.

The registry identifies the trial as a pilot but does not report a sample-size justification or a statistical analysis plan. It lists seven outcomes and analyses without reporting multiplicity handling. The masked party, allocation concealment, and detailed randomization procedures are not reported in the registry record. Finally, the primary endpoint is a short-term hormone measure after three-week exposure periods; longer-term hormone outcomes and clinical outcomes are not established by these posted results.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Alcohol and Breast Cancer (ABC) Trial — NCT05423730.
• Registry record last updated 2024-12-20; status last verified 2024-11.
• Results first posted 2024-12-20.
• 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

NCT05423730, the Alcohol and Breast Cancer (ABC) Trial, is listed as a completed, randomized, single-masked crossover study with phase recorded as NA. It enrolled 23 participants and lists Beth Israel Deaconess Medical Center as sponsor. The registry gives a start date of 2022-09-01 and a primary completion date of 2023-07-31.

The study compared three weeks of daily white wine with three weeks of daily white grape juice, with a two-week washout period described before each drinking period. Its primary endpoint was blood total estradiol concentration on a log scale, pg/mL, with post-period estimates described as adjusted for baseline levels. The posted comparison was a mean difference in final values of -11.12, with a 95% confidence interval from -49.75 to 57.20; no p-value or comparison method is reported.

The registry also lists six secondary hormone outcomes. It reports zero serious adverse events, zero other adverse events, and zero deaths in each exposure group, with 20 participants at risk listed for each group. The record does not report the analysis population, a sample-size justification, or the statistical plan.