Through purposive sampling, we plan to conduct interviews with men from two groups: those with high-risk BCR PCa but no ADT+/-ARPI experience, and men with ADT+/-ARPI experience who have experienced breast-related side effects from this treatment. To inform an understanding of how perception of breast-related symptoms might inform treatment preferences, it is important to understand perspectives regarding the hypothetical risk of side-effects as well as those based on actual experience.

this t study will use qualitative methods to explore men's views of gynaecomastia from high-risk BCR PCa treatments (Stage 1) to inform attributes and levels for a later DCE to examine patient treatment preferences (Stage 2).

The outcome will be the set of themes and subthemes identified through qualitative analysis of semi-structured interviews. Interviews will be conducted with three groups: (1) men with high-risk BCR prostate cancer; (2) men with ADT ± ARPI experience; and (3) men who have experienced breast-related side effects from prostate cancer treatment.

The outcome will be a finalised set of attributes and levels for a DCE. Attributes and levels will be generated through semi-structured qualitative interviews with patients, analysed iteratively across participant groups, and refined with input from an advisory panel. A 'generator developed' approach will then be used to design the final set of attributes and levels for inclusion in the DCE.