Median Survival or Mean Survival: Which Measure Is the Most Appropriate for Patients, Physicians, and Policymakers?

Introduction: Understanding the efficacy of treatments is crucial for patients, physicians, and policymakers. Median survival, the most common measure used in the outcome reporting of oncology clinical trials, is easy to understand; however, it describes only a single time point. The interpretation of the hazard ratio is difficult, and its underlying statistical assumptions are not always met. The objective of this study was to evaluate alternative measures based on the mean benefit of novel oncology treatments.

Materials and methods: We reviewed all U.S. Food and Drug Administration (FDA) approvals for oncology agents between 2013 and 2017. We digitized survival curves as reported in the clinical trials used for the FDA approvals and implemented statistical transformations to calculate for each trial the restricted mean survival time (RMST), as well as the mean survival using Weibull distribution. We compared the mean survival with the median survival benefit in each clinical trial.

Results: The FDA approved 83 solid tumor indications for oncology agents between 2013 and 2017, of which 27 approvals based on response rates, whereas 49 approvals were based on survival endpoints (progression-free survival and overall survival). The average improvement in median overall survival or progression-free survival was 4.6 months versus 3.6 months improvement in the average RMST and 6.1 months improvement in mean survival using Weibull distribution.

Conclusion: Mean survival may supply valuable information for different stakeholders. Its inclusion should be considered in the reporting of prospective clinical trials.

Implications for practice: Mean survival may supply valuable information for different stakeholders. Its inclusion should be considered in the reporting of clinical trials.