Background: Multiple treatments exist for mPC, and optimal treatment choice is not defined. Shared decision making (SDM) in which physicians communicate treatment purpose, risks, and benefits, and patients (pts) communicate values/preferences can be used to determine treatment. SDM is associated with superior health outcomes in non-cancer populations, but whether it is used in mPC is unknown. We assessed mPC pt and caregiver perceptions of decision locus of control (DLOC) (SDM vs physician (PD) or pt (PtD) directed decisions), and characteristics associated with DLOC. Methods: Between 12/16 and 11/17, mPC patients and caregivers completed surveys of decision making practices after a clinical encounter in which a decision occurred. To evaluate the relationship between pt perception of DLOC type and categorical variables we used Fisher’s exact test, and Kruskal-Wallis was used to evaluate the relationship between DLOC and age. Results: 50 pt/caregivers participated, with median pt age of 72 yo. Most pts were Caucasian (96%), married (90%), and reported good health or better (18% excellent, 58% good, 24% fair). 66% of pts reported SDM, 10% reported PD only, 12% reported PD considering patient’s preferences, and 12% reported PtD considering physician’s recommendation. Caregivers reported numerically lower rates of SDM (56%), PD only (6%), and PD considering patient’s preferences (8%), but greater PtD considering physician’s recommendation (30%), (p=0.28). Neither reported PtD without considering physician recommendations. There was no association between pt DLCO and age (p=0.70) or clinician type, (p=0.13). All pts reporting PtD considering physician’s recommendation saw medical oncologists rather than urologists. Conclusions: Both pts and caregivers perceived a majority of decisions as SDM, indicating a high level of patient engagement in mPC decision making, and clinician type and patient age were not associated with pt reported DLOC. Pts seen by medical oncology in this cohort reported directing treatment choice when considering physician’s recommendation. Efforts to assess and support decision making in more diverse patient populations and explore the association between SDM, pt satisfaction and quality of life are underway.