In a study published in The BMJ, around half of trials that supported new cancer drug approvals in Europe between 2014 and 2016 were judged to be at high risk of bias, which indicates that treatment effects may have been exaggerated.

In the European Union, the European Medicines Agency (EMA) is responsible for evaluating the clinical effectiveness and safety of new medicines.

In 2017, more than a quarter (24 of 92) of EMA approvals were for cancer drugs, most of which were based on evidence from randomised controlled trials, considered to be the “gold standard” for evaluating treatment effectiveness.

However, flaws in the design, conduct, analysis, and reporting of randomised controlled trials can distort estimates of treatment effect, potentially jeopardising the validity of their findings.

To evaluate these flaws in more detail, a team of international researchers from the London School of Economics, King’s College London, University of Bristol, and Queen’s University examined the design, risk of bias, and reporting of randomised controlled trials that supported European approvals of cancer drugs from 2014 to 2016.

This page is intended to serve as a “living review” companion to the above study, providing an interactive presentation for the risk of bias analysis, as well as the underlying data set. As new cancer drugs are approved by the EMA, this data and analysis will be updated.


Risk of Bias Tree

The figure below presents the results of the risk of bias analysis as an interactive tree. The tree is organized by therapeutic area, so you can click on an area node to expand (or collapse) the branch and see all the EMA-approved drugs for that indication. Then click on a drug to see all the randomised controlled trials supporting the approval, and click on a trial to see its risk of bias scores. A high risk of bias is colored red, low risk of bias is green, and an unclear risk of bias is yellow.

Risk of Bias Data Table

The complete data set for this risk of bias analysis is presented below. Since this data table is meant to function as the foundation for a living review, we anticipate that it will grow and evolve over time. If you have extracted relevant data and would like to contribute to this project (or if you have identified errors or have questions about the data), please contact the study’s lead author, Huseyin Naci (


The development of this living review page was supported by funding from Health Action International.