Endpoints in clinical trials for liver cancer and their value in evidence-based clinical decision making: An unresolved Gordian knot

The design and execution of clinical trials relies on strict definitions and criteria to avoid heterogeneous decisions by investigators at different sites. Ideally, definitions and decision making in clinical practice should mimic those implemented in trials, but this is not the case. Target populations are narrowly defined in trials, with the goal of evaluating activity and toxicity, and ultimately, demonstrating a survival benefit. In real-world practice, patients may not fit into the stringent inclusion/exclusion criteria of clinical trials. The evaluation of activity may also differ and the common policy to stop therapy upon progression may not be followed if progression is minor. Indeed, registration of progression may not reflect treatment failure or resistance. Parameters such as response according to RECIST criteria, time to progression and progression-free survival are not fully informative and cannot be assumed as a definitive surrogate for survival, which is the hardest endpoint in therapeutic cancer studies. This difference is because of the varying methods used to evaluate drug activity and tumour evolution, which ultimately dictates patient outcome. This expert opinion exposes the current discrepancies between research trials and clinical practice. Understanding the origin and limitations of such a conundrum should be the first step in refining the criteria that define drug activity, toxicity and treatment failure. Otherwise, evidencebased clinical practice and precision oncology will be an unattainable reality. (c) 2021 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.