Background: Persons diagnosed with cancer spend a lot of their time in cancer outpatient clinics. It is important that they feel welcomed, safe and secure. There is much known about symptom management and patient reported outcomes related to cancer therapies. But little is known about what matters most to service users when they stay in the cancer outpatient clinic and how they experience their stays. However, this insight would be helpful in promoting person-centred care and offers valuable information to describe the current workplace culture. Aim: This inquiry, which is part of a participatory PhD research about person-centred culture in a Swiss cancer outpatient clinic, aimed to explore these questions using conversational interviews. Methods: Nine service users undergoing cancer treatment participated in the conversational interviews. The interviews were analysed by the lead researcher and the co-researchers (healthcare professionals and service users) enrolled in the PhD research in a participatory way, using a hermeneutic approach and critical dialogues. Findings: There is not “the one thing” that matters most to the service users when they stay in the cancer outpatient clinic. For most of the service users, staying in the cancer outpatient clinic is a good and appreciative experience. Feeling safe and secure, being perceived as person and the healthcare professionals’ competence stands out. However, some of the participants perceived communication and organisational aspects as challenging. The positive experiences were confirmed by the service user co-researchers. Both experience and what matters most might correlate with personal strategies of coping with the illness. Conclusion: Conversational interviews help gaining in-depth insights in how the care is experienced. Adding critical dialogues amongst the co-researchers to the hermeneutic analysis process offers another twist in evaluating the findings and shows which additional factors influence the service users’ experiences in outpatient cancer care.