Introduction: Malignant pleural mesothelioma is a rare, incurable cancer arising from previous asbestos exposure; patients have a poor prognosis, with a median survival rate of 8-14 months. Variation in mesothelioma clinical decision-making remains common with a lack of multidisciplinary knowledge sharing, leading to inconsistencies in treatment decisions. The study aimed to explore which factors impacted on clinicians' decision-making in mesothelioma care, with a view to optimising the mesothelioma care pathway.

Methods: This mixed methods study consisted of documentary analysis of local and national guidelines, policies or documents pertaining to mesothelioma care pathways, secondary analysis of mesothelioma patient data, and interviews with clinicians attending lung cancer and/or mesothelioma-specific multidisciplinary team meetings. The study took place at three National Health Service trusts in England. Documentations relating to patients' treatment pathways were collated and reviewed qualitatively. Records of patients with mesothelioma were extracted from hospital patient records and data collected on diagnosis date, treatment, mortality rates, survival postdiagnosis, age and clinical care team. Data were statistically analysed. Interviews with clinicians explored influences on clinical decision-making, including challenges or barriers involved. Data were thematically analysed. The Strengthening the Reporting of Observational Studies in Epidemiology reporting checklist was used.

Results: There were differences in the structure and delivery of mesothelioma treatment and care between trusts. Four main themes were identified: 'collaboration and communication', 'evidence base and knowledge', 'role of the clinician' and 'role of the patient'. Two cross-cutting themes relating to the role of the mesothelioma nurse specialist and the impact of COVID-19 were identified.

Discussion: There is a need to review the structure of mesothelioma multidisciplinary team meetings to ensure patients are reviewed by clinicians with appropriate knowledge, expertise and understanding of how, why and when decisions should be made. There is a need for expert clinicians in mesothelioma care to promote an up-to-date evidence and knowledge base within the wider multidisciplinary team.