Treatment Decision-Making in Metastatic Prostate Cancer: Perceptions of Locus of Control Among Patient, Caregiver, and Physician Triads

Background: Multiple treatments for metastatic prostate cancer have similar efficacy, leaving patients with complicated treatment choices. Shared decision-making can facilitate difficult treatment decisions, but the extent to which this is used for metastatic prostate cancer is unknown. We assessed patient, caregiver, and physician perceptions of decision locus of control (shared decision-making vs physician- or patient-directed decisions) and the degree of agreement between groups. Methods: Triads of patients, caregivers, and physicians completed surveys of decisionmaking practices after a clinic visit in which a decision occurred. To evaluate the degree of agreement for decision locus of control, we used the quadratic-weighted kappa coefficient (Kappa). We used relative frequencies to evaluate which knowledge learned and treatment factors were most strongly endorsed by patients as informing and influencing their treatment decision-making, respectively. Results: Fifty triads participated, with median patient age of 72 years. A majority of patients, caregivers, and physicians reported shared decision-making (66%, 56%, and 52%, respectively). Patients and physicians demonstrated minimal agreement about decision locus of control (44%, Kappa=0.35 [SD = 0.52]), but caregiver reports were not statistically significantly associated with physician and patient reports (38%, Kappa=0.23, [SD = 0.28]), p=0.055; 44%, Kappa=0.34 [SD = 1.98], p=0.14). Treatment efficacy was the most common patientreported factor influencing treatment decisions (44%). Conclusion: This study characterized metastatic prostate cancer patients', caregivers', and physicians' experiences and communication preferences for treatment decision-making. Patients and physicians had greater agreement in decision locus of control compared with caregivers, yet patient-physician agreement was minimal. Metastatic prostate cancer patients report being influenced by information about treatment efficacy and clear next steps, and a desire for patient-friendly language and an invitation to be as involved in decision making at their preferred level. Emphasizing these may increase agreement in decision locus of control between all participants in the decision-making process.