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Non-inferiority Interpretation — SCE Medical Oncology MCQ

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ModerateClinical Trials & StatisticsNon-inferiority InterpretationSCE Medical Oncology

A non-inferiority trial of 6 months vs 12 months of adjuvant trastuzumab for HER2-positive breast cancer sets a non-inferiority margin of HR 1.30 for disease-free survival. The trial reports HR 1.08 (95% CI 0.93-1.25). What is the correct interpretation?

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Correct answer: D — 6 months is non-inferior to 12 months — the upper CI (1.25) does not cross the non-inferiority margin (1.30)

Non-inferiority is declared when the upper bound of the 95% CI for the HR does not cross the pre-specified non-inferiority margin. Here, upper CI 1.25 < margin 1.30, so non-inferiority is demonstrated. This was the approach used in the PERSEPHONE (6 vs 12 months trastuzumab) and PHARE trials. The HR of 1.08 indicates a small numerical disadvantage for the shorter duration, but this falls within the acceptable margin. The clinical relevance is that 6 months of trastuzumab reduces cost, toxicity and treatment burden while maintaining acceptable efficacy.

Reference: PERSEPHONE Earl et al Lancet 2019; ESMO 2024 Early Breast Cancer; ICH E10