Abstract
INTRODUCTION: Clinical trials lead the progress in healthcare. To ensure reliable research conclusions, it is essential to enroll diverse patient groups. Identifying and understanding patient-reported barriers to clinical trials may help enhance recruitment among diverse patient groups.The clinical potential of proton therapy (PT) to reduce late effects is being investigated in clinical trials worldwide. Thus, for some patients, PT is only accessible by participating in clinical trials.Individuals with smoking-related head and neck cancer (HNC) are sometimes socioeconomically deprived, leading to barriers to trial participation. This study aims to identify barriers to their participation in a randomised controlled trial (RCT) involving PT. METHOD: Interviews were conducted with 14 HNC patients declining participation in an RCT involving PT. The interviews were transcribed and systematically analysed using an inductive approach identifying categories and themes. RESULTS: The identified barriers to RCT-participation are: (1) existential distress, which influenced participants' mental and cognitive capacities, (2) insufficient RCT-related knowledge arising from information overload during clinical consultations, (3) the wish for safety and familiarity during the treatment trajectory, particularly for participants needing accommodation during radiotherapy, and (4) the motivation for study participation was impacted by uncertainty due to randomisation and clinical equipoise. Existential distress is identified as an overarching theme because it influences and amplifies the other three themes. CONCLUSION: Existential distress is a central theme that influences and amplifies other participation barriers in PT RCTs. It affects participants' comprehension of trial information, their preference for familiar environments, and their motivation to participate in clinical trials.