AbstractExperiences of advanced cancer are assembled and (re)positioned with reference to illness, symptoms and maintaining ‘wellbeing’. Medical cannabis is situated at a borderline in this and the broader social domain: between stigmatised and normalised; recreational and pharmaceutical; between perception, experience, discourse and scientific proof of benefit. Yet, in the hyper‐medicalised context of randomised clinical trials (RCTs), cancer, wellbeing and medical cannabis are narrowly assessed using individualistic numerical scores. This article attends to patients’ perceptions and experiences at this borderline, presenting novel findings from a sociological sub‐study embedded within RCTs focused on the use of medical cannabis for symptom relief in advanced cancer. Through a Deleuzo–Guattarian‐informed framework, we highlight the fragmentation and reassembling of bodies and propose body‐situated experiences of wellbeing in the realm of advanced cancer. Problematising ‘biopsychosocial’ approaches that centre an individualised disconnected patient body in understandings of wellbeing, experiences of cancer and potential treatments, our findings foreground relational affect and embodied experience, and the role of desire in understanding what wellbeing is and can be. This also underpins and enables exploration of the affective reassembling ascribed to medical cannabis, with particular focus on how it is positioned within RCTs.