Endpoints in paediatric oncology

Abstract

The purpose of this review is to address the issue of endpoints in paediatric oncology. Oncologists use this term to refer to an outcome they are trying to measure with a clinical trial, which may become accordingly the object of scientific articles. The outcome measured may concern both efficacy and safety, although from different perspectives. Based on both literature and experience developed in clinical trials, the different types of endpoints have been critically analysed in their power to provide the highest information of therapeutic interest (efficacy and safety) with the least risk and discomfort for the individual. Primary, secondary and surrogate endpoints have been distinguished. The most relevant differences have been discussed in comparison with adult oncology settings of endpoints. The rarity of cancer in childhood and adolescence and the objective difficulty of enrolling statistically conceivable numbers of individuals have determined the utmost positive development of large scale, multinational clinical trials. The most interesting consequence is that the impact of multiplicity interferences, which is usually present in virtually all clinical trials developed for adults with cancer, is not a common event in paediatric oncology. Nevertheless, many of the questions concerning the different impact on outcome and survival of clinical trials developed in adult oncology remain unanswered due to the objective limitations still existing in terms of cure compared with paediatric oncology. The powerful consistency of cure rate, as the most relevant endpoint of clinical trials developed in paediatric oncology, addresses additional considerations to support the relevant differences existing between adult and paediatric oncology: both the development of clinical trials with different aims (confirmatory versus primary response) and the limited impact of multiplicity limitations may determine different implications regarding the meaning of endpoints in paediatric and adult oncology. The aim of cancer treatment is to improve survival (SUR) and quality of life (QoL), but some restraints on the conduct of clinical trials may make these goals unattainable. Clinical trial endpoints represent a measure method aimed to grant answers to questions addressed by the clinical trial itself. The effect of the new regulation is expected to stimulate high-quality research and provide robust information on paediatric drugs to increase the availability of such drugs to children.