Background Despite an increasing emphasis on shared decision-making in healthcare settings, judgements relating to diagnostic testing for cancer remain largely provider-driven. Evidence suggests involving patients in care and treatment decisions improves outcomes, boosts satisfaction and increases knowledge, self-advocacy and adherence. This thesis used ovarian cancer as an exemplar to demonstrate how discrete choice experiments (DCEs) can be used to understand preferences towards cancer testing with the purpose of improving diagnostic outcomes in primary care. Methods The thesis began with a systematic review of existing DCEs in the field of cancer testing. Proceeding chapters described the development and implementation and of a DCE eliciting preferences towards ovarian cancer. Barriers to ovarian cancer diagnosis mean the development of an ovarian cancer screening programme continues to be a priority, despite a lack of efficacy within clinical trials to date. In response, a further DCE investigated preferences towards ovarian cancer screening, specifically focusing on the benefit-harm trade-offs. A final component of this thesis sought to investigate methodological challenges relating to the application of DCEs in the field of cancer testing. Specific investigations included the presence and impact of indifferent preferences and stated attribute non-attendance. Results The systematic review demonstrated the current neglect of preferences in diagnostic settings and highlighted several methodological challenges that may limit the application of discrete choice findings to clinical and policy-related settings. Demand for diagnostic testing was high, even when the risk of cancer was as low as 1%. Preferences appeared to centre around the trade-off between accuracy and timeliness. Although test accuracy was consistently found to be the most important attribute to respondents even where additional waiting times have a substantial impact on survival. Preferences towards ovarian cancer screening were more heterogeneous. Latent class analysis revealed approximately half of respondents strongly prioritised mortality reduction while remaining respondents placed low importance on this aspect of testing and instead largely focused on the high presence of false positive results. Conclusion This thesis demonstrates women’s willingness and ability to engage in diagnostic decision-making. Preference heterogeneity further highlights the importance of an individualised approach to care. Comparisons of preferences in screening and diagnostic settings demonstrate fundamental differences, suggesting the large body of cancer screening DCEs are not automatically transferable to diagnostic settings. A greater understanding of preferences and priorities about testing in symptomatic populations is needed. In response, this thesis provides an insight into some of the challenges when conducting DCEs in this domain and offers suggestions for future researchers.