Purpose <p>Longitudinal studies are essential for investigating outcome evolution among cancer survivors. However, longitudinal designs pose specific challenges, such as attrition and premature dropout. We aimed to assess experiences and perspectives on participation in longitudinal studies among survivors of early-stage breast cancer, and inform interventions aiming to reduce attrition.</p> Methods <p>Motivation, facilitators, challenges, and perspectives regarding participation in a longitudinal study were qualitatively assessed via interviews and focus groups. A thematic content analysis was performed.</p> Results <p>Between May and August 2023, 30 patients previously enrolled in the longitudinal CANTO cohort study (NCT01993498) were included: 17 participated in individual semi-structured interviews and 13 in two separate focus groups involving distinct participants. We identified four key themes: (1) joining the study as an expression of purpose and personal security, (2) ongoing engagement, as a response to flexible processes, a reassuring study environment, and personal commitment, (3) ongoing engagement, challenged by accumulating (practical and emotional) burdens and a reduced sense of connection to the study, and (4) participant-identified needs for a more supportive study experience. Findings emphasized the importance of enhancing communication with study participants, flexibility enabling decentralized participation, reducing burden of patient-generated data via repetitive questionnaires, supporting navigation of study procedures and minimizing the risk of a digital divide, and routinely disseminating study findings.</p> Conclusion <p>These findings will inform strategies to reduce attrition and enhance the overall participant experience in longitudinal studies.</p>